CA1333756C - Process for the production of a telecentric light beam, device for carrying out this process and process for the production of an hoe - Google Patents
Process for the production of a telecentric light beam, device for carrying out this process and process for the production of an hoeInfo
- Publication number
- CA1333756C CA1333756C CA000533580A CA533580A CA1333756C CA 1333756 C CA1333756 C CA 1333756C CA 000533580 A CA000533580 A CA 000533580A CA 533580 A CA533580 A CA 533580A CA 1333756 C CA1333756 C CA 1333756C
- Authority
- CA
- Canada
- Prior art keywords
- optical element
- holographic optical
- telecentric
- light
- light beam
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
- G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
- G02B26/10—Scanning systems
- G02B26/12—Scanning systems using multifaceted mirrors
- G02B26/125—Details of the optical system between the polygonal mirror and the image plane
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/08—Measuring arrangements characterised by the use of optical techniques for measuring diameters
- G01B11/10—Measuring arrangements characterised by the use of optical techniques for measuring diameters of objects while moving
- G01B11/105—Measuring arrangements characterised by the use of optical techniques for measuring diameters of objects while moving using photoelectric detection means
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/32—Holograms used as optical elements
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S359/00—Optical: systems and elements
- Y10S359/90—Methods
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Holo Graphy (AREA)
- Diffracting Gratings Or Hologram Optical Elements (AREA)
- Adornments (AREA)
- Length Measuring Devices By Optical Means (AREA)
- Mechanical Optical Scanning Systems (AREA)
Abstract
A light beam is repeatedly deflected in the longitudinal direction through a holographic element HOE by means of a rotating multi-faceted mirror. This HOE is so formed that the beam entering at different angles leaves the HOE
as a telecentric beam. Through a further HOE the telecentric beam is diffracted onto a opto-electric transducer. In the region of the telecentric beam is located an object to be measured, and the time of the interruption of the telecentric beam by means of this object enables the dimension of the latter to be determined.
The production of the telecentric beam and the deflection of the latter onto the transducer by means of the HOE
allows a simple cost-effect manufacture as well as a simple evaluation of the measurements with increased precision.
The manufacture of the HOE is likewise simple.
as a telecentric beam. Through a further HOE the telecentric beam is diffracted onto a opto-electric transducer. In the region of the telecentric beam is located an object to be measured, and the time of the interruption of the telecentric beam by means of this object enables the dimension of the latter to be determined.
The production of the telecentric beam and the deflection of the latter onto the transducer by means of the HOE
allows a simple cost-effect manufacture as well as a simple evaluation of the measurements with increased precision.
The manufacture of the HOE is likewise simple.
Description
~ 1~33756 Process for the production of a telecentric light beam, device for carrying out this process - and process for the production of an HOE
BACKGROUND OF THE INVENTION
The present invention concerns a process for the production of a telecentric light beam, especially for the measurement of the dimension and/or the position of an object in the region of the deflection stroke of the light beam, wherein the light beam is deflected through an angular range at the focal point of an optical element and is turned by means of the optical element into the telecentric direction.
Such processes are known, wherein the periodic deflection of the light beam through a defined angle is effected by means of a multi-faceted rotating mirror. The optical element for turning the light beam into the telecentric direction, as well as a further optical element for turning the telecentric light beam on to an opto-electric transducer, are formed as relatively expensive lens systems. In spite of the high cost for these lens systems it is hardly possible to achieve the shifting of the telecentric light beam linearly or exactly according to a defined function, more especially an angular function. The cost of the lens systems is especially high when a larger deflection stroke of the telecentric light beam is necessary for the measurement of larger objects.
A further disadvantage of the known process for the production of telecentric light beams lies in the fact that apart from the telecentric light beam serving for the exemplified dimensional measurement no portion of the beam is available that could be used for auxiliary purposesO
The extraction of such a partial beam would be complicated and expensive.
BACKGROUND OF THE INVENTION
The present invention concerns a process for the production of a telecentric light beam, especially for the measurement of the dimension and/or the position of an object in the region of the deflection stroke of the light beam, wherein the light beam is deflected through an angular range at the focal point of an optical element and is turned by means of the optical element into the telecentric direction.
Such processes are known, wherein the periodic deflection of the light beam through a defined angle is effected by means of a multi-faceted rotating mirror. The optical element for turning the light beam into the telecentric direction, as well as a further optical element for turning the telecentric light beam on to an opto-electric transducer, are formed as relatively expensive lens systems. In spite of the high cost for these lens systems it is hardly possible to achieve the shifting of the telecentric light beam linearly or exactly according to a defined function, more especially an angular function. The cost of the lens systems is especially high when a larger deflection stroke of the telecentric light beam is necessary for the measurement of larger objects.
A further disadvantage of the known process for the production of telecentric light beams lies in the fact that apart from the telecentric light beam serving for the exemplified dimensional measurement no portion of the beam is available that could be used for auxiliary purposesO
The extraction of such a partial beam would be complicated and expensive.
-- SUMMARY OF THE INVENTION
It is the object of the present invention to achieve bo~h a simplification and reduction in the cost of the known process and a qualitative improvement therein.
The invention accordingly provides a process for the production of a telecentric light beam, wherein a light beam is deflected through an angular range at the focal point of an optical element, and is turned by means of the optical element into the telecentric direction wherein the optical element comprises at least one holographic optical element which is arranged to turn said light beam by diffraction.
The use of a holographic optical element instead o~
conventional optical elements has the following advantages:
reduced weight; simple geometry; lower cost; larger aperture relatively to shorter focal length; and minimal lens errors with optimum reconstruction geometry and clear mathematical function between the entry angle of the light beam and its distance from a reference axis. Further advantages will be apparent from the following description.
The invention concerns also a device for carrying out the above related process including means for the deflecti~ of the light beam at least approximately at the focal point of a system including at least one holographic optical element which is arranged to alter the geometry of the beam and/or to turn the light beam into the telecentric direction.
The invention further provides a process for the production of a holographic optical element for use in the production of a telecentric beam.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 shows a front view of a device for the determination of the dimension and position of an object, 1~33756 Fig. 2 shows a plan view of this device, Figs. 3 to 5 show modified embodiments of the device according to Fig. 1, Figs. 6 and 7 serve for the explanation of the production of a holographic optical element and its operation in the production of a telecentric beam, Fig. 8 shows diagrammatically a further embodiment of a measuring device, Figs. 9 and 10 show the use of two co-operating HOE for the linearisation of the deflection of the beam~
Fig. 11 shows a further embodiment with linear deflection of the telecentric beam.
DESCRIPTION OF PREFERRED EMBODIMENTS
Figs. 1 and 2 show a device for the determination of a dimension or the position of an object 1 indicated in these figures in dot and dashed lines, for example a cable or pipe issuing from an extruder. The determination of at least one dimension of such a product is of especial importance in order continuously to ascertain and to correct production errors. The measuring device comprises a transmitter part 2 which serves for the production of a telecentric light beam in the region of measurementO
It is provided with a laser light source 3, which conducts a continually monochromatic light beam via a mirror 4 to a spherical expanding lens 5 from which the expanded beam enters a cylindrical expanding lens 6. By this means a flat light beam is produced, of which the plane lies parallel to the longitudinal axis of the object to be measured. This is indicated in Figs. 1 and 2, in that the light beam 7 comprises a relatively small thickness in the region of the object in the projection according to Fig. 1, but in the projection according to Fig. 2 has a certain width~
This light beam 7 is projected via further deflecting mirrors 8 and 9 on to an eight sided rotatable mirror 10. During .he rotation of this mirror in the clock-wise direction the light beam 7 impinging thereon is deflected periodically through an angular range indicated in Fig. 1 by broken lines, from above to below. It then impinges on to a holographic optical element 11, referred to below as HOE for short. This HOE, of which the optically effective layer is very thin and is located on a thin optically transparent carrier, is coupled with a prism body 12 and thus mechanically stabilised. A certain portion of the light beam of 0-order 70 passes through the HOE 11 undefracted and impinges from within on to the front wall 13 of the housing of the transmitter 2. The main part of the impinging beam 7 is diffracted however and passes from the HOE as a first order beam 71 at a defined angle. It is reflected at a totally reflecting or mirrored surface 14 of the prism body 12 and projected through a window 15 into the measure-ment region. At the position of impingement of the exiting beam of 0-order 7O one or more opto-electric transducers 16 may be arranged. The beam 71 at the opposite side of the measurement region enters through a window 15 in the housing of a receiver 17, in which is located a prism body 18 formed in a manner corres-ponding with that of the prism body 12 with an HOE19 corresponding with the HOE 11. The entering light beam is, by way of the reflecting surface 20 of the prism body 18, projected on to the HOE 19 which directs the beam constantly on to an opto-electric transducer 21, for example a photocell.
During the periodic deflection of the telecentric beam about the deflection stroke bounded by the broken lines in Fig. 1, the beam reaches the transducer 21, as long as it is not masked by the object 1. From the duration of the masking and from the points in `- 1333756 time at which the masking begins and ends, both the dimension and the position of the object 1 can be ascertained. For a deflection angle ~ of the beam 7 reflected relatively to the longitudinal symmetrical axis A of the device, the distance H of the telecentric beam from this longitudinal symmetrical axis is given by H = a x tan ~, wherein a is the distance between the position of reflection at the mirror 10 and the HOE 11. Provided that the HOE has a negligibly small thickness, is flat and at right angles to the longi-tudinal symmetrical axis A of the device, and providedthat the angular velocity of the beam 7 reflected at the mirror 10 is constant, the deflection of the tele~entric beam 71 is effected exactly according to a tangent function. During the evaluation of the measurement signals issuing from the transducer 21, this tangent function can thus be taken into consider-ation so that an exact determination of the dimension and position of the object 1 can be achieved without especial calibration of the device. If, in addition, the exact point in time of the transition of the tele-centric beam through the longitudinal symmetrical axis of the device is determined by means of the opto-electric transducer 16, all measurement values can be referenced to this 0-transition, at which tan = 0. It is thus demonstrated that the turning of the light beam through an HOE not only achieves an especial simplicity of the optical element but also, additionally, a simplicity and exactitude of the measurement.
Figs. 3 to 5 show several variations of the optical system of the transmitter 2 and the receiver 17, wherein corresponding parts are indicated with the same reference numerals as in Figs. 1 and 2. According to Fig. 3 the HOE 11 is arranged on a flat transparent -- 6 - 13~3756 carrier 22. The diffracted beam 71 is in this case turned on to a reflector 23. A reflector 24 is corres-pondingly arranged in the receiver 17 and the HOE 19 of the receiver 17 is arranged on a flat carrier 250 According to Fig. 4 the HOE 11 and 19 are correspond-ingly arranged on flat carriers 22 and 25, and the turning of the beam is effected via refracting prisms 26 and 27.
According to Fig. 5 the HOE 11 and 19 are arranged on prism bodies 28 and 29, and the telecentric beam 71 is turned through refraction at the prism surfaces 30 and 31.
Fig. 6 shows one possible way of producing an HOE 11 or 19. A flat plane strip with a light-sensitive layer is illuminat,ed with coherent light from an He-Ne-Gaslaser, from a point source of light produced by means of a space filter 32, and simultaneously with a collimated beam or a plane wave front 33 of the same laser. This illumination simultaneously with the 2G spherical wave from the point light source and the space filter 32 and with the plane wave front 33 produces, after corresponding development of the light sensitive material, an HOE, which produces a turning - of a light beam of corresponding light, as described with reference to Figs. 1 and 2. This presupposes that the point light source 32 is located with respect to the light sensitive material in a corresponding location at the place or above the place of the subse-quent deflection point on the rotating mirror 10.
The distance a according to Fig. 6 should also correspond with the distance a of Fig. 1. An HOE
produced in this manner has the described effect in a similar manner, to turn telecentrically the beam 7 deflected through the ansle ~ , and alsc to turn this telecentric beam on to the transducer 21. It is thus to be assumed that in Fig. 1 similar HOE 11 and 19 are used, i.e. that the distance or focal length a will be the same in both casesO
Naturally, differently dimensioned HOE can also be-used. It is especially possible to utilise in the receiver an HOE 19 of somewhat lesser quality or with lesser focal length a since there the only requirement is that a considerable part of the light of the beam 71 should be projected on to the transducer 21. HOE
manufactured for fixed measurements can subsequently be manufactured cheaply and simply in desired numbers through simple optical copying processes, more especially as holographic contact copies. Thus the costs in relation to conventional optical systems can be decisively lowered.
Fig. 7 shows the installation of the HOE manufactured according to Fig. 6 in a diagrammatically illustrated arrangement according to Fig. 1. Corresponding parts and dimensions are indicated with the same reference numerals as in Fig. 1. In contrast to Fig. 1, it is the case here that the beam 7 deflected by means of the rotating mirror 10 moves in a plane that lies oblique to the plane of the HOE 11, whereas the exiting telecentric 1. order beam 71 issues at right angles to the plane of the HOE. Such an arrangement is self-evidently also possible.
Fig. 8 shows diagrammatically an especially favourable construction of a measuring device taking advantage of the characteristics of the HOE. Corresponding parts are indicated with the same reference numerals as in Figs. 1 and 2. The transmitter 2 and the receiver 17 are in this case arranged as flat housings on both sides of the measuring region and parallel to the direction of the path of the object 1 to be measured. The path of the beam between the laser 3, the elements 5 and 6 not illustrated, the rotating mirror 10 and the HnE, in this case lies in a plane w~hich is parallel to the direction of the path of the object 1. The HOE 11 is arranged on a transparent carrier 34. The diffracted beam 71 issues from the HOE 11, inclined for example at 45 , at right angles to the direction of the path of the object 1 and to the plane of the path of the beam 7 in the transmitter 2. The HOE 19 in the receiver 17 is correspondingly arranged and located on a carrier 35. It diffracts the beam on to the transducer 21, whereby the plane of this beam again lies parallel to the direction of the path of the object 1. In this manner an especially favourable space saving arrangement of flat housing parts on both sides of the measurement region is possible. As likewise shown in Fig. 8, the exit and entry openings 15 for the telecentric beam are closed hy means of windows 36.
Figs. 9 and 10 show diagrammatically an arrangement for the linearisation of the relationship between the deflection angle ~ of the light beam 7 and the distance H of the telecentric beam 7 from the longit-udinal symmetrical axis A of the device. Fig. 10involves a certain unwinding of the arrangement of Fig. 9 and shows only one half of the region. The light beam deflected by means of the rotating mirror impinges on a first HOE 37 which is so arranged that the di~racted beam 7' upon impingement upon a second HOE 38 is displaced from the axis of symmetry A by a distance H proportional to the angle ~. This second HOr 38 is, for its part, so arranged that the impinging beam 7' is constantly dif~racted in the telecentric direction parallel to ~ the symmetrical 9- 133375~
axis A, and thus issues as the telecentric beam 7''0 There thus exists the relationship H = K x ~, wherein K is a constant. In Fig. 10 it is thereby indicated that the telecentric beam 7'' has, at an angle of ~ - a distance H from the symmetrical axis A, whi~lel for an angle 2 ~ it has a distance of 2H. This solution provides a further simplification of the evaluation of the products of measurement, in thatl assuming a constant angular velocity of the beam 7 deflected by the rotating mirror 10, the telecentric beam 7'' is shifted over the measurement region at a constant speed.
For the production of the two HOE 37 and 38 the following procedure can be adopted: the HOE 37 is produced with the aid of a computer-calculation.
This is thus a question of a so-called computer-generated hologram or CGH. The correspondingly produced CGH 37 is now arranged in the position indicated in Fig. 9, with reference to a point light source at the place of origin of the beam 7. At the position of the HOE 38 in Fig. 9 there is arranged a light-sensitive material which is now illuminated collectively from the point light source via the CGH
and by means of a collimated beam or plane wave front in the telecentric direction. This produces an HOE
which effects the prescribed refraction of the beam 7' into the desired direction of the beam 7'' as described with reference to Figs. 9 and 10.
The process can also be reversed, in that first the HOE 38 is produced on the basis of computer-calculation, whereupon, via this HOE, a plane wave front is projected on to light-sensitive material at the position of the HOE 37, from the telecentric direction, the light-sensitive material also being illuminated with a converging spherical wave from the location of the origin of the deflected beam 7. It would then eventually be possible to use again one of the HOE
in order to produce the other HOE by holographic means, whereby an improvement of such an HOE would -5 be possible. -Such a procedure could above all be of interest since the production of a CGH of larger dimensions in sufficient sharpness or with sufficient resolving power could cause difficulties. The desc-ribed improvement can be expected, since in the case of a CGH of limited resolution several undesired higher orders occur relatively strongly, which are not usable and also cannot be suppressed. The efficiency of diffraction for the 1. order correspondingly becomes worse. With the holographic reproduction of an HOE
by means of the CGH the 1. order wave can be made effective almost exclusively, which leads to an HOE
that for its part has essentially improved character-istics for the 1. order diffraction.
Fig. 11 shows a further possibility of the lineari-sation of the telecentric beam, i.e. the production of a linear relationship between the deflection angle of the beam 7 and the displacement H of the telecentric beam 71 . According to Fig. 11 there is provided an HOE 39 curved according to a predetermined calculated curve. The curvature is so selected that for each desired deflection angle ~ of the beam 7 reflected at the rotating mirror 10 the point of impingement of this beam on the optically effective layer of the HOE 39 lies at a distance H from the longitudinal symmetrical axis A which is proportional to the angle.
The HOE is so constituted that the diffracted beam 71 issues constantly in a parallel telecentric direction, as shown in Fig. 11.
The manufacture of the HOE 39 can be effected by means -of a process wherein light sensitive material curved in the manner determined by calculation is located at the position of the HOE 39 and illuminated simult-aneously by means of a point light source at the position of reflection of the beam 7 and by means of a plane wave front from the telecentric direction.
Thus the desired HOE is generated.
In order to achieve optimum characteristics, certain conditions must be maintained. Apart from the fact that the geometry of the system must be maintained very exactly, it is also necessary to take care that this geometry is not altered during the process, and especially that no dimensional alteration of the HOE
or CGH occurs. The latter can be achieved through air-tight sealing for the prevention of the absorption of humidity by the photographic layer. For example, a sandwich construction can be used incorporating covering glass and contact cement for matching of the refractive index between the cover glass and the photographic material. Furthermore a covering lacquer could be applied, or a direct vapour deposition with SiO or the like could be effected. In the embodiments according to Figs. 2 and 5 a direct adhesion or sealing of the photographic carrier on to the deflection prism could be effected by means of optical cement. Care must further be taken that the conditions of polaris-ation are maintained in the whole system. Also, a direct application of the photographic layer on to the deflection prism could be effected.
When all these conditions are maintained a higher efficiency, that is to say a good light-gain can be obtained, and with optimal geometry minimum lens abberations can be expected. Thus it is possible to achieve a relatively large aperture and short focal length.
- 12 ~ 1 3337 56 In many cases an ideal integration of the system is for example possible, in the sense that an HOE
with its carrier can be used directly as a window.
That would be possible for example in the embodiments according to Figs. 1 and 2, where the prisms 12 and 18 could serve directly as windows at the openings 15.
As already described above; light of the same wave-length should preferably be used for the production of the HO~ and in the later utilisation of the manufactures grating for the production of the telecentric beam. Correspondingly, it is naturally also possible to use the same light source for both operations, for example a Helium-Neon-Laser.
In the exemplified embodiments transmission holograms are concerned, with the exception of the reflection hologram according to Fig. 11. Any preferred hologram can be used, however, in accordance with the situation. Thus the HOE according to Fig. 11 could also be realised as a transmission hologram. In the case of the arrangement according to Figs. 9 and 10 the two HOE could, as necessary, be realised advantageously as reflection holograms, whereby a favourable space saving transmission of the beam is possible.
It is the object of the present invention to achieve bo~h a simplification and reduction in the cost of the known process and a qualitative improvement therein.
The invention accordingly provides a process for the production of a telecentric light beam, wherein a light beam is deflected through an angular range at the focal point of an optical element, and is turned by means of the optical element into the telecentric direction wherein the optical element comprises at least one holographic optical element which is arranged to turn said light beam by diffraction.
The use of a holographic optical element instead o~
conventional optical elements has the following advantages:
reduced weight; simple geometry; lower cost; larger aperture relatively to shorter focal length; and minimal lens errors with optimum reconstruction geometry and clear mathematical function between the entry angle of the light beam and its distance from a reference axis. Further advantages will be apparent from the following description.
The invention concerns also a device for carrying out the above related process including means for the deflecti~ of the light beam at least approximately at the focal point of a system including at least one holographic optical element which is arranged to alter the geometry of the beam and/or to turn the light beam into the telecentric direction.
The invention further provides a process for the production of a holographic optical element for use in the production of a telecentric beam.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 shows a front view of a device for the determination of the dimension and position of an object, 1~33756 Fig. 2 shows a plan view of this device, Figs. 3 to 5 show modified embodiments of the device according to Fig. 1, Figs. 6 and 7 serve for the explanation of the production of a holographic optical element and its operation in the production of a telecentric beam, Fig. 8 shows diagrammatically a further embodiment of a measuring device, Figs. 9 and 10 show the use of two co-operating HOE for the linearisation of the deflection of the beam~
Fig. 11 shows a further embodiment with linear deflection of the telecentric beam.
DESCRIPTION OF PREFERRED EMBODIMENTS
Figs. 1 and 2 show a device for the determination of a dimension or the position of an object 1 indicated in these figures in dot and dashed lines, for example a cable or pipe issuing from an extruder. The determination of at least one dimension of such a product is of especial importance in order continuously to ascertain and to correct production errors. The measuring device comprises a transmitter part 2 which serves for the production of a telecentric light beam in the region of measurementO
It is provided with a laser light source 3, which conducts a continually monochromatic light beam via a mirror 4 to a spherical expanding lens 5 from which the expanded beam enters a cylindrical expanding lens 6. By this means a flat light beam is produced, of which the plane lies parallel to the longitudinal axis of the object to be measured. This is indicated in Figs. 1 and 2, in that the light beam 7 comprises a relatively small thickness in the region of the object in the projection according to Fig. 1, but in the projection according to Fig. 2 has a certain width~
This light beam 7 is projected via further deflecting mirrors 8 and 9 on to an eight sided rotatable mirror 10. During .he rotation of this mirror in the clock-wise direction the light beam 7 impinging thereon is deflected periodically through an angular range indicated in Fig. 1 by broken lines, from above to below. It then impinges on to a holographic optical element 11, referred to below as HOE for short. This HOE, of which the optically effective layer is very thin and is located on a thin optically transparent carrier, is coupled with a prism body 12 and thus mechanically stabilised. A certain portion of the light beam of 0-order 70 passes through the HOE 11 undefracted and impinges from within on to the front wall 13 of the housing of the transmitter 2. The main part of the impinging beam 7 is diffracted however and passes from the HOE as a first order beam 71 at a defined angle. It is reflected at a totally reflecting or mirrored surface 14 of the prism body 12 and projected through a window 15 into the measure-ment region. At the position of impingement of the exiting beam of 0-order 7O one or more opto-electric transducers 16 may be arranged. The beam 71 at the opposite side of the measurement region enters through a window 15 in the housing of a receiver 17, in which is located a prism body 18 formed in a manner corres-ponding with that of the prism body 12 with an HOE19 corresponding with the HOE 11. The entering light beam is, by way of the reflecting surface 20 of the prism body 18, projected on to the HOE 19 which directs the beam constantly on to an opto-electric transducer 21, for example a photocell.
During the periodic deflection of the telecentric beam about the deflection stroke bounded by the broken lines in Fig. 1, the beam reaches the transducer 21, as long as it is not masked by the object 1. From the duration of the masking and from the points in `- 1333756 time at which the masking begins and ends, both the dimension and the position of the object 1 can be ascertained. For a deflection angle ~ of the beam 7 reflected relatively to the longitudinal symmetrical axis A of the device, the distance H of the telecentric beam from this longitudinal symmetrical axis is given by H = a x tan ~, wherein a is the distance between the position of reflection at the mirror 10 and the HOE 11. Provided that the HOE has a negligibly small thickness, is flat and at right angles to the longi-tudinal symmetrical axis A of the device, and providedthat the angular velocity of the beam 7 reflected at the mirror 10 is constant, the deflection of the tele~entric beam 71 is effected exactly according to a tangent function. During the evaluation of the measurement signals issuing from the transducer 21, this tangent function can thus be taken into consider-ation so that an exact determination of the dimension and position of the object 1 can be achieved without especial calibration of the device. If, in addition, the exact point in time of the transition of the tele-centric beam through the longitudinal symmetrical axis of the device is determined by means of the opto-electric transducer 16, all measurement values can be referenced to this 0-transition, at which tan = 0. It is thus demonstrated that the turning of the light beam through an HOE not only achieves an especial simplicity of the optical element but also, additionally, a simplicity and exactitude of the measurement.
Figs. 3 to 5 show several variations of the optical system of the transmitter 2 and the receiver 17, wherein corresponding parts are indicated with the same reference numerals as in Figs. 1 and 2. According to Fig. 3 the HOE 11 is arranged on a flat transparent -- 6 - 13~3756 carrier 22. The diffracted beam 71 is in this case turned on to a reflector 23. A reflector 24 is corres-pondingly arranged in the receiver 17 and the HOE 19 of the receiver 17 is arranged on a flat carrier 250 According to Fig. 4 the HOE 11 and 19 are correspond-ingly arranged on flat carriers 22 and 25, and the turning of the beam is effected via refracting prisms 26 and 27.
According to Fig. 5 the HOE 11 and 19 are arranged on prism bodies 28 and 29, and the telecentric beam 71 is turned through refraction at the prism surfaces 30 and 31.
Fig. 6 shows one possible way of producing an HOE 11 or 19. A flat plane strip with a light-sensitive layer is illuminat,ed with coherent light from an He-Ne-Gaslaser, from a point source of light produced by means of a space filter 32, and simultaneously with a collimated beam or a plane wave front 33 of the same laser. This illumination simultaneously with the 2G spherical wave from the point light source and the space filter 32 and with the plane wave front 33 produces, after corresponding development of the light sensitive material, an HOE, which produces a turning - of a light beam of corresponding light, as described with reference to Figs. 1 and 2. This presupposes that the point light source 32 is located with respect to the light sensitive material in a corresponding location at the place or above the place of the subse-quent deflection point on the rotating mirror 10.
The distance a according to Fig. 6 should also correspond with the distance a of Fig. 1. An HOE
produced in this manner has the described effect in a similar manner, to turn telecentrically the beam 7 deflected through the ansle ~ , and alsc to turn this telecentric beam on to the transducer 21. It is thus to be assumed that in Fig. 1 similar HOE 11 and 19 are used, i.e. that the distance or focal length a will be the same in both casesO
Naturally, differently dimensioned HOE can also be-used. It is especially possible to utilise in the receiver an HOE 19 of somewhat lesser quality or with lesser focal length a since there the only requirement is that a considerable part of the light of the beam 71 should be projected on to the transducer 21. HOE
manufactured for fixed measurements can subsequently be manufactured cheaply and simply in desired numbers through simple optical copying processes, more especially as holographic contact copies. Thus the costs in relation to conventional optical systems can be decisively lowered.
Fig. 7 shows the installation of the HOE manufactured according to Fig. 6 in a diagrammatically illustrated arrangement according to Fig. 1. Corresponding parts and dimensions are indicated with the same reference numerals as in Fig. 1. In contrast to Fig. 1, it is the case here that the beam 7 deflected by means of the rotating mirror 10 moves in a plane that lies oblique to the plane of the HOE 11, whereas the exiting telecentric 1. order beam 71 issues at right angles to the plane of the HOE. Such an arrangement is self-evidently also possible.
Fig. 8 shows diagrammatically an especially favourable construction of a measuring device taking advantage of the characteristics of the HOE. Corresponding parts are indicated with the same reference numerals as in Figs. 1 and 2. The transmitter 2 and the receiver 17 are in this case arranged as flat housings on both sides of the measuring region and parallel to the direction of the path of the object 1 to be measured. The path of the beam between the laser 3, the elements 5 and 6 not illustrated, the rotating mirror 10 and the HnE, in this case lies in a plane w~hich is parallel to the direction of the path of the object 1. The HOE 11 is arranged on a transparent carrier 34. The diffracted beam 71 issues from the HOE 11, inclined for example at 45 , at right angles to the direction of the path of the object 1 and to the plane of the path of the beam 7 in the transmitter 2. The HOE 19 in the receiver 17 is correspondingly arranged and located on a carrier 35. It diffracts the beam on to the transducer 21, whereby the plane of this beam again lies parallel to the direction of the path of the object 1. In this manner an especially favourable space saving arrangement of flat housing parts on both sides of the measurement region is possible. As likewise shown in Fig. 8, the exit and entry openings 15 for the telecentric beam are closed hy means of windows 36.
Figs. 9 and 10 show diagrammatically an arrangement for the linearisation of the relationship between the deflection angle ~ of the light beam 7 and the distance H of the telecentric beam 7 from the longit-udinal symmetrical axis A of the device. Fig. 10involves a certain unwinding of the arrangement of Fig. 9 and shows only one half of the region. The light beam deflected by means of the rotating mirror impinges on a first HOE 37 which is so arranged that the di~racted beam 7' upon impingement upon a second HOE 38 is displaced from the axis of symmetry A by a distance H proportional to the angle ~. This second HOr 38 is, for its part, so arranged that the impinging beam 7' is constantly dif~racted in the telecentric direction parallel to ~ the symmetrical 9- 133375~
axis A, and thus issues as the telecentric beam 7''0 There thus exists the relationship H = K x ~, wherein K is a constant. In Fig. 10 it is thereby indicated that the telecentric beam 7'' has, at an angle of ~ - a distance H from the symmetrical axis A, whi~lel for an angle 2 ~ it has a distance of 2H. This solution provides a further simplification of the evaluation of the products of measurement, in thatl assuming a constant angular velocity of the beam 7 deflected by the rotating mirror 10, the telecentric beam 7'' is shifted over the measurement region at a constant speed.
For the production of the two HOE 37 and 38 the following procedure can be adopted: the HOE 37 is produced with the aid of a computer-calculation.
This is thus a question of a so-called computer-generated hologram or CGH. The correspondingly produced CGH 37 is now arranged in the position indicated in Fig. 9, with reference to a point light source at the place of origin of the beam 7. At the position of the HOE 38 in Fig. 9 there is arranged a light-sensitive material which is now illuminated collectively from the point light source via the CGH
and by means of a collimated beam or plane wave front in the telecentric direction. This produces an HOE
which effects the prescribed refraction of the beam 7' into the desired direction of the beam 7'' as described with reference to Figs. 9 and 10.
The process can also be reversed, in that first the HOE 38 is produced on the basis of computer-calculation, whereupon, via this HOE, a plane wave front is projected on to light-sensitive material at the position of the HOE 37, from the telecentric direction, the light-sensitive material also being illuminated with a converging spherical wave from the location of the origin of the deflected beam 7. It would then eventually be possible to use again one of the HOE
in order to produce the other HOE by holographic means, whereby an improvement of such an HOE would -5 be possible. -Such a procedure could above all be of interest since the production of a CGH of larger dimensions in sufficient sharpness or with sufficient resolving power could cause difficulties. The desc-ribed improvement can be expected, since in the case of a CGH of limited resolution several undesired higher orders occur relatively strongly, which are not usable and also cannot be suppressed. The efficiency of diffraction for the 1. order correspondingly becomes worse. With the holographic reproduction of an HOE
by means of the CGH the 1. order wave can be made effective almost exclusively, which leads to an HOE
that for its part has essentially improved character-istics for the 1. order diffraction.
Fig. 11 shows a further possibility of the lineari-sation of the telecentric beam, i.e. the production of a linear relationship between the deflection angle of the beam 7 and the displacement H of the telecentric beam 71 . According to Fig. 11 there is provided an HOE 39 curved according to a predetermined calculated curve. The curvature is so selected that for each desired deflection angle ~ of the beam 7 reflected at the rotating mirror 10 the point of impingement of this beam on the optically effective layer of the HOE 39 lies at a distance H from the longitudinal symmetrical axis A which is proportional to the angle.
The HOE is so constituted that the diffracted beam 71 issues constantly in a parallel telecentric direction, as shown in Fig. 11.
The manufacture of the HOE 39 can be effected by means -of a process wherein light sensitive material curved in the manner determined by calculation is located at the position of the HOE 39 and illuminated simult-aneously by means of a point light source at the position of reflection of the beam 7 and by means of a plane wave front from the telecentric direction.
Thus the desired HOE is generated.
In order to achieve optimum characteristics, certain conditions must be maintained. Apart from the fact that the geometry of the system must be maintained very exactly, it is also necessary to take care that this geometry is not altered during the process, and especially that no dimensional alteration of the HOE
or CGH occurs. The latter can be achieved through air-tight sealing for the prevention of the absorption of humidity by the photographic layer. For example, a sandwich construction can be used incorporating covering glass and contact cement for matching of the refractive index between the cover glass and the photographic material. Furthermore a covering lacquer could be applied, or a direct vapour deposition with SiO or the like could be effected. In the embodiments according to Figs. 2 and 5 a direct adhesion or sealing of the photographic carrier on to the deflection prism could be effected by means of optical cement. Care must further be taken that the conditions of polaris-ation are maintained in the whole system. Also, a direct application of the photographic layer on to the deflection prism could be effected.
When all these conditions are maintained a higher efficiency, that is to say a good light-gain can be obtained, and with optimal geometry minimum lens abberations can be expected. Thus it is possible to achieve a relatively large aperture and short focal length.
- 12 ~ 1 3337 56 In many cases an ideal integration of the system is for example possible, in the sense that an HOE
with its carrier can be used directly as a window.
That would be possible for example in the embodiments according to Figs. 1 and 2, where the prisms 12 and 18 could serve directly as windows at the openings 15.
As already described above; light of the same wave-length should preferably be used for the production of the HO~ and in the later utilisation of the manufactures grating for the production of the telecentric beam. Correspondingly, it is naturally also possible to use the same light source for both operations, for example a Helium-Neon-Laser.
In the exemplified embodiments transmission holograms are concerned, with the exception of the reflection hologram according to Fig. 11. Any preferred hologram can be used, however, in accordance with the situation. Thus the HOE according to Fig. 11 could also be realised as a transmission hologram. In the case of the arrangement according to Figs. 9 and 10 the two HOE could, as necessary, be realised advantageously as reflection holograms, whereby a favourable space saving transmission of the beam is possible.
Claims (13)
1. A device for the production of a telecentric light beam, comprising:
at least one holographic optical element, having a focal point; and means located at least approximately at the focal point of said at least one holographic optical element for deflecting a beam of light through an angular range to produce a continuum of beams diverging toward the at least one holographic optical element so that the diverging beams are received thereby in the angular range; and said at least one holographic optical element comprising means for deflecting the diverging beams at all angles in the angular range, such that the diverging beams are deflected by diffraction in one direction, thereby to obtain a telecentric light beam, wherein the at least one holographic optical element includes a flat holographic element formed on a prism as a carrier, whereby the prism is adapted for deflecting the diffracted light beams from the one direction into another direction.
at least one holographic optical element, having a focal point; and means located at least approximately at the focal point of said at least one holographic optical element for deflecting a beam of light through an angular range to produce a continuum of beams diverging toward the at least one holographic optical element so that the diverging beams are received thereby in the angular range; and said at least one holographic optical element comprising means for deflecting the diverging beams at all angles in the angular range, such that the diverging beams are deflected by diffraction in one direction, thereby to obtain a telecentric light beam, wherein the at least one holographic optical element includes a flat holographic element formed on a prism as a carrier, whereby the prism is adapted for deflecting the diffracted light beams from the one direction into another direction.
2. A device according to claim 1, wherein said at least one holographic optical element, comprises a first holographic element, further comprising a second holographic optical element and a photoelectric transducer, said second holographic optical element serving as a collecting lens for projecting the telecentric beam onto said photo-electric transducer.
3. A device according to claim 2, wherein said first and second holographic optical elements are respectively inclined to a first optical plane of the diverging beams and a second optical plane of the telecentric beam deflected by said first holographic optical element in such a manner that the second plane is perpendicular to the first plane and to a third plane in which the telecentric beam lies after issuing from said second holographic optical element.
4. A device as claimed in claim 3, wherein said first and second holographic optical elements are respectively inclined at 45° to said first and second optical planes.
5. A process for the production of a telecentric light beam, comprising the step of:
deflecting a beam of light through an angular range at the focal point of at least one holographic optical element, to produce continuum of beams diverging toward the at least one holographic optical element so that the diverging beams are received thereby in the angular range; and for all angles of the diverging beams in the angular range, deflecting the diverging beams with the at least one holographic optical element, such that the diverging beams are deflected by diffraction in one direction, thereby to obtain a telecentric light beam, wherein in addition to the telecentric light beam diffracted by the at least one holographic optical element a further light beam of a different order of diffraction is deflected by the at least one holographic optical element and is utilized for auxiliary functions.
deflecting a beam of light through an angular range at the focal point of at least one holographic optical element, to produce continuum of beams diverging toward the at least one holographic optical element so that the diverging beams are received thereby in the angular range; and for all angles of the diverging beams in the angular range, deflecting the diverging beams with the at least one holographic optical element, such that the diverging beams are deflected by diffraction in one direction, thereby to obtain a telecentric light beam, wherein in addition to the telecentric light beam diffracted by the at least one holographic optical element a further light beam of a different order of diffraction is deflected by the at least one holographic optical element and is utilized for auxiliary functions.
6. A process as claimed in claim 5, wherein the telecentric light beam is of the first order of diffraction and the further light beam is of zero order.
7. A process according to claim 5, wherein the light beam of a different order of diffraction is projected onto at least one electro-optic transducer in order to detect the movement of the telecentric beam without influencing the telecentric beam.
8. A process as in claim 5, further comprising the steps of detecting the further light beam and the respective portions of the telecentric light beam originating at corresponding angles of the diverging beams, so that the angles of the corresponding diverging beams may be referenced to the angle of a diverging beam detected comtemporaneously with detection of the further light beam.
9. A process for the production of a telecentric light beam comprising the steps of:
deflecting a beam of light through an angular range at the focal point of at least one holographic optical element, to produce a continuum of beams diverging toward the at least one holographic optical element so that the diverging beams are received thereby in the angular range; and for all angles of the diverging beams in the angular range, deflecting the diverging beams with the at least one holographic optical element, such that the diverging beams are deflected by diffraction in one direction, thereby to obtain a telecentric light beam, wherein the at least one holographic optical element comprises first and second holographic optical elements, said step of deflecting the diverging beams with at least one holographic optical element including the step of deflecting the diverging beams with the first holographic optical element onto the second holographic optical element and deflecting the beam deflected by the first holographic optical element with the second holographic optical element such that the telecentric light beam is formed in a single plane and such that the distance measured in the plane in a direction perpendicular to the one direction between portions of the telecentric light beam originating at any two spaced apart angles in the diverging beams is linearly related to the difference between the two angles.
deflecting a beam of light through an angular range at the focal point of at least one holographic optical element, to produce a continuum of beams diverging toward the at least one holographic optical element so that the diverging beams are received thereby in the angular range; and for all angles of the diverging beams in the angular range, deflecting the diverging beams with the at least one holographic optical element, such that the diverging beams are deflected by diffraction in one direction, thereby to obtain a telecentric light beam, wherein the at least one holographic optical element comprises first and second holographic optical elements, said step of deflecting the diverging beams with at least one holographic optical element including the step of deflecting the diverging beams with the first holographic optical element onto the second holographic optical element and deflecting the beam deflected by the first holographic optical element with the second holographic optical element such that the telecentric light beam is formed in a single plane and such that the distance measured in the plane in a direction perpendicular to the one direction between portions of the telecentric light beam originating at any two spaced apart angles in the diverging beams is linearly related to the difference between the two angles.
10. A process for the production of a telecentric light beam, comprising the step of:
deflecting a beam of light through an angular range at the focal point of at least one holographic optical element, to produce a continuum of beams diverging toward the at least one holographic optical element so that the diverging beams are received thereby in the angular range; and for all angles of the diverging beams in the angular range, deflecting the diverging beams with the at least one holographic optical element, such that the diverging beams are deflected by diffraction in one direction, thereby to obtain a telecentric light beam, wherein the at least one holographic optical element comprises a single curved holographic optical element, the step of deflecting the diverging beams with at least one holographic optical element including the step of deflecting the diverging beam with the curved holographic optical element such that the telecentric light beam is formed in a single plane and such that the distance measured in the plane in a direction perpendicular to the one direction between portions of the telecentric light beam originating at any two spaced apart angles in the diverging beams is linearly related to the difference between the two angles.
deflecting a beam of light through an angular range at the focal point of at least one holographic optical element, to produce a continuum of beams diverging toward the at least one holographic optical element so that the diverging beams are received thereby in the angular range; and for all angles of the diverging beams in the angular range, deflecting the diverging beams with the at least one holographic optical element, such that the diverging beams are deflected by diffraction in one direction, thereby to obtain a telecentric light beam, wherein the at least one holographic optical element comprises a single curved holographic optical element, the step of deflecting the diverging beams with at least one holographic optical element including the step of deflecting the diverging beam with the curved holographic optical element such that the telecentric light beam is formed in a single plane and such that the distance measured in the plane in a direction perpendicular to the one direction between portions of the telecentric light beam originating at any two spaced apart angles in the diverging beams is linearly related to the difference between the two angles.
11. A method of producing a first holographic optical element from a light sensitive material, that can be combined with a second holographic optical element to direct a telecentric light beam from the first holographic optical element in a plane in a telecentric direction, by diffraction of a light beam deflected through an angular range at a focal point of the combination of the first holographic optical element and the second holographic optical element, the method comprising the steps of:
disposing a point light source, the second holographic optical element and the light sensitive material in successively spaced relation with the second holographic optical element between the point light source and the light sensitive material, the point light source and the second holographic optical element being disposed at positions relative to the light sensitive material that are the same as the respective positions, in the combination, of the intended focal point of the combination and the second holographic optical element relative to the first holographic optical element to be produced;
illuminating the second holographic optical element with coherent wavefronts of radiation from the point light source;
directing the radiation from the second holographic optical element onto the light sensitive material such that the radiation impinges on the light sensitive element at respective positions which are spaced apart by respective distances measured in the plane in a direction perpendicular to the intended telecentric direction of the telecentric beam, the distances being linearly related to angles of the radiation relative to the point light source as it leaves the point light source; and concurrently with said steps of illuminating and directing, illuminating the light sensitive material with wavefronts of coherent light from a plane wave running in the intended telecentric direction.
disposing a point light source, the second holographic optical element and the light sensitive material in successively spaced relation with the second holographic optical element between the point light source and the light sensitive material, the point light source and the second holographic optical element being disposed at positions relative to the light sensitive material that are the same as the respective positions, in the combination, of the intended focal point of the combination and the second holographic optical element relative to the first holographic optical element to be produced;
illuminating the second holographic optical element with coherent wavefronts of radiation from the point light source;
directing the radiation from the second holographic optical element onto the light sensitive material such that the radiation impinges on the light sensitive element at respective positions which are spaced apart by respective distances measured in the plane in a direction perpendicular to the intended telecentric direction of the telecentric beam, the distances being linearly related to angles of the radiation relative to the point light source as it leaves the point light source; and concurrently with said steps of illuminating and directing, illuminating the light sensitive material with wavefronts of coherent light from a plane wave running in the intended telecentric direction.
12. A method of producing a holographic optical element from a light sensitive material, that can be combined with a computer generated hologram to direct a telecentric light beam from the holographic optical element in a plane in a telecentric direction, by diffraction of a light beam deflected through an angular range at a focal point of the combination of the holographic optical element and a computer generated hologram, the method comprising the steps of:
disposing a point light source, the computer generated hologram and the light sensitive material in successively spaced relation with the computer generated hologram between the point light source and the light sensitive material, the point light source and the computer generated hologram being disposed at positions relative to the light sensitive material that are the same as the respective positions, in the combination, of the intended focal point of the combination and the computer generated hologram relative to the holographic optical element to be produced;
illuminating the computer generated hologram with coherent wavefronts of radiation from the point light source;
directing the radiation from the computer generated hologram onto the light sensitive material such that the radiation impinges on the light sensitive element at respective positions which are spaced apart by respective distances measured in the plane in a direction perpendicular to the intended telecentric direction of the telecentric beam, the distances being linearly related to angles of the radiation relative to the point light source as it leaves the point light source; and concurrently with said steps of illuminating and directing, illuminating the light sensitive material with wavefronts of coherent light from a plane wave running in the intended telecentric direction of the telecentric beam.
disposing a point light source, the computer generated hologram and the light sensitive material in successively spaced relation with the computer generated hologram between the point light source and the light sensitive material, the point light source and the computer generated hologram being disposed at positions relative to the light sensitive material that are the same as the respective positions, in the combination, of the intended focal point of the combination and the computer generated hologram relative to the holographic optical element to be produced;
illuminating the computer generated hologram with coherent wavefronts of radiation from the point light source;
directing the radiation from the computer generated hologram onto the light sensitive material such that the radiation impinges on the light sensitive element at respective positions which are spaced apart by respective distances measured in the plane in a direction perpendicular to the intended telecentric direction of the telecentric beam, the distances being linearly related to angles of the radiation relative to the point light source as it leaves the point light source; and concurrently with said steps of illuminating and directing, illuminating the light sensitive material with wavefronts of coherent light from a plane wave running in the intended telecentric direction of the telecentric beam.
13. A method of producing first and second holographic optical elements respectively from first and second light sensitive members, that can be combined for directing a telecentric light beam in a plane in a telecentric direction, by diffraction of a light beam deflected through an angular range at a focal point of the combination of the holographic optical elements, the method comprising the steps of:
disposing a point light source, a computer generated hologram and the first light sensitive member in successively spaced relation with the computer generated hologram between the point light source and the first light sensitive member, the point light source and the computer generated hologram being disposed at positions relative to the first light sensitive member that are the same as the respective positions, in the combination to be produced, of the intended focal point of the combination and second holographic optical element to be produced relative to the first holographic optical element to be produced;
illuminating the computer generated hologram with coherent wavefronts of radiation from the point light source;
directing the radiation from the computer generated hologram onto the first light sensitive member such that the radiation impinges on the first light sensitive member at respective positions which are spaced apart by respective distances measured in the plane in a direction perpendicular to the intended telecentric direction of the telecentric beam, the distances being linearly related to angles of the radiation relative to the point light source as it leaves the point light source;
concurrently with said steps of illuminating and directing, illuminating the first light sensitive member with wavefronts of coherent light from a plane wave running in the intended telecentric direction of the telecentric beam, to obtain the first holographic optical element; and producing a reproduction of the computer generated member, the reproduction forming the second holographic optical element, said step of producing a reproduction including the steps of:
disposing a second light sensitive member between a point light source and the first holographic optical element, illuminating the first holographic optical element with wavefronts of coherent light from a plane wave, directing the radiation from the first holographic optical element onto the second light sensitive member, and concurrently with said steps of illuminating the first holographic optical element and directing the radiation, illuminating the second light sensitive member with convergent spherical wavefronts of radiation to obtain the reproduction of the computer generated hologram which forms the second holographic optical element.
disposing a point light source, a computer generated hologram and the first light sensitive member in successively spaced relation with the computer generated hologram between the point light source and the first light sensitive member, the point light source and the computer generated hologram being disposed at positions relative to the first light sensitive member that are the same as the respective positions, in the combination to be produced, of the intended focal point of the combination and second holographic optical element to be produced relative to the first holographic optical element to be produced;
illuminating the computer generated hologram with coherent wavefronts of radiation from the point light source;
directing the radiation from the computer generated hologram onto the first light sensitive member such that the radiation impinges on the first light sensitive member at respective positions which are spaced apart by respective distances measured in the plane in a direction perpendicular to the intended telecentric direction of the telecentric beam, the distances being linearly related to angles of the radiation relative to the point light source as it leaves the point light source;
concurrently with said steps of illuminating and directing, illuminating the first light sensitive member with wavefronts of coherent light from a plane wave running in the intended telecentric direction of the telecentric beam, to obtain the first holographic optical element; and producing a reproduction of the computer generated member, the reproduction forming the second holographic optical element, said step of producing a reproduction including the steps of:
disposing a second light sensitive member between a point light source and the first holographic optical element, illuminating the first holographic optical element with wavefronts of coherent light from a plane wave, directing the radiation from the first holographic optical element onto the second light sensitive member, and concurrently with said steps of illuminating the first holographic optical element and directing the radiation, illuminating the second light sensitive member with convergent spherical wavefronts of radiation to obtain the reproduction of the computer generated hologram which forms the second holographic optical element.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH01299/86-6 | 1986-04-03 | ||
| CH1299/86A CH674774A5 (en) | 1986-04-03 | 1986-04-03 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1333756C true CA1333756C (en) | 1995-01-03 |
Family
ID=4207181
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000533580A Expired - Fee Related CA1333756C (en) | 1986-04-03 | 1987-04-01 | Process for the production of a telecentric light beam, device for carrying out this process and process for the production of an hoe |
Country Status (10)
| Country | Link |
|---|---|
| US (2) | US4832426A (en) |
| EP (1) | EP0245198B1 (en) |
| JP (1) | JPH0786594B2 (en) |
| AT (1) | ATE61106T1 (en) |
| AU (1) | AU607412B2 (en) |
| CA (1) | CA1333756C (en) |
| CH (1) | CH674774A5 (en) |
| DE (1) | DE3768137D1 (en) |
| ES (1) | ES2021389B3 (en) |
| ZA (1) | ZA872375B (en) |
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|---|---|---|---|---|
| JPH0687099B2 (en) * | 1986-10-08 | 1994-11-02 | 富士通株式会社 | Laser optical scanning device |
| GB8803283D0 (en) * | 1988-02-12 | 1988-03-09 | Ciba Geigy Ag | Copying holograms |
| GB8807029D0 (en) * | 1988-03-24 | 1988-04-27 | Ciba Geigy Ag | Preparing hologram |
| GB8807030D0 (en) * | 1988-03-24 | 1988-04-27 | Ciba Geigy Ag | Preparing hologram |
| US4973112A (en) * | 1988-12-01 | 1990-11-27 | Holotek Ltd. | Hologon deflection system having dispersive optical elements for scan line bow correction, wavelength shift correction and scanning spot ellipticity correction |
| US5245170A (en) * | 1988-12-20 | 1993-09-14 | Fujitsu Limited | Optical scanner using planar reflection holograms |
| US5231277A (en) * | 1988-12-20 | 1993-07-27 | Fujitsu Limited | Optical scanner using plannar reflecting holograms |
| US5296689A (en) * | 1992-02-28 | 1994-03-22 | Spectra-Physics Scanning Systems, Inc. | Aiming beam system for optical data reading device |
| US5255065A (en) * | 1992-03-10 | 1993-10-19 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Conically scanned holographic lidar telescope |
| AU6410594A (en) * | 1993-03-10 | 1994-09-26 | Richard W Pease | Light beam image recording and input apparatus and method |
| US5625402A (en) * | 1993-04-30 | 1997-04-29 | Eastman Kodak Company | Digital printers using multiple lasers or laser arrays with different wavelengths |
| US5774278A (en) * | 1995-11-30 | 1998-06-30 | Eastman Kodak Company | Spectral filter |
| JP2001108523A (en) * | 1999-10-14 | 2001-04-20 | Matsushita Electric Ind Co Ltd | Spectrometry instrument |
| EP1429111A1 (en) * | 2002-12-09 | 2004-06-16 | Zumbach Electronic Ag | Holographic optical element having a plurality of interference patterns |
| EP1429112B1 (en) * | 2002-12-09 | 2018-03-21 | Zumbach Electronic Ag | Holographic optical element having a plurality of interference patterns |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3658403A (en) * | 1968-06-20 | 1972-04-25 | Rca Corp | High fidelity readout of a hologram performing the function of a complex wave modifying structure |
| US3739173A (en) * | 1970-02-18 | 1973-06-12 | Thomson Csf | Interlaced multiplexing electro optical system |
| FR2122007A5 (en) * | 1971-01-14 | 1972-08-25 | Thomson Csf | |
| JPS5343300B2 (en) * | 1972-11-02 | 1978-11-18 | ||
| US3951509A (en) * | 1973-04-17 | 1976-04-20 | Fuji Photo Film Co., Ltd. | Apparatus for deflecting light and scanning line conversion system |
| US3807829A (en) * | 1973-04-30 | 1974-04-30 | Hughes Aircraft Co | Extended-field holographic lens arrays |
| NL7606290A (en) * | 1975-06-25 | 1976-12-28 | Xerox Corp | LASER SCANNING SYSTEM USING CALCULATING MACHINE GENERATED HOLOGRAMS. |
| US4245882A (en) * | 1977-11-04 | 1981-01-20 | Environmental Research Institute Of Michigan | Doubly modulated on-axis thick hologram optical element |
| CH645462A5 (en) * | 1980-03-25 | 1984-09-28 | Zumbach Electronic Ag | METHOD AND DEVICE FOR THE CONTACTLESS MEASUREMENT OF A DIMENSION OF AT LEAST ONE OBJECT. |
| CH658523A5 (en) * | 1981-06-04 | 1986-11-14 | Zumbach Electronic Ag | METHOD AND DEVICE FOR GENERATING A TELECENTRIC LIGHT BEAM AND APPLICATION OF THE METHOD. |
| JPS58106519A (en) * | 1981-12-19 | 1983-06-24 | Ricoh Co Ltd | Light scanning optical system |
| US4505537A (en) * | 1982-06-24 | 1985-03-19 | Ricoh Company, Ltd. | Light scanning apparatus |
| US4639141A (en) * | 1982-11-12 | 1987-01-27 | Mitutoyo Mfg. Co., Ltd. | Scanning ray beam generator for optical measuring device |
| JPS6026905A (en) * | 1983-07-25 | 1985-02-09 | Hitachi Ltd | Spherical hologram lens |
| CA1252321A (en) * | 1983-10-03 | 1989-04-11 | Hiroyuki Ikeda | Method for constructing and reconstructing hologram |
| JPS60108802A (en) * | 1983-11-18 | 1985-06-14 | Fuji Photo Film Co Ltd | Method and device for optical beam synthesis |
-
1986
- 1986-04-03 CH CH1299/86A patent/CH674774A5/de unknown
-
1987
- 1987-03-23 US US07/029,436 patent/US4832426A/en not_active Expired - Lifetime
- 1987-03-24 DE DE8787810171T patent/DE3768137D1/en not_active Expired - Lifetime
- 1987-03-24 ES ES87810171T patent/ES2021389B3/en not_active Expired - Lifetime
- 1987-03-24 EP EP87810171A patent/EP0245198B1/en not_active Expired - Lifetime
- 1987-03-24 AT AT87810171T patent/ATE61106T1/en not_active IP Right Cessation
- 1987-03-30 JP JP62074586A patent/JPH0786594B2/en not_active Expired - Fee Related
- 1987-03-31 AU AU70970/87A patent/AU607412B2/en not_active Ceased
- 1987-04-01 CA CA000533580A patent/CA1333756C/en not_active Expired - Fee Related
- 1987-04-01 ZA ZA872375A patent/ZA872375B/en unknown
-
1988
- 1988-10-27 US US07/224,990 patent/US4955694A/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS62239120A (en) | 1987-10-20 |
| ZA872375B (en) | 1987-11-25 |
| ATE61106T1 (en) | 1991-03-15 |
| EP0245198B1 (en) | 1991-02-27 |
| DE3768137D1 (en) | 1991-04-04 |
| EP0245198A1 (en) | 1987-11-11 |
| CH674774A5 (en) | 1990-07-13 |
| US4832426A (en) | 1989-05-23 |
| ES2021389B3 (en) | 1991-11-01 |
| US4955694A (en) | 1990-09-11 |
| AU7097087A (en) | 1987-10-08 |
| JPH0786594B2 (en) | 1995-09-20 |
| AU607412B2 (en) | 1991-03-07 |
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