DE102016107210A1 - Method and device for producing a hologram headlamp - Google Patents

Abstract

The invention relates to a method for producing a hologram headlight for vehicles in that a computer-generated hologram is produced, wherein an object beam of a laser light of predetermined wavelength impinges on a light modulator and is modulated by this to holographic information, with which a photosensitive recording material is exposed, in addition an unmodulated reference beam of the laser light strikes, wherein the holographic information is introduced sequentially onto cells of the photosensitive recording material, so that the hologram consists of a plurality of sub-holograms assigned in a matrix-like manner to the cells, the sub-holograms each containing information regarding a shape and / or Partial form of a light distribution, wherein a reconstruction plane of the hologram is inclined in a direction to an extension plane of the hologram or the sub-hologram, and / or a phase information having a wavelength emitted by the reconstruction light source associated with the hologram and / or phase information of a wavefront shape and / or a light incidence angle of the reconstruction light source.

Description

The invention relates to a method for producing a hologram headlight for vehicles in that a computer-generated hologram is produced, wherein an object beam of a laser light of predetermined wavelength impinges on a light modulator and is modulated by this to holographic information, with which a photosensitive recording material is exposed, in addition an unmodulated reference beam of the laser light hits.

Furthermore, the invention relates to a device for writing a hologram for a hologram headlight for vehicles with a laser source for generating a laser beam of a predetermined wavelength, wherein the laser beam is split into an object beam and a coherent reference beam to the same, a light modulator, which is associated with the object beam, an optical unit for writing holographic information on the photosensitive material, wherein the optical unit is disposed downstream of the light modulator, and the holographic information is incident on an exposure location of the recording material, positioning means for positioning the recording material relative to the exposure location.

It is known to produce holograms for the three-dimensional representation of objects, wherein the object is illuminated with a coherent light. For this purpose, an object beam and a reference beam of the same laser source are directed onto a photosensitive recording material, so that after exposure, a hologram is formed whose holographic image essentially corresponds to the size of the holographic object. From the US Pat. No. 7,324,248 B2 For example, a device for writing a hologram (holographic printer) is known, which has a laser source for generating a laser beam, so that an object beam and a coherent reference beam to it can be formed. Furthermore, the device has a light modulator, by means of which the object-related holographic information can be applied to a photosensitive recording material via an optical unit. The holographic information is computer generated so that the given object can be printed.

The object of the present invention is to provide a method for producing a hologram for light applications in the vehicle sector or a device for writing such a hologram, so that the use of holograms in automotive applications is simplified.

To achieve this object, the invention in conjunction with the preamble of claim 1, characterized in that the holographic information is introduced sequentially onto cells of the photosensitive recording material, so that the hologram consists of a plurality of sub-holograms each assigned to the cells, arranged in a matrix-like manner, the sub-holograms each having information regarding a shape and / or a partial shape of a light distribution, wherein a reconstruction plane of the hologram is inclined in an extension plane of the hologram or sub-hologram, and / or phase information of a wavelength emitted from the reconstruction light source associated with the hologram, and / or or phase information of a wavefront shape and / or a light incidence angle of the reconstruction light source.

According to the method of the invention, a sequential exposure process is carried out to generate computer-generated holograms which are suitable for use in automobiles, in particular for generating light distributions in headlamps. Cells of a photosensitive recording material are sequentially applied with the holographic information, so that spatially delimited sub-holograms are arranged, which are arranged distributed in a matrix, so that the hologram is formed by a plurality of sub-holograms. Advantageously, a predetermined light distribution can be generated by superimposing a plurality of sub-holograms. For this purpose, the sub-holograms can be optimized in the production of the same or different parameters of the light distribution. Such parameters are in particular a form and / or partial form of a light distribution, phase information per wavelength of a reconstruction light source, with which the finished hologram is illuminated, a wavelength emitted by the reconstruction light source and / or a wavefront shape or a light incidence angle of the reconstruction light source. Advantageously, this makes it possible, in particular, to make use of holograms in the headlight area.

According to a preferred embodiment of the invention, the photosensitive recording material is moved stepwise in a plane (XY direction of a Cartesian coordinate system) sequentially during the standstill of the recording material, the cells are described with the holographic information. This results in succession a plurality of sub-holograms, which together form the hologram. Depending on the application, different holographic information can thus be introduced into the sub-holograms by exposure.

According to a development of the invention, a reduced image of the holographic information to be exposed is carried out by means of an optical unit, so that a plurality of spatially small sub-holograms can be created.

According to a development of the invention, the calculated hologram can be checked by simulation for practicality. For this purpose, the hologram calculated by means of a simulation program is subjected to a simulated reconstruction light source, wherein the individual sub-holograms of the hologram are sequentially illuminated by corresponding partial beams of the reconstruction light source and lead to a partial light distribution. By partial light distributions generated by the sub-holograms, by superimposing the partial light distributions into a total light distribution and comparing them with a given light distribution, a decision can be made as to whether the hologram should be created in the calculated form or not. Advantageously, the sequential simulation algorithm allows the simulation of relatively large holograms with sufficient sampling rate, the necessary memory can be kept relatively small.

According to a development of the invention, the laser source is designed to describe the hologram as a green spectral color emitting laser. Advantageously, this allows the creation of a hologram, by means of which a white light distribution can be generated.

To achieve the object, the invention in connection with the preamble of claim 6, characterized in that the positioning means are formed such that the exposure sequentially distributed matrix-like arranged cells of the recording material covers for writing sub-holograms in each of these cells.

The particular advantage of the device according to the invention is that a computer-generated hologram can be produced by the creation of relatively small sub-holograms, by means of which in conjunction with a reconstruction light source and optionally an additional optical unit, a predetermined light distribution can be generated, which meets the conditions for use in the vehicle sector. In particular, this makes it possible to implement a light distribution whose projection surface is arranged inclined to an extension plane of the hologram. Subholograms can produce shapes or partial shapes of the given light distributions universally and flexibly, so that optimum adaptation to light sources in the automotive sector is ensured. The basic idea here is the writing or grouping of holographic information in cells arranged in a matrix of a recording material, which generate the predetermined light distribution in the operating case by superposition of the holographic information contained sub-holograms of the corresponding light emitted from the light source (reconstruction light source) light beams.

According to a preferred embodiment of the device, the dimension of the sub-holograms in the micron range, for example, an extent in the range of 400 microns to 800 microns, so that the resulting hologram composed of a plurality of sub-holograms. Advantageously, different parameters can be "planted" in the hologram, so that a wide variety of light distributions can be generated.

According to a development of the invention, the hologram is designed as a transmission hologram element, so that it can be positioned relatively space-saving, for example within a headlight. Optionally, the hologram can be integrated in a cover of the headlight.

Embodiments of the invention are explained below with reference to the drawings.

Show it:

1 a perspective view of an apparatus for writing a computer-generated hologram,

2a a representation of a predetermined light distribution, which runs on a measuring screen rectangular,

2 B exemplary representations of differently positioned sub-holograms in the hologram,

2c an arrangement of the hologram in relation to a reconstruction light source in the operating case, wherein holographic information of the sub-holograms are adapted to a light incidence angle or wavelength of the light source,

3a a schematic representation of a given information light distribution as an arrow for navigation,

3b a representation of the parts of the predetermined information light distribution, wherein the parts are generated by different sub-holograms,

3c exemplary representations of differently positioned sub-holograms in the hologram,

3d an arrangement of the hologram in relation to a reconstruction light source in the operating case, wherein holographic information of the sub-holograms are adapted to a light incidence angle or wavelength of the light source,

4a a representation of a first simulated reconstruction wave following a first sub-hologram of the calculated information light distribution 3a meets,

4b a representation of the part of the information light distribution generated by the first sub-hologram,

4c a representation of an n-th reconstruction wave, which after an n-th sub-hologram of the calculated information light distribution after 3a meets,

4d a representation of the generated by the n-th sub-hologram part of the information light distribution and

4e a representation of all parts of the information light distribution generated by the sub-holograms.

An apparatus for writing a hologram H is shown schematically in FIG 1 shown. It comprises a laser source, not shown, for generating a laser beam of a predetermined wavelength. In the present embodiment, it is a laser source emitting coherent light of green light color. By means not shown, the laser beam emitted by the laser source is split into an object beam W _obj and a reference beam W _ref . The object beam W _obj is directed to a light modulator SLM (Spatial Light Modulator), which may have a quadrangular or square shape. The light modulator SLM can be controlled by a computer unit in such a way that holographic information can be reproduced. This holographic information is received by the object beam W _obj and by means of an optical unit downstream of the light modulator SLM 1 , which may for example consist of a plurality of lenses, imaged on a small area. This small area is covered by a cell 2 a photosensitive recording material 3 formed on the object beam W _obj and the reference beam W _ref hits in a write _step . The photosensitive recording material 3 is for example formed as a flat plate, which is movable over not shown positioning means in a plane (XY direction of a Cartesian coordinate system). By moving the photosensitive material relative to those in an exposure location B in the plane of the recording material 3 _hitting laser beams W _obj , W _ref can successively (sequentially) the cells 2 provided with holographic information or be described by exposure. In the cells 2 In each case relevant holographic information is introduced for generating a light distribution in vehicles, so that a light beam generated by a light source (reconstruction light source) during operation of the illumination device is diffracted in a defined angular and / or spectral range. There are thus matrix-like, preferably the same size, arranged cells 2 described with holographic information, later in operation sub-holograms 4 form such that they diffract light according to a shape and / or partial shape of a light distribution, phase information of wavelength of the light source 5 generated light contained and / or information, in particular phase information, with respect to a wavefront shape and / or light incidence angle of the light source 5 have, and thus form a hologram H.

According to a first embodiment of the invention, the light modulator SLM is driven in such a way by means of an algorithm that a rectangular light distribution L1, for example a low-beam light distribution, according to FIG 2a is produced. For this the cells become 2 of the light-sensitive material 3 sequentially substantially equally exposed, so that identically formed sub-holograms 4 ' arise. The sub-holograms 4 ' are only relative to their relative position to the light source 5 adjusted so that the from the light source 5 radiated, and on different sub-holograms 4 ' incident light bundles 6 . 6 ' at the sub-holograms 4 ' be bent so that the diffracted light beams 6 . 6 ' on a screen ( 2a ) superpose to the desired light distribution. The desired light distribution is thus superimposed by the sub-holograms 4 ' of the hologram H diffracted light.

According to another embodiment according to the 3a to 3d can be an information light distribution according to an arrow symbol 7 be generated. This arrow symbol 7 , this in 3a is displayed on a screen, is projected onto the road for navigation purposes, for example. For this purpose, the arrow light distribution 7 in shares 8.1 . 8.2 . 8.3 . 8.4 . 8.5 . 8.6 divided by different sub-holograms 40.1 . 40.2 . 40.3 . 40.4 . 40.5 . 40.6 be generated. The sub-holograms 40.1 . 40.2 . 40.3 . 40.4 . 40.5 . 40.6 can each be formed by single or multiple identical sub-holograms. In the present Embodiment, the hologram H has a number of sub-holograms, by six, ie the number of shares 40.1 . 40.2 . 40.3 . 40.4 . 40.5 . 40.6 is divisible. The light modulator SLM is in this case controlled so that in the sub-holograms 40.1 . 40.2 . 40.3 . 40.4 . 40.5 . 40.6 corresponding holographic information is written to corresponding cells. When controlling the light modulator SLM, the relative position of the light source is also taken into account 5 to the individual sub-holograms 40.1 . 40.2 . 40.3 . 40.4 . 40.5 . 40.6 , so that in the operating state at radiation of the corresponding light beam 16 . 16 ' the corresponding sub-holograms the corresponding parts of the target light distribution according to 3b produce.

Before the recording material is exposed, a simulation of the calculated hologram H, see 4a to 4e , For this purpose, the light source 5 simulates and from her the reconstruction light beams 17.1 ... to 17.6 in the direction of the corresponding sub-holograms 40.1 . 40.2 . 40.3 . 40.4 . 40.5 . 40.6 generated. According to 4a . 4b causes the radiation of the reconstruction light beam 17.1 the generation of a share 8.1 corresponding partial light distribution 41.1 while emitting the reconstruction light beam 17.6 that to the share 8.6 corresponding light distribution 41.6 generated. By superimposing the through the sub-holograms 40.1 . 40.2 . 40.3 . 40.4 . 40.5 . 40.6 produced partial light distributions 41.1 to 41.6 this results in the total light distribution 42 that with the given light distribution 7 is compared. If they match, the exposure of the photosensitive material takes place according to the selected driving of the light modulator SLM. If there is no match, the control of the light modulator SLM is corrected until a match is established as a result of the simulation.

The laser light source generated to create the hologram H. 5 emits laser light of green spectral color.

The optical unit 1 causes a reduced image of the holographic information generated by the light modulator SLM on the cells 2 ,

The photosensitive recording material is preferably formed as a flat plate. The cells 2 have dimensions in the micron range, for example, a feature size in the range of 400 microns to 800 microns, on. The same applies to the sub-holograms.

The hologram H is designed as a transmission hologram, preferably as a volume hologram.

The light source 5 and the hologram H formed light unit is preferably provided as a headlight for generating one or more light distributions. Optionally, the hologram H can also be integrated in a cover of the headlamp. Optionally, the lighting device thus formed can also be used for other purposes in or on the vehicle.

The recording material 3 extends in an extension plane, which is usually at an angle to a reconstruction plane of the hologram H. The reconstruction plane of the hologram H forms a projection plane in which a flat light distribution is generated. The angle between the projection plane and the plane of extent is preferably formed as an acute angle.

LIST OF REFERENCE NUMBERS

1

 optical unit

2

 cell

3

 recording material

4,4 '

sub-hologram

5 l

maybe source

6.6 '

light beam

7

 arrow icon

8.1,8.2

 shares

16.16 '

light beam

17.1-17.6

 Reconstruction light beam

40.1-40.6

 sub-hologram

41.1-41.6

 Partial light distribution

H

hologram

SLM

 light modulator

W _obj

object beam

W _ref

reference beam

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 7324248 B2 [0003]

Claims (10)

Method for producing a hologram headlamp for vehicles, that a computer-generated hologram (H) is produced, wherein an object beam (W _obj ) of a laser light of predetermined wavelength is _incident on and modulated by a light modulator (SLM) to holographic information, with which a photosensitive recording material ( 3 ), to which additionally an unmodulated reference beam (W _ref ) of the laser light strikes, characterized in that the holographic information is sequentially applied to cells ( 2 ) of the light-sensitive material ( 3 ) are introduced, so that the hologram (H) from a plurality of each of the cells ( 2 ), distributed in a matrix-like manner arranged sub-holograms ( 4 . 4 ' . 40.1 . 40.2 . 40.3 . 40.4 . 40.5 . 40.6 ), the sub-holograms ( 4 . 4 ' . 40.1 . 40.2 . 40.3 . 40.4 . 40.5 . 40.6 ) information with respect to a shape and / or partial shape of a light distribution, wherein a reconstruction plane of the hologram (H) in a to an extension plane of the hologram (H) or the sub-hologram ( 4 . 4 ' . 40.1 . 40.2 . 40.3 . 40.4 . 40.5 . 40.6 ), and / or - phase information of a reconstruction light source associated with the hologram (H) ( 5 ) and / or phase information of a wavefront shape and / or a light incidence angle of the reconstruction light source. Method according to claim 1, characterized in that the cells ( 2 ) of the recording material ( 3 ) successively by stepwise moving the recording material ( 3 ) in the XY direction of a Cartesian coordinate system relative to an exposure _location (B) predetermined by the reference beam (W _ref ) and the object beam (W _obj ), with the holographic information being exposed during the exposure of the cells ( 2 ) the recording material ( 3 ) is arranged stationary to the exposure location (B). A method according to claim 1 or 2, characterized in that the holographic information about an optical unit ( 1 ) on the cells ( 2 ) of the recording material ( 3 ) for downsizing the holographic information generated by the light modulator (SLM). Method according to one of claims 1 to 3, characterized in that the sub-holograms ( 4 . 4 ' . 40.1 . 40.2 . 40.3 . 40.4 . 40.5 . 40.6 ) of the calculated hologram (H) successively with a wave of a simulated reconstruction light source ( 17.1 . 17.6 ) are used to calculate one of the respective sub-holograms ( 4 . 4 ' . 40.1 . 40.2 . 40.3 . 40.4 . 40.5 . 40.6 ) generated partial light distribution ( 41.1 . 41.6 ), that the partial light distributions ( 41.1 . 41.6 ) are superimposed to a total light distribution ( 42 ) and that the total light distribution ( 42 ) is compared with a predetermined light distribution ( 7 ). Method according to one of the claims 1 to 4, characterized in that the recording material ( 3 ) is exposed with a green spectral color emitting laser light source. Apparatus for writing a hologram for a hologram headlamp for vehicles, comprising - a laser source for generating a laser beam of a predetermined wavelength, the laser beam being _split into an object beam (W _obj ) and a coherent reference beam (Wr _ef ), - a light modulator (SLM ) to which the object beam (W _obj ) is assigned, - an optical unit ( 1 ) for writing holographic information on the light-sensitive material ( 3 ), wherein the optical unit ( 1 ) is arranged downstream of the light modulator (SLM) and the holographic information on an exposure location (B) of the recording material ( 3 ), - positioning means for positioning the recording material ( 3 ) relative to the exposure location (B), characterized in that the positioning means are formed such that the exposure location (B) sequentially arranged in a matrix-like distributed cells ( 2 ) of the recording material ( 3 ) covered for writing sub-holograms ( 4 . 4 ' . 40.1 . 40.2 . 40.3 . 40.4 . 40.5 . 40.6 ) in each of these cells ( 2 ). Device according to claim 6, characterized in that the recording material ( 3 ) is formed as a flat plate. Apparatus according to claim 6 or 7, characterized in that the sub-holograms ( 4 . 4 ' . 40.1 . 40.2 . 40.3 . 40.4 . 40.5 . 40.6 ) have the dimension in a micron range, in particular in a range of 400 microns to 800 microns. Device according to one of claims 6 to 8, characterized in that the hologram (H) is designed as a transmission hologram. Device according to one of claims 6 to 9, characterized in that the holographic information has light distribution information for the road space.

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