WO2008033920A2 - Optical print head - Google Patents
Optical print head Download PDFInfo
- Publication number
- WO2008033920A2 WO2008033920A2 PCT/US2007/078267 US2007078267W WO2008033920A2 WO 2008033920 A2 WO2008033920 A2 WO 2008033920A2 US 2007078267 W US2007078267 W US 2007078267W WO 2008033920 A2 WO2008033920 A2 WO 2008033920A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- optical
- print head
- optical fiber
- light
- wavelength range
- Prior art date
Links
- 230000003287 optical effect Effects 0.000 title claims abstract description 73
- 239000013307 optical fiber Substances 0.000 claims abstract description 36
- 230000008878 coupling Effects 0.000 claims description 9
- 238000010168 coupling process Methods 0.000 claims description 9
- 238000005859 coupling reaction Methods 0.000 claims description 9
- 239000000835 fiber Substances 0.000 claims description 5
- 239000004038 photonic crystal Substances 0.000 claims description 4
- 230000001427 coherent effect Effects 0.000 claims 1
- 238000009826 distribution Methods 0.000 description 7
- 239000011248 coating agent Substances 0.000 description 6
- 238000000576 coating method Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 6
- 239000000463 material Substances 0.000 description 4
- 230000005855 radiation Effects 0.000 description 4
- 230000007704 transition Effects 0.000 description 4
- 230000001902 propagating effect Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 2
- 230000003993 interaction Effects 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 230000000644 propagated effect Effects 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/435—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material
- B41J2/447—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material using arrays of radiation sources
- B41J2/46—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material using arrays of radiation sources characterised by using glass fibres
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J3/00—Typewriters or selective printing or marking mechanisms characterised by the purpose for which they are constructed
- B41J3/407—Typewriters or selective printing or marking mechanisms characterised by the purpose for which they are constructed for marking on special material
- B41J3/4071—Printing on disk-shaped media, e.g. CDs
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/42—Coupling light guides with opto-electronic elements
- G02B6/4201—Packages, e.g. shape, construction, internal or external details
- G02B6/4204—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms
- G02B6/4214—Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms the intermediate optical element having redirecting reflective means, e.g. mirrors, prisms for deflecting the radiation from horizontal to down- or upward direction toward a device
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/002—Recording, reproducing or erasing systems characterised by the shape or form of the carrier
- G11B7/0037—Recording, reproducing or erasing systems characterised by the shape or form of the carrier with discs
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/123—Integrated head arrangements, e.g. with source and detectors mounted on the same substrate
- G11B7/124—Integrated head arrangements, e.g. with source and detectors mounted on the same substrate the integrated head arrangements including waveguides
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/125—Optical beam sources therefor, e.g. laser control circuitry specially adapted for optical storage devices; Modulators, e.g. means for controlling the size or intensity of optical spots or optical traces
- G11B7/127—Lasers; Multiple laser arrays
- G11B7/1275—Two or more lasers having different wavelengths
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
- G11B7/1353—Diffractive elements, e.g. holograms or gratings
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
- G11B7/1372—Lenses
- G11B7/1374—Objective lenses
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/42—Coupling light guides with opto-electronic elements
- G02B6/4201—Packages, e.g. shape, construction, internal or external details
- G02B6/4246—Bidirectionally operating package structures
Definitions
- This invention relates generally to optical recording and more particularly to optical print heads.
- thermochromic imageable coating In light-activated thermal label-recording technology, a surface of the medium is coated with a writable layer of a material that changes appearance when it absorbs laser light of a predetermined wavelength.
- the color change interaction in a thermochromic imageable coating is enabled by phase transitions of the coating materials occurring at elevated temperatures. These phase transitions do not occur (and, so color does not develop) until the coating temperature reaches a certain value specific to the coating material. If the coating is irradiated with laser energy density that is not high enough to reach the phase transition, the color is not developed.
- FIG. 1 is a schematic optical diagram of a first embodiment of an optical print head.
- FIG. 2 is a schematic optical diagram of a portion of a second embodiment of an optical print head.
- FIG. 3 is a schematic optical diagram of a third embodiment of an optical print head.
- FIGS. 4A - 4D are graphs depicting various irradiance distributions of laser light. DETAILED DESCRIPTION OF EMBODIMENTS
- recordable medium and “recordable media” as used in this specification and the appended claims refer to media capable of having information recorded thereon by exposure to optical radiation such as laser light.
- Such recordable media may include, for example, a compact disk (CD), a digital versatile disk (DVD), an HD-DVD, a Blu-ray DiscTM (BD), a holographic versatile disk (HVD), or a video disk, but are not limited to such forms.
- Recordable media may also include such media having pre-recorded information readable from at least one side and having an optically-recordable coating on at least the other side for writing a label on the media.
- the term “recording” means recording or printing a label or other information on a recordable medium such as an optical storage disk.
- an optical print head including a number of lasers having laser emissions within a desired wavelength range, an optical fiber receiving combined light from the lasers at one end and emitting combined output light at its other end, and including a hybrid optical element optically coupled to the exit end of the optical fiber.
- the hybrid optical element is adapted to focus the combined output light within the desired wavelength range on a medium for recording.
- the optical fiber may be a single-mode optical fiber. For example, when a single- mode fiber is used, not all the modes of a multi-mode laser are propagated by the optical fiber.
- FIG. 1 schematically shows an optical diagram of a first embodiment of an optical print head 100.
- a number of lasers such as the three lasers 110, 120, and 130 shown, have laser emissions within a desired wavelength range.
- the desired wavelength range may include wavelengths between about 365 nanometers and about 1600 nanometers, for example.
- the laser emissions of lasers 110, 120, and 130 may be directed substantially parallel to each other in parallel beams, the parallel beams being optically combined into a beam of combined light.
- FIG. 1 shows three lasers, any convenient number of multiple lasers may be used.
- the laser emissions of the lasers may have various different wavelengths within the desired wavelength range, or they may all have substantially the same wavelength, e.g., 780 nanometers.
- Such a monochromatic laser light source can provide a higher power combined output light without the disproportionately higher cost of a single high-power laser.
- An optical fiber 150 receives combined light from the lasers at one end 155 and emits combined output light at its other end 160.
- the laser emissions from lasers 110, 120, and 130 are combined and optically coupled to optical fiber 150 by coupling lenses 115, 125, and 135 respectively, using one or more mirrors 140 or their equivalents if needed to direct the light toward the entrance end 155 of optical fiber 150.
- Mirrors 140 may be one or more dichroic mirrors to combine light from the various lasers into a combined beam.
- Each coupling lens 115, 125, and 135 optically coupled with its respective laser may be movable in a direction substantially parallel to its own optical axis for focusing. Automatic-focusing-servo arrangements such as those using "voice-coil" actuators for moving lenses are known in the art.
- Optical fiber 150 may be, for example, a photonic crystal fiber (PCF).
- the photonic crystal fiber is adapted for single-mode operation in a wavelength range including the desired wavelength range, e.g., a wavelength range including wavelengths between about 365 nanometers and about 1600 nanometers.
- Such a single-mode optical fiber 150 has a mode field area substantially independent of wavelength.
- the mode field diameter of the optical fiber 150 may be made equal to or larger than a desired recording track width, e.g., about 20 micrometers.
- a hybrid optical element 170 optically coupled to the exit end 160 of the optical fiber 150 focuses the combined output light within the desired wavelength range into a spot 195 on a recording medium 190 for recording.
- Hybrid optical element 170 has a diffractive portion 175 and a refractive portion 180 represented schematically in FIG. 1 by digital features and a curved surface respectively.
- hybrid optical element 170 may include a single lens having a first surface 175 formed as a diffractive surface and having a second surface 180 formed as a refractive surface.
- hybrid optical element 170 is not limited to that specific arrangement, or even to separating the two functions (diffractive and refractive) into separate surfaces.
- diffractive portion 175 and refractive portion 180 may be combined at a single surface of hybrid optical element 170.
- the combined output light from optical fiber 150 may be affected first by refractive portion 180 and secondly by diffractive portion 175.
- FIG. 1 shows the laser, optical fiber, and lens as being aligned to combine coaxially
- the individual lasers and/or lenses may be oriented to project their light at small angles to the optical fiber axis in order to prevent an unwanted amount of reflected light from returning to the laser after reflection from the medium, which could otherwise cause undesired side effects, such as oscillation in the source laser.
- Various embodiments may include one or more sensors such as photodiodes to detect light reflected from the medium.
- the sensor may be used to read the data recorded and/or to follow a track on the recording medium.
- the combination of a beam splitter and quarter-wave plate may be used to guide the reflected beam to a sensor and prevent the reflected beam from returning to the source laser. For example, laser light propagating from left to right in FIG. 3 and incident on the quarter-wave plate 335 after passing through the beam splitter 330 is linearly polarized, and after passing through the quarter-wave plate it is circularly polarized.
- Reflection from medium 190 reverses the sense of the circularly polarized light. That circularly polarized light propagating from right to left in FIG. 3 is converted to linearly polarized light in its second passage through the quarter-wave plate, but with a polarization at right angles to the polarization it had previously when propagating in the original left-to-right direction. Thus, this linearly polarized light is reflected in the beam splitter and directed downward along the light path toward sensor 350.
- the quarter- wave plate is configured to direct the light reflected from the medium to the sensor 350.
- Hybrid optical element 170 is not necessarily a simple monolithic lens element.
- FIG. 2 shows a portion of a second embodiment of an optical print head, in which the function of hybrid optical element 170 is performed by a combination of hybrid optical elements 210 and 240 cooperating to provide a desired demagnification of the laser light from exit end 160 of the optical fiber 150, with desired effective numerical apertures (NA) to efficiently collect combined laser light from optical fiber 150 on one side and to form a focused spot 195 of suitable diameter on recording medium 190 on the other side, with suitable working distances on each side.
- the first discrete lens 210 of this optical arrangement may have a diffractive portion 220 and a refractive portion 230 as shown, represented schematically by digital features and a curved surface respectively as in FIG. 1.
- hybrid optical element 170 may include a number of hybrid lenses, each lens having a first surface formed as a diffractive surface and having a second surface formed as a refractive surface.
- Hybrid optical element 170 may advantageously be made substantially achromatic for wavelengths within the desired wavelength range.
- Hybrid optical element 170 may also be made free of spherical aberration.
- the optical arrangement of FIG. 2 may have an entrance numerical aperture (NA) of about 0.05 to match the exit NA of optical fiber 150 and may also have an exit NA of about 0.05, for example.
- NA numerical aperture
- FIG. 3 schematically shows an optical diagram of a third embodiment of an optical print head.
- This embodiment has two lasers 305 and 310 having laser emissions within a desired wavelength range, at least one beam splitter 330, and at least one sensor 350.
- Lasers 305 and 310 may be diode lasers as in FIG. 1.
- quarter-wave plate 335 may also be included, positioned between beam splitter 330 and the recording medium 190 as shown.
- the beam splitter 330 is disposed to direct a portion of light reflected from the medium for recording to the at least one sensor.
- a lens 345 may be provided to focus reflected light on sensor 350.
- Hybrid optical element 210 may be equipped with actuators 215, providing motion parallel to its own optical axis for focusing with an automatic-focusing- servo system.
- Actuators 215 may be voice coils, for example, or their functional equivalent.
- the optical fiber 150 of FIGS. 1 and 2 may be included in the embodiment of FIG. 3 between beam splitter 330 and lens 210 to carry the combined laser beams 315 and 320 to lens 210 for focusing into single spot 195 on recording medium 190 and to carry reflected light 340 from recording medium 190 back to beam splitter 330 for delivery to sensor 350.
- the optical fiber may advantageously be a single-mode optical fiber.
- FIGS. 4A - 4D are graphs depicting various irradiance distributions of laser light.
- Irradiance (I) is plotted in the vertical direction vs. linear distance (y) from the center of each beam, plotted in the horizontal direction.
- FIG. 4A shows a conventional Gaussian irradiance distribution 400 that is normally formed when the output beam of a single laser is focused on a recording medium.
- the horizontal dashed line 410 represents a threshold of irradiance for recording. Irradiance values less than 410 are not effective in recording on the recording medium.
- the vertical dashed lines 420 and 430 represent the distances from the beam center that irradiance falls below threshold 410.
- the combined irradiance 490 is shown in FIG. 4D (normalized to FIGS. 4A, 4B, and 4C). While the combined irradiance may have more energy outside the effective region than in FIG. 4A (outside lines 420 and 430), the energy from the combined power of two or more lasers in the central peak of this combined irradiance more than compensates for that deficiency.
- the various embodiments of an optical print head disclosed herein by including a number of lasers having laser emissions within a desired wavelength range, provide higher power at lower cost for monochromatic recording or provide for color optical recording by incorporating multiple wavelengths in the same optical print head.
- the optical fiber e.g., in the form of a single-mode photonic crystal optical fiber
- receiving combined light from the lasers at one end and emitting combined output light at its other end combines the various laser emissions efficiently and allows separation of the heat-producing lasers from that portion of the print head adjacent to the recording medium. That portion may thus be made smaller and lighter than in an optical print head with lasers near the recording medium.
- the hybrid optical element of these embodiments optically coupled to the exit end of the optical fiber and focusing the combined output light on the recording medium, provides efficient and low-cost coupling of laser light to the recording medium.
- Optical print head embodiments having laser light sources incorporating multiple lasers including various wavelengths are useful in color optical recording.
- Optical print head embodiments having laser light sources incorporating multiple lasers of the same wavelength are useful in optical recording at relatively high power.
- Optical print head embodiments employing an optical fiber may be used when separation of lasers from other components is required to avoid thermal interactions.
Abstract
An optical print head (100) for recording on a medium (190) includes a plurality of lasers (110, 120, 305, 310) having laser emissions within a desired wavelength range, an optical fiber (150) adapted to receive combined light from the plurality of lasers at a first end (155) and to emit combined output light at a second end (160), and includes a hybrid optical element (170) optically coupled to the second end (160) of the optical fiber and adapted to focus the combined output light (195) within the desired wavelength range on the medium (190).
Description
OPTICAL PRINT HEAD
CROSS-REFERENCE TO RELATED APPLICATION
This application is related to co-pending and commonly assigned application serial number 11/520,514, filed on the same date herewith (attorney docket no. 200600001 -1 ), the entire disclosure of which is incorporated herein by reference.
TECHNICAL FIELD
This invention relates generally to optical recording and more particularly to optical print heads.
BACKGROUND Optical recording technology that enables consumers and others to record laser-written labels on specially coated recordable CD and DVD media has enjoyed notable commercial success. In light-activated thermal label-recording technology, a surface of the medium is coated with a writable layer of a material that changes appearance when it absorbs laser light of a predetermined wavelength. The color change interaction in a thermochromic imageable coating is enabled by phase transitions of the coating materials occurring at elevated temperatures. These phase transitions do not occur (and, so color
does not develop) until the coating temperature reaches a certain value specific to the coating material. If the coating is irradiated with laser energy density that is not high enough to reach the phase transition, the color is not developed. Thus, if a writable layer is exposed to laser radiation with an irradiance distribution in which significant portions have insufficient irradiance to reach the color-forming (phase transition) temperature, some of the energy of the laser radiation is wasted. When relatively high-power laser radiation is required, cost increases can occur due to disproportionately higher laser cost. When multiple laser wavelengths are required, such as for color recording, differences in focal distance for the various laser wavelengths may require optics compatible with a focusing servo system. Thus, there is a need for further improvement in marking of media.
BRIEF DESCRIPTION OF THE DRAWINGS
The features and advantages of the disclosure will readily be appreciated by persons skilled in the art from the following detailed description when read in conjunction with the drawings, wherein:
FIG. 1 is a schematic optical diagram of a first embodiment of an optical print head. FIG. 2 is a schematic optical diagram of a portion of a second embodiment of an optical print head.
FIG. 3 is a schematic optical diagram of a third embodiment of an optical print head.
FIGS. 4A - 4D are graphs depicting various irradiance distributions of laser light.
DETAILED DESCRIPTION OF EMBODIMENTS
For clarity of the description, the drawings are not drawn to a uniform scale. In particular, vertical and horizontal scales may differ from each other and may vary from one drawing to another. In this regard, directional terminology, such as "top," "bottom," "front," "back," "leading," "trailing," etc., is used with reference to the orientation of the drawing figure(s) being described. Because components of the invention can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. Similarly, for purposes of illustration but in no way limiting, optical diagrams may be drawn to non-uniform scales and may show elements with non-proportional dimensions.
The terms "recordable medium" and "recordable media" as used in this specification and the appended claims refer to media capable of having information recorded thereon by exposure to optical radiation such as laser light. Such recordable media may include, for example, a compact disk (CD), a digital versatile disk (DVD), an HD-DVD, a Blu-ray Disc™ (BD), a holographic versatile disk (HVD), or a video disk, but are not limited to such forms. Recordable media may also include such media having pre-recorded information readable from at least one side and having an optically-recordable coating on at least the other side for writing a label on the media. The term "recording" means recording or printing a label or other information on a recordable medium such as an optical storage disk.
One aspect of the invention provides embodiments of an optical print head including a number of lasers having laser emissions within a desired wavelength range, an optical fiber receiving combined light from the lasers at one end and emitting combined output light at its other end, and including a hybrid optical element optically coupled to the exit end of the optical fiber. The hybrid optical element is adapted to focus the combined output light within the desired wavelength range on a medium for recording. For many embodiments, the optical fiber may be a single-mode optical fiber. For example, when a single-
mode fiber is used, not all the modes of a multi-mode laser are propagated by the optical fiber.
FIG. 1 schematically shows an optical diagram of a first embodiment of an optical print head 100. A number of lasers, such as the three lasers 110, 120, and 130 shown, have laser emissions within a desired wavelength range. The desired wavelength range may include wavelengths between about 365 nanometers and about 1600 nanometers, for example. The laser emissions of lasers 110, 120, and 130 may be directed substantially parallel to each other in parallel beams, the parallel beams being optically combined into a beam of combined light. While FIG. 1 shows three lasers, any convenient number of multiple lasers may be used. Depending on the application, the laser emissions of the lasers may have various different wavelengths within the desired wavelength range, or they may all have substantially the same wavelength, e.g., 780 nanometers. Such a monochromatic laser light source can provide a higher power combined output light without the disproportionately higher cost of a single high-power laser.
An optical fiber 150 receives combined light from the lasers at one end 155 and emits combined output light at its other end 160. The laser emissions from lasers 110, 120, and 130 are combined and optically coupled to optical fiber 150 by coupling lenses 115, 125, and 135 respectively, using one or more mirrors 140 or their equivalents if needed to direct the light toward the entrance end 155 of optical fiber 150. Mirrors 140 may be one or more dichroic mirrors to combine light from the various lasers into a combined beam. Each coupling lens 115, 125, and 135 optically coupled with its respective laser may be movable in a direction substantially parallel to its own optical axis for focusing. Automatic-focusing-servo arrangements such as those using "voice-coil" actuators for moving lenses are known in the art.
Optical fiber 150 may be, for example, a photonic crystal fiber (PCF). The photonic crystal fiber is adapted for single-mode operation in a wavelength range including the desired wavelength range, e.g., a wavelength range including wavelengths between about 365 nanometers and about 1600
nanometers. Such a single-mode optical fiber 150 has a mode field area substantially independent of wavelength. The mode field diameter of the optical fiber 150 may be made equal to or larger than a desired recording track width, e.g., about 20 micrometers. A hybrid optical element 170 optically coupled to the exit end 160 of the optical fiber 150 focuses the combined output light within the desired wavelength range into a spot 195 on a recording medium 190 for recording. Hybrid optical element 170 has a diffractive portion 175 and a refractive portion 180 represented schematically in FIG. 1 by digital features and a curved surface respectively. Thus, hybrid optical element 170 may include a single lens having a first surface 175 formed as a diffractive surface and having a second surface 180 formed as a refractive surface.
While the combined output light from optical fiber 150 is shown in FIG. 1 as being affected first by diffractive portion 175 and secondly by refractive portion 180, hybrid optical element 170 is not limited to that specific arrangement, or even to separating the two functions (diffractive and refractive) into separate surfaces. In some embodiments, diffractive portion 175 and refractive portion 180 may be combined at a single surface of hybrid optical element 170. In other embodiments, the combined output light from optical fiber 150 may be affected first by refractive portion 180 and secondly by diffractive portion 175.
Although FIG. 1 shows the laser, optical fiber, and lens as being aligned to combine coaxially, in practice the individual lasers and/or lenses may be oriented to project their light at small angles to the optical fiber axis in order to prevent an unwanted amount of reflected light from returning to the laser after reflection from the medium, which could otherwise cause undesired side effects, such as oscillation in the source laser.
Various embodiments may include one or more sensors such as photodiodes to detect light reflected from the medium. When the optical print head is used to record digital data on an optical storage disk, for example, the sensor may be used to read the data recorded and/or to follow a track on the recording medium.
In some embodiments, such as the embodiment of FIG. 3, the combination of a beam splitter and quarter-wave plate may be used to guide the reflected beam to a sensor and prevent the reflected beam from returning to the source laser. For example, laser light propagating from left to right in FIG. 3 and incident on the quarter-wave plate 335 after passing through the beam splitter 330 is linearly polarized, and after passing through the quarter-wave plate it is circularly polarized. Reflection from medium 190 reverses the sense of the circularly polarized light. That circularly polarized light propagating from right to left in FIG. 3 is converted to linearly polarized light in its second passage through the quarter-wave plate, but with a polarization at right angles to the polarization it had previously when propagating in the original left-to-right direction. Thus, this linearly polarized light is reflected in the beam splitter and directed downward along the light path toward sensor 350. Thus, the quarter- wave plate is configured to direct the light reflected from the medium to the sensor 350.
At least some of the embodiments described herein are believed to operate in accordance with this partial description of FIG. 3. However, the invention should not be construed as being limited to the consequences of any particular theory of operation. FIG. 3 is described in more detail below. Hybrid optical element 170 is not necessarily a simple monolithic lens element. FIG. 2 shows a portion of a second embodiment of an optical print head, in which the function of hybrid optical element 170 is performed by a combination of hybrid optical elements 210 and 240 cooperating to provide a desired demagnification of the laser light from exit end 160 of the optical fiber 150, with desired effective numerical apertures (NA) to efficiently collect combined laser light from optical fiber 150 on one side and to form a focused spot 195 of suitable diameter on recording medium 190 on the other side, with suitable working distances on each side. The first discrete lens 210 of this optical arrangement may have a diffractive portion 220 and a refractive portion 230 as shown, represented schematically by digital features and a curved surface respectively as in FIG. 1. Similarly, the second discrete lens 240 of this optical arrangement may have a diffractive portion 250 and a refractive portion 260 as
shown. Thus, hybrid optical element 170 may include a number of hybrid lenses, each lens having a first surface formed as a diffractive surface and having a second surface formed as a refractive surface. Hybrid optical element 170 may advantageously be made substantially achromatic for wavelengths within the desired wavelength range. Hybrid optical element 170 may also be made free of spherical aberration.
For a focused spot 195 with diameter matching a recording track width of about 23 micrometers, for example, the optical arrangement of FIG. 2 may have an entrance numerical aperture (NA) of about 0.05 to match the exit NA of optical fiber 150 and may also have an exit NA of about 0.05, for example.
FIG. 3 (partially described above) schematically shows an optical diagram of a third embodiment of an optical print head. This embodiment has two lasers 305 and 310 having laser emissions within a desired wavelength range, at least one beam splitter 330, and at least one sensor 350. Lasers 305 and 310 may be diode lasers as in FIG. 1. As described above, quarter-wave plate 335 may also be included, positioned between beam splitter 330 and the recording medium 190 as shown. The beam splitter 330 is disposed to direct a portion of light reflected from the medium for recording to the at least one sensor. A lens 345 may be provided to focus reflected light on sensor 350. The initially separate laser beams 315 and 320 from lasers 305 and 310 respectively pass through beam splitter 330 and quarter-wave plate 335 (if present) and are combined by hybrid optical element 210 into a single focused spot 195 on recording medium 190. Hybrid optical element 210 may be equipped with actuators 215, providing motion parallel to its own optical axis for focusing with an automatic-focusing- servo system. Actuators 215 may be voice coils, for example, or their functional equivalent.
The optical fiber 150 of FIGS. 1 and 2 may be included in the embodiment of FIG. 3 between beam splitter 330 and lens 210 to carry the combined laser beams 315 and 320 to lens 210 for focusing into single spot 195 on recording medium 190 and to carry reflected light 340 from recording medium 190 back to beam splitter 330 for delivery to sensor 350. As in all the embodiments
described herein, the optical fiber may advantageously be a single-mode optical fiber.
FIGS. 4A - 4D are graphs depicting various irradiance distributions of laser light. Irradiance (I) is plotted in the vertical direction vs. linear distance (y) from the center of each beam, plotted in the horizontal direction. FIG. 4A shows a conventional Gaussian irradiance distribution 400 that is normally formed when the output beam of a single laser is focused on a recording medium. The horizontal dashed line 410 represents a threshold of irradiance for recording. Irradiance values less than 410 are not effective in recording on the recording medium. The vertical dashed lines 420 and 430 represent the distances from the beam center that irradiance falls below threshold 410. In FIG. 4A, only the portion 460 above line 410 and between lines 420 and 430 is effective. Thus, energy in the portions of the distribution outside the region 460, denoted by reference numerals 440 and 450, is wasted. When laser beams from distinct lasers, such as lasers 110, 120, and 130 of FIG. 1 or lasers 305 and 310 of FIG. 3, are focused onto recording medium 190 from directions not coinciding with the central optical axis of hybrid optical element 170 or 210, the beams may still be made to focus at nearly the same focal spot 195 on recording medium 190, but their individual irradiance distributions at that focal spot (curves 470 and 480), as shown in FIGS. 4B and 4C, may not be symmetric Gaussian distributions, i.e., they may be distorted as shown. The combined irradiance 490 is shown in FIG. 4D (normalized to FIGS. 4A, 4B, and 4C). While the combined irradiance may have more energy outside the effective region than in FIG. 4A (outside lines 420 and 430), the energy from the combined power of two or more lasers in the central peak of this combined irradiance more than compensates for that deficiency.
The various embodiments of an optical print head disclosed herein, by including a number of lasers having laser emissions within a desired wavelength range, provide higher power at lower cost for monochromatic recording or provide for color optical recording by incorporating multiple wavelengths in the same optical print head. The optical fiber (e.g., in the form of a single-mode photonic crystal
optical fiber) receiving combined light from the lasers at one end and emitting combined output light at its other end, combines the various laser emissions efficiently and allows separation of the heat-producing lasers from that portion of the print head adjacent to the recording medium. That portion may thus be made smaller and lighter than in an optical print head with lasers near the recording medium. The hybrid optical element of these embodiments, optically coupled to the exit end of the optical fiber and focusing the combined output light on the recording medium, provides efficient and low-cost coupling of laser light to the recording medium. INDUSTRIAL APPLICABILITY
Devices made in accordance with the disclosed embodiments and their equivalents are useful in optical recording. Optical print head embodiments having laser light sources incorporating multiple lasers including various wavelengths are useful in color optical recording. Optical print head embodiments having laser light sources incorporating multiple lasers of the same wavelength are useful in optical recording at relatively high power. Optical print head embodiments employing an optical fiber may be used when separation of lasers from other components is required to avoid thermal interactions. Although the foregoing has been a description and illustration of specific embodiments of the invention, various modifications and changes thereto can be made by persons skilled in the art without departing from the scope and spirit of the invention as defined by the following claims. For example, various equivalent materials or optical elements may be substituted for those described herein. For another example, hybrid optical element 170 may include an electrohologram for electronic control of focal length, NA, or other optical parameter.
What is claimed is:
Claims
1. An optical print head for recording on a medium, comprising: a) a plurality of lasers having laser emissions within a desired wavelength range, b) an optical fiber adapted to receive combined light from the plurality of lasers at a first end thereof and to emit combined output light at a second end thereof, and c) a hybrid optical element optically coupled to the second end of the optical fiber and adapted to focus the combined output light within the desired wavelength range onto the medium.
2. The optical print head of claim 1 , wherein the optical fiber is a single-mode fiber.
3. The optical print head of claim 1 , wherein the laser emissions of the plurality of lasers are directed substantially parallel to each other in parallel beams and the parallel beams are combined into the combined light.
4. The optical print head of claim 1 , wherein the laser emissions of the plurality of lasers have differing wavelengths within the desired wavelength range.
5. The optical print head of claim 1 , further comprising: d) at least one coupling lens, each laser being optically coupled with the at least one coupling lens, the at least one coupling lens having an optical axis and being movable in a direction substantially parallel to its own optical axis.
6. The optical print head of claim 1 , further comprising: d) a plurality of coupling lenses, each laser being optically coupled with a different one of the coupling lenses.
7. The optical print head of claim 1 , wherein the optical fiber is a photonic crystal fiber adapted for single-mode operation in a wavelength range including the desired wavelength range.
8. The optical print head of claim 1 , wherein the optical fiber is a single-mode optical fiber having a mode field area substantially independent of wavelength.
9. The optical print head of claim 1 , wherein the optical fiber is a single-mode optical fiber having a mode field diameter equal to or larger than a desired recording track width.
10. An optical print head for recording a label on a medium, comprising: a) a plurality of means for emitting coherent light having emissions within a desired wavelength range, b) means for guiding light, adapted to receive combined light from the plurality of means for emitting at a first end thereof and to emit combined output light at a second end thereof, and c) hybrid means for optically coupling, coupled to the second end of the means for guiding light and adapted to focus the combined output light within the desired wavelength range onto the medium.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US11/520,281 | 2006-09-12 | ||
US11/520,281 US7301879B1 (en) | 2006-09-12 | 2006-09-12 | Optical print head |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2008033920A2 true WO2008033920A2 (en) | 2008-03-20 |
WO2008033920A3 WO2008033920A3 (en) | 2008-05-08 |
Family
ID=38721993
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US2007/078267 WO2008033920A2 (en) | 2006-09-12 | 2007-09-12 | Optical print head |
Country Status (2)
Country | Link |
---|---|
US (1) | US7301879B1 (en) |
WO (1) | WO2008033920A2 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2008033918A2 (en) * | 2006-09-12 | 2008-03-20 | Hewlett-Packard Development Company, L.P. | Optical print head with non-gaussian irradiance |
CN109491214A (en) * | 2018-12-04 | 2019-03-19 | 中国科学院上海光学精密机械研究所 | Integrated super-resolution laser direct-writing device and direct-write methods |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8248905B2 (en) * | 2010-10-15 | 2012-08-21 | General Electric Company | Method of parallel bit-wise holographic data storage source using a parallel light source |
EP2602662A1 (en) * | 2011-12-09 | 2013-06-12 | AKK GmbH | Lighting system with a beam combinator for producing sreenprinting templates |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5349471A (en) * | 1993-02-16 | 1994-09-20 | The University Of Rochester | Hybrid refractive/diffractive achromatic lens for optical data storage systems |
US5625403A (en) * | 1993-11-05 | 1997-04-29 | Orbotech Ltd. | Method and apparatus for recording on optically-sensitive media |
US5666447A (en) * | 1994-11-21 | 1997-09-09 | Eastman Kodak Company | Using optical fiber multiplexer to combine light beams in a laser printer |
US5715091A (en) * | 1993-12-29 | 1998-02-03 | Eastman Kodak Company | Hybrid refractive/diffractive achromatic camera lens |
WO2001057580A2 (en) * | 2000-02-03 | 2001-08-09 | Kodak Polychrome Graphics Co. Ltd. | High power laser head system |
US20040190427A1 (en) * | 2003-03-25 | 2004-09-30 | Tatsuro Ide | Optical head |
DE10316534A1 (en) * | 2003-04-10 | 2004-11-04 | Carl Zeiss | Hybrid-optical head mounted display device, has chromatic error correction provided by pre-scaling of image data to provide wavelength-dependent compensation of the imaging scale |
Family Cites Families (28)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4626679A (en) | 1982-09-22 | 1986-12-02 | Canon Kabushiki Kaisha | Optical head and method of detecting the focus thereof |
US4771415A (en) | 1985-02-27 | 1988-09-13 | Brother Kogyo Kabushiki Kaisha | Optical data storage and readout apparatus and head, using optical fibers between stationary and movable units |
JPH02278533A (en) | 1989-04-19 | 1990-11-14 | Eastman Kodatsuku Japan Kk | Optical head device for optical disk |
US5218582A (en) | 1990-12-03 | 1993-06-08 | Eastman Kodak Company | Magneto-optic readout using a polarization-preserving optical guide |
US5453961A (en) | 1993-01-15 | 1995-09-26 | Eastman Kodak Company | Pick-up device for optical disk readout using waveguide gratings |
US5526338A (en) * | 1995-03-10 | 1996-06-11 | Yeda Research & Development Co. Ltd. | Method and apparatus for storage and retrieval with multilayer optical disks |
US5940549A (en) | 1996-07-30 | 1999-08-17 | Seagate Technology, Incorporated | Optical system and method using optical fibers for storage and retrieval of information |
US5850375A (en) | 1996-07-30 | 1998-12-15 | Seagate Technology, Inc. | System and method using optical fibers in a data storage and retrieval system |
US6081499A (en) | 1997-05-05 | 2000-06-27 | Seagate Technology, Inc. | Magneto-optical data storage system having an optical-processing flying head |
US6034938A (en) | 1996-07-30 | 2000-03-07 | Seagate Technology, Inc. | Data storage system having an optical processing flying head |
JP3403327B2 (en) | 1998-02-27 | 2003-05-06 | 古河電気工業株式会社 | Field distribution conversion optical fiber and laser diode module using the field distribution conversion optical fiber |
US6298027B1 (en) | 1998-03-30 | 2001-10-02 | Seagate Technology Llc | Low-birefringence optical fiber for use in an optical data storage system |
US6088322A (en) | 1998-05-07 | 2000-07-11 | Broome; Barry G. | Single objective lens for use with CD or DVD optical disks |
JP2000067458A (en) | 1998-08-24 | 2000-03-03 | Sony Corp | Optical disk device |
DE60034825T2 (en) | 1999-01-22 | 2008-03-13 | Konica Minolta Opto, Inc., Hachioji | Optical scanning device for information recording and information reproduction |
US6545807B2 (en) | 1999-12-28 | 2003-04-08 | Pentax Corporation | Refractive-diffractive hybrid lens |
US20020164106A1 (en) | 2000-05-30 | 2002-11-07 | Takeshi Mizuno | Optical disk device and optical pickup device |
KR100708097B1 (en) | 2000-07-24 | 2007-04-16 | 삼성전자주식회사 | Optical recoding and/or reproducing apparatus using swing arm actuator and Optical disc adopting thereof |
US6873590B2 (en) | 2001-03-09 | 2005-03-29 | Pentax Corporation | Objective lens for optical pick-up |
FR2822243B1 (en) | 2001-03-16 | 2003-06-20 | Cit Alcatel | DUAL SHEATH PHOTONIC OPTICAL FIBER |
US7206276B2 (en) * | 2001-10-12 | 2007-04-17 | Konica Corporation | Objective lens, optical element, optical pick-up apparatus and optical information recording and/or reproducing apparatus equipped therewith |
JP2003207672A (en) | 2002-01-17 | 2003-07-25 | Sony Corp | Optical fiber, optical fiber module, and optical pickup |
KR100468855B1 (en) | 2002-11-11 | 2005-01-29 | 삼성전자주식회사 | Hybrid lens with high numerical number |
JP3909014B2 (en) | 2002-12-11 | 2007-04-25 | 日本電信電話株式会社 | Single mode photonic crystal optical fiber |
CA2509790C (en) | 2003-08-13 | 2010-10-12 | Nippon Telegraph And Telephone Corporation | Structured tellurite glass optical fiber and production method thereof |
US7483184B2 (en) | 2003-10-09 | 2009-01-27 | Hewlett-Packard Development Company, L.P. | Method and system for using an optical sensor array to control a labeling device |
US7315493B2 (en) | 2004-01-30 | 2008-01-01 | Hewlett-Packard Development Company, L.P. | Apparatus and method for calibrating a laser imagible apparatus |
US7231122B2 (en) | 2004-04-08 | 2007-06-12 | Omniguide, Inc. | Photonic crystal waveguides and systems using such waveguides |
-
2006
- 2006-09-12 US US11/520,281 patent/US7301879B1/en not_active Expired - Fee Related
-
2007
- 2007-09-12 WO PCT/US2007/078267 patent/WO2008033920A2/en active Application Filing
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5349471A (en) * | 1993-02-16 | 1994-09-20 | The University Of Rochester | Hybrid refractive/diffractive achromatic lens for optical data storage systems |
US5625403A (en) * | 1993-11-05 | 1997-04-29 | Orbotech Ltd. | Method and apparatus for recording on optically-sensitive media |
US5715091A (en) * | 1993-12-29 | 1998-02-03 | Eastman Kodak Company | Hybrid refractive/diffractive achromatic camera lens |
US5666447A (en) * | 1994-11-21 | 1997-09-09 | Eastman Kodak Company | Using optical fiber multiplexer to combine light beams in a laser printer |
WO2001057580A2 (en) * | 2000-02-03 | 2001-08-09 | Kodak Polychrome Graphics Co. Ltd. | High power laser head system |
US20040190427A1 (en) * | 2003-03-25 | 2004-09-30 | Tatsuro Ide | Optical head |
DE10316534A1 (en) * | 2003-04-10 | 2004-11-04 | Carl Zeiss | Hybrid-optical head mounted display device, has chromatic error correction provided by pre-scaling of image data to provide wavelength-dependent compensation of the imaging scale |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2008033918A2 (en) * | 2006-09-12 | 2008-03-20 | Hewlett-Packard Development Company, L.P. | Optical print head with non-gaussian irradiance |
WO2008033918A3 (en) * | 2006-09-12 | 2008-07-31 | Hewlett Packard Development Co | Optical print head with non-gaussian irradiance |
CN109491214A (en) * | 2018-12-04 | 2019-03-19 | 中国科学院上海光学精密机械研究所 | Integrated super-resolution laser direct-writing device and direct-write methods |
Also Published As
Publication number | Publication date |
---|---|
WO2008033920A3 (en) | 2008-05-08 |
US7301879B1 (en) | 2007-11-27 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US6650612B1 (en) | Optical head and recording reproduction method | |
JP3014553B2 (en) | Recording and / or reproducing apparatus for optical recording tape | |
US7616550B2 (en) | Optical pickup unit | |
US6211511B1 (en) | Dual-wavelength optical pickup head | |
US7809259B2 (en) | Optical disk and optical disk device | |
JP6289384B2 (en) | Optical storage device using direct reading after writing | |
US7301879B1 (en) | Optical print head | |
EP1327977A1 (en) | Optical record medium, optical information processing apparatus, and optical recording/reproducing method | |
JP2003123307A (en) | Optical head and disk device | |
JP2008262692A (en) | Optical pickup device compensating thickness deviation of optical recording medium | |
JP4186526B2 (en) | Information recording and / or reproducing apparatus and optical head | |
US6912234B2 (en) | Optical pickup apparatus and laser diode chip | |
US20080062242A1 (en) | Optical print head with non-Gaussian irradiance | |
JP2000132859A (en) | Optical storage device and optical pickup | |
JPWO2005101383A1 (en) | Information processing device | |
JP2004335060A (en) | Optical recording medium, and optical recording and reproducing device | |
JP2002319157A (en) | Signal recording device, signal reproducing device, and method for signal recording and signal reproducing | |
JP2001126290A (en) | Optical pickup device | |
US8427924B2 (en) | Optical pickup apparatus | |
US7839754B2 (en) | Optical head and optical disk device | |
JP2006309850A (en) | Optical head device and information recording and reproducing apparatus | |
JP2002133703A (en) | Optical pickup device and optical disk device | |
US7848212B2 (en) | Acousto-optic reading/recording head for high-density optical disks | |
US7729216B2 (en) | Methods and apparatus for marking media with collimated electromagnetic radiation beam | |
JP4248314B2 (en) | Optical pickup device |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 07842324 Country of ref document: EP Kind code of ref document: A2 |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 07842324 Country of ref document: EP Kind code of ref document: A2 |