WO2006030789A1 - 光ヘッド装置 - Google Patents
光ヘッド装置 Download PDFInfo
- Publication number
- WO2006030789A1 WO2006030789A1 PCT/JP2005/016851 JP2005016851W WO2006030789A1 WO 2006030789 A1 WO2006030789 A1 WO 2006030789A1 JP 2005016851 W JP2005016851 W JP 2005016851W WO 2006030789 A1 WO2006030789 A1 WO 2006030789A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- wavelength
- optical
- phase plate
- optical head
- head device
- Prior art date
Links
Classifications
-
- 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
- G11B7/1365—Separate or integrated refractive elements, e.g. wave plates
- G11B7/1369—Active plates, e.g. liquid crystal panels or electrostrictive elements
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
- G02B5/3083—Birefringent or phase retarding elements
-
- 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
- G11B7/1365—Separate or integrated refractive elements, e.g. wave plates
-
- 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
- G11B2007/0003—Recording, reproducing or erasing systems characterised by the structure or type of the carrier
- G11B2007/0006—Recording, reproducing or erasing systems characterised by the structure or type of the carrier adapted for scanning different types of carrier, e.g. CD & DVD
Definitions
- the present invention relates to an optical head device equipped with a broadband phase plate for controlling the phase state of laser light.
- An optical head device is used to write optical information on an optical recording medium such as an optical disk and a magneto-optical disk and to read optical information.
- This optical head device collects light emitted from a semiconductor laser as a light source on a recording surface of a disk-shaped optical recording medium (hereinafter referred to as “optical disk”) by an objective lens, and writes and reads information. Make out. When information is read out, the emitted light reflected from the information recording surface of the optical disk is received by a photodetector.
- this optical head device has shortened the wavelength of light emitted from the light source (405 nm). Is underway.
- this optical head device it is necessary to be able to simultaneously perform reproduction with long-wavelength (660 nm and 790 nm) laser beams for many optical disks that have been widely used. For this reason, various system powers having compatibility of an optical disk with conventional laser light on the longer wavelength side and laser light on the shorter wavelength side have been proposed, for example, in JP-A-2004-158118.
- the forward path refers to the direction in which the emitted light from the light source travels toward the optical disk
- the return path refers to the reflected light reflected from the information recording surface of the optical disk. In this direction, the reflected light is directed toward the photodetector, that is, the reflected return light travels.
- FIG. 14 shows an example of the configuration of an optical head device having a polarization optical system using three different, ie, three types of laser beams.
- the linearly polarized laser beams from the semiconductor laser 101A having an emission wavelength of 405 nm, the semiconductor laser 101B having a wavelength of 660 nm, and the semiconductor laser 101C having a wavelength of 790 nm are highly transmissive for incident linearly polarized light.
- the polarization hologram 102A, the 660 nm polarization hologram 102B, and the 790 nm polarization hologram 102C are respectively transmitted.
- the linearly polarized laser light is linearly polarized by the 405 nm 1/4 wavelength plate 103A, the 660 nm 1/4 wavelength plate 103B and the 790 nm 1Z4 wavelength plate 103C, which are integrated with the polarization hologram, respectively.
- Force Converted to circularly polarized light After that, the laser light becomes parallel light by the collimating lens 104A, the collimating lens 104B, and the collimating lens 104C that are individually arranged, and is transmitted and reflected by the beam splitter 105 having the characteristics of 405 nm transmission and 660 nm reflection. And transmits and reflects the beam splitter 106 having the characteristics of 790 nm reflection and strong 660 nm transmission.
- This laser light is collected on the information recording surface of the optical disc D (hereinafter simply referred to as “the surface of the optical disc!”) By the objective lens 108 that is held in the actuator 107 and is common to the three wavelengths. To do.
- the reflected light of the optical disk D force including information of pits formed on the surface of the optical disk travels in the opposite direction along each path. That is, the circularly polarized light whose rotation direction is reversed by the reflection of the surface of the optical disk D is transmitted again through the 1Z4 wavelength plate 103A, the 1Z4 wavelength plate 103B, and the 1Z4 wavelength plate 103C, respectively, and has a polarization direction orthogonal to the incident polarization direction. It is converted into linearly polarized light, and is diffracted by the polarization hologram 102A, the polarization hologram 102B, and the polarization hologram 102C, respectively, and becomes diffracted light.
- the information on the pits of the optical disk D possessed by these diffracted lights is detected on the surface of the optical disk D by detecting the photodiodes 109A, 109B and 790nm photodiodes 109A and 790nm, which are photodetectors for 405nm.
- the recorded information is read out.
- an optical element such as a 1Z4 wavelength plate is shared. It has been proposed (see, for example, JP-A-10-68816).
- phase plate (1Z4 wavelength plate) that converts linearly polarized light of two wavelengths, for example, linearly polarized light of wavelengths 405 nm and 660 nm into circularly polarized light, is completely circularly polarized for linearly polarized light of wavelength 790 nm
- a phase plate that converts linearly polarized light with wavelengths of 660 nm and 790 nm to circularly polarized light cannot be completely circularly polarized with respect to 405 nm linearly polarized light, and the desired characteristics cannot be obtained.
- Japanese Patent Application Laid-Open No. 14-156528 describes that a broadband phase plate can be formed by a single sheet without laminating phase plates.
- This broadband phase plate is designed so that the retardation value decreases as the wavelength becomes shorter.
- material design is extremely difficult and high light utilization is required. It was not satisfactory for high recording density.
- Blu-Ray Disk which is expected as a next-generation standard in which the wavelength of the light source is further shortened, is required to have higher light utilization efficiency.
- optical elements such as the aforementioned 1Z4 wavelength plate do not have sufficient characteristics.
- the volume of the device is increased and time is required for assembly adjustment.
- the present invention has been made in view of the above circumstances, and in an optical head device using laser light of three or more different wavelengths as a light source, by sharing an optical element at each wavelength, Small and cost-saving, reducing the number of parts and shortening assembly time
- An object of the present invention is to provide an optical head device capable of achieving the above.
- the present invention has the following gist.
- optical head device in which linearly polarized laser light emitted from a light source is collected by an objective lens and guided to an optical recording medium, and reflected light from the optical recording medium is received by a photodetector.
- the laser beam is one of three or more laser beams having different wavelengths, and a broadband phase plate for controlling the phase state of the laser beam is installed between the light source and the objective lens.
- the broadband phase plate is formed by stacking two phase plates so that their optical axes cross each other, and the laser beam has a wavelength of 1, ⁇
- the laser beam has any one of a wavelength, ⁇ , and
- the at least one phase plate has a retardation value R () tR (
- the retardation value R () / R (;)> is larger than the wavelength ratio value ( ⁇ / ⁇ ).
- R () / R ()) is the ratio of the ratio of the wavelength R () tR () and the ratio of the wavelengths ( ⁇ / ⁇ )
- R () / R (;)> is a ratio value with a retardation value R () tR () greater than 3 2 2 3 2 3
- the retardation value of the phase plate on which the laser beam is incident on the first is larger than the retardation value of the phase plate on which the laser beam is incident on the second, and 3.
- the optical head device according to 1 or 2 above, wherein the ratio of the two retardation values is 1.8 to 2.2.
- Cross angle force of each optical axis of the two phase plates is in the range of 0-70 degrees, 4.
- the optical head device according to any one of items 1 to 3.
- optical head device according to any one of 1 to 4, wherein the broadband phase plate has substantially the same ellipticity in each wavelength region when the laser beams having the three wavelengths are transmitted.
- the two phase plates are overlapped via an adhesive layer, and the thickness of the adhesive layer is 10
- optical head device according to any one of 1 to 5 above, which is not more than / z m.
- At least one of the two broadband phase plates to be stacked has a phase in which the retardation value decreases as the wavelength decreases.
- a plate By using a plate, it can function as a 1Z4 wavelength plate for one linearly polarized laser beam with three or more wavelengths to be transmitted, and linearly polarized light can be made circularly polarized. Can be shared, reduce the number of parts, shorten the assembly time, and provide a compact and low-cost optical head device.
- FIG. 1 is a configuration diagram showing an optical head device according to an embodiment of the present invention.
- FIG. 2 is a schematic cross-sectional view showing a configuration of a broadband phase plate according to an embodiment of the present invention.
- FIG. 3 is a graph showing the wavelength dependence of the retardation value for the transmitted light of the broadband phase plate of the present invention shown in FIG.
- FIG. 4 is a graph showing the wavelength dependence of ellipticity with respect to the transmitted light of the broadband phase plate in the present invention.
- FIG. 5 is a graph showing the wavelength dependence of the retardation value for the transmitted light of the comparative broadband phase plate.
- FIG. 6 is a graph showing the wavelength dependence of the ellipticity with respect to the transmitted light of the broadband phase plate of the comparative example.
- FIG. 7 is a graph showing the wavelength dependence of the retardation value for the transmitted light in the phase plate of Example 2
- FIG. 8 is a graph showing the wavelength dependence of ellipticity with respect to the transmitted light of the broadband phase plate of Example 2.
- FIG. 9 is a graph showing the wavelength dependence of the retardation value for the transmitted light in the phase plate of Example 3.
- FIG. 10 is a graph showing the wavelength dependence of ellipticity with respect to the transmitted light of the broadband phase plate of Example 3.
- FIG. 12 A graph showing FIG. 11 in three dimensions.
- FIG. 14 is a configuration diagram showing a conventional optical head device.
- FIG. 1 shows an optical head device according to an embodiment of the present invention.
- This optical head device includes a light source 1, collimating lenses 2A to 2C, first and second beam splitters 3 and 4,
- the polarization hologram 8 In addition to the objective lens 6 common to the three wavelengths held by the actuator 5 and the light receiving element 7, the polarization hologram 8 and (composed of a broadband phase plate that controls the phase state of the three types of laser light) 1Z4
- a broadband optical element 10 in which a wave plate 9 is integrated is installed between a light source 1 and an objective lens 6.
- the light source 1 is composed of semiconductor lasers 1A, IB, and 1C that emit three types of laser beams having different wavelengths.
- the light receiving element 7 also uses the first to third photodiodes 7A to 7C according to the wavelength of each laser beam.
- the polarization hologram 8 and the 1Z4 wavelength plate 9 are integrally formed and are mounted substantially horizontally with respect to the objective lens 6 mounted on the actuator 5.
- the 1Z4 wave plate 9 used here is a broadband phase plate 90 according to the present invention.
- the broadband phase plate 90 has a structure in which two phase plates are integrally stacked so as to cross the optical axes.
- the broadband phase plate 90 of the present embodiment has a wavelength of laser light
- the retardation value at each wavelength that is, the ratio value of R (), R () and R ()
- Equation (1) shows that R () ⁇ R () ⁇ R () between the retardation values at each wavelength.
- phase difference generated by the phase plate increases with an increase in wavelength, and the longer the wavelength, the larger the phase difference, and a broadband phase plate can be obtained.
- the broadband phase plate 90 functions as a substantially 1Z4 wavelength plate with respect to a linearly polarized laser beam of any wavelength that passes therethrough, and the linearly polarized light can be substantially circularly polarized.
- a birefringent material used for a broadband phase plate has a wavelength dependency that the retardation value increases as the wavelength becomes shorter, such as a polycarbonate film that has been made birefringent by stretching.
- the birefringent material used in the present invention has a characteristic that the retardation value decreases as the wavelength becomes shorter (hereinafter referred to as “abnormal dispersion characteristic”).
- the birefringent material having the anomalous dispersion characteristics include the following materials: As long as the material exhibits anomalous dispersion characteristics, the phase plate material of the present invention is not limited at all.
- a copolymer comprising a monomer unit of a polymer having a positive birefringence (that is, a difference between an extraordinary refractive index and an ordinary refractive index) and a monomer unit of a polymer having a negative birefringence. And a film obtained by stretching a cocoon or blend polymer (see Japanese Patent Application Laid-Open No. 2002-156528),
- R 3 each independently a hydrogen atom or a methyl group.
- R 2 an alkyl group having 2 to 8 carbon atoms.
- J 2 and J 3 each independently a single bond, OCO or COO—.
- E 2 , E 3 each independently 1, 4 phenylene group or trans 1, 4 cyclohexylene group.
- the hydrogen atom in these groups may be substituted with a chlorine atom, a fluorine atom, a methyl group or a cyan group! /.
- W 2 Independently, naphthalene 1,4-diinole group, naphthalene 1,1,5 diyl group, anthracene 1,1,4 diyl group, anthracene 1,5-diyl group, anthracene 1,1,10 diyl group, anthracene one 4,9 diyl group, anthracene 5,9 diyl group or anthracene—9,10 diyl group.
- the hydrogen atom in these groups may be substituted with a chlorine atom, a fluorine atom, a methyl group or a cyan group.
- M A group represented by the following formulas (a) to (f) is also selected, which is a deviation group.
- Examples of such materials include the following compounds.
- the description will be made assuming that the emitted laser light has a configuration with three different wavelength forces.
- the laser light used in the optical head device of the present invention is not limited to this. There may be.
- typical phase difference combinations of two phase plates (this are referred to as “first and second phase plates”) constituting the broadband phase plate 90 in the present embodiment are as follows, for example. To do.
- the retardation values generated by the first and second phase plates, that is, the first and second phase plates are respectively represented by R1 and Let R2.
- the retardation value generated when light of wavelength 1 is incident on the first phase plate is R (e), and light of wavelength ⁇ is the second
- the retardance value generated when entering the phase plate is defined as R ( ⁇ ).
- the ratio of the retardation value R at each wavelength satisfies the above-mentioned equation (1), that is, R ( ⁇ ) / R () and R () / R () are smaller than 1, respectively R () / R ()
- Equation (3) The relationship between the retardation value ratio and the wavelength ratio expressed by Equation (3) is that the wavelength is ⁇
- Equation (3) is derived by modifying Equation (4), which is a condition that the rate of change in the retardation value is smaller than the proportion of change in wavelength.
- equation (3) is more gradual than the ratio of decreasing (or increasing!) Wavelength.
- the phase difference decreases (or increases) and becomes a condition.
- the phase difference of the wavelength changes more gradually, and therefore the change of the phase difference becomes smaller than the rate of change of the incident wavelength. The effect that the ratio is difficult to change is obtained.
- the retardation value generated by the first phase plate is approximately 1Z2 times the wavelength, and the retardation value R at each wavelength R (the second phase plate is
- the resulting retardation value is approximately 1Z4, and the ratio R of these retardation values is
- One wavelength is about 9 ⁇ 2 times, and the retardation value R at each wavelength is about 9 ⁇ 4.
- the ratio R ZR may be 1.8 to 2.2. Again, wideband 1Z4 wavelength
- It can be a board.
- the change in ellipticity angle from 8 to 2.2 is shown in a two-dimensional display, and the graph in Fig. 12 shows the same change in a three-dimensional display (wavelength is 695 nm).
- the ellipticity is 1.0 or the maximum value very close to this. If the ellipticity is 0.8 or more, it functions practically as a 1Z4 wavelength plate, and if it is 0.9 or more, it is more preferable. Also, you can understand this situation well by looking at the 3D graph. However, in the graph of Fig. 12, the area where the ellipticity is smaller than 0.8 is also drawn as 0.8 for easy understanding.
- the ellipticity is expressed as I / ⁇ b a where the major axis intensity of the transmitted elliptical polarization is Ia and the minor axis intensity is lb. When the ellipticity is 1, it corresponds to perfect circular polarization.
- the thickness of the two phase plates in the present invention is determined from the problems of light transmission efficiency and manufacturing process.
- the birefringence amount ⁇ of the birefringent material that is preferably in the range of 2 to L0 m is ,wave When the length is 589 nm, it is preferable that the phase difference is in the range of 0.01 to 0.2 because the phase difference can be freely selected.
- an adhesive film, a UV curable adhesive, or a thermosetting adhesive can be used to overlap the two phase plates.
- the adhesive layer In order to reduce wavefront aberration and improve temperature characteristics and reliability of broadband phase plates, it is desirable to make the adhesive layer as thin as possible, and in particular, the adhesive layer thickness should be 10 m or less.
- the crossing angle of the optical axes of the first and second phase plates when superposed is such that the ellipticity increases in a wide wavelength range from 40 to 70 degrees and a wavelength of about 400 nm force to about 79 Onm. Although it is preferable for the reason that it can be made to be 8 or more, it is not particularly limited as long as it is overlapped at each optimized crossing angle of the optical axis.
- the angles formed by the optical axis directions of the first and second phase plates constituting the broadband phase plate and the polarization direction of the linearly polarized light incident on the broadband phase plate are ⁇ , ⁇
- the ellipticity is very close to 1.0 at these wavelengths.
- the graph shows the distance between two peak wavelengths where the ellipticity is 1.0 by changing the value of a.
- the position can be designed freely. At this time, the ellipticity of the third wavelength is large as described above.
- the position may be either the wavelength or the wavelength, or the wavelength or the wavelength.
- Figure 13 shows the general theory and
- the broadband phase plate according to the present invention it is desirable that the surface be smoothed or adhered and held by the substrate in order to avoid deterioration of wavefront aberration of transmitted light. Specifically, it is desirable to use a broadband phase plate bonded to at least one transparent substrate. When a broadband phase plate is used alone without being laminated and integrated with other optical elements, a configuration in which it is sandwiched between two transparent substrates is desirable in terms of reducing wavefront aberration and ensuring strength.
- the broadband phase plate according to the present invention can be used alone, but by stacking and integrating with other optical elements used in the optical head device, the number of parts can be reduced, the assembly of the optical head device can be simplified, and the device Miniaturization can be realized. Therefore, the broadband phase plate is preferably integrated with at least one optical element that changes the optical properties of the laser light.
- an optical element is a phase correction element that uses, for example, liquid crystal to improve the light collection characteristics on an optical disc, or a diffraction grating that guides signal light to a detector by diffraction, especially the difference in diffraction characteristics depending on the polarization direction. And a polarization type diffraction grating using.
- the wideband phase plate according to the present invention is particularly effective when used in an optical head device having an optical element that utilizes the difference in characteristics depending on the polarization direction. Recording and reproduction of optical information that is required to be further reduced in size and weight. Suitable for parts for optical head devices used in Next, the operation of the present embodiment will be described with reference to FIG.
- the laser beams emitted from the semiconductor laser 1A having a wavelength of 405 nm, the semiconductor laser IB having a wavelength of 660 nm, and the semiconductor laser 1C having a wavelength of 790 nm are collimated by the collimating lenses 2 A to 2 C, and pass through the beam splitter 3 and the beam splitter 4. Then, the light passes through the polarization hologram 8 and the 1Z4 wavelength plate 9 and is focused on the optical disk D by the objective lens 6. On the other hand, the reflected light including the pit information reflected by the pits formed on the surface of the optical disc D travels in the opposite directions.
- the return light from the optical disk D transmitted or reflected by the beam splitter 4 and the beam splitter 3 is transmitted through the collimating lenses 2A to 2C, respectively, and the 405 nm photodiode 7A, the 660 nm photodiode 7B, and the 790 nm photodiode 7C. Is detected.
- the polarization hologram 8 is optimized for a laser beam having one of three wavelengths, or is optimized for 405 nm and 660 nm. For all wavelengths, the forward path exhibits high transmission characteristics, and the return path does not cause a problem of reduced efficiency.
- the broadband phase plate 90 of the present embodiment is formed by integrating first and second phase plates 9A and 9B.
- a transparent substrate having a diameter of 12.5 cm and a thickness of 0.5 mm in which a low-reflection coating film 91A is applied to one side surface (lower surface in the figure) on which laser light is incident.
- a glass substrate 92A is prepared, a polyimide film is formed on the surface opposite to the light source 1 (see Fig. 1) of the glass substrate 92A (the upper surface in the figure), and a horizontal alignment process is performed by rubbing to obtain a polyimide film.
- 93A On this glass substrate 92A subjected to the alignment treatment, 310 beads (3.3 111 in diameter) (in order to maintain a gap with a glass substrate surface 92B, which is a transparent substrate to be described later, which becomes a liquid crystal cell)
- the entire liquid crystal material is irradiated with UV light having a wavelength of 365 nm, and the entire liquid crystal monomer composition is polymerized and solidified in the horizontal alignment state, thereby fixing the entire composition of the glass substrate.
- the horizontally aligned counter glass substrate (not shown) was removed from the mold, and the horizontally aligned polymer liquid crystal thin film with a thickness of 6.6 m 9
- the organic thin film 4 is formed to produce the phase plate 9A.
- phase plate 9B on which an organic thin film of a horizontally aligned polymer liquid crystal thin film 95 having a thickness of 3.3 m is formed. create.
- the retardation values of the first phase plate 9A and the second phase plate 9B are measured, anomalous dispersion characteristics can be obtained in which the retardation value decreases as the wavelength decreases, as shown in FIG.
- the retardation ratio at each wavelength of the first phase plate 9A and the second phase plate 9B is almost double in the wavelength band of 400 to 800 nm.
- the birefringence of the organic thin film at this time is 0.0361 when the wavelength is 405 nm, 0.0473 when the wavelength is 660 nm, and 0.05 when the wavelength is 790 nm.
- ⁇ represents a retardation value for each wavelength of the first phase plate 9A
- ⁇ represents a retardation value for each wavelength of the first phase plate 9A.
- R () / at each wavelength is calculated and its it force is 8.91: 7.17: 6.33 for wavelengths of 405 nm, 660 nm, and 790 nm, and decreases as the wavelength increases. You can see that That is, the increase rate of the retardation value is smaller than the increase rate of the wavelength.
- each organic thin film side of the first phase plate 9A and the second phase plate 9B is set inside, and a UV curable adhesive is dropped between them and placed in a spin coater, and the rotational speed of lOOOrpm Rotate at a rotational speed of 5000 rpm for 20 seconds at 100 rpm for a thickness of 5 m of adhesive layer 96 .
- the first phase plate 9A and the second phase plate 9B are arranged so that the intersection angle of the optical axes is 57 degrees.
- Broadband phase plate 90 is diced to 5mm x 5mm with a reference of the direction of the first phase plate 9A relative to the optical axis of 20A (the horizontal direction on the paper is 0 °). A phase plate element is obtained.
- the light emitted from a semiconductor laser with a wavelength of 860 nm is used as the fundamental wave, the second harmonic wavelength 430 nm laser light generated using nonlinear optical crystal KNbO and the wavelength 660 ⁇
- the ellipticity of the broadband phase plate 90 is measured using the light emitted from the m semiconductor laser and the light emitted from the semiconductor laser having a wavelength of 789 nm.
- the ellipticity to be measured is about 0.96 for laser light with a wavelength of 430 nm, about 0.97 for laser light with a wavelength of 660 nm, and about 0.97 for laser light with a wavelength of 789 nm. It is a sufficient characteristic.
- the wavefront aberration of the broadband phase plate 90 of this example is less than 25 ml rms (root mean square) when measured using a He-Ne laser with a wavelength of 633 nm, and can be used as an optical element sufficiently. Is a level.
- This broadband phase plate 90 is incorporated as a 1 Z4 wavelength plate 9 of the optical head device shown in FIG.
- 405 nm, 660 nm, and 790 nm semiconductor lasers are respectively installed as the light source 1 of the optical head device. As a result, satisfactory circularly polarized light can be obtained for laser light having three wavelengths of 405 nm, 660 nm, and 790 nm, and signal light can be obtained with high light utilization efficiency.
- the birefringent material having the normal dispersion characteristic a monomer that forms a general side chain polymer liquid crystal is used.
- a broadband phase plate using this liquid crystal monomer is prepared in the same way as “Example 1”.
- the thickness of the first phase plate on the incident side is 5.2 / ⁇ ⁇
- the emission side The thickness of the second phase plate is 2.
- the phase plates are arranged so that the crossing angle of the optical axes is 56 degrees.
- the retardation values of the incident-side and emission-side phase plates in this broadband phase plate are as shown in the graphs ⁇ and ⁇ in FIG. 5, and the retardation value increases as the wavelength becomes shorter, that is, it has normal dispersion characteristics. I understand.
- the birefringence of the organic thin film at this time is 0.0508 at a wavelength of 405 nm, 0.0453 at a wavelength of 660 nm, and 0.0443 at a wavelength of 790 nm.
- the wavelength dispersion of the ellipticity in each wavelength region was investigated using the broadband phase plate of this comparative example, the wavelength dispersion of this ellipticity is as shown in FIG. It showed about 0.99 for light, about 0.99 for laser light with a wavelength of 660 nm, and about 0.82 for laser light with a wavelength of 789 nm.
- Example 2 shows the case where two types of liquid crystal monomers are used as materials having anomalous dispersion characteristics.
- the two types of liquid crystal monomers have a birefringence amount of 0.0361 at a wavelength of 405 nm, 0473 at a wavelength of 660 nm, and 0 at a wavelength of 790 nm.
- a liquid crystal monomer of 0500 and a liquid crystal monomer of 0.0194 at a wavelength of 405 nm, 0.0239 at a wavelength of 660 nm and 0.0250 at a wavelength of 790 nm are used.
- a broadband phase plate is produced in the same manner as in “Example 1”. At this time, the thickness of the first phase plate on the incident side is 6.6 m, and the thickness of the second phase plate on the output side is 6.
- the crossing angle of the optical axes of these phase plates is 61 degrees. Arrange them as follows.
- the retardation values of the first and second phase plates on the incident side and the emission side are as shown in FIG. 7, and the retardation value on the emission side becomes shorter as the wavelength becomes shorter. It has anomalous dispersion characteristics with a small value.
- this wavelength dispersion is as shown in FIG. 8, and is about 0.9 for a laser beam having a wavelength of 430 nm. 6. About 0.96 for laser light with a wavelength of 660 nm and about 0.96 for laser light with a wavelength of 789 nm. Comparing Fig. 8 with Fig. 4, which is the expected result of ellipticity chromatic dispersion performed in "Example 1", it can be seen that the chromatic dispersion characteristics are almost the same. In addition, as is clear from FIG. 8 of “Example 2”, the ellipticity is constant regardless of the wavelength, compared to FIG. 6 of Comparative Example 1, and almost perfect in a broad wavelength band. It can be seen that it is a 1Z4 wavelength plate.
- the following compound (1A), the following compound (1B), the following compound (1C) and the following compound (1U) were mixed in a 6: 8: 6: 5 (molar ratio) to obtain a liquid crystal composition A.
- the amount of birefringence was 0.0071 at a wavelength of 405 nm, 0.0105 at a wavelength of 660 ⁇ m, and 0.005 at a wavelength of 790 nm. Met.
- R () / at each wavelength is calculated from these values, its it force is 1.65: 1.59: 1.35 for wavelengths 405nm, 660nm and 790nm, and decreases with increasing wavelength. You can see that That is, the increase rate of the retardation value is smaller than the increase rate of the wavelength.
- a broadband phase plate is produced in the same manner as in “Example 1”.
- the thickness of the first phase plate on the incident side is 31.5 / ⁇ ⁇
- the thickness of the second phase plate on the output side is 15.
- the crossing angle of the optical axes of these phase plates is 59 degrees. Arrange to be at an angle.
- anomalous dispersion characteristics were obtained in which the retardation value decreased as the wavelength decreased as shown in FIG.
- the retardation ratio at each wavelength of the second phase plate 9A and the second phase plate 9B is almost double in the wavelength band of 400 to 800 nm.
- Fig. 10 is the measurement result of ellipticity chromatic dispersion performed in "Example 1”
- Fig. 4 which is the measurement result of ellipticity chromatic dispersion performed in "Example 1”
- the ellipticity is constant regardless of the wavelength, compared to FIG. 6 of Comparative Example 1, and almost perfect in a wide band of power. It can be seen that it is a 1Z4 wavelength plate.
- the present invention is not limited to the above-described embodiment, and can be implemented in various forms without departing from the gist thereof. That is, it is obvious that the present invention can be applied not only to the wideband castle 1 Z4 wavelength plate but also to the broadband 1Z2 wavelength plate and the broadband 3Z4 wavelength plate. In addition, various applications can be made without departing from the effects of the present invention.
- the optical head device of the present invention has a retardation value that decreases as the wavelength decreases in at least one of the two wideband phase plates to be laminated.
- a phase plate By using such a phase plate, it functions as a 1Z4 wavelength plate for the linearly polarized laser beam having three or more wavelengths to be transmitted, and has the effect that the linearly polarized light can be made circularly polarized. For this reason, it is possible to share an optical element for each wavelength, reduce the number of parts, and provide a compact and low-cost optical head device with reduced assembly time.
- the broadband phase plate of the present invention acts as a substantially complete 1Z4 wavelength plate in the entire wavelength band to be used, there is a problem even if the wavelength of light emitted from the semiconductor laser varies due to a lot difference or the like. Linearly polarized light can be converted to circularly polarized light.
Landscapes
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Optical Head (AREA)
- Polarising Elements (AREA)
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2006535152A JP5034501B2 (ja) | 2004-09-14 | 2005-09-13 | 光ヘッド装置 |
US11/686,131 US7986606B2 (en) | 2004-09-14 | 2007-03-14 | Optical head device |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2004266728 | 2004-09-14 | ||
JP2004-266728 | 2004-09-14 |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11/686,131 Continuation US7986606B2 (en) | 2004-09-14 | 2007-03-14 | Optical head device |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2006030789A1 true WO2006030789A1 (ja) | 2006-03-23 |
Family
ID=36060040
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2005/016851 WO2006030789A1 (ja) | 2004-09-14 | 2005-09-13 | 光ヘッド装置 |
Country Status (5)
Country | Link |
---|---|
US (1) | US7986606B2 (ja) |
JP (1) | JP5034501B2 (ja) |
KR (1) | KR20070048778A (ja) |
TW (1) | TW200623097A (ja) |
WO (1) | WO2006030789A1 (ja) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2008198244A (ja) * | 2007-02-08 | 2008-08-28 | Asahi Glass Co Ltd | 広帯域波長板 |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7894321B2 (en) * | 2005-09-28 | 2011-02-22 | Epson Toyocom Corporation | Laminated wave plate and optical pickup using the same |
US7907499B2 (en) * | 2006-07-26 | 2011-03-15 | Konica Minolta Holdings, Inc. | Optical element, optical element manufacturing method and optical pickup device |
JP5316409B2 (ja) * | 2007-07-27 | 2013-10-16 | 旭硝子株式会社 | 位相差素子および光ヘッド装置 |
KR20170011306A (ko) * | 2015-07-22 | 2017-02-02 | 삼성전자주식회사 | 광학 필름, 그 제조 방법 및 표시 장치 |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2001004841A (ja) * | 1999-06-24 | 2001-01-12 | Matsushita Electric Ind Co Ltd | 光学素子と光ヘッドと光記録再生装置 |
JP2001101700A (ja) * | 1999-09-30 | 2001-04-13 | Asahi Glass Co Ltd | 光ヘッド装置 |
JP2002156528A (ja) * | 1998-10-30 | 2002-05-31 | Teijin Ltd | 熱可塑性高分子フィルム |
JP2003098350A (ja) * | 2001-09-21 | 2003-04-03 | Ricoh Co Ltd | 光学素子、該光学素子を用いた光ピックアップ装置及び光ディスクドライブ装置 |
JP2003329840A (ja) * | 2002-05-16 | 2003-11-19 | Teijin Ltd | 熱安定性に優れた位相差フィルム、及び偏光変換素子 |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH1068816A (ja) | 1996-08-29 | 1998-03-10 | Sharp Corp | 位相差板及び円偏光板 |
TW424154B (en) * | 1998-10-30 | 2001-03-01 | Teijin Ltd | Phase film and optical device using same |
US6580674B1 (en) * | 1999-08-26 | 2003-06-17 | Asahi Glass Company, Limited | Phase shifter and optical head device mounted with the same |
US7050380B2 (en) * | 2000-04-18 | 2006-05-23 | Ricoh Company, Ltd. | Optical element, optical pickup unit, and optical disk drive unit |
US6812983B2 (en) * | 2000-05-17 | 2004-11-02 | Fuji Photo Film Co., Ltd. | Retardation plate and fabrication method thereof, and plate for circularly polarizing light, ½ wave plate and reflection-type liquid crystal display device utilizing the retardation plate |
JP4175092B2 (ja) | 2002-11-06 | 2008-11-05 | 日本電気株式会社 | 光ヘッド装置および光学式情報記録再生装置 |
-
2005
- 2005-09-13 KR KR1020077005415A patent/KR20070048778A/ko active IP Right Grant
- 2005-09-13 JP JP2006535152A patent/JP5034501B2/ja not_active Expired - Fee Related
- 2005-09-13 WO PCT/JP2005/016851 patent/WO2006030789A1/ja active Application Filing
- 2005-09-14 TW TW094131682A patent/TW200623097A/zh unknown
-
2007
- 2007-03-14 US US11/686,131 patent/US7986606B2/en not_active Expired - Fee Related
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2002156528A (ja) * | 1998-10-30 | 2002-05-31 | Teijin Ltd | 熱可塑性高分子フィルム |
JP2001004841A (ja) * | 1999-06-24 | 2001-01-12 | Matsushita Electric Ind Co Ltd | 光学素子と光ヘッドと光記録再生装置 |
JP2001101700A (ja) * | 1999-09-30 | 2001-04-13 | Asahi Glass Co Ltd | 光ヘッド装置 |
JP2003098350A (ja) * | 2001-09-21 | 2003-04-03 | Ricoh Co Ltd | 光学素子、該光学素子を用いた光ピックアップ装置及び光ディスクドライブ装置 |
JP2003329840A (ja) * | 2002-05-16 | 2003-11-19 | Teijin Ltd | 熱安定性に優れた位相差フィルム、及び偏光変換素子 |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2008198244A (ja) * | 2007-02-08 | 2008-08-28 | Asahi Glass Co Ltd | 広帯域波長板 |
Also Published As
Publication number | Publication date |
---|---|
US7986606B2 (en) | 2011-07-26 |
JPWO2006030789A1 (ja) | 2008-05-15 |
TW200623097A (en) | 2006-07-01 |
KR20070048778A (ko) | 2007-05-09 |
JP5034501B2 (ja) | 2012-09-26 |
US20070159932A1 (en) | 2007-07-12 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
KR100569633B1 (ko) | 위상자 및 이것을 탑재한 광헤드 장치 | |
US7738346B2 (en) | Polarizing diffraction element and optical head device | |
JP2002318306A (ja) | 波長選択性回折素子および光ヘッド装置 | |
WO2006030789A1 (ja) | 光ヘッド装置 | |
JP4518009B2 (ja) | 3波長用回折素子、位相板付3波長用回折素子および光ヘッド装置 | |
WO2004097816A1 (ja) | 回折素子および光ヘッド装置 | |
JP3671768B2 (ja) | 光ヘッド装置 | |
JP5316409B2 (ja) | 位相差素子および光ヘッド装置 | |
KR20090025273A (ko) | 레이저광용 광학 부품 | |
JP4930084B2 (ja) | 広帯域波長板 | |
JP4631135B2 (ja) | 位相子 | |
JP4218393B2 (ja) | 光ヘッド装置 | |
JP4349335B2 (ja) | 光ヘッド装置 | |
KR101097078B1 (ko) | 회절 소자 및 광헤드 장치 | |
EP1562186B1 (en) | Double-wavelength light source unit and optical head device | |
JP5131244B2 (ja) | 積層位相板及び光ヘッド装置 | |
US8040781B2 (en) | Wavelength selecting wavelength plate and optical head device using it | |
JP2001344800A (ja) | 光ヘッド装置 | |
JP3968593B2 (ja) | 光ヘッド装置 | |
KR100536186B1 (ko) | 광대역 위상지연판 및 이를 갖는 광학소자 및/또는광헤드장치 | |
JP2002040257A (ja) | 開口制限素子および光ヘッド装置 | |
WO2004051326A1 (ja) | 位相板および光情報記録再生装置 | |
JP5083014B2 (ja) | 広帯域波長板および光ヘッド装置 | |
JP2010244681A (ja) | 光ヘッド装置 | |
JP2010186526A (ja) | 選択光学素子及び光ピックアップ装置 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AK | Designated states |
Kind code of ref document: A1 Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BW BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE EG ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KM KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NA NG NI NO NZ OM PG PH PL PT RO RU SC SD SE SG SK SL SM SY TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW |
|
AL | Designated countries for regional patents |
Kind code of ref document: A1 Designated state(s): BW GH GM KE LS MW MZ NA SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LT LU LV MC NL PL PT RO SE SI SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG |
|
DPEN | Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed from 20040101) | ||
121 | Ep: the epo has been informed by wipo that ep was designated in this application | ||
WWE | Wipo information: entry into national phase |
Ref document number: 2006535152 Country of ref document: JP |
|
WWE | Wipo information: entry into national phase |
Ref document number: 1020077005415 Country of ref document: KR |
|
WWE | Wipo information: entry into national phase |
Ref document number: 11686131 Country of ref document: US |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
WWP | Wipo information: published in national office |
Ref document number: 11686131 Country of ref document: US |
|
122 | Ep: pct application non-entry in european phase |