JP2005011417A - Optical pickup device and optical information recording/reproducing device equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pickup device capable of reducing the chromatic aberration caused by the change in oscillation wavelengths of the light emitted from a light source due to the manufacturing tolerance or a temperature change, and an optical information recording/reproducing device equipped with the same. <P>SOLUTION: This optical pickup device is provided with: a semiconductor laser 11; a collimator lens 12 for collimating light emitted from the semiconductor laser 11; a chromatic aberration correction optical device 13 for correcting the chromatic aberration of the parallel light from the collimator lens 12; and an objective lens 15 for condensing the light emitted from the chromatic aberration correction optical device 13 to a predetermined diameter and converging the light on an optical disk 16. The collimator lens 12 is arranged at a position for reducing chromatic aberration which is caused by the change in the wavelengths of the light emitted from the semiconductor laser 11. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical pickup device and an optical information recording / reproducing device including the same, and more particularly to chromatic aberration caused by variation in oscillation wavelength generated in light emitted from a light source due to manufacturing tolerances and temperature changes, and during recording. The present invention relates to an optical pickup device capable of reducing chromatic aberration caused by a change in oscillation wavelength during reproduction, and an optical information recording / reproducing device including the same.
[0002]
[Prior art]
Conventionally, in an optical pickup device that performs recording / reproduction or only reproduction of an optical disc (optical information recording medium) such as a CD (compact disc) or a DVD (digital versatile disc), a laser diode (LD) is used as a light source. However, in this laser diode (LD), variations occur in the center wavelength of the emitted laser light due to manufacturing tolerances, temperature changes over time, and the like. Appears as chromatic aberration.
[0003]
Further, in the optical pickup device that performs recording / reproduction, the oscillation wavelength changes (shifts) between reading (reproducing) R and writing (recording) W as shown in FIG. For example, when the optical output of the laser beam at the time of reading R is 3 mW and the pulse width is 1 nm, the optical output of the laser beam when switching from the reading time R to the writing time W is 100 mW and the pulse width is 0.5 nm. . Due to this change (shift) in the oscillation wavelength, chromatic aberration appears in the optical pickup device.
As described above, when chromatic aberration occurs in the optical pickup device, the spot diameter on the optical disk becomes large, and there arises a problem that jitter is deteriorated. Therefore, in a normal optical pickup device, a method for correcting on an electric circuit in anticipation of an offset has been adopted in advance.
[0004]
By the way, in recent years, in a blue optical disc (Blu-ray Disc) or a smaller and thinner next-generation optical disc, it is necessary to perform high-density recording. Therefore, a blue-violet laser diode (LD) having a wavelength of 405 nm is used as a laser light source. ), And an optical pickup apparatus using an objective lens having a numerical aperture (NA) exceeding 0.6 as an objective lens for condensing the laser beam on the recording surface of the optical disc has been proposed. . However, in this optical pickup device, since the NA of the objective lens is large, the occurrence of chromatic aberration is large, and some countermeasure is required.
Therefore, in order to correct this chromatic aberration, for example, a correction element in which a concave lens and a hologram element having a single hologram pattern are integrated is arranged between the collimating lens and the objective lens, and the correction element corrects the chromatic aberration. A method (for example, see Patent Document 1) or a method in which a convex lens and a concave lens are arranged between a collimating lens and an objective lens, and chromatic aberration is corrected by the convex lens and the concave lens (for example, see Patent Document 2) is proposed. Has been.
[0005]
[Patent Document 1]
JP 2001-256672 A
[Patent Document 2]
JP 2000-131603 A
[0006]
FIG. 9 is a schematic configuration diagram showing an optical pickup device generally called a zoom lens system. In FIG. 9, reference numeral 1 denotes a semiconductor laser (LD: light source), and 2 denotes an output from the semiconductor laser (LD) 1. A collimating lens that collimates incident light, 3 is a chromatic aberration correcting optical element that corrects chromatic aberration of the parallel light, 4 is a light that is emitted from the chromatic aberration correcting optical element 3 and is condensed to a predetermined diameter and collected on an optical disk (optical information recording medium) 5. It is an objective lens that emits light.
The chromatic aberration correcting optical element 3 is constituted by a concave lens 6 and a convex lens 8 having holograms 7a and 7b formed on both sides, and the objective lens 4 is constituted by two convex lenses 4a and 4b called so-called achromatic lenses. Has been.
In this optical pickup apparatus, holograms 7a and 7b are formed on both surfaces of the convex lens 8 to correct chromatic aberration caused by fluctuations in the oscillation wavelength of the laser light. Further, the chromatic aberration caused by the variation in the center wavelength of the laser light is reduced by adjusting the distance D between the concave lens 6 and the convex lens 8.
[0007]
[Problems to be solved by the invention]
However, the conventional zoom lens type optical pickup device has the following problems.
(1) When the objective lens 4 is a single aspherical lens or when its working distance (WD) is increased, the amount of chromatic aberration generated in the objective lens 4 increases, so that correction of chromatic aberration is not possible only with the zoom lens system. It is enough.
(2) When the size of the optical pickup device for blue optical disc (Blu-ray Disc) is reduced to the same size as CD and DVD, there is no space for accommodating an adjusting mechanism for adjusting the distance D between the concave lens 6 and the convex lens 8. The optical system cannot be optimized.
[0008]
FIG. 10 is a diagram illustrating an example of chromatic aberration correction of a zoom lens type optical pickup device. When reading without using a liquid crystal wavefront aberration correcting element (when reproducing) and when writing after switching (when recording), FIG. The relationship between the wavelength of and the wavefront aberration (rms) is shown. The wavelength λ at the time of writing is the wavelength λ at the time of reading. ₀ Is shifted by +1.5 nm.
From this figure, it can be seen that the wavefront aberration does not match between reading and writing, and in particular, the wavefront aberration deteriorates during writing.
[0009]
The present invention has been made in view of the above circumstances, and the chromatic aberration caused by variations in the oscillation wavelength generated in the light emitted from the light source due to manufacturing tolerances and temperature changes, and the oscillation wavelength during recording and reproduction. An object of the present invention is to provide an optical pickup device capable of reducing chromatic aberration caused by a change, and an optical information recording / reproducing device including the same.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides the following optical pickup device and an optical information recording / reproducing device including the same.
In other words, the optical pickup device according to claim 1 has a light source, a collimating lens that can move forward and backward with respect to the light source, and parallel light from the light source, and chromatic aberration of parallel light from the collimating lens. A chromatic aberration correcting optical element to be corrected, and an objective lens for condensing the light emitted from the chromatic aberration correcting optical element to a predetermined diameter and condensing the light on an optical information recording medium, and the collimating lens has a wavelength of the emitted light from the light source It is characterized in that it is arranged at a position where chromatic aberration caused by variations in the color is reduced.
[0011]
In this optical pickup device, the collimating lens is disposed at a position to reduce chromatic aberration caused by the variation in the wavelength of light emitted from the light source, so that the center wavelength of the light caused by the manufacturing tolerance of the light source can be reduced. A change in the center wavelength caused by variations, a temperature change with time, etc. is corrected. This corrects chromatic aberration caused by variations in the center wavelength and changes in the center wavelength.
[0012]
The optical pickup device according to claim 2, a light source, a collimating lens that collimates the light emitted from the light source, a chromatic aberration correcting optical element that corrects chromatic aberration of the parallel light from the collimating lens, and the chromatic aberration correcting optics. An objective lens for condensing the light emitted from the element to a predetermined diameter and condensing it on an optical information recording medium. The magnitude of the applied voltage between the chromatic aberration correcting optical element and the objective lens is recorded and reproduced. And a spherical aberration correction element that corrects the spherical aberration of light during recording and during reproduction by changing the above.
[0013]
In this optical pickup device, the spherical aberration of light during recording and reproduction is corrected by changing the magnitude of the applied voltage between the chromatic aberration correcting optical element and the objective lens during recording and during reproduction. By providing the spherical aberration correction element, the aberration characteristic of light during recording and reproduction is made uniform and the aberration is reduced.
[0014]
The optical pickup device according to claim 3 corrects the chromatic aberration of the light source, the collimating lens that can be moved forward and backward with respect to the light source and that makes the emitted light from the light source parallel light, and the parallel light from the collimating lens. A chromatic aberration correcting optical element; and an objective lens for condensing the light emitted from the chromatic aberration correcting optical element to a predetermined diameter and condensing the light on an optical information recording medium, wherein the collimating lens has a wavelength variation of the emitted light from the light source. Is arranged at a position to reduce chromatic aberration caused by the above, and the light applied during recording and reproduction is changed between the chromatic aberration correcting optical element and the objective lens by changing the magnitude of applied voltage between recording and reproduction. A spherical aberration correction element for correcting the spherical aberration is provided.
[0015]
In this optical pickup device, the collimating lens is disposed at a position to reduce chromatic aberration caused by the variation in the wavelength of light emitted from the light source, so that the center wavelength of the light caused by the manufacturing tolerance of the light source can be reduced. A change in the center wavelength caused by variations, a temperature change with time, etc. is corrected.
A spherical aberration correction element that corrects the spherical aberration of light during recording and reproduction by changing the magnitude of the applied voltage between the chromatic aberration correction optical element and the objective lens during recording and reproduction. Thus, the light aberration characteristics during recording and reproduction are made uniform and the aberration is reduced.
[0016]
An optical pickup device according to a fourth aspect is the optical pickup device according to the first, second, or third aspect, wherein the chromatic aberration correcting optical element includes at least a concave lens and a convex lens, and a plurality of intervals between the concave lens and the convex lens. It is characterized by being able to change.
[0017]
In this optical pickup device, since the interval between the concave lens and the convex lens constituting the chromatic aberration correcting optical element can be changed in a plurality of ways, the optical axis of the chromatic aberration correcting optical element and the objective lens can be changed when the optical axis of the objective lens is shifted. The coma due to the deviation generated between the optical axis of the lens is reduced.
[0018]
The optical pickup device according to claim 5 is the optical pickup device according to claim 4, wherein the interval between the concave lens and the convex lens can be changed in a plurality of ways by selectively using a plurality of types of spacers having different thicknesses. It is characterized by that.
[0019]
In this optical pickup device, the distance between the concave lens and the convex lens can be changed in a plurality of ways by selecting and using a plurality of types of spacers having different thicknesses, thereby easily using a plurality of types of spacers having different thicknesses. The coma aberration can be easily reduced with a simple operation.
[0020]
An optical pickup device according to a sixth aspect is the optical pickup device according to the first, second, or third aspect, wherein the chromatic aberration correcting optical element includes at least an uneven lens.
[0021]
In this optical pickup device, since the chromatic aberration correcting optical element is constituted by at least a concave-convex lens, it occurs between the optical axis of the chromatic aberration correcting optical element and the optical axis of the objective lens when the optical axis of the objective lens is shifted. The coma caused by the shift is reduced.
[0022]
An optical pickup device according to a seventh aspect is the optical pickup device according to the fourth, fifth or sixth aspect, wherein the convex lens or the concave-convex lens is provided with a diffractive optical element.
In this optical pickup device, the convex lens or the concave-convex lens is provided with a diffractive optical element, thereby reducing chromatic aberration during reproduction / recording.
[0023]
An optical information recording / reproducing apparatus according to an eighth aspect includes the optical pickup apparatus according to any one of the first to seventh aspects.
In this optical information recording / reproducing apparatus, by providing the optical pickup device according to any one of claims 1 to 7, due to manufacturing tolerances and temperature variations caused by variations in oscillation wavelength generated in light emitted from the light source. Chromatic aberration that occurs, and chromatic aberration that occurs when the oscillation wavelength changes between recording and reproduction are reduced.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of an optical pickup device and an optical information recording / reproducing device including the same will be described with reference to the drawings.
These embodiments show one aspect of the present invention, and the present invention is not limited to these embodiments, and can be arbitrarily changed within the scope of the technical idea of the present invention. is there.
[0025]
“First Embodiment”
FIG. 1 is a schematic configuration diagram showing an optical pickup device according to a first embodiment of the present invention. In the figure, reference numeral 11 denotes a semiconductor laser (e.g., a semiconductor laser that emits light L having an emission wavelength of 408 (± 8) nm). LD: light source), 12 is a collimating lens that makes the emitted light from the semiconductor laser (LD) 11 parallel light, 13 is a chromatic aberration correcting optical element that corrects chromatic aberration of the parallel light, and 14 is light emitted from the chromatic aberration correcting optical element 13. A spherical aberration correction element 15 for correcting the spherical aberration of the objective lens 15, and an objective lens 15 for condensing the light emitted from the spherical aberration correction element 14 to a predetermined diameter and condensing it on the optical disk (optical information recording medium) 16.
[0026]
The collimating lens 12 is movable between the semiconductor laser 11 and the chromatic aberration correcting optical element 13 along the optical axis Ax and can be fixed at an arbitrary position on the optical axis Ax. The collimating lens 12 is placed on the optical axis Ax. And is fixed at a position where the chromatic aberration generated by the variation in the wavelength of the light emitted from the semiconductor laser 11 is the lowest, the variation in the central wavelength of the light caused by the manufacturing tolerance of the semiconductor laser 11 Chromatic aberration caused by a change in the center wavelength caused by a change in temperature over time is corrected.
[0027]
The chromatic aberration correcting optical element 13 corrects the chromatic aberration of the parallel light from the collimating lens 12, and includes a concave lens 21 and a convex lens 23 having hologram elements (diffractive optical elements) 22a and 22b formed on both sides. The concave lens 21 and the convex lens 23 are arranged at a predetermined interval on the optical axis Ax.
The hologram elements 22a and 22b are not necessarily provided on both surfaces of the convex lens 23, and may be configured on one surface.
The hologram elements 22a and 22b reduce chromatic aberration caused by the change (shift) of the oscillation wavelength when the oscillation wavelength is changed (shifted) during reading (reproduction) R and writing (recording) W. It is an element.
[0028]
The spherical aberration correction element 14 corrects spherical aberration by controlling the phase of light such as polarized light of parallel light emitted from the chromatic aberration correction optical element 13. For example, the liquid crystal is corrected by a pair of glass substrates (transparent substrates). A liquid crystal correction element that is sandwiched is preferably used. This liquid crystal correction element can correct the spherical aberration of light over the entire wavelength band by controlling the applied voltage.
By changing the magnitude of the applied voltage, for example, the peak value of the bias voltage, when reading (reproducing) and writing (recording), the light intensity during reading (reproducing) and writing (recording) The aberration characteristics are made uniform, and the aberration itself is reduced.
[0029]
FIG. 2 is a diagram showing an example of wavefront aberration correction by the spherical aberration correction element 14, and the optimum applied voltages at the time of reading (reproduction) / writing (recording) in the spherical aberration correction element 14 are shown. The relationship between the wavelength and wavefront aberration at the time of reading (reproducing) / writing (recording) when this optimum applied voltage is applied to the spherical aberration correction element 14 as a bias voltage is shown.
Here, the wavelength λ at the time of writing is the wavelength λ at the time of reading. ₀ Is shifted by +1.5 nm. The offset of spherical aberration is 0.02λ.
[0030]
According to this figure, it can be seen that the wavefront aberrations are substantially the same at the time of reading (reproducing) and at the time of writing (recording), and correction of chromatic aberration is sufficient.
Moreover, in both cases of reading (reproducing) and writing (recording), the wavefront aberration is the wavelength λ (= λ) during reading (reproducing). ₀ (+1.5 nm) is generally suppressed to 0.03λ or less.
[0031]
By mounting this optical pickup device on an optical disk recording / reproducing device (optical information recording / reproducing device), variations in the center wavelength of light caused by manufacturing tolerances of the semiconductor laser 11, temperature changes with time, etc. The chromatic aberration due to the change in the central wavelength caused by the cause is reduced, and the spherical aberration of the light is corrected over the entire wavelength band. This reduces chromatic aberration caused by variations in the oscillation wavelength generated in the light emitted from the semiconductor laser 11 due to manufacturing tolerances and temperature changes, and chromatic aberration caused by the change in oscillation wavelength during recording and reproduction.
[0032]
As described above, according to the optical pickup device of this embodiment, the collimator lens 12 is moved along the optical axis Ax, and the position where the chromatic aberration generated due to the variation in the wavelength of the light emitted from the semiconductor laser 11 becomes the lowest. Therefore, it is possible to reduce the chromatic aberration caused by the change in the center wavelength caused by the variation in the center wavelength of light caused by the manufacturing tolerance of the semiconductor laser 11 and the temperature change over time.
[0033]
Further, by changing the magnitude of the applied voltage between the chromatic aberration correcting optical element 13 and the objective lens 15 between the recording time W and the reproducing time R, the spherical aberration of light at each of the recording time W and the reproducing time R is corrected. Since the spherical aberration correction element 14 is provided, it is possible to make the aberration characteristics of the light uniform during recording and reproduction R and to reduce the amount of aberration.
[0034]
In addition, since the optical pickup device of this embodiment is mounted on an optical disc recording / reproducing device, chromatic aberration caused by variations in oscillation wavelength generated in light emitted from the semiconductor laser 11 due to manufacturing tolerances and temperature changes, and recording and reproduction. It is possible to reduce chromatic aberration caused by a change in oscillation wavelength with time. Therefore, the spot diameter on the optical disk 16 can be narrowed, and there is no possibility of deteriorating jitter.
[0035]
“Second Embodiment”
FIG. 3 is a schematic configuration diagram showing a chromatic aberration correcting optical element of an optical pickup device according to the second embodiment of the present invention. The chromatic aberration correcting optical element 31 is different from the chromatic aberration correcting optical element 13 of the first embodiment. In the chromatic aberration correcting optical element 13 of the first embodiment, the concave lens 21 and the convex lens 23 on which the hologram elements 22a and 22b are formed are arranged at a predetermined interval on the optical axis Ax. In the chromatic aberration correcting optical element 31, a plurality of types of spacers 32 having different thicknesses are prepared, and a spacer 32 having a desired thickness is selected from these spacers 32 and disposed between the concave lens 21 and the convex lens 23. is there.
[0036]
As shown in FIG. 4, the spacer 32 has, for example, a thickness t and an outer diameter D. ₁ , Inner diameter D ₂ It is made of a metal such as stainless steel or phosphor bronze.
The interval between the concave lens 21 and the convex lens 23 can be changed in a plurality of ways by appropriately selecting and using a plurality of types of spacers 32 having different thicknesses t.
[0037]
For example, a spacer 32 having a thickness t of 0.6 mm is used for light having an oscillation wavelength of 402 to 405 nm, and a spacer 32 having a thickness t of 0.35 mm is used for light having an oscillation wavelength of 406 to 409 nm. If the spacer 32 is not used for light having an oscillation wavelength of 410 to 416 nm, the distance between the concave lens 21 and the convex lens 23 is set to 0.6 mm and 0.35 mm by appropriately selecting and using these spacers 32. , 0 mm can be changed.
[0038]
Further, most of the variation of the semiconductor laser 11 is caused by the variation of the characteristics between the production lots. Therefore, if the thickness t of the spacer 32 is managed in accordance with the production lot of the semiconductor laser 11, the production lot is different for each production lot. Chromatic aberration correction of the semiconductor laser 11 can be performed.
[0039]
By using the spacer 32, coma aberration due to a shift generated between the optical axis of the chromatic aberration correcting optical element 31 and the optical axis of the objective lens 15 is reduced even when the optical axis of the objective lens 15 is shifted. The
In addition, since the interval between the concave lens 21 and the convex lens 23 can be changed in a plurality of ways by selectively using a plurality of types of spacers 32 having different thicknesses, a simple operation of properly using a plurality of types of spacers 32 having different thicknesses. Therefore, coma can be easily reduced.
[0040]
FIG. 5 is a diagram showing an example of correction of wavefront aberration by the chromatic aberration correcting optical element 31, and reading when the shift amount of the optical axis of the objective lens 15 is 0 mm and correction is made by the spherical aberration correcting element 14. The relationship between wavelength and wavefront aberration at each time (reproduction) / write (recording) is shown.
Here, the wavelength λ at the time of writing is the wavelength λ at the time of reading. ₀ Is shifted by +1.5 nm.
[0041]
According to this figure, when the shift amount of the optical axis of the objective lens 15 is 0 mm, the wavefront aberrations are almost the same at the time of reading (reproducing) and writing (recording) as in FIG. I understand.
Moreover, in both cases of reading (reproducing) and writing (recording), the wavefront aberration is the wavelength λ (= λ) during reading (reproducing). ₀ (+1.5 nm) is generally suppressed to 0.03λ or less.
[0042]
FIG. 6 is a diagram showing another example of wavefront aberration correction by the chromatic aberration correcting optical element 31. The amount of shift of the optical axis of the objective lens 15 is set to 0.2 mm, and correction is performed by the spherical aberration correcting element 14. The relationship between the wavelength and the wavefront aberration at the time of reading (reproducing) / writing (recording) is shown.
Again, the wavelength λ at the time of writing is the wavelength λ at the time of reading. ₀ Is shifted by +1.5 nm.
[0043]
According to this figure, even when the shift amount of the optical axis of the objective lens 15 is 0.2 mm, the wavefront aberrations are almost the same during reading (reproducing) and writing (recording). I understand.
Moreover, in both cases of reading (reproducing) and writing (recording), the wavefront aberration is the wavelength λ (= λ) during reading (reproducing). ₀ (+1.5 nm) is generally suppressed to 0.03λ or less.
[0044]
Also in the pickup device of this embodiment, the same effects as the optical pickup device of the first embodiment can be obtained.
Moreover, a chromatic aberration correcting optical element 31 in which a spacer 32 having a desired thickness is appropriately selected from a plurality of types of spacers 32 having different thicknesses between the concave lens 21 and the convex lens 23 on which the hologram elements 22a and 22b are formed. Therefore, even when the optical axis of the objective lens 15 is shifted, the wavefront aberrations at the time of reading (during reproduction) and at the time of writing (during recording) can be made substantially coincident, and this amount of aberration can be reduced. it can.
[0045]
“Third Embodiment”
FIG. 7 is a schematic configuration diagram showing an optical pickup device according to a third embodiment of the present invention. The optical pickup device is different from the optical pickup device according to the first embodiment in that the optical pickup device according to the first embodiment. In this apparatus, the chromatic aberration correcting optical element 13 has a configuration in which a concave lens 21 and a convex lens 23 having hologram elements 22a and 22b formed on both sides are arranged on the optical axis Ax at a predetermined interval. In the optical pickup device according to the embodiment, the chromatic aberration correcting optical element 41 includes a meniscus lens (concave / convex lens) 42 in which the concave lens 21 and the convex lens 23 are integrated, and hologram elements 22a and 22b formed on both surfaces of the meniscus lens 42. It is a point that has been configured.
[0046]
In this case, considering that the hologram elements 22a and 22b are formed on both surfaces of the meniscus lens 42, the material of the meniscus lens 42 is easier to manufacture than plastic than glass.
Here, the hologram elements 22 a and 22 b are formed on both surfaces of the meniscus lens 42, but the hologram elements are not necessarily formed on both surfaces, and may be formed on one surface of the meniscus lens 42.
[0047]
The collimating lens 12 is preferably a spherical combination lens or an aspherical single lens. In consideration of dispersibility, glass is more preferable than plastic because dispersibility is greater. Thus, if the glass collimating lens 12 is used, chromatic aberration can be reduced as a whole.
[0048]
In this chromatic aberration correcting optical element 41, since the meniscus lens 42 is used, the optical axis of the objective lens 15 is shifted to cause a deviation between the optical axis of the meniscus lens 42 and the optical axis of the objective lens 15, and this deviation is caused. Even in the case where coma aberration is caused, this coma aberration can be reduced.
Further, since the hologram elements 22a and 22b are formed on both surfaces of the meniscus lens 42, it is possible to reduce chromatic aberration in both reading (reproduction) and writing (recording).
[0049]
Also in the pickup device of this embodiment, the same effects as the optical pickup device of the first embodiment can be obtained.
In addition, the chromatic aberration correcting optical element 41 of the first embodiment is formed by integrating the concave lens 21 and the convex lens 23 into a meniscus lens 42, and hologram elements 22a and 22b are formed on both sides of the meniscus lens 42. Since the optical axis of the objective lens 15 is shifted, the coma aberration caused by the deviation between the optical axis of the meniscus lens 42 and the optical axis of the objective lens 15 can be reduced.
[0050]
Further, since the hologram elements 22a and 22b are formed on both surfaces of the meniscus lens 42, chromatic aberration can be reduced both in reading (reproducing) and writing (recording).
Further, the chromatic aberration correcting optical element 41 has a simple configuration and can be easily reduced in size, so that it can cope with higher density and reduction in size.
[0051]
【The invention's effect】
As described above, according to the optical pickup device of the present invention, the collimating lens is disposed at a position to reduce chromatic aberration caused by the variation in the wavelength of the light emitted from the light source. It is possible to correct the change in the center wavelength caused by the variation in the center wavelength of the light and the temperature change with time. Therefore, it is possible to correct chromatic aberration caused by variations in the center wavelength and changes in the center wavelength.
[0052]
According to another optical pickup device of the present invention, a spherical surface of light at the time of recording and at the time of reproduction is obtained by changing the magnitude of the applied voltage between the chromatic aberration correcting optical element and the objective lens at the time of recording and at the time of reproduction. Since the spherical aberration correction element for correcting the aberration is provided, the aberration characteristic of light during recording and reproduction can be made uniform, and the aberration characteristic itself can be reduced.
[0053]
According to still another optical pickup device of the present invention, the collimating lens is disposed at a position to reduce chromatic aberration caused by the variation in the wavelength of the light emitted from the light source, so that the light generated due to the manufacturing tolerance of the light source. It is possible to correct the change in the center wavelength caused by the variation in the center wavelength and the temperature change with time. Therefore, it is possible to correct chromatic aberration caused by variations in the center wavelength and changes in the center wavelength.
[0054]
In addition, a spherical aberration correction element is provided between the chromatic aberration correction optical element and the objective lens to correct the spherical aberration of light during recording and reproduction by changing the magnitude of the applied voltage between recording and reproduction. Therefore, the aberration characteristics of light during recording and reproduction can be made uniform, and the aberration characteristics themselves can be reduced.
[0055]
Further, if the distance between the concave lens and the convex lens constituting the chromatic aberration correcting optical element can be changed in plural ways, the optical axis of the chromatic aberration correcting optical element and the light of the objective lens generated when the optical axis of the objective lens is shifted. It is possible to reduce coma aberration caused by a deviation generated between the shaft and the shaft.
[0056]
Also, if the distance between the concave lens and the convex lens can be changed in multiple ways by selecting and using multiple types of spacers with different thicknesses, coma aberration can be easily achieved with a simple operation of using different types of spacers with different thicknesses. Can be reduced.
[0057]
Further, if the chromatic aberration correcting optical element is composed of at least a concave-convex lens, a coma caused by a shift that occurs between the optical axis of the chromatic aberration correcting optical element and the optical axis of the objective lens when the optical axis of the objective lens is shifted. Even when aberration occurs, this coma aberration can be reduced.
[0058]
Further, if a diffractive optical element is provided on the convex lens or the concave / convex lens, chromatic aberration during reproduction / recording can be reduced.
[0059]
In addition, since the optical information recording / reproducing apparatus of the present invention includes the optical pickup apparatus of the present invention, chromatic aberration caused by variations in oscillation wavelength generated in light emitted from the light source due to manufacturing tolerances and temperature changes, Chromatic aberration caused by the change in the oscillation wavelength during reproduction can be effectively reduced.
In addition, since this optical pickup device has a simple configuration and can be easily downsized, the optical information recording / reproducing device can be further increased in density and size.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram illustrating an optical pickup device according to a first embodiment of the present invention.
FIG. 2 is a diagram showing an example of wavefront aberration correction according to the first embodiment of the present invention.
FIG. 3 is a schematic configuration diagram illustrating a chromatic aberration correcting optical element according to a second embodiment of the present invention.
FIG. 4 is a perspective view showing a spacer of a chromatic aberration correcting optical element according to a second embodiment of the present invention.
FIG. 5 is a diagram illustrating an example of wavefront aberration correction by a chromatic aberration correcting optical element according to a second embodiment of the present invention.
FIG. 6 is a diagram showing another example of wavefront aberration correction by the chromatic aberration correcting optical element according to the second embodiment of the present invention.
FIG. 7 is a schematic configuration diagram illustrating an optical pickup device according to a third embodiment of the present invention.
FIG. 8 is a schematic diagram showing oscillation wavelengths at the time of reading and writing of a conventional optical pickup device.
FIG. 9 is a schematic configuration diagram showing a conventional zoom lens type optical pickup device;
FIG. 10 is a diagram illustrating an example of chromatic aberration correction of a conventional zoom lens type optical pickup device.
[Explanation of symbols]
11 Semiconductor laser (LD: Light source)
12 Collimating lens
13 Chromatic aberration correcting optical element
14 Spherical aberration correction element
15 Objective lens
16 Optical disc (optical information recording medium)
21 concave lens
22a, 22b Hologram element (diffractive optical element)
23 Convex lens
31 Chromatic aberration correction optical element
32 Spacers
41 Chromatic aberration correction optical element
42 Meniscus lens
Ax optical axis

Claims (8)

A light source, a collimating lens that can move forward and backward with respect to the light source, and that emits parallel light from the light source, a chromatic aberration correcting optical element that corrects chromatic aberration of the parallel light from the collimating lens, and the chromatic aberration correcting optics An objective lens for condensing the light emitted from the element to a predetermined diameter and condensing on the optical information recording medium,
An optical pickup device, wherein the collimating lens is arranged at a position to reduce chromatic aberration caused by variation in wavelength of light emitted from the light source. A light source, a collimating lens that collimates the light emitted from the light source, a chromatic aberration correcting optical element that corrects chromatic aberration of the collimated light from the collimating lens, and light emitted from the chromatic aberration correcting optical element to a predetermined diameter An objective lens for condensing on the narrowed-down optical information recording medium,
A spherical aberration correction element is provided between the chromatic aberration correction optical element and the objective lens to correct the spherical aberration of light during recording and reproduction by changing the magnitude of the applied voltage between recording and reproduction. An optical pickup device characterized by comprising: A light source, a collimating lens that can move forward and backward with respect to the light source, and that emits parallel light from the light source, a chromatic aberration correcting optical element that corrects chromatic aberration of the parallel light from the collimating lens, and the chromatic aberration correcting optics An objective lens for condensing the light emitted from the element to a predetermined diameter and condensing it on the optical information recording medium,
The collimating lens is disposed at a position to reduce chromatic aberration caused by variation in wavelength of light emitted from the light source,
A spherical aberration correction element is provided between the chromatic aberration correction optical element and the objective lens to correct the spherical aberration of light during recording and reproduction by changing the magnitude of the applied voltage between recording and reproduction. An optical pickup device characterized by comprising: The chromatic aberration correcting optical element includes at least a concave lens and a convex lens,
4. The optical pickup device according to claim 1, wherein the interval between the concave lens and the convex lens can be changed in a plurality of ways. 5. The optical pickup device according to claim 4, wherein the interval between the concave lens and the convex lens can be changed in a plurality of ways by selectively using a plurality of types of spacers having different thicknesses. 4. The optical pickup device according to claim 1, wherein the chromatic aberration correcting optical element includes at least an uneven lens. 7. The optical pickup device according to claim 4, wherein the convex lens or the concave-convex lens is provided with a diffractive optical element. An optical information recording / reproducing apparatus comprising the optical pickup device according to claim 1.

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