JP2002184024A - Optical pickup device - Google Patents

Abstract

(57) [Problem] To provide an optical pickup device capable of reading information recorded on an optical disc of a plurality of standards with high accuracy without increasing the number of component parts. SOLUTION: In an optical pickup device 21, an optical axis alignment component 25A is constituted by a triangular prism 31.
The incident surface 32 reflects the laser light of the first wavelength λ1,
This is a dichroic mirror having wavelength selectivity such that a laser beam of wavelength λ2 is transmitted. The collimated light having the first wavelength λ1 incident on the incident surface 32 in the first direction C1 is reflected on the incident surface 32 in the second direction C2. The collimated light having the second wavelength λ2 is transmitted through the incident surface 32 and reflected by the first reflecting surface 33 and the second reflecting surface 34, and then from the incident surface 32 in the second direction C.
2 The optical axes of the collimated light emitted from the incident surface 32 are parallel and the light intensity centers coincide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device that emits a plurality of laser beams having different wavelengths and reads information recorded on optical disks of different types and standards.

[0002]

2. Description of the Related Art It is used for reading information recorded on optical disks such as compact disks (abbreviation: CD) and digital versatile disks (abbreviation: DVD), and for recording information on recordable CDs and DVDs. For the optical pickup device, two laser beams having wavelengths different from each other and optimal for each optical disk are used. As a prior art of such an optical pickup device using two laser beams, for example, Japanese Patent Application Laid-Open No. 10-1990
There is an optical pickup device disclosed in Japanese Patent Application Publication No. 2
One laser beam is emitted from each of two different laser elements. In the optical pickup device, each laser element is arranged at a different position from each other, and two laser lights having different wavelengths emitted from each laser element are in a state where the optical axes are not parallel to each other or at the center of the light intensity (light intensity). The position where the intensity is the highest is shifted.

In an optical pickup device, laser light emitted from a laser element is converted by a collimator lens into collimated light which is parallel light. It is desirable that the collimated light has an intensity distribution such that the light intensity becomes maximum on the optical axis. Maximizing the intensity of light condensed on the information recording surface of the optical disc by matching the axis of the objective lens that condenses light on the information recording surface of the optical disc with the optical axis of light incident on the objective lens be able to.

[0004]

In such an optical pickup apparatus using two laser beams having different wavelengths according to the prior art, when two laser beams having different wavelengths share one objective lens, each laser beam is used. The center of intensity of each laser beam and the axis of the objective lens cannot be matched due to the shift of the center of intensity of the optical disk. The reading accuracy and the recording accuracy of are reduced.

[0005] Further, when two laser elements are mounted at different positions in the optical pickup device and the two laser lights share one collimator lens, the optical axes of the two laser lights are not parallel to each other. As a result, the incident angles of the two laser beams incident on the objective lens are different from each other, and the wavefront aberration generated when the incident light deviates from the axis of the objective lens greatly influences the light to converge on the information recording surface of the optical disc. The spot shape collapses.

[0006] Even if the collimator lens is moved to an appropriate position with respect to each laser beam, if the two laser beams share one objective lens, the center axis of the intensity of each laser beam and the axis of the objective lens are not aligned. In order to match, it is necessary for the actuator that drives the objective lens to also perform the position offset of the objective lens, so that the control of the actuator becomes complicated and the load on the actuator increases.

In order to solve the above-mentioned problems, if the optical pickup device is configured to provide a dedicated optical path for each laser beam, the size of the optical pickup device itself is increased and the configuration of the optical pickup device is improved. The number of optical components to be used increases.

Japanese Patent Application Laid-Open No. Hei 10-199019 discloses a technique in which a cubic prism is used to make the optical path length different between normal light and abnormal light, but the optical axes of the two laser lights coincide with each other. There is no mention of what to do.

Accordingly, an object of the present invention is to provide an optical pickup device capable of reading information recorded on an optical disc of a plurality of standards with high accuracy without increasing the number of components.

[0010]

SUMMARY OF THE INVENTION The present invention provides at least two
In an optical pickup device using two different wavelengths of laser light, a prism having one incident surface and a plurality of reflecting surfaces, wherein two collimated light beams having non-parallel optical axes and different wavelengths are incident on the prism incident surface. The optical axis of the collimated light of one wavelength reflected on the incident surface when reflected on the incident surface, and the collimated light of the other wavelength transmitted from the incident surface, reflected on the reflecting surface, transmitted again on the incident surface, and emitted from the prism And a prism for making the centers of light intensity coincide with each other.

For example, a first wavelength λ1 and a second wavelength λ2
Is made incident on a collimator lens having a fixed position and shared by two wavelengths, so that collimated light having optical axes that are not parallel to each other is obtained. When two such collimated lights having different wavelengths are made incident on the incident surface of the prism of the present invention, the intensity center of the collimated light that passes through the incident surface, is reflected a plurality of times by the reflecting surface, and exits the incident surface again, The collimated light reflected by the incident surface is emitted while overlapping the center of intensity. In this way, the intensity centers of the two collimated lights incident on the objective lens can be matched, the intensity of the light condensed on the information recording surface of the optical disc can be maximized, and the information recording surface of the optical disc can be maximized. It is possible to prevent the shape of the formed spot from being lost.

The present invention also relates to an optical pickup device using at least two laser beams having different wavelengths, wherein the collimator lens is displaceable in accordance with the optical axis of the incident light. A prism having one incident surface and a plurality of reflecting surfaces, wherein the collimating lens is converted into a plurality of collimated lights whose optical axes are parallel to each other by displacing the collimating lenses and whose light intensity centers are shifted from each other. When the two collimated light beams having different wavelengths, which are transmitted through the collimator lens and whose optical axes are parallel to each other, are incident on the incident surface of the prism,
The center of the intensity of the collimated light of one wavelength reflected by the incident surface and the intensity of the collimated light of the other wavelength transmitted through the incident surface, reflected by the reflecting surface, transmitted through the incident surface again, and emitted from the prism are matched. An optical pickup device comprising a prism.

According to the present invention, since the collimator lens is movable, by moving the collimator lens in accordance with the laser position, the divergent light from the two positions can be converted into two light beams having optical axes parallel to each other and having different wavelengths. It can be converted to collimated light. By making such parallel light incident on the prism of the present invention, the intensity centers of the two emitted lights can be matched. As a result, the intensity centers of the two collimated lights incident on the objective lens can be overlapped and matched, so that the intensity of light condensed on the information recording surface of the optical disc can be maximized, and the information recording surface of the optical disc can be maximized. It is possible to prevent the shape of the formed spot from being lost.

Further, the present invention is characterized in that the incidence surface of the prism is a dichroic mirror having wavelength selectivity.

According to the present invention, the dichroic mirror provided on the entrance surface of the prism reflects the collimated light of one wavelength out of the two collimated lights having different wavelengths, and the collimated light of the other wavelength. Can be transmitted. As a result, the intensity center of the collimated light of one wavelength reflected on the incident surface and the light of the other collimated light transmitted through the incident surface, reflected on a plurality of reflecting surfaces, transmitted again through the incident surface, and emitted from the prism. Can be matched.

Further, the present invention is characterized in that the entrance surface of the prism is a half mirror. According to the present invention, the half mirror provided on the incident surface of the prism reflects 50% of the collimated light of one wavelength among the two collimated lights having different wavelengths incident on the incident surface,
50% of the collimated light of the other wavelength can be transmitted. As a result, the collimated light of one wavelength reflected by the incident surface by 50% and the other collimated light transmitted by 50% through the incident surface, reflected by a plurality of reflecting surfaces, transmitted through the incident surface again, and emitted from the prism are reflected. The light intensity centers can be matched.

Further, the present invention is characterized in that an auxiliary plate for correcting wavefront aberration is attached to the entrance surface of the prism.

According to the present invention, by attaching the wavefront aberration correcting auxiliary plate, both the light reflected on the incident surface, the light transmitted through the incident surface, and the light reflected from the incident surface and emitted from the incident surface a plurality of times are transmitted. By transmitting through the wavefront aberration correction plate, the wavefront aberration generated by the prism of the present invention can be suppressed.

The present invention is further characterized in that a quarter-wave plate is attached to the wavefront aberration correcting auxiliary plate.

According to the present invention, 1/4 of the wavefront aberration auxiliary plate
By attaching the wave plate, it is possible to maintain a state where the centers of the light intensities coincide with each other even on the return path from the optical disk to the light receiving element.

Further, the present invention is characterized in that a plurality of the above-mentioned prisms are combined, and a plurality of laser beams having different wavelengths from each other are emitted in such a manner that all the intensity centers thereof coincide with each other.

According to the present invention, by combining a plurality of the prisms, all the intensity centers of the plurality of collimated lights can be matched.

Also, in the present invention, there is provided an even number of laser beams having different wavelengths, and the even number of laser beams incident on the prism is emitted in a direction substantially perpendicular to the incident direction, so that the prism is used as a rising mirror. It is characterized by functioning.

According to the present invention, by combining an odd number of the prisms, it is possible to make all the intensity centers of the even number of collimated lights one greater than the number of the prisms coincide with each other, and also to make the center perpendicular to the incident direction of the collimated light. Light in an appropriate direction, and can function as a rising mirror.

[0025]

FIG. 1 is a schematic diagram showing an optical pickup device 21 according to an embodiment of the present invention.
The optical pickup device 21 includes a laser light source 22, a collimator lens 23, and a deflecting beam splitter (abbreviation: PBS).
24, an optical axis alignment component 25, an objective lens 26, and a light receiving element 27.

The laser light source 22 has a first laser element 22a for emitting a laser beam of a first wavelength λ1 and a second laser element 22b for emitting a laser beam of a second wavelength λ2.
Wavelength laser. The collimator lens 23 converts the light incident on the collimator lens 23 into light that becomes a light flux parallel to the optical axis, that is, collimated light that is parallel light, and emits the light. The deflecting beam splitter 24 emits light incident on the first surface 24a from a second surface 24b parallel to the first surface 24a, and transmits light incident on the second surface 24b to a third surface 24c perpendicular to the second surface 24b. Emitted from The objective lens 26 focuses the incident light on the information recording surface of the optical disc 100 and forms a spot on the information recording surface. The light receiving element 27 receives light reflected on the information recording surface of the optical disc 100 and converts the light into an electric signal.

In the optical pickup device 21, the laser light source 22, the collimator lens 23, the deflecting beam splitter 24, and the optical axis alignment component 25 are arranged in order in the first direction C1. The collimator lens 23 is arranged such that the axis of the collimator lens 23 and the optical axis of the laser light of the first wavelength λ1 emitted from the first laser element 22a match. Optical axis alignment component 25 and objective lens 2
6 are arranged in order in a second direction C2 perpendicular to the first direction C1. The deflection beam splitter 24 and the light receiving element 27 are sequentially arranged in a direction perpendicular to the first direction C1. The optical disc 100 is arranged on the second direction C2 side of the objective lens 26 perpendicular to the second direction C2. In the laser light source 22, the second laser element 22b is disposed on the second direction C2 side of the first laser element 22a. In the optical pickup device 21, the optical axis of the laser light of the first wavelength λ1 incident on the optical axis alignment component 25 is parallel to the first direction C1, and the optical axis of the laser light of the second wavelength λ2 and the first wavelength λ1
Forms an angle α with the optical axis of the laser light. That is, the optical axis of the laser light having the second wavelength λ2 and the first direction C1 form an angle α.

FIG. 2 shows an optical pickup device 21 according to the present invention.
5 is a schematic view showing an optical axis aligning part 25A which is a first embodiment of the optical axis aligning part 25 in FIG. The optical axis alignment component 25 </ b> A is composed of a triangular prism 31. The three side surfaces of the triangular prism 31 are an entrance surface 32, a first reflection surface 33, and a second reflection surface 34, respectively. The incident surface 32 is a dichroic mirror having wavelength selectivity that reflects the laser light of the first wavelength λ1 and transmits the laser light of the second wavelength λ2. In the optical pickup device 21, the triangular prism 31 is disposed such that the incident surface 32 forms an angle of 45 degrees in the first direction C1 and the second direction C2, and the incident surface 32 faces the PBS 24 and the objective lens 26.

First wavelength λ1 incident on triangular prism 31
And the laser light of the second wavelength λ2 are converted into collimated light by the collimator lens 23. The collimated light having the first wavelength λ1 incident on the incident surface 32 of the triangular prism 31 in the first direction C1
The light is reflected in the direction C2. The collimated light of the second wavelength λ2 incident at an angle α with the first direction C1 is transmitted through the incident surface 32, is refracted, is reflected by the first reflective surface 33, and is reflected by the second reflective surface 34. The light is refracted and transmitted through the incident surface 32 and exits from the triangular prism 31 in the second direction C2. At this time,
The collimated light of the first wavelength λ1 reflected by the incident surface 32 and transmitted through the incident surface 32, then reflected by the first reflecting surface 33 and the second reflecting surface 34, transmitted through the incident surface 32 again, and emitted from the triangular prism 31 The optical axis of the collimated light having the second wavelength λ2 becomes parallel and the intensity center of the light coincides.

The triangular prism 31 reflects the collimated light of the first wavelength λ1 reflected on the incident surface 32 and, after passing through the incident surface 32, reflects off the first and second reflecting surfaces 33 and 34 to re-enter the incident surface 32 again. The incident surface 32 is formed so that the optical axis of the collimated light having the second wavelength λ2 transmitted and emitted from the triangular prism 31 becomes parallel and the intensity center of the light coincides.
, The angle formed by the incident surface 32 and the second reflective surface 34, and the refractive index of the triangular prism 31 are set.

The incident surface 32 of the triangular prism 31 constituting the optical axis alignment component 25A may be a half mirror that reflects 50% of the incident light and transmits the remaining 50%. At this time, 50% of the collimated light having the first wavelength λ1 incident on the triangular prism 31 in the first direction C1
2 in the second direction C2. Triangular prism 3
1 at an angle α with the first direction C1.
50% of the collimated light 2 is transmitted through the incident surface 32 and refracted, is reflected by the first reflective surface 33 of the triangular prism 31, is reflected by the second reflective surface 34, and is then refracted by the incident surface 32 and transmitted. Then, the light is emitted from the triangular prism 31 in the second direction C2. At this time, the collimated light of the first wavelength λ1 reflected by the incident surface 32 and the first reflecting surface 33 after passing through the incident surface 32
In addition, the optical axis of the collimated light having the second wavelength λ2, which is reflected by the second reflecting surface 34, transmits through the incident surface 32 again, and emerges from the triangular prism 31, becomes parallel and the intensity center of the light coincides.

FIG. 3 shows an optical pickup device 21 of the present invention.
5 is a schematic view showing an optical axis aligning part 25B which is a second embodiment of the optical axis aligning part 25 in FIG. The optical axis aligning component 25B is a pentaprism 41 having a pentagonal cross section, and includes a quadrangular prism 42 having a rectangular cross section and a triangular prism-shaped wavefront aberration correcting member 43 having an isosceles right triangular cross section.

One of the four side surfaces of the square prism 42 is an incident surface 44, the side surface adjacent to the incident surface 44 on one side is a first reflecting surface 45, and the side surface adjacent to the incident surface 44 is the other. The second reflecting surface 46. The entrance surface 44 is
This is a dichroic mirror having wavelength selectivity that reflects laser light of wavelength λ1 and transmits laser light of second wavelength λ2. The wavefront aberration correction member 43 corrects the wavefront aberration of the incident light. The three side surfaces of the wavefront aberration correcting member 43 are a first side surface 47, a second side surface 48, and a third side surface 49, respectively. The angles formed by the adjacent first and second side surfaces 47 and 48, and the adjacent sides. The angle formed by the first side surface 47 and the third side surface 49 that are continuous with each other is 45 degrees. The angle formed between the second side surface 48 and the third side surface 49 that are adjacent to each other is 90 degrees.

The incident surface 44 of the square prism 42 and the first side surface 47 of the wavefront aberration correcting member 43 are combined to form a pentagonal prism 41 having a pentagonal cross section. In the optical pickup device 21, in the pentaprism 41, the incident surface 44 faces the PBS 24 and the objective lens 26, the incident surface 44 forms 45 degrees with the first direction C1, and the second direction C2 and 45 forms
It is arranged to make a degree. At this time, the normal direction of the second side surface 48 is the first direction C1, and the normal direction of the third side surface 49 is the second direction C2.

First wavelength λ incident on pentaprism 41
The laser light of the first wavelength and the laser light of the second wavelength λ2 are converted into collimated light by the collimator lens 23. The light enters the second side surface 48 of the pentaprism 41 and enters the entrance surface 4.
4, the collimated light having the first wavelength λ1 incident in the first direction C1 is reflected by the incident surface 44 in the second direction C2 and exits from the third side surface 49. The light enters the second side surface 48 of the pentaprism 41 at an angle α with the first direction C1, and the second direction C from the position on the incident surface 44 where the first wavelength λ1 is incident.
The collimated light of the second wavelength λ2 that is incident on the opposite side of the light 2 passes through the incident surface 44 and is refracted, reflected by the first reflecting surface 45, reflected by the second reflecting surface 46, and then reflected by the incident surface 44. The light is refracted and transmitted, and exits from the third side surface 49 in the second direction C2. At this time, the collimated light of the first wavelength λ1 reflected on the incident surface 44, and transmitted through the incident surface 44, then reflected on the first reflecting surface 45 and the second reflecting surface 46, transmitted again through the incident surface 44, and transmitted from the prism. The optical axis of the emitted collimated light of the second wavelength λ2 becomes parallel, and the intensity center of the light coincides. The wavefront aberration of the two collimated lights emitted from the pentaprism 41 is corrected by the wavefront aberration correction member 43.

The pentaprism 41 reflects the collimated light of the first wavelength λ1 reflected on the incident surface 44, and after being transmitted through the incident surface 44, is reflected by the first reflecting surface 45 and the second reflecting surface 46 to re-enter the incident surface 44. The angle formed by the incident surface 44 and the first reflecting surface 45 and the angle of incidence so that the optical axis of the collimated light of the second wavelength λ2 transmitted through and emitted from the pentaprism 41 becomes parallel and the center of intensity of the light coincides. Face 44 and second
The angle formed by the reflection surface 46 and the refractive index of the square prism 42 are set.

The incident surface 44 of the square prism 42 of the pentaprism 41 constituting the optical axis aligning component 25B may be a half mirror that reflects 50% of the incident light and transmits the remaining 50%. At this time, the pentaprism 41
50% of the collimated light having the first wavelength λ1 incident on the first direction C1 is reflected by the incident surface 44 in the second direction C2. 50% of the collimated light of the second wavelength λ2 incident on the pentaprism 41 at an angle α with the first direction C1 is:
After being transmitted through the incident surface 44 and refracted, reflected by the first reflecting surface 45 of the pentaprism 41 and reflected by the second reflecting surface 46,
The light is refracted and transmitted through the incident surface 44 and exits from the pentaprism 41 in the second direction C2. At this time, the collimated light of the first wavelength λ1 reflected on the incident surface 44, and transmitted through the incident surface 44, then reflected on the first reflecting surface 45 and the second reflecting surface 46, transmitted again through the incident surface 44, and then transmitted through the pentaprism The optical axis and the light intensity center of the collimated light having the second wavelength λ2 emitted from 41 coincide with each other.

FIG. 4 shows an optical pickup device 21 of the present invention.
13 is a schematic view showing an optical axis aligning part 25C which is a third embodiment of the optical axis aligning part 25 in FIG. The optical axis alignment component 25C is the same as the pentaprism 41 described in the second embodiment.
And a 波長 wavelength plate 50. 1/4 wavelength plate 5
0 is attached to the third side surface 49 of the pentaprism 41. The 波長 wavelength plate 50 converts the linearly polarized light into circularly polarized light when it is incident, and emits the circularly polarized light.

The deflecting beam splitter 24 of the optical pickup device 21 converts the collimated light incident on the first surface 24a into a linearly polarized light, more specifically, a P-polarized collimated light, and converts the collimated light into a P-polarized collimated light. The light exits from the two surfaces 24b. The incident surface 44 of the pentaprism 41 reflects the laser light of the first wavelength λ1 and the laser light of the second wavelength λ2 for the S-polarized laser light, and reflects the first light for the P-polarized laser light. This is a dichroic mirror having wavelength selectivity that reflects laser light of wavelength λ1 and transmits laser light of second wavelength λ2.

The P-polarized collimated light having the first wavelength λ1 reflected by the incident surface 44 of the pentaprism 41, and the first and second reflecting surfaces 45 and 4 after passing through the incident surface 44.
The collimated light of the second wavelength λ2 of the P-polarized light reflected at 6 and transmitted again through the incident surface 44 and emitted from the prism becomes two collimated lights whose optical axes are parallel and whose light intensity centers coincide with each other. The light exits from the three side surfaces 49. Pentaprism 41
The two p-polarized collimated lights having the same optical axis and the same intensity center emitted from the third side surface 49 pass through the quarter-wave plate 50, and are rotated clockwise around the light traveling direction as an axis. It is converted into polarized light (abbreviation: RHC). Thereafter, the RHC collimated light is focused on the information recording surface of the optical disc 100 by the objective lens 26.

When the condensed RHC laser light is reflected by the information recording surface of the optical disc 100, it is converted to left-handed circularly polarized light (abbreviation: LHC) with the light traveling direction as an axis.
The light is converted into collimated light by the objective lens 26,
The light enters the four-wavelength plate 50. The two collimated lights of the LHC having different wavelengths are converted into linearly-polarized, specifically S-polarized, collimated light by transmitting through the quarter-wave plate 50. The two S-polarized collimated lights transmitted through the 波長 wavelength plate 50 are reflected by the incident surface 44 of the pentaprism 41 in a direction opposite to the first direction C1. At this time, the optical axes of the two collimated lights remain coincident. Two collimated light beams having the same optical axis and emitted from the pentaprism 41 in the opposite direction of the first direction C1 enter the PBS 24, are reflected in a direction perpendicular to the first direction C1, and enter the light receiving element 27. .

FIG. 5 shows an optical pickup device 21 of the present invention.
12 is a schematic view showing an optical axis aligning part 25D which is a fourth embodiment of the optical axis aligning part 25 in FIG. The optical axis alignment component 25D is the same as the pentaprism 41 described in the second embodiment.
This is substantially the same as a combination of the first pentaprism 41A, the second pentaprism 41B, and the third pentaprism 41C having the same configuration as that of FIG. Specifically, the third side surface 49A of the first pentaprism 41A and the second side surface 48B of the second pentaprism 41B abut, and the third side surface 49B of the second pentaprism 41B and the third pentaprism 41 are contacted.
The optical axis aligning component 25D is configured in such a manner that the second side surface 48C of the C is in contact with the second side 48C. Actually, the first pentaprism 41
A wavefront aberration correcting member 43A and the second pentaprism 4
The wavefront aberration correcting member 43B of 1B and the wavefront aberration correcting member 43C of the third pentaprism 41C are integrated into one wavefront aberration correcting plate 51 having a trapezoidal cross section. Also, the first
The entrance surface 44A of the pentaprism 41A and the entrance surface 44C of the third pentaprism 41C are flush with each other, and the two entrance surfaces 44A and 44C are parallel to the entrance surface 44B of the second pentaprism 41B. are doing. The wavefront aberration correction plate 51 corrects the wavefront aberration of the incident light. In the optical axis alignment component 25D, the incident surface 44A of the first pentaprism 41A is a first incident surface 44A, the incident surface 44B of the second pentaprism 41B is a second incident surface 44B, and the incident surface 44C of the third pentaprism 41C. To the third incident surface 4
4C. The optical axis alignment component 25D is arranged such that the second side surface 48A of the first pentaprism 41A is perpendicular to the first direction C1, and the third side surface 4C of the third pentaprism 41C.
The optical pickup device 21 is arranged on the optical pickup device 21 such that 9C is perpendicular to the second direction C2. At this time, the first incident surface 44
A and the third incident surface 44C face the PBS 24 and the objective lens 26, and are in the first direction C1 and the second direction C2.
And 45 degrees.

The optical axis alignment component 25D has a first wavelength λ1
, The second wavelength λ2, the third wavelength λ3, and the fourth wavelength λ4.
The four laser beams have different wavelengths and optical axes are parallel or non-parallel to each other. The first incident surface 44A is the first
This is a dichroic mirror having wavelength selectivity that reflects only laser light of wavelength λ1 and transmits laser light of other wavelengths. The dichroic mirror has wavelength selectivity such that the second incident surface 44B reflects the laser light of the first wavelength λ1 and the laser light of the second wavelength λ2 and transmits the laser light of other wavelengths. Third incidence surface 44C
Are the laser light of the first wavelength λ1, the second wavelength λ2 and the third
This is a dichroic mirror having wavelength selectivity that reflects laser light of wavelength λ3 and transmits laser light of other wavelengths.

The laser light of the first wavelength λ1, the laser light of the second wavelength λ2, and the third wavelength λ incident on the optical axis alignment component 25D
The laser light of No. 3 and the laser light of the fourth wavelength λ4 pass through the wavefront aberration correcting plate 51 and enter the first incident surface 44A.
On the first incident surface 44A, only the collimated light of the first wavelength λ1 incident from the first direction C1 is reflected in the second direction C2. The collimated lights of the second wavelength λ2, the third wavelength λ3, and the fourth wavelength λ4 pass through the first incident surface 44A, are reflected by the first reflecting surface 45A of the first pentaprism 41A, and are further reflected by the first pentaprism 41A. After being reflected by the second reflection surface 46A, the light again passes through the first incidence surface 44A and the wavefront aberration correction plate 51, and enters the second incidence surface 44B.

In the second incident surface 44B, the second direction C2
The collimated light of the first wavelength λ1 and the second wavelength λ2, which is incident from, is reflected in the first direction C1. The collimated light having the third wavelength λ3 and the fourth wavelength λ4 is transmitted through the second incident surface 44B, and the first reflecting surface 45B of the second pentaprism 41B.
Then, after being reflected by the second reflection surface 46B of the second pentaprism 41B, the light again passes through the second incidence surface 44B and the wavefront aberration correction plate 51, and enters the third incidence surface 44C.

On the third incident surface 44C, the first direction C1
The collimated light of the first wavelength λ1, the second wavelength λ2, and the third wavelength λ3, which is incident from the, is reflected in the second direction C2. The collimated light having the fourth wavelength λ4 is transmitted through the third incident surface 44C, reflected by the first reflecting surface 45C of the third pentaprism 41C, and further reflected by the second reflecting surface 46C of the third pentaprism 41C. Then, the light again passes through the third incident surface 44C and the wavefront aberration correction plate 51 in the second direction C2.

According to the optical axis aligning component 25D of the present embodiment, by combining the pentaprisms 41A, 41B and 41C, all the intensity centers of the collimated lights of four different wavelengths can be made to coincide. In this embodiment, the number of pentaprisms to be combined is three, but if the number of collimated light beams whose optical axes are to be aligned is n (n: a natural number of 3 or more), the number of pentaprisms required to align the optical axes is Are (n-1). The incident surface of each pentaprism is a dichroic mirror with wavelength selectivity corresponding to the wavelength of each collimated light. The angle formed by the first reflection surface and the second reflection surface in each pentaprism is a value suitable for the incident angle of each collimated light. The refractive index of the square prism in each pentaprism is a value suitable for the wavelength of each collimated light.

In the case where a plurality of pentaprisms 41 are combined as in the above-described optical axis aligning component 25D, an even number of pentaprisms, for example, 2m (m: natural number) are combined to enter the first direction C1. The (2m + 1) collimated light beams having the same intensity center and the first direction C
Emitted to 1. Similarly, when an odd number of pentaprisms, for example, (2m-1) (m: natural number) are combined, 2m collimated lights incident in the first direction C1 have the same light intensity center and have the second intensity. The light exits in the direction C2. That is, by using an optical axis aligning component in which an odd number of pentaprisms are combined, an even number of collimated lights, which is one more than the number of the pentaprisms incident on the optical axis aligning component from the first direction C1, are shifted in the second direction C2. Can be emitted. That is, this optical axis alignment component can function as a rising mirror.

In this embodiment, the incident surfaces 44A, 44B and 44C of the optical axis alignment component 25D are dichroic mirrors, but may be half mirrors.

FIG. 6 shows an optical pickup device 21 of the present invention.
15 is a schematic view showing an optical axis aligning part 25E which is a fifth embodiment of the optical axis aligning part 25 in FIG. The optical axis alignment component 25E is a pentaprism 41 described in the second embodiment.
It is composed of a pentaprism 41 and a positioning member 52 having the same configuration as the above. The positioning member 52 is a triangular prism. The first side surface 52a of the positioning member 52 is attached to the second reflection surface 46 of the pentaprism 41, and the second side surface 52b of the positioning member 52 is connected to the housing surface 28 of the housing (not shown) of the optical pickup device 21. Mounted. Thus, the optical axis alignment component 25E is attached to the optical pickup device 21. At this time, the pentaprism 41 is set so that the entrance surface 44 of the pentaprism 41 is
Forming an angle of 45 degrees with the direction C1 and the second direction C2,
By being arranged so as to face the BS 24 and the objective lens 26, it functions as a rising mirror.

Using the positioning member 52 in this embodiment, the optical axis alignment components 25A to 25A in the first to fourth embodiments are used.
D is mounted on the housing surface 28 of the optical pickup device 21 in the same manner.
A to 25D can function as rising mirrors.

FIG. 7 shows an optical pickup device 21 of the present invention.
15 is an outline view showing an optical axis aligning part 25F which is a sixth embodiment of the optical axis aligning part 25 in FIG. The optical axis alignment component 25F includes a wavefront aberration correcting member 61, a prism 62,
It comprises a 波長 wavelength plate 63 and a positioning member 64.

The wavefront aberration correcting member 61 is a triangular prism having an isosceles right triangle cross section, and corrects the wavefront aberration of the incident light.
First side surface 61a and second side surface 61 of wavefront aberration correcting member 61
The angle between the second side surface 61b and the third side is 90 degrees.
The angle between the side surface 61c and the angle between the third side surface 61c and the first side surface 61a is 45 degrees. The refractive index of the wavefront aberration correcting member 61 is such that when the light
The refractive index is such that it is refracted at a refraction angle β when incident on 1.

The prism 62 is a prism having a substantially triangular cross section. The incident surface 62a of the prism 62 reflects the laser light of the first wavelength λ1 and the laser light of the second wavelength λ2 for the S-polarized laser light, and reflects the first wavelength for the P-polarized laser light. This is a dichroic mirror having wavelength selectivity that reflects the laser light of λ1 and transmits the laser light of the second wavelength λ2. First reflection surface 62b of prism 62
The angle φ1 formed by the second reflecting surface 62c and (45 + β /
2) degrees. The 波長 wavelength plate 63 converts the light into a circularly polarized light when the linearly polarized light is incident, and emits the light. The positioning member 64 is a triangular prism having a triangular cross section. The angle φ2 formed by the first side surface 64a and the second side surface 64b of the positioning member 64 is 22.5 degrees.

In the wavefront aberration correcting member 61, the third side surface 61 c of the wavefront aberration correcting member 61 is different from the incident surface 62 of the prism 62.
a. The 波長 wavelength plate 63 is 、
One side surface of the wave plate 63 is fixed in close contact with the second side surface 61 b of the wavefront aberration correction member 61. The positioning member 64
The first side surface 64a of the positioning member 64 is fixed in close contact with the second reflection surface 62c of the prism 62. The optical axis aligning component 25F is configured such that the second side surface 64b of the positioning member 64 is fixed in close contact with the housing surface 28 of the housing of the optical pickup device 21.
1 and functions as a start-up mirror. At this time, the incident surface 62a is in the first direction C1 and the second direction C1.
45 degrees with the direction C2, and the incident surface 62a is PBS2
4 and the objective lens 26.

The collimated light having the first wavelength λ1 and the second wavelength λ2 transmitted through the PBS 24 is
The collimated light having the first wavelength λ1 is converted into polarized collimated light, and the collimated light having the second wavelength λ2 is incident on the optical axis aligning component 25F in a direction forming an angle α with the first direction C1. I do. The collimated light having the first wavelength λ1 is perpendicular to the first side surface 61a of the wavefront aberration correcting member 61,
That is, the light enters at an incident angle of 0, and travels straight in the first direction C1. Thereafter, the collimated light having the first wavelength λ1 enters the incident surface 62a of the prism 62 and is reflected in the second direction C2.

The collimated light having the second wavelength λ2 is incident on the first side surface 61a of the wavefront aberration correcting member 61 at an incident angle α.
The light is refracted at the refraction angle β and passes through the wavefront aberration correction member 61.
After that, the collimated light of the second wavelength λ2 is
Through the incident surface 62a. Incident surface 62 of prism 62
a of the collimated light having the second wavelength λ2 transmitted through
The angle θ1 formed with 2a is (β + 45) degrees. Incident surface 6
The collimated light having the second wavelength λ2 that has passed through 2a is incident on the first reflection surface 62b of the prism 62 and is reflected, and is incident on the second reflection surface 62c and is reflected. First reflection surface 62b
Is made (β + 45) degrees between the collimated light incident on the first reflecting surface 62b and the collimated light reflected by the first reflecting surface 62b. Collimated light incident on the second reflecting surface 62c;
The angle θ3 formed with the collimated light reflected by the reflection surface 62c is 45 degrees.

The collimated light having the second wavelength λ2 reflected by the second reflecting surface 62c of the prism 62 is incident on the incident surface 62a of the prism 62 and is transmitted. Incident surface 62 of prism 62
The angle θ4 between the collimated light having the second wavelength λ2 incident on the inside of the prism 62 and the incident surface 62a is 45 degrees. The optical axis of the collimated light having the second wavelength λ2 transmitted through the incident surface 62a from the inside of the prism 62 is the first wavelength λ1
Is parallel to the optical axis of the collimated light, and the center of intensity of the first wavelength λ1 coincides with the center of intensity of the second wavelength λ2.

The two collimated lights having the first wavelength λ1 and the second wavelength λ2 emitted from the wavefront aberration correcting member 61 in the second direction C2 are transmitted through the quarter-wave plate 63 and converted into collimated lights having RHC bias. The light is converted, transmitted through the objective lens 26, and focused on the information recording surface of the optical disc 100. The collimated light reflected by the information recording surface and transmitted through the objective lens 26 in the reverse direction of the second direction C2 is converted into a collimated light having a bias of LHC, and thereafter, the １ ／ wavelength plate 63
And is converted into S-polarized collimated light. The collimated light of the first wavelength λ1 and the second wavelength λ2 having the polarization of the S-polarized light in the opposite direction of the second direction C2 is reflected in the incident surface 62a in the opposite direction of the first direction C1 while keeping the optical axis coincident. , And the light reflected by the PBS 24 in a direction perpendicular to the first direction C1 and enters the light receiving element 27.

FIG. 8 is a schematic configuration diagram showing an optical pickup device 21A according to another embodiment of the present invention. The optical pickup device 21A includes, similarly to the optical pickup device 21, a laser light source 22, a deflection beam splitter 24, an optical axis alignment component 25, an objective lens 26, and a light receiving element 27.
When the laser beam of the first wavelength λ1 emitted from the first laser element 22a of the laser light source 22 is used, the collimator lens 23A has the first wavelength λ1.
When the laser light of the second wavelength λ2 emitted from the second laser element 22b of the laser light source 22 is used at the first position P1 where the optical axis of the laser light coincides with the axis of the collimator lens 23A, the second wavelength λ2 Can be moved to a second position P2 where the optical axis of the laser light of the above and the axis of the collimator lens 23A coincide. As a result, the laser light having the first wavelength λ1 and the laser light having the second wavelength λ2 pass through the collimator lens 23A, and are converted into collimated light having optical axes parallel to each other and having different light intensity centers. The optical axis of the two collimated lights can be matched by the optical axis alignment component 25 with the center of the intensity of the light. As the optical axis alignment component 25, the above-described optical axis alignment components 25A to 25F are used.

[0061]

As described above, according to the present invention, the intensity centers of the two collimated lights incident on the objective lens can be made coincident, and the intensity of the light focused on the information recording surface of the optical disk is maximized. In addition to this, it is possible to prevent the shape of the spot formed on the information recording surface of the optical disk from being lost. As a result, information recorded on the optical disc can be read with high accuracy, and also information can be recorded on the optical disc that can be recorded with high accuracy. Further, since it is not necessary to provide different optical paths for the collimated lights having different wavelengths, the number of components can be reduced, and the optical pickup device can be downsized.

Further, according to the present invention, the intensity centers of the two collimated lights entering the objective lens can be overlapped and matched, and the intensity of the light focused on the information recording surface of the optical disk can be maximized. In addition, the shape of the spot formed on the information recording surface of the optical disc can be prevented from being lost. As a result, information recorded on the optical disc can be read with high accuracy, and also information can be recorded on the optical disc that can be recorded with high accuracy. Further, since it is not necessary to provide different optical paths for the collimated lights having different wavelengths, the number of components can be reduced, and the optical pickup device can be downsized.

According to the present invention, the collimated light having one wavelength reflected by the incident surface and the other collimated light transmitted through the incident surface, reflected by a plurality of reflecting surfaces, transmitted through the incident surface again, and emitted from the prism. The center of the intensity of the collimated light can be matched.

Further, according to the present invention, the collimated light of one wavelength reflected by 50% on the incident surface and the collimated light of 50%
%, The center of the intensity of the other collimated light emitted from the prism after being transmitted through the incident surface after being reflected by the plurality of reflection surfaces can be matched.

According to the present invention, by attaching the wavefront aberration correcting auxiliary plate, light reflected on the incident surface, light transmitted through the incident surface, and reflected plural times after transmission and emitted from the incident surface can be reduced. The wavefront aberration generated by the prism of the present invention can be suppressed by transmitting the wavefront aberration correction plate.

According to the present invention, the wavefront aberration auxiliary plate has
By attaching the 波長 wavelength plate, it is possible to maintain a state where the centers of the light intensities coincide with each other even on the return path from the optical disk to the light receiving element.

Further, according to the present invention, by combining a plurality of the prisms, it is possible to make all the intensity centers of the plurality of collimated lights coincide.

According to the present invention, by combining an odd number of the prisms, the number of prisms can be reduced by one.
It is possible to make all the intensity centers of the even number of collimated lights coincide with each other, emit the collimated light in a direction perpendicular to the incident direction of the collimated light, and function as a rising mirror.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an optical pickup device 21 according to an embodiment of the present invention.

FIG. 2 is a schematic view showing an optical axis alignment component 25A which is a first embodiment of the optical axis alignment component 25 in the optical pickup device 21 of the present invention.

FIG. 3 is a schematic view showing an optical axis alignment component 25B which is a second embodiment of the optical axis alignment component 25 in the optical pickup device 21 of the present invention.

FIG. 4 is a schematic view showing an optical axis aligning part 25C which is a third embodiment of the optical axis aligning part 25 in the optical pickup device 21 of the present invention.

FIG. 5 is a schematic view showing an optical axis aligning part 25D which is a fourth embodiment of the optical axis aligning part 25 in the optical pickup device 21 of the present invention.

FIG. 6 is a schematic view showing an optical axis aligning part 25E which is a fifth embodiment of the optical axis aligning part 25 in the optical pickup device 21 of the present invention.

FIG. 7 is a schematic view showing an optical axis aligning part 25F which is a sixth embodiment of the optical axis aligning part 25 in the optical pickup device 21 of the present invention.

FIG. 8 is a schematic configuration diagram showing an optical pickup device 21A according to another embodiment of the present invention.

[Explanation of symbols]

21, 21A Optical pickup device 22 Laser light source 22a, 22b Laser element 23, 23A Collimator lens 25, 25A to 25F Optical axis alignment component 31, 42, 62 Prism 32, 44, 44A to 44C, 62a Incident surface 33, 34, 45A ~ 45C, 46A ~ 46C, 62
b, 62c Reflection surface 43, 61 Wavefront aberration correction member 50, 63 Quarter-wave plate 51 Wavefront aberration correction plate 52, 64 Positioning member

Claims (8)

[Claims] 1. An optical pickup device using at least two laser beams having different wavelengths, comprising: a prism having one incident surface and a plurality of reflecting surfaces, wherein two optical axes are non-parallel to each other and have different wavelengths. When the collimated light is incident on the incident surface of the prism, the collimated light of one wavelength reflected on the incident surface, and the other transmitted through the incident surface, reflected on the reflecting surface, transmitted again on the incident surface, and emitted from the prism. An optical pickup device, comprising: a prism that makes an optical axis of collimated light having a wavelength parallel and aligns a center of light intensity. 2. An optical pickup device using at least two laser beams having different wavelengths, wherein the collimator lens is displaceable in accordance with the optical axis of the incident light, and outputs a plurality of laser beams having different wavelengths from each other. A collimator lens that converts a plurality of collimated light beams into a plurality of collimated light beams whose optical axes are parallel to each other and whose light intensity centers are displaced from each other by displacing the collimator, and a prism having one incidence surface and a plurality of reflection surfaces, When two collimated light beams having different wavelengths, which are parallel to each other and have different optical axes, are transmitted through a lens, the collimated light beam having one wavelength reflected on the incident surface of the prism and a reflecting surface after being transmitted through the incident surface. And the collimated light of the other wavelength emitted from the prism after being transmitted through the incident surface again to match the intensity center of the collimated light. Optical pickup device characterized by comprising an arm. 3. The method according to claim 1, wherein the incident surface of the prism is a dichroic mirror having wavelength selectivity.
Or the optical pickup device according to 2. 4. The optical pickup device according to claim 1, wherein the entrance surface of the prism is a half mirror. 5. The optical pickup device according to claim 1, wherein a wavefront aberration correcting auxiliary plate is attached to an incident surface of the prism. 6. The optical pickup device according to claim 5, wherein a quarter-wave plate is attached to the wavefront aberration correcting auxiliary plate. 7. The method according to claim 1, wherein a plurality of said prisms are combined, and a plurality of incident laser beams having different wavelengths are emitted with their light intensity centers all coincident with each other.
7. The optical pickup device according to any one of 6. 8. An even number of laser beams having different wavelengths, and the even number of laser beams incident on the prism is emitted in a direction substantially perpendicular to an incident direction, thereby causing the prism to function as a rising mirror. The optical pickup device according to claim 1, wherein: