JP2002170271A - Optical path adjusting optical device, light source device and optical head device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical path adjusting optical device, a light source device and an optical head device capable of adjusting the length of an optical path before the divergent light emitted from two light sources at nearly the same position enters a collimator lens, and capable of preventing astigmatism or a coma aberration from being generated at that time. SOLUTION: In the light source device 2 of the optical head device 1, even if a first laser beam source 11 and a second laser beam source 12 exist at nearly the same position while distances from the first and second laser beam sources to the collimator lens 7 are equal, the first laser beam L1 (S polarizing beam) is reflected on a polarized beam separating plane 21 of the polarized beam splitter 20 and advances to the collimator lens 7, while the second laser beam L2 (P polarizing beam) is made to exit toward the collimator lens 7 after reciprocating in an optical path from the polarized beam separating surface 21 to a first reflection surface 27 and an optical path from the polarized beam separating plane 21 to a second reflection surface 29. Thus, the optical path up to the collimator lens 7 of the first laser beam L1 is optically shorter than the optical path up to the collimator lens 7 of the second laser beam L2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical path adjusting optical device used for an optical head device and the like, a light source device using the optical path adjusting optical device, and an optical head device using the light source device. . More specifically, the present invention relates to a technique for providing a difference in the length of an optical path between two types of light emitted from a light source unit.

[0002]

2. Description of the Related Art In an optical head device, as is well known, a CD is used.
When reproducing or recording on a CD-R, a laser beam having a wavelength of 780 nm is used.
0 nm laser light is used. Therefore, an optical head device for reproducing a DVD and a CD / CD-R and recording a CD-R emits a laser beam having a wavelength of 780 nm as disclosed in Japanese Patent Application Laid-Open No. 2000-99978. Laser light source for CD, wavelength 650
and a laser light source for DVD that emits laser light of nm.

As shown in FIG. 6, an optical head device disclosed in this publication includes a laser light source 111 for a CD and a D light source.
A VD laser light source 112 is provided, and a beam splitter 113 and a collimator lens 11 are provided on an optical path from these light sources 111 and 112 to the optical recording medium.
4 and an objective lens 115 are arranged.

[0004] At the time of reproducing a DVD, it is necessary to form a small spot on the optical recording medium. Therefore, it is necessary to make the light intensity distribution uniform for DVD light, while recording on a CD-R. In this case, it is necessary to form a spot having a large power. Therefore, in the optical head device shown in FIG. 6, the polarization holograms 121 and 1 are placed on the optical path from the collimator lens 114 to the objective lens 115.
An aperture member 120 on which a 波長 wavelength plate 122 and a wavelength filter 123 are stacked, and a beam shaping unit 130 are arranged.

[0005] The beam shaping means 130 comprises a first optical component 131 and a second optical component 135. The first surface 132 of the first optical component 131 has a laser light source 1 for CD.
11 is a surface on which light emitted from the laser light source 11 is reflected while light emitted from the laser light source 112 for DVD is refracted. In the first optical component 131, the second surface 133 facing the second optical component 135 is such that the DVD light incident on the first optical component 131 is the second optical component 1.
35 is a surface on which the light reflected by the second optical component 135 is refracted and incident, and the light incident from the second surface 133 is the first optical component. 131, the first surface 1
The light is refracted from 32 toward the objective lens 115. Therefore, the light emitted from the DVD laser light source 112 is emitted toward the objective lens 115 in a state where the intensity distribution is made uniform by the beam shaping means 130.

Further, the optical path from the laser light source 111 for the CD to the collimator lens 114 is set shorter than the optical path from the laser light source 112 for the DVD to the collimator lens 114, so that a sufficient power for recording on the CD-R is provided. Spots can be formed.

[0007]

However, in recent years,
Laser light source 111 for CD and laser light source 11 for DVD
2 are housed in a common package to reduce the size and cost. When such a configuration is adopted, as in the optical head device described with reference to FIG. There is a problem that the distance from the laser light sources 111 and 112 to the collimator lens 114 cannot be changed for CD and DVD.

Therefore, the beam shaping means 130 described with reference to FIG. 6 is arranged between the laser light sources 111 and 112 housed in a common package and the collimator lens 114. A configuration is conceivable in which the length of the optical path from the light sources 111 and 112 to the collimator lens 114 is different.

However, the laser light sources 111 and 112
The first optical component 1 of the beam shaping unit 130 described with reference to FIG.
The configuration in which the refraction light is incident on the beam 31 has a problem that astigmatism or coma cannot be prevented from occurring. Therefore, it is conceivable to make the second optical component 132 wedge-shaped so that aberrations can be eliminated, but with this configuration, it is difficult to remove both astigmatism and coma. Further, since the light is obliquely incident on the first optical component 131, the amount of the aberration generated fluctuates rapidly depending on the diverging state of the incident light, and it is difficult to design with such accuracy that such fluctuation can be absorbed. It is.

[0010] In view of the above problems, an object of the present invention is to provide:
The length of the optical path can be adjusted before divergent light emitted from two light sources located at substantially the same position enters the collimator lens, and at this time, astigmatism or coma does not occur. An object of the present invention is to provide an optical path adjusting optical device, a light source device using the optical path adjusting optical device, and an optical head device using the light source device.

[0011]

In order to solve the above-mentioned problems, according to the present invention, the length of the optical path for the light of the first wavelength band and the light of the second wavelength which are incident substantially in parallel from the light source section side. Optical path adjusting optical device for giving a difference to and emitting the light,
When the polarization components whose polarization planes are orthogonal to each other are defined as a first polarization light and a second polarization light, respectively, about the center of the incident optical axis of the light in the first wavelength range and the light in the second wavelength range. A polarization splitting surface that forms an angle of 45 degrees, and reflects the first polarized light of the light in the first wavelength range in a direction orthogonal to the polarization splitting surface, and the polarization splitting surface in the second wavelength range. A polarizing beam splitter through which the second polarized light of light passes, a first λ / 4 plate through which the light of the second wavelength band transmitted through the polarization splitting surface passes, and the first λ / 4 plate A first reflection surface for transmitting the light of the second wavelength band transmitted through the first again through the first λ / 4 plate and reflecting the light as the second polarized light toward the polarization splitting surface; The second λ / which transmits the light in the second wavelength band reflected as the second polarized light on the separation surface.
Four plates and the light of the second wavelength band transmitted through the second λ / 4 plate are transmitted again through the second λ / 4 plate and directed to the polarization separation surface as first polarized light. And a second reflecting surface that reflects light.

In the present invention, on a light path from a light source section having two laser light sources at substantially the same position to an optical recording medium,
When the collimator lens and the objective lens are arranged in this order, the light in the first wavelength range is reflected by the polarization splitting surface of the polarization beam splitter as the first polarized light and travels toward the collimator lens. On the other hand, the light in the second wavelength range passes through the polarization splitting surface of the polarizing beam splitter as the second polarized light, then passes through the first λ / 4 plate, and is reflected by the first reflecting surface. Then, the light again passes through the first λ / 4 plate and travels toward the polarization splitting surface. Meanwhile, since the light in the second wavelength range has been converted into the first polarized light, it is reflected on the polarization splitting surface, and then transmitted through the second λ / 4 plate, and then reflected on the second reflecting surface. The reflected light is transmitted again through the second λ / 4 plate and travels to the polarization splitting surface. Meanwhile, since the light in the second wavelength band has been converted into the second polarized light, it passes through the polarization splitting surface of the polarizing beam splitter and passes through the substantially same optical path as the light in the first wavelength band to the collimator lens. It is emitted toward.

Therefore, even if the light source that emits light in the first wavelength range and the light source that emits light in the second wavelength range are at substantially the same position and the distance to the collimator lens is equal, the light in the first wavelength range will While the light in the second wavelength range is reflected by the polarization splitting surface of the polarization beam splitter and directly travels toward the collimator lens, the light in the second wavelength range is transmitted from the polarization splitting surface to the first reflection surface, and the second wavelength band The light is reciprocated on the optical path to the reflection surface, and then emitted toward the collimator lens. Therefore, optically, the optical path of the light in the first wavelength range to the collimator lens is shorter than the optical path of the light in the second wavelength range to the collimator lens. Therefore, for light in the first wavelength range,
Since a large power spot can be formed on the optical recording medium, recording on a CD-R can be performed. Also,
The light in the second wavelength range is reflected by the first reflection surface and the second reflection surface in the optical path adjusting optical device and is incident on the collimator lens in a state where the light intensity distribution is uniform. Because spots can be formed on optical recording media,
DVD playback can be performed. Further, since the incident end face of the polarizing beam splitter is arranged at right angles to the central optical axes of the light in the first wavelength range and the light in the second wavelength range, astigmatism and coma do not occur.

In a light source device using the optical path adjusting optical device according to the present invention, a first laser light source for emitting light in the first wavelength range and a second laser for emitting light in the second wavelength range are provided. Even when the light source and the light source are arranged close to each other, as described above, the length of the optical path can be adjusted before the divergent light emitted from the two light sources located at substantially the same position enters the collimator lens, and At this time, astigmatism or coma does not occur.

In the present invention, in the light source unit, when the first laser light source and the second laser light source are displaced in a direction perpendicular to the optical axis center of the light source unit, At least one of the first reflecting surface and the second reflecting surface moves the position of the second laser light source closer to the first laser light source when the optical path adjusting optical device is viewed from the emission side. In order to make it look like, it is preferable to be arranged obliquely with respect to the end face of the polarizing beam splitter. This configuration is equivalent to arranging two light sources on the same optical axis, so that the influence of off-axis aberration can be reduced.

In the optical head device using the light source device according to the present invention, on the optical path from the light source to the optical recording medium,
The optical path adjusting optical device, a collimator lens that converts light emitted from the optical path adjusting optical device into a parallel light beam, and an objective lens that converges the light that has been converted into a parallel light beam by the collimator lens to an optical recording medium are arranged in this order. Have been.

In the present invention, the light in the second wavelength range is
The wavelength is shorter than the light in the first wavelength range. For example, the first
The light in the wavelength range is for a CD having a wavelength of about 780 nm, and the light in the second wavelength range is for a DVD having a wavelength of about 650 nm.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of a two light source type optical head device to which the present invention is applied will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing the structure of an optical system of a two-light source type optical head device to which the present invention is applied. In FIG. 1, return light from the optical recording medium is transmitted from the light source to the optical recording medium. Configurations such as a beam splitter and a light receiving element that are separated from the optical path toward the optical path are omitted. FIG. 2 is a plan view showing an arrangement position of two laser light sources in a light source unit of the light source device used in the optical head device. FIG. 3 is an explanatory diagram showing a state of polarization conversion performed by the optical path adjusting optical device used in the optical head device shown in FIG.

An optical head device 1 shown in FIG. 1 is for reproducing a DVD and a CD / CD-R and recording a CD-R.
A collimator lens 7 and an objective lens 8 are arranged in this order on the optical path toward DVD.

In the optical head device 1, the light source device 2
Is composed of a light source unit 10 and an optical path adjusting optical device 3, and the light source unit 10 has a wavelength band of 780 nm (first wavelength band).
A first laser light source 11 (laser light source for CD) composed of a laser diode for emitting the first laser light L1 (laser light for CD), and a second laser light L2 in a wavelength band of 650 nm (second wavelength band) (DVD laser light) and a second laser light source 12 (DVD
Laser light source).

As shown in FIG. 2, the first laser light source 11 and the second laser light source 12 are arranged in a common package (not shown) at right angles to the emission optical axes of the respective laser light sources 11 and 12. However, the distance is slightly, for example, about 80 μm at the maximum. The first laser light L1 and the second laser light L2 are both emitted from each laser light source 11 as divergent light, but the first laser light L1 has a wavelength longer than that of the second laser light L2. Since it is long, the divergence angle α1 of the first laser light L1 is larger than the divergence angle α2 of the second laser light L2. Therefore, the second laser light L2 is emitted so as to be located inside the light flux of the first laser light L1, and the first laser light L1 and the second laser light L2 are regarded as one light flux. Can be.

Referring again to FIG. 1, in the light source device 2, an optical path adjusting device is disposed between the light source unit 10 and the collimator lens 7 at right angles to the emission optical axes of the first laser light source 11 and the second laser light source 12. Polarizing beam splitter 2 of optical device 3
0, and the polarization splitting surface 21 of the polarization beam splitter 20 is approximately 45 degrees with respect to the outgoing optical axis of the first laser light source 11 and the second laser light source 12 (the incident optical axis with respect to the polarizing beam splitter 20). At an angle.

In the optical path adjusting optical device 3, the polarizing beam splitter 20 includes the first laser light source 11 and the second laser light source 11.
An incident surface 22 facing the laser light source 12, an exit surface 23 facing the collimator lens 7 at a position adjacent to the incident surface 22, and a second surface facing the incident surface 22 with the polarization splitting surface 21 interposed therebetween. 1 and the second input / output end face 2 opposed to the output end face 23 with the polarization splitting surface 21 interposed therebetween.
5 is provided.

Further, in the optical path adjusting optical device 3, a first λ / 4 plate 26 facing the first input / output end face 24 of the polarizing beam splitter 20 in a posture parallel to the end face, and Behind the first λ / 4 plate 26, a first reflection surface 27 facing the first input / output end surface 24 of the polarization beam splitter 20 in a posture parallel to the first input / output end surface 24 is formed.
Further, in the optical path adjusting optical device 3, the second λ / 4 plate 28 facing the second input / output end face 25 of the polarization beam splitter 20 in a posture parallel to the end face, and the second λ / 4 plate 28. Behind the λ / 4 plate 28, a second reflection surface 29 that is opposed to the second input / output end surface 25 of the polarization beam splitter 20 in a parallel state is formed.

Here, the second λ / 4 plate 28 and the second reflecting surface 29 are arranged in close contact with the second input / output end face 25 of the polarizing beam splitter 20, while the first
The λ / 4 plate 26 and the first reflection surface 27 are arranged at a distance L from the first input / output end surface 24 of the polarization beam splitter 20.

In the light source device 2 configured as described above, as shown in FIG.
Is emitted as S-polarized light (first polarized light), the S-polarized light of the first laser light L1 is incident on the incident surface 22 of the polarizing beam splitter 20 at right angles, and then polarized. The light is reflected at a right angle by the separation surface 21 and is emitted from the emission surface 23 toward the collimator lens 7.

On the other hand, when the second laser light L2 is emitted as P-polarized light (second polarized light) from the second laser light source L2, the P-polarized light of the second laser light L2 becomes ,
After being incident on the incidence surface 22 of the polarization beam splitter 20 at right angles, the light passes through the polarization splitting surface 21 of the polarization beam splitter 20, then passes through the first λ / 4 plate 26, and then passes through the first reflection surface 27. Is reflected again by the first λ / 4 plate 26, enters the first input / output end face 24, and enters the polarization splitting surface 2.
Go to 1. Meanwhile, since the second laser light L2 has been converted into S-polarized light, the second laser light L2 is reflected at a right angle by the polarization splitting surface 22 and emitted from the second input / output surface 25, and the second λ / 4 plate 28 After being transmitted through the second reflection surface 29, the light is reflected by the second reflection surface 29, again passes through the second λ / 4 plate 28, and passes through the second entrance / exit surface 25.
From the polarization separation surface 21. Meanwhile, since the second laser light L2 has been converted into P-polarized light, it passes through the polarization splitting surface 21 of the polarization beam splitter 20 and, like the first laser light, is transmitted from the emission surface 23 to the collimator lens 7. It is emitted toward.

Therefore, even if the first laser light source 11 and the second laser light source 12 are located at substantially the same position and the distances to the collimator lens 7 are equal, the first laser light L1 is emitted from the polarization beam splitter 20. While the second laser light L2 is reflected by the polarization splitting surface 21 and proceeds to the collimator lens 7 as it is, the second laser light L2
And the second reflection surface 2 from the polarization separation surface 21
9 is emitted toward the collimator lens 7 after reciprocating in the optical path reaching the first laser beam L.
The optical path to the first collimator lens 7 is shorter than the optical path of the second laser light L2 to the collimator lens 7. That is, when viewed from the collimator lens 7, the second laser light source 12 is apparently disposed at a position, for example, 1.5 times as far as the first laser light source 12. Accordingly, in the present embodiment, a diffraction type is used as the collimator lens 7, and the focal length of the diffraction type collimator lens 7 with respect to the first laser light L1 is:
For example, it is set to 16 mm, and the focal length for the second laser light L2 is set to, for example, 24 mm.

As described above, according to this embodiment, even if the first laser light source 11 and the second laser light source 12 are located at substantially the same position and the distances to the collimator lens 7 are equal, the polarization beam splitter 20 Only by changing the distance L from the first reflection surface 24 to the first reflection surface 27, the length of the optical path of the first laser light L1 to the collimator lens 7 and the length of the optical path of the second laser light L2 to the collimator lens 7 A difference can be given to the length of the optical path with respect to the optical path. Therefore, the collimator lens 7
Even if the apertures are the same, the optical path from the first laser light source 11 to the collimator lens 7 is short, so that a large power spot suitable for CD-R recording can be formed. Since light having a uniform light intensity distribution can be used, a small spot suitable for DVD reproduction can be formed.

Further, the polarization beam splitter 2 is arranged with respect to the central optical axes of the first laser light L1 and the second laser light L2.
Since the zero incidence end face 22 and the like are arranged at right angles, astigmatism and coma do not occur.

[Other Embodiments] In the light source unit 10 described with reference to FIG. 2, the first laser light source 11 and the second laser light source 12 are slightly different from each other in a direction orthogonal to the center of the optical axis. It is shifted. Since such a shift causes off-axis aberration, it is preferable to configure the optical path adjusting device 3 as shown in FIGS. 4 and 5 to eliminate the off-axis aberration.

FIGS. 4 and 5 are explanatory views showing an improved example of the optical path adjusting optical device 3 to which the present invention is applied. In FIG. 4, the optical path adjusting optical device 3 includes:
An optical axis center of the first laser beam L1 emitted from the first light source 11 is indicated by a two-dot chain line, and a first reflecting surface disposed parallel to the first input / output end surface 24 of the polarizing beam splitter 20. 27, and the emission direction in such a configuration is indicated by a dashed line, while the first direction of the polarization beam splitter 20 is
The first reflection surface 27 arranged obliquely to the input / output end face 24 of the light emitting device and the emission direction in such a configuration are shown by solid lines. Also, in FIG.
, The center of the optical axis of the first laser light L1 emitted from the first light source 11 is indicated by a two-dot chain line, and the second laser light L1 is disposed in parallel with the second input / output end face 25 of the polarization beam splitter 20. While the reflecting surface 29 and the emission direction when configured in this manner are indicated by dashed lines, the second reflecting surface 29 disposed obliquely to the second input / output end surface 25 of the polarizing beam splitter 20, and the like. Are shown by solid lines.

First, as shown by the two-dot chain line and the one-dot chain line in FIG. 4, when the first reflecting surface 27 is arranged in parallel to the first input / output end face 24 of the polarizing beam splitter 20,
First laser beam L1 emitted from optical path adjusting optical device 3
The optical axis of the second laser beam L2 is shifted from the center of the second laser beam L2 due to the shift of the positions of the first laser light source 11 and the second laser light source 12.

Accordingly, in the present embodiment, as shown by a solid line in FIG.
The first reflection surface 27 is disposed obliquely with respect to 4. For this reason, the second laser light L2 emitted from the optical path adjusting optical device 3 is emitted slightly inclined in the direction indicated by the arrow A from the emitted light beam indicated by the one-dot chain line as indicated by the solid line L2 '. Therefore, when the optical path adjusting optical device 1 is viewed from the side of the emission surface 23, the second laser light source 12 appears to overlap the first laser light source 11 on an extension of the solid line L2 '. Therefore, off-axis aberrations caused by the first laser light source 11 and the second laser light source 12 being slightly displaced in a direction orthogonal to the optical axis center can be eliminated.

As shown by the two-dot chain line and the one-dot chain line in FIG. 5, when the first reflecting surface 27 is arranged in parallel to the first input / output end face 24 of the polarizing beam splitter 20,
First laser beam L1 emitted from optical path adjusting optical device 3
Although the optical axis center of the second laser light L2 is shifted, in the present embodiment, as shown by the solid line in FIG. 5, the second reflection is made on the second input / output end face 25 of the polarization beam splitter 20. The surface 29 is arranged obliquely.

For this reason, the second laser beam L2 emitted from the optical path adjusting optical device 3 is slightly inclined in the direction shown by the arrow A from the emitted light beam shown by the dashed line as shown by the solid line L2 '. Since the light is emitted, the optical path adjusting optical device 1
When viewed from the exit surface 23 side, the second laser light source 12
Appears to overlap the first laser light source 11 on an extension of the solid line L2 '. Therefore, the first laser light source 1
Off-axis aberrations caused by the first and second laser light sources 12 being slightly displaced in the direction orthogonal to the optical axis center can be eliminated.

[0038]

As described above, according to the present invention, the first
Even if the light source that emits light in the wavelength range and the light source that emits light in the second wavelength range are located at substantially the same position and the distances to the collimator lens are equal, the light in the first wavelength range will be polarized by the polarization beam splitter. On the other hand, the light in the second wavelength range is reflected on the surface and travels directly to the collimator lens, while the light in the second wavelength range travels along the optical path from the polarization splitting surface to the first reflecting surface and the optical path from the polarization splitting surface to the second reflecting surface. After reciprocating, the light is emitted toward the collimator lens. Therefore, optically, the optical path of the light in the first wavelength range to the collimator lens is shorter than the optical path of the light in the second wavelength range to the collimator lens. Therefore,
With respect to the light in the first wavelength range, a spot having a large power can be formed on the optical recording medium, so that recording on a CD-R can be performed. For the light in the second wavelength range, the first reflection surface and the second reflection surface in the optical path adjusting optical device are used.
Since the light is reflected by the reflective surface and is incident on the collimator lens in a state where the light intensity distribution is uniform, a small spot can be formed on the optical recording medium, so that the DVD can be reproduced. Further, since the incident end face of the polarizing beam splitter is arranged at right angles to the central optical axes of the light in the first wavelength range and the light in the second wavelength range, astigmatism and coma do not occur.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a configuration of an optical system of an optical head device of a two light source type to which the present invention is applied.

FIG. 2 is a plan view showing an arrangement position of two laser light sources in a light source unit of the light source device used in the optical head device shown in FIG.

FIG. 3 is an explanatory diagram showing a state of polarization conversion performed by an optical path adjusting optical device used in the optical head device shown in FIG.

FIG. 4 is an explanatory view showing an improved example of the optical path adjusting optical device shown in FIG. 1;

FIG. 5 is an explanatory diagram showing another improved example of the optical path adjusting optical device shown in FIG. 1;

FIG. 6 is a schematic configuration diagram showing a configuration of an optical system of a conventional two light source type optical head device.

[Explanation of symbols]

Reference Signs List 1 optical head device 2 light source device 3 optical path adjusting optical device 7 collimator lens 8 objective lens 10 light source unit 11 first laser light source (CD laser light source) 12 second laser light source (DVD laser light source) 20 polarization beam splitter DESCRIPTION OF SYMBOLS 21 Polarization separation surface 22 Incident surface 23 Outgoing surface 24 First entrance / exit surface 25 Second entrance / exit end surface 26 First λ / 4 plate 27 First reflection surface 28 Second λ / 4 plate 29 Second Reflection surface L1 First laser light (CD laser light in first wavelength range) L2 Second laser light (DVD laser light in second wavelength range)

Claims (5)

[Claims] 1. A first light source which is incident substantially parallel from a light source unit side.
An optical path adjusting optical device for giving a difference in the length of an optical path between light in a wavelength range and light in a second wavelength and emitting the light, wherein polarization components whose polarization planes are orthogonal to each other are each a first polarization. And a polarization splitting surface forming an angle of about 45 degrees with respect to an incident optical axis of the light in the first wavelength range and the light in the second wavelength range, when the light and the second polarized light are formed. A polarizing beam splitter that reflects the first polarized light of the light of the first wavelength band in a direction orthogonal to the surface, while transmitting the second polarized light of the light of the second wavelength band through the polarization splitting surface; A first λ / 4 plate through which the light of the second wavelength band transmitted through the polarization splitting surface is transmitted, and a light of the second wavelength band transmitted through the first λ / 4 plate again, A first reflection surface that transmits through the first λ / 4 plate and reflects as the second polarized light toward the polarization separation surface; A second λ / 4 plate through which the light of the second wavelength band reflected as the second polarized light at the light separating surface is transmitted; and a second λ / 4 plate of the second wavelength band transmitted through the second λ / 4 plate. A second reflection surface for transmitting the light through the second λ / 4 plate again and reflecting the light as the first polarized light toward the polarization separation surface. 2. A light source device comprising: the optical path adjusting optical device defined in claim 1; and the light source unit, wherein the light source unit emits light in the first wavelength range. And a second laser light source that emits light in the second wavelength range is disposed in close proximity to the light source device. 3. The light source unit according to claim 2, wherein the first laser light source and the second laser light source are displaced in a direction orthogonal to an optical axis center of the light source unit. At least one of the first reflecting surface and the second reflecting surface moves the position of the second laser light source closer to the first laser light source when the optical path adjusting optical device is viewed from the emission side. Characterized in that the light source device is arranged obliquely with respect to an end face of the polarizing beam splitter so as to make the light beam look like. 4. An optical head device using the light source device defined in claim 2 or 3, wherein the optical path adjusting optical device and the optical path adjusting optical device are provided on an optical path from the light source unit to the optical recording medium. An optical head device comprising: a collimator lens for converting a light beam emitted from an optical device into a parallel light beam; and an objective lens for converging light parallelized by the collimator lens to an optical recording medium. . 5. The optical head device according to claim 4, wherein the light in the second wavelength band has a shorter wavelength than the light in the first wavelength band.