JPH07307034A - Optical head - Google Patents

Abstract

PURPOSE:To provide an optical head capable of achieving high speed access by eliminating a track offset and reducing the weight of a movable optical system. CONSTITUTION:A beam splitter 21 for transmitting a part of outgoing light A emitted from a fixed optical system 1 and a reflecting member 23 for reflecting a part of the light transmitted through this beam splitter 21 are provided in the movable optical system 2. Then, compensating light B reflected by the reflecting member 23 and splitted into plural beams is received by using a photodetector 22 for receiving reflected light C from an optical information recording medium 8 arranged in the fixed optical system 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head provided with an optical system in which a fixed optical system and a movable optical system are separated.

[0002]

2. Description of the Related Art First, as a first conventional example, Japanese Patent Laid-Open No. 63-63
There is one disclosed in "-263637" as "optical head device". As shown in FIG. 11A, this is a separation type device in which a fixed optical system 1 and a movable optical system 2 are separated. First, the light emitted from the semiconductor laser 3 serving as a laser light source in the fixed optical system 1 is transmitted or reflected by the first beam splitter 4 and two lights A,
It is divided into B. The transmitted light A (light for information detection) is reflected by the second beam splitter 5, bent vertically by the reflection mirror 6 in the movable optical system 2, passes through the objective lens 7, and records optical information. The surface of the optical disk 8 serving as a medium is irradiated with the light, whereby information is recorded. Then, the reflected light from the optical disc 8 is
It follows a path opposite to the incident optical path, is guided again into the fixed optical system 1, is transmitted through the second beam splitter 5 and is received by the two-divided light receiving element 9, whereby the well-known push-pull method or the like is used. Tracking servo can be performed by detecting a track error signal. On the other hand, the light B (correction light) reflected by the first beam splitter 4 is guided to the half mirror 10, and a part of the light is incident on the two-divided light receiving element 11 attached to the back surface of the half mirror 10, and the remaining light. The light is reflected and guided to the two-divided light receiving element 12.

In the case where the optical axis of the light B and the movable optical system 2 are relatively misaligned with each other, FIG.
The amounts of light incident on the two light receiving surfaces a and b of the two-divided light receiving element 11 as shown in (b) are different, which causes the output of the differential amplifier 13 to be a positive or negative output. Further, when the optical axis of the light B and the movable optical system 2 are relatively inclined, the amounts of light incident on the two light receiving surfaces c and d of the two-divided light receiving element 12 are different and the differential amplifier The output of 14 becomes positive or negative. Therefore, the tracking offset can be removed by correcting the optical axis by the control mechanism (not shown) so that the output values of both the differential amplifiers 13 and 14 become zero.

Next, as a second conventional example, Japanese Patent Application No. 4-2.
Japanese Patent No. 49332 has filed as an "optical head" by the present applicant. As shown in a simplified form in FIG. 12, this is a semiconductor device provided in the movable optical system 2 in order to remove a track offset due to an optical axis shift in a separation type device composed of a fixed optical system 1 and a movable optical system 2. A beam splitter 15 having a polarizing film 15a that transmits a part of the emitted light A from the laser 3 and a reflecting surface 15b that reflects a part or all of the light transmitted through the polarizing film 15a is provided. The light receiving element 16 is attached to one surface. Of the reflected light C from the optical disk 8, the light re-introduced into the fixed optical system 1 is reflected by the beam splitter 17 and then separated into two by the beam splitter 18 and detected by the light receiving elements 19 and 20. As a result, a track error signal, a reproduction signal, etc. can be obtained.

In this case, the light receiving element 16 reflects the emitted light A on the optical disk 8 and reflects the reflected light C, and the emitted light A passes through the beam splitter 15 and is corrected by the reflected light B on the reflecting surface 15b. And are being guided.
When the optical axis of the outgoing light A entering the optical system is displaced due to the displacement of the movable optical system 2, the light receiving element 16
The track offset can be removed by utilizing the phenomenon that the two light spots move in opposite directions on the plane.

[0006]

However, the first conventional example has various problems as described below. First, since the optical axis deviation occurring in the signal detecting light A is read by using the correcting light B as a substitute, the actual optical axis deviation is not detected and the track offset is accurately corrected. I can't. The track offset due to the optical axis shift is determined by how much the optical axis shifts and tilts at the position of the reflection mirror 6 of the movable optical system 2, and the optical element attached to the housing of the movable optical system 2. Even if you judge the optical axis deviation with
Due to the manufacturing accuracy of the housing, the mounting error of the reflection mirror 6, and the like, it is not always possible to apply the correction that matches the original optical axis shift. Further, in addition to the light receiving element for detecting the track error signal (two-divided light receiving element 9), a light receiving element (two-divided light receiving elements 11, 12) dedicated to the track offset correction of the track error signal is required. As a result, the number of parts of the light receiving element is increased, and the number of electric system circuits and adjustment points related thereto are also increased, resulting in high cost.

In the case of the second conventional example, the movable optical system 2
Since the light receiving element 16 dedicated to the track offset correction is separately provided therein, and the electric system circuit provided in the light receiving element 16 is also required, the weight of the movable optical system 2 itself increases, and as a result, There is a problem that a high-speed access operation cannot be performed.

[0008]

According to a first aspect of the present invention, the emitted light emitted from the laser light source disposed in the fixed optical system is guided to the movable optical system, and the emitted light incident into the movable optical system. In the optical head for recording, reproducing, and erasing information by irradiating the optical information recording medium by condensing with an objective lens, a beam splitter that transmits a part of the emitted light emitted from the fixed optical system, A reflecting member for reflecting a part of the light transmitted through the beam splitter is provided in the movable optical system, and the correction light reflected by the reflecting member in the movable optical system and divided into a plurality of pieces and the optical information recording medium. A light-receiving element for receiving the reflected light from is arranged in the fixed optical system.

According to a second aspect of the present invention, in the first aspect of the invention, a beam splitter that transmits a part of the light emitted from the fixed optical system and a part of the light that passes through the beam splitter are reflected. The reflecting member is integrally formed.

According to a third aspect of the invention, in the first aspect of the invention, the reflecting member is composed of a reflection type diffraction grating in which diffraction gratings having different pitches or grating directions are formed.

According to a fourth aspect of the invention, in the third aspect of the invention, a beam splitter which transmits a part of the light emitted from the fixed optical system and a diffraction grating having a different pitch or grating direction are formed. The reflection type diffraction grating is integrally provided.

According to a fifth aspect of the invention, in the first aspect of the invention, the reflecting member is composed of a reflecting prism in which the traveling directions of the light reflected by the regions are different.

According to a sixth aspect of the present invention, in the first aspect of the present invention, the beam splitter is provided with polarization characteristics in which the incident light has different reflectances for P-polarized light and S-polarized light.

According to a seventh aspect of the present invention, in the first aspect of the invention, the light incident on the beam splitter has polarization characteristics in which the P-polarized light and the S-polarized light have different reflectances. A reflecting member for reflecting a part of the transmitted light is integrally provided.

[0015]

According to the present invention, a part of the emitted light passes through the beam splitter and enters the reflecting member, and the correction light reflected by the reflecting member is divided into a plurality of pieces and fixed. It is guided to the light receiving element in the optical system. At this time, in the light receiving element in the fixed optical system, the reflected light from the optical information recording medium is used to detect the track error signal by the push-pull method, and at the same time, the optical information recording medium is detected according to the optical axis shift amount of the movable optical system. The correction light that causes a spot fluctuation in the opposite direction to the reflected light from the light receiving surface is detected. As a result, the received light output from the correction light and the received light output from the reflected light caused by the optical axis shift of the movable optical system act to cancel each other, so that the occurrence of the track offset of the track error signal can be suppressed. It will be possible.

According to the second aspect of the invention, since the beam splitter and the reflecting member are integrally provided,
While reducing the number of parts to reduce the weight of the movable optical system,
It is possible to simplify the assembly adjustment.

According to the third aspect of the present invention, the correction light for detecting the positional deviation of the movable optical system and the reflected light for detecting the track error signal are guided to the respective light receiving surfaces of the light receiving elements, and therefore, these two It is possible to adjust the gain of two lights.

According to the fourth aspect of the present invention, the reflection type diffraction grating is directly formed on the beam splitter to be integrated with the beam splitter, so that a stable signal can be obtained against a positional displacement with time caused by vibration in the movable optical system. In addition to being able to detect, it is possible to reduce the number of parts and achieve weight reduction.

According to the invention described in claim 5, since the reflecting member is composed of the reflecting prism, the light utilization efficiency can be made higher than that of the case where the reflecting member is formed by the diffraction grating. Further, as a result, the zero-order light is not generated, so that flare light is not generated.

In the sixth aspect of the present invention, the beam splitter is provided with a polarization characteristic, so that the correction light for detecting the displacement of the movable optical system and the reflection light for detecting the track error signal can have the polarization characteristic. Therefore, it is possible to separate these two lights into a large angle (for example, 90 °) and detect them by separate light receiving elements.

According to the seventh aspect of the present invention, the beam splitter having a polarization characteristic and the reflecting member are integrally provided to reduce the weight of the movable optical system and separate the correction light and the reflected light. It is possible to detect the light receiving elements separately.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the invention described in claims 1 and 2 is shown in FIGS.
It will be described with reference to FIG. The description of the same parts as in the conventional example is omitted, and the same parts are denoted by the same reference numerals. First, an outline of the overall configuration of the optical head will be described with reference to FIG. Emitted light A emitted from the semiconductor laser 3
Is collimated by the collimator lens 3a, passes through the beam splitter 17, exits from the fixed optical system 1, and is guided into the movable optical system 2. The outgoing light A that has entered this movable optical system is reflected by the beam splitter 21, condensed by the objective lens 7 above, and irradiated onto the surface of the optical disk 8, thereby recording information and the like. Further, the reflected light C from the optical disk 8 follows the reverse path from the objective lens 7 to the beam splitter 21, returns to the fixed optical system 1 again, is reflected by the beam splitter 17 this time, and then is detected by the detection lens 18. The light is collected and guided to the light receiving element 22. As a result, reproduction of information and detection of a track error signal and a focus error signal are performed.

In such an optical head, the beam splitter 21 arranged in the movable optical system 2 has a function of transmitting a part of the emitted light A emitted from the fixed optical system 1.
Further, a reflecting plate 23 as a reflecting member for reflecting a part of the light transmitted through the beam splitter 21 is provided on the carriage 2a located behind the beam splitter 21 in the movable optical system 2. 2A shows the shape of the reflection plate 23 on the front side, and FIG. 2B shows the optical arrangement near the reflection plate 23. The reflecting plate 23 has a transmitting surface 23b for transmitting light in the center thereof and reflecting surfaces 23a for reflecting the light on both sides thereof. Further, the light receiving element 22 arranged in the fixed optical system 1 here
In addition to receiving the reflected light C from the optical disc 8 as described above, the correction light B reflected by the reflecting plate 23 in the movable optical system 2 is also received. Since the present invention aims to remove the track offset in the separate type optical head, a method of detecting the track error signal will be described below.

The operation of arranging the reflecting plate 23 and the beam splitter 21 in the movable optical system 2 and the light receiving element 22 in the fixed optical system 1 in such a structure will be described. The light receiving element 22 detects the reflected light C from the optical disk 8, and the emitted light A partially passes through the beam splitter 21 and is reflected by the reflecting surface 23a of the reflecting plate 23.
Thereby, the reflected light B divided into a plurality of pieces is detected. Then, as shown in FIG. 3B, when the center O of the movable optical system 21 and the incident optical axis of the outgoing light A incident on the movable optical system 21 coincide with each other, FIG. As shown in
The light spot due to the reflected light C from the optical disk 8 is located at the center of the two light receiving surfaces a and b of the light receiving element 22 in the fixed optical system 1, that is, on the dividing line, and due to the correction light B from the reflecting surface 23a. The light spots are applied to the light receiving surfaces a and b of the light receiving element 22 in equal sizes. In this case, the light receiving output on the light receiving surface a and the light receiving output on the light receiving surface b are equal. As a result, the track error signal Te becomes Te = ab = 0 (1) and no track offset occurs. On the other hand, when the movable optical system 2 is displaced with respect to the incident optical axis of the outgoing light A as shown in FIG. 3A, the reflected light C from the optical disk 8 is shown as shown in FIG. 4A. The light spot due to is shifted to the light receiving surface a side, and the light receiving output on the light receiving surface a side becomes large, and the track error signal Te becomes: Te = ab> 0 (2). In such a normal state. Track offset occurs. However, in this embodiment, the light spot of the correction light B from the reflection surface 23a is larger on the light receiving surface b side opposite to the reflection light C. Then, the received light output on the light receiving surface b side increased by the correction light B acts so as to cancel the received light output on the light receiving surface a side increased by the reflected light C. As a result, the occurrence of the track offset due to the positional deviation on the movable optical system 2 side is suppressed, so that the track error signal can be detected with high accuracy. In addition, FIG. 3C and FIG.
It is possible to obtain the same effect as in the case of (a) and FIG. 4 (a).

Further, in the above-mentioned example, the case where the reflecting plate 23 having the reflecting surface 23a divided into two and the corresponding light receiving element 22 having the light receiving surfaces a and b divided into two are described. However, the present invention is not limited to this, and for example, as shown in FIG. 5, the reflecting plate 23 and the light receiving element 22 may each be divided into four parts. By increasing the number of divisions in this way, it is possible to more accurately remove the track offset caused by the displacement of the movable optical system 2.

Further, here, the beam splitter 21
, And the reflection plate 23 are provided separately, but these two members may be integrated. That is, as shown in FIG. 6, a reflection film 24 as a reflection member is directly formed on one surface of the beam splitter 21 by vapor deposition. This reflective film 2
The area between 4 is a transparent surface 21a. Besides this,
The reflector 23 may be directly attached to one surface of the beam splitter 21. Since the assembly and adjustment can be simplified and the weight can be reduced by integrally forming by vapor deposition or adhesion as described above, the access operation can be performed at a higher speed.

Next, an embodiment of the invention described in claims 3, 4 and 5 will be described with reference to FIGS. The description of the same parts as in the conventional example is omitted, and the same parts are denoted by the same reference numerals. In this embodiment, as shown in FIG. 7, a reflection type diffraction grating 25 in which diffraction gratings 25a having different pitches or grating directions are formed is provided as a reflection member. FIG. 8A shows the shape of the diffraction grating 25a, and the diffraction grating 25a is formed in different directions with the dividing line at the center as a boundary. With such a configuration, the correction light B transmitted through the beam splitter 21, diffracted by the diffraction grating 25a and divided into a plurality of light beams (here, divided into two) is guided to the light receiving element 22 in the fixed optical system 1. FIG. 8B shows the shape of the light receiving element 22. The diffracted light spot from the correction light B is received by the light receiving surfaces a and d among the four light receiving surfaces a to d, and the optical disc is obtained. The reflected light C from 8 is received by the light receiving surfaces b and c. As a result, the track error signal Te is detected as Te = (bc)-[alpha] (d-a) (3) [alpha]: constant. At this time, the intensity change of the light spot due to the displacement of the movable optical system 2 is considered as in FIG. 3 described above, and the light spot of the correction light B moves so as to cancel the track offset in which the light spot of the reflected light C occurs. In this way, the track error signal can be detected with high accuracy.

Further, in this embodiment, since each light spot of the correction light B is detected by the different light receiving surfaces a and d of the light receiving element 22, the gain adjustment of the electric circuit can be performed. By this gain adjustment, the detection sensitivity of the track error signal can be optimized, and the beam splitter 21
It is possible to correct the light intensity of each light spot due to variations in the reflectance of the light and the diffraction efficiency of the diffraction grating 25a. Further, as described above, the beam splitter 21 and the reflection type diffraction grating 25 may be integrally formed, which allows the movable optical system 2 to be reduced in weight and can be accessed at high speed.

Also, considering that the purpose of the reflecting member is to divide the light into a plurality of pieces, instead of using the reflection type diffraction grating 25 as described above, as shown in FIG. You may comprise using the reflection prism 26 in which the advancing direction of the reflected light differs. Since the 0th-order light is not generated unlike the diffraction grating by using the prism shape, the flare light is small and the light can be used without waste, which may reduce the light use efficiency. Moreover, stable signal detection can be performed even with respect to wavelength fluctuations.

Next, an embodiment of the invention described in claims 6 and 7 will be described with reference to FIG. The description of the same parts as in the conventional example is omitted, and the same parts are denoted by the same reference numerals. In the present embodiment, as the beam splitter, instead of using the beam splitter 21 as described above, a polarization beam splitter 27 having a polarization characteristic with different reflectance depending on the polarization direction of incident light is used. In addition, along with this, in the movable optical system 2,
As shown in (a), a quarter wavelength plate 28 is arranged between the polarization beam splitter 27 and the objective lens 7. Also,
As shown in FIG. 10B, a polarization beam splitter 29 having a similar polarization separation characteristic is provided in the fixed optical system 1, and the P and S polarized lights separated by this polarization beam splitter 29 are received. Light receiving elements 30 and 31 are provided.

In such a configuration, the polarization beam splitter 27 has, for example, a polarization characteristic that the reflectance of P-polarized light frequently used in a magneto-optical disk is 30% and the reflectance of S-polarized light is 100%. An example will be described.
The output light A from the fixed optical system 1 is the polarization beam splitter 2
30% of the P-polarized light is reflected by entering 7
Circularly polarized light by the quarter-wave plate 28 is radiated to the optical disk 8 surface through the objective lens 7, and the reflected light C enters the quarter-wave plate 28 again to become S-polarized light.
The S-polarized light is 100% by the polarization beam splitter 27.
It is reflected and returns to the fixed optical system 1. On the other hand, 70% of the P-polarized light of the outgoing light A is transmitted through the polarization beam splitter 27, reflected by the reflection surface 23a of the reflection plate 23, transmitted through the polarization beam splitter 27 again, and returned to the fixed optical system 1, It is used as the correction light B. As a result, the reflected light C from the optical disk 8 becomes S-polarized light, and the correction light B from the reflection plate 23 becomes P-polarized light. Therefore, the fixed optical system 1
In the inside, the correction light B is received by the light receiving element 30, and the reflected light C
Is received by the light receiving element 31.

Since the correction light B and the reflected light C can be detected by the separate light receiving elements 30 and 31 in this way,
As described above, the gain adjustment can be performed and the detection sensitivity of the track error signal can be optimized. In addition, since the separation method by the polarization beam splitter 27 is performed not by the difference in the angle of the incident optical axis of the outgoing light A entering the movable optical system 2, but by the polarized light separation, the light receiving elements 30 and 31 and the light spot are separated. The alignment is extremely easy, assembly adjustment is simplified, and productivity is improved. Also in this embodiment, the polarization beam splitter 27 and the reflection plate 23 are integrally configured,
The weight can be reduced and a high-speed access operation can be performed.

[0033]

According to the first aspect of the present invention, the emitted light emitted from the laser light source disposed in the fixed optical system is guided to the movable optical system, and the emitted light incident into the movable optical system is guided by the objective lens. In an optical head that records, reproduces, and erases information by collecting and irradiating the optical information recording medium,
A beam splitter that transmits a part of the emitted light emitted from the fixed optical system and a reflecting member that reflects a part of the light transmitted through the beam splitter are provided in the movable optical system. Since the light receiving element for receiving the correction light reflected by the reflecting member and divided into a plurality of lights and the reflected light from the optical information recording medium is arranged in the fixed optical system, the movable optical system is arranged on the light receiving element surface. The correction light corresponding to the amount of optical axis deviation and the reflected light from the optical information recording medium cause spot fluctuations in the opposite directions, so that the mutual light reception outputs can be canceled. As a result, it is possible to provide an optical head capable of removing the track offset and detecting a highly reliable and stable track error signal.
Further, since the track offset can be detected by using the conventional light receiving element, the structure of the movable optical system can be simplified and high speed access can be performed.

According to a second aspect of the present invention, in the first aspect of the invention, a beam splitter that transmits a part of the light emitted from the fixed optical system and a part of the light that passes through the beam splitter are reflected. Since the reflecting member is integrally provided, the number of parts of the movable optical system can be reduced, high-speed access can be performed, and the assembly and adjustment can be facilitated to reduce the cost.

According to a third aspect of the present invention, in the first aspect of the present invention, the reflecting member is composed of a reflection type diffraction grating in which diffraction gratings having different pitches or grating directions are formed. It is possible to guide the correction light for detecting the error and the reflected light for detecting the track error signal to the respective light receiving surfaces of the light receiving elements, which facilitates the gain adjustment of the electric circuit and enables highly reliable signal detection. It can be carried out.

According to a fourth aspect of the present invention, in the third aspect of the invention, a beam splitter that transmits a part of light emitted from the fixed optical system and a diffraction grating having a different pitch or grating direction are formed. Since it is integrated with the reflection type diffraction grating, the number of parts can be reduced, weight can be reduced, high-speed access can be performed, and positional deviation of parts in the movable optical system with time can be suppressed as much as possible. .

According to a fifth aspect of the invention, in the first aspect of the invention, since the reflecting member is composed of a reflecting prism in which the traveling direction of the light reflected by the region is different, flare light is not generated. , High light utilization efficiency,
Highly accurate signal detection can be performed.

According to a sixth aspect of the present invention, in the first aspect of the present invention, the beam splitter is provided with polarization characteristics in which the incident light has different reflectances for P-polarized light and S-polarized light. And can be easily separated, which facilitates assembly and adjustment and enables highly accurate signal detection.

According to a seventh aspect of the present invention, in the first aspect of the present invention, the light incident on the beam splitter has polarization characteristics in which the P-polarized light and the S-polarized light have different reflectances. Since a reflecting member that reflects a part of the transmitted light is provided integrally,
The number of parts of the movable optical system can be reduced to achieve weight reduction, high-speed access can be achieved, and correction light and reflected light can be easily separated, which facilitates assembly adjustment and highly accurate signal detection. it can.

[Brief description of drawings]

FIG. 1 is an optical path diagram showing an embodiment of the invention described in claim 1.

FIG. 2A is a front view of a reflecting member, and FIG. 2B is a side view showing an optical path state of a movable optical system near the reflecting member.

FIG. 3 is a schematic diagram showing a state in which the movable optical system is displaced with respect to the incident optical axis.

FIG. 4 is a schematic diagram showing a beam state on a light receiving element surface.

5A is a front view of a reflecting member having a reflecting surface divided into four parts, and FIG. 5B is a front view of a light receiving element having a light receiving surface divided into four parts.

FIG. 6 is a perspective view showing a state in which a reflecting surface is formed on one surface of a beam splitter showing an embodiment of the invention described in claim 2;

FIG. 7 is a side view showing an embodiment of the invention according to claim 3;

8A is a front view of a reflection type diffraction grating, and FIG. 8B is a front view showing a beam state on a light receiving element surface.

FIG. 9 is a side view showing an embodiment of the invention as set forth in claim 5;

10A and 10B show an embodiment of the invention described in claim 6, wherein FIG. 10A is a side view showing a movable optical system, and FIG. 10B is a plan view showing a fixed optical system.

FIG. 11 is an optical path diagram showing a first conventional example.

FIG. 12 is an optical path diagram showing a second conventional example.

[Explanation of symbols]

 1 Fixed Optical System 2 Movable Optical System 3 Laser Light Source 7 Objective Lens 8 Optical Information Recording Medium 21 Beam Splitter 22 Photoreceptor 23, 24 Reflecting Member 25 Reflective Diffraction Grating 25a Diffraction Grating 26 Reflecting Prism 27 Beam Splitter A Emission Light B Correcting Light C reflected light

Claims (7)

[Claims] 1. An optical information recording medium in which emitted light emitted from a laser light source arranged in a fixed optical system is guided to a movable optical system, and the emitted light incident in the movable optical system is condensed by an objective lens. Recording and reproducing information by irradiating
In an optical head for erasing, a beam splitter that transmits a part of the emitted light emitted from the fixed optical system,
A reflecting member for reflecting a part of the light transmitted through the beam splitter is provided in the movable optical system, and the correction light reflected by the reflecting member in the movable optical system and divided into a plurality of pieces and the optical information recording medium. An optical head, characterized in that a light receiving element for receiving the reflected light from is arranged in the fixed optical system. 2. A beam splitter that transmits a part of the light emitted from the fixed optical system and a reflecting member that reflects a part of the light transmitted through the beam splitter are integrally provided. The optical head according to claim 1, wherein 3. The optical head according to claim 1, wherein the reflecting member is a reflection type diffraction grating in which diffraction gratings having different pitches or grating directions are formed. 4. A beam splitter which transmits a part of light emitted from a fixed optical system and a reflection type diffraction grating in which diffraction gratings having different pitches or grating directions are formed are integrally provided. The optical head according to claim 3, wherein 5. The optical head according to claim 1, wherein the reflecting member comprises a reflecting prism in which traveling directions of light reflected by the regions are different. 6. The optical head according to claim 1, wherein the beam splitter has polarization characteristics in which the incident light has different reflectances for P-polarized light and S-polarized light. 7. The beam splitter has such a polarization characteristic that incident light has different reflectances for P-polarized light and S-polarized light, and the beam splitter and a reflecting member for reflecting a part of the light transmitted through the beam splitter are integrated. The optical head according to claim 1, wherein the optical head is provided by being formed into a plurality.