JPH04295648A - Optical information recording reproducing device - Google Patents

Abstract

PURPOSE:To reduce the size and weight of a whole optical system, and provide an optical information recording reproducing device which is capable of detecting a stabilized signal though it is easy to be mounted and adjusted. CONSTITUTION:An 1/2 wavelength board 16, a beam dividing means 15a, a polarization and separation means 15b and a total reflected plane 15c are integrally formed so as to produce an integrated optical device. This integrated optical device is fixedly installed to a member where a laser light source 14, a first light receiving device 17a, a second light receiving device 17b, and a third light receiving device 17c are integrated into one piece.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording/reproducing apparatus for recording, reproducing, and erasing information using reflected light from an optical information recording medium.

0002

2. Description of the Related Art Conventional optical information recording and reproducing apparatuses include, for example, the first conventional example published in Japanese Patent Application Laid-open No. 63-22.
There is one disclosed in Japanese Patent No. 8423. This will now be explained based on FIGS. 5 to 7. Light emitted from a laser light source 1 passes through a beam splitter 2, is focused by an objective lens 3, and is irradiated onto the surface of a magneto-optical disk 4, thereby reading information. and,
The reflected light that has been rotated by the Kerr effect is guided to the beam splitter 2 again, where it is reflected by 1/2.
The light undergoes polarization rotation of 45° by the wave plate 5 and enters the separation prism 6. As shown in FIG. 6, the separating prism 6 has a trapezoidal column shape, and is an optical element formed by integrating polarization separating films 6a, 6b and a total reflection surface 6c. The separating prism 6 has a luminous flux incident on it of 2
The light beam is arranged so as to pass between two polarization separation films 6a and 6b. Of the polarization components S and P of the incident light beam, the S polarization component is transmitted through the polarization separation film 6b, reflected by the total reflection surface 6c, and received by the light receiving element 7, and the other is the polarization component transmitted by the polarization separation film 6b. The P-polarized light component is reflected and received by the light-receiving element 8, while the P-polarized light component is separated by the polarization separation films 6a, 6.
b and is received by the light receiving element 9. in this case,
As shown in FIG. 7, when the light-receiving surfaces of the light-receiving elements 7, 8, and 9 are respectively a, b, c, d, and e, the magneto-optical signal Mo, focus error signal Fo, and track error signal Tr are detected by various signals. It can be obtained as follows. Mo=e-(a+b+c+d) Fo=(c-d)+(a-b) Tr=(c+d)-(a+b) Therefore, with this configuration, the light receiving elements 7 formed in the same plane , 8, and 9, thereby making it possible to obtain a small and lightweight device with a small number of parts.

As a second conventional example, there is a device as shown in FIG. A separation prism 11 is disposed on the optical path of the light emitted from the laser light source 10 toward an optical information recording medium (not shown). This separation prism 11 is formed with a semi-transparent layer 11a, a polarizing film 11b, and a total reflection surface 11c. In this case, the reflected light from the optical information recording medium is reflected by the semi-transparent layer 11a,
It is transmitted or reflected by the polarizing film 11b, and the reflected light is 3
The transmitted light is detected by the divided light receiving element 12 and the total reflection surface 1
1c and detected by the three-part light receiving element 13,
Thereby, a magneto-optical signal, a focus error signal, and a track error signal can be detected using the beam size method.

Therefore, by configuring the laser light source 10 and the three-divided light receiving elements 12 and 13 into a package in this way, it is possible to create a compact and stable structure against vibrations and changes over time.
A lightweight device can be obtained.

[0005]

[Problem to be solved by the invention] In the case of the first conventional example,
Although the signal detection optical system itself can be made smaller by providing the separation prism 6, since the laser light source 1 and the light receiving elements 7, 8, and 9 are on separate optical paths, the overall configuration of the optical pickup is In this case, it is not possible to achieve sufficient miniaturization, and furthermore, in this case, the casing must also be made of aluminum, which limits the weight reduction.

In the case of the second conventional example, laser light sources 10 and 3
Since the divided light-receiving elements 12 and 13 are integrated, the overall configuration of the device can be miniaturized and stable signal detection can be performed. There is a problem that it is necessary to adjust the parts to the center at the same time, and it takes time to assemble and adjust them.

[0007]

[Means for Solving the Problems] In the invention as set forth in claim 1, the light emitted from the laser light source is focused by an objective lens and irradiated onto the surface of an optical information recording medium, thereby recording and reproducing information. In an optical information recording and reproducing apparatus that performs erasing, a beam splitter and a half-wave plate are sequentially disposed on the optical path of the light emitted from the laser light source toward the objective lens, and a beam splitter and a half-wave plate are sequentially disposed on the optical path of the light emitted from the laser light source toward the objective lens, A polarization separation means is provided for polarizing and separating the light reflected by the beam splitting means, and a part of one of the light beams after being polarized and separated by the polarization separation means is guided back to the beam splitting means. A first light-receiving element is provided on the optical path that passes through as it is, and a part of the one light beam that has been polarized and separated by the polarization separation means is reflected by the beam splitting means, and a first light receiving element is provided on the optical path where it is reflected again by the polarization separation means. Two light-receiving elements were provided, a total reflection surface was provided to reflect the other beam after polarization separation by the polarization separation means, and a third light-reception element was provided on the optical path of the light beam reflected by the total reflection surface.

In the invention according to claim 2, in the invention according to claim 1, the 1/2 wavelength plate, the beam splitting means, the polarization separation means, and the total reflection surface are integrally formed; The optical element was fixedly disposed on a member in which the laser light source, the first light receiving element, the second light receiving element, and the third light receiving element were integrated.

[0009] According to the third aspect of the invention, the optical information recording device records, reproduces, and erases information by condensing light emitted from a laser light source by an objective lens and irradiating the surface of the optical information recording medium. In the reproducing device, a diffraction grating, a beam splitting means, and a 1/2 wavelength plate are sequentially disposed on the optical path of the light emitted from the laser light source toward the objective lens, and a diffraction grating, a beam splitting means, and a 1/2 wavelength plate are sequentially disposed on the optical path of the light emitted from the laser light source, and the light is reflected from the optical information recording medium. A polarization separation means is provided for polarizing and separating the light separated by the beam splitting means, and a part of one of the light beams after being polarized and separated by the polarization separation means is guided again to the beam splitting means and passes therethrough as is. A first light-receiving element is provided on the optical path, and a second light-receiving element is provided on the optical path where a part of the one light beam that has been polarized and separated by the polarization separation means is reflected by the beam splitter and reflected again by the polarization separation means. Provide an element,
Optical information characterized in that a total reflection surface is provided that reflects the other light beam after the polarization separation by the polarization separation means, and a third light receiving element is provided on the optical path of the light beam reflected by the total reflection surface. Recording and playback device.

In the invention according to claim 4, in the invention according to claim 3, the diffraction grating, the 1/2 wavelength plate, the beam splitting means, the polarization separation means, and the total reflection surface are integrally formed, and these are integrated. The optical element formed by the laser light source and the first
The light receiving element, the second light receiving element, and the third light receiving element were fixedly disposed on an integrated member.

[0011]

[Operation] In the invention as claimed in claim 1, the device can be made smaller and lighter, and the polarization direction can be adjusted and optimized by the 1/2 wavelength plate, thereby performing highly sensitive signal detection. Can be done.

In the invention as claimed in claim 2, since the optical element is integrated, it is possible to achieve miniaturization, and furthermore, since the laser light source and the light receiving element are integrated into one package, it is resistant to changes over time. It can be made stable.

In the third aspect of the invention, since the diffraction grating is used to form two beams, it is possible to cope with overwriting of magnetic field modulation.

In the fourth aspect of the invention, since the diffraction grating is also integrated, it is possible to further reduce the size and improve stability.

[0015]

[Embodiment] A first embodiment of the present invention will be explained based on FIGS. 1 and 2. First, the overall configuration of this device will be described based on FIG. 1. Optical information recording/reproduction in which the light emitted from the laser light source 14 is focused by an objective lens (not shown) and irradiated onto the surface of a magneto-optical disk as an optical information recording medium (not shown), thereby recording, reproducing, and erasing information. In the apparatus, on the optical path of the light emitted from the laser light source 14 toward the objective lens, a prism 15 having a beam splitting surface 15a (for example, a half mirror) as a beam splitting means, and a prism 15 are provided. /2 wavelength plates 16 are sequentially arranged. Further, on the optical path where the reflected light from the magneto-optical disk is separated by the beam splitting surface 15a, there is provided a polarization separation surface 15b as a polarization separation means for polarization separation of the incident light. 15b
A total reflection surface 15c is provided on the optical path of the light that has passed through. In this case, the beam splitting surface 15a, the polarization separation surface 15b, and the total reflection surface 15c are the prism 1
The prism 15 and the 1/2 wavelength plate 16 are provided integrally.

A light receiving element 17 as a first light receiving element is disposed on the optical path where a part of the light beam that has been polarized and reflected by the polarization separation surface 15b is guided again to the beam splitting surface 15a and passes through this as it is. has been done. Further, a light receiving element as a second light receiving element is placed on the optical path where a part of the light beam polarized and reflected by the polarization separation surface 15b is reflected by the beam splitting surface 15a and reflected again by the polarization separation surface 15b. 17b is provided. Furthermore, a light receiving element 17c as a third light receiving element is disposed on the optical path of the light flux that has been polarized and transmitted by the polarization separation surface 15b and is reflected by the total reflection surface 15c. In this case, each of the light receiving elements 17a to 17c formed on the same substrate 18 and the laser light source 14 are
They are enclosed in the same package 19.

In such a configuration, the laser light source 14
The light emitted from the beam passes through the beam splitting surface 15a, and
By entering the half-wave plate 16, the polarization direction is aligned with the track direction of the disk surface, and the light is focused by the objective lens and irradiated onto the surface of the magneto-optical disk. The reflected light from the magneto-optical disk reads the signal recorded on the disk surface, undergoes rotation of polarization due to the Kerr effect, is reflected, returns to the 1/2 wavelength plate 16, and undergoes rotation of the polarization direction. (that is, in substantially the same direction as the laser emitted light), it is then reflected by the beam splitting surface 15a and guided to the polarization splitting surface 15b. The S-polarized light is reflected by the polarization separation surface 15b, and the P-polarized light is transmitted as is. The reflected S-polarized light is separated into light that travels straight as it is and light that has half of its luminous flux reflected in the middle of its optical path, and the straight-traveled light is guided to the light receiving element 17a, where half of the luminous flux is reflected. is again reflected by the polarization separation surface 15b and guided to the light receiving element 17b. On the other hand, the P-polarized light that has passed through the polarization separation surface 15b is reflected by the total reflection surface 15c and then guided to the light receiving element 17c.

In this case, as shown in FIG.
7a has an undivided light receiving surface a, the light receiving element 17b has two divided light receiving surfaces b and c, and the light receiving element 17c has a two divided light receiving surface d.
, e, the values of the various signals detected by each of these light-receiving surfaces, that is, the magneto-optical signal Mo, the focus error signal Fo (knife-edge method), and the track error signal Tr (push-pull method), are as follows: Mo=( It can be detected by: a+b+c)-(d+e) Fo=b-c Tr=de. By detecting various signals using this method, the positioning of the light spot on the light receiving element only needs to be done in one direction, making it easier than other detection methods such as the beam size method and the astigmatism method. It becomes possible to shorten the time required for assembly adjustment. In addition, in this embodiment, a prism 15 is provided with a beam splitting surface 15a, a polarization separation surface 15b, and a total reflection surface 15c.
and the 1/2 wavelength plate 16, it is possible to achieve further miniaturization, and the laser light source 14
and each of the light receiving elements 17a to 17c are included in one package 19.
Since the optical pickup is sealed inside the optical pickup, it can be made stable against changes over time, and since the housing can be made of plastic, the overall structure of the optical pickup can be made lighter.

Next, a second embodiment of the present invention will be explained based on FIGS. 3 and 4. In general, overwriting is an essential technique for achieving high-speed transfer in optical information recording and reproducing devices. Therefore, in this embodiment, in addition to the configuration of the first embodiment (see FIG. 1) described above, a diffraction grating is newly provided to cope with overwriting of magnetic field modulation. That is, as shown in FIG. 3, the diffraction grating 20 is formed on one surface of the prism 15 on the optical path between the laser light source 14 and the beam splitting surface 15a.

In such a configuration, the diffraction grating 20 transforms the light beam emitted from the laser light source 14 into zero-order light T (solid line).
and the primary light K (broken line). Here, the 0th order light T is used for Write, and the 1st order light K is used for Verification.
They are used for each purpose, and during writing (erasing), they are converted into two beams so that verification can be performed immediately after overwriting. FIG. 4 shows the shape of the light receiving element used in this example, and the first light receiving element is the light receiving element 21a.
A light receiving element 21b is provided as the second light receiving element, a light receiving element 21c is provided as the third light receiving element, and a light receiving element 21d and a light receiving element e are provided as the third light receiving element. The elements 21a to 21e are integrated on the same substrate 22.

In this case, of the 0th-order light T and the 1st-order light K reflected from the magneto-optical disk surface, the light spots of the 0th-order light T are detected by the light receiving elements 21a, 21c, and 21d, respectively. Each of these light receiving elements 21a, 21c, 21d
are the light receiving elements 17a, 17b, 1 of the first embodiment described above.
7c, so that the focus error signal Fo and the track error signal Tr can also be detected in the same manner. In addition, when detecting the magneto-optical signal Mo, the primary light K for verification is used to combine the S-polarized light reflected by the polarization separation surface 15b and received by the light receiving element 21b, and the S-polarized light transmitted through the polarization separation surface 15b. It can be detected by determining the difference in the amount of received light from the P-polarized light received by the light receiving element 21e after being reflected by the total reflection surface 15c. In this case, since the first-order light K has a certain angle caused by the diffraction grating 20 compared to the zero-order light T, the S polarized light is the zero-order light T.
As shown in FIG. 2, the beam is directly guided to the light receiving element 21b without being exposed to the beam splitting surface 15a. Although the number of light-receiving elements increases by adopting such a configuration, the increased light spot only needs to enter the light-receiving element, so the difficulty of assembly can be considered in the same way as in the first embodiment described above. can.

As mentioned above, using the diffraction grating 20,
Since it is in the form of a beam, it can be adapted to overwrite magnetic field modulation, thereby making it possible to increase the transfer rate. Further, the diffraction grating 20 can be mass-produced at low cost by etching or the 2P method, and if its shape is blazed, it is possible to suppress the generation of -1st order light and improve the light utilization efficiency.

[0023]

Effects of the Invention The invention according to claim 1 provides a method for recording, reproducing, and erasing information by emitting light from a laser light source and condensing it by an objective lens and irradiating it onto the surface of an optical information recording medium. In the information recording and reproducing apparatus, a beam splitting means and a half-wave plate are sequentially disposed on the optical path of the light emitted from the laser light source toward the objective lens, so that the reflected light from the optical information recording medium is A polarization separation means is provided for polarizing and separating the light separated by the beam splitting means, and a part of one of the light beams after being polarized and separated by the polarization separation means is guided back to the beam splitting means and passes through it as it is. A first light-receiving element is provided on the road, and a second light-receiving element is provided on the optical path where a part of the one light beam that has been polarized and separated by the polarization separation means is reflected by the beam splitter and reflected again by the polarization separation means. A total reflection surface is provided for reflecting the other beam after the polarization separation by the polarization separation means, and a third light receiving element is provided on the optical path of the beam reflected by the total reflection surface, thereby reducing the size of the device. In addition to being able to reduce the size and weight, the polarization direction can be adjusted and optimized using a 1/2 wavelength plate, and highly sensitive signal detection can be performed.

According to the second aspect of the invention, the 1/2 wavelength plate, the beam splitting means, the polarized light separating means, and the total reflection surface are integrally formed, and the optical element formed by integrating these is used as a laser light source and a laser light source. Since the first light-receiving element, the second light-receiving element, and the third light-receiving element are fixedly disposed on an integrated member, it is possible to achieve further miniaturization because the optical elements are integrated. Since the laser light source and the light receiving element are integrated into one package, it can be made stable against changes over time.

The invention according to claim 3 provides an optical information recording system in which information is recorded, reproduced, and erased by condensing light emitted from a laser light source by an objective lens and irradiating it onto the surface of an optical information recording medium. In the reproducing device, a diffraction grating, a beam splitting means, and a 1/2 wavelength plate are sequentially disposed on the optical path of the light emitted from the laser light source toward the objective lens, and a diffraction grating, a beam splitting means, and a 1/2 wavelength plate are sequentially disposed on the optical path of the light emitted from the laser light source, and the light is reflected from the optical information recording medium. A polarization separation means is provided for polarizing and separating the light separated by the beam splitting means, and a part of one of the light beams after being polarized and separated by the polarization separation means is guided again to the beam splitting means and passes therethrough as is. A first light-receiving element is provided on the optical path, and a second light-receiving element is provided on the optical path where a part of the one light beam that has been polarized and separated by the polarization separation means is reflected by the beam splitter and reflected again by the polarization separation means. A total reflection surface is provided to reflect the other light beam after the polarization separation by the polarization separation means, and a third light receiving element is provided on the optical path of the light beam reflected by the total reflection surface. By creating two beams using a grating, it is possible to cope with overwriting of magnetic field modulation.

The invention according to claim 4 is the invention according to claim 3, in which the diffraction grating, the 1/2 wavelength plate, the beam splitting means, the polarization separation means, and the total reflection surface are formed integrally, and these are integrated. Since the optical element formed by the laser light source, the first light receiving element, the second light receiving element, and the third light receiving element are fixedly disposed in the integrated member, the diffraction grating is also integrated in this way. This makes it possible to further reduce the size and further improve the stability of signal detection.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a front view showing the state of the light receiving element of the first embodiment.

FIG. 3 is a configuration diagram showing a second embodiment of the present invention.

FIG. 4 is a front view showing the state of the light receiving element of the second embodiment.

FIG. 5 is a configuration diagram showing a first conventional example.

FIG. 6 is a side view of a prism in a first conventional example.

FIG. 7 is a front view of a light receiving element in a first conventional example.

FIG. 8 is a configuration diagram showing a second conventional example.

[Explanation of symbols]

14 Laser light source 15a
Beam splitting means 15b
Polarization separation means 15c
Total reflection surface 16 1
/2 wavelength plate 17a First light receiving element 17b Second light receiving element 17c
Third light receiving element 20
Diffraction gratings 21a, 21b first light receiving element 21c second light receiving element 21d,
21e Third light receiving element

Claims (4)

[Claims] 1. An optical information recording and reproducing apparatus that records, reproduces, and erases information by condensing light emitted from a laser light source by an objective lens and irradiating it onto the surface of an optical information recording medium, wherein the laser A beam splitting means and a half-wave plate are sequentially disposed on the optical path of the light emitted from the light source toward the objective lens, and the reflected light from the optical information recording medium is separated by the beam splitting means. A first beam splitter is provided on the optical path in which a part of one of the light beams after polarization separation by the polarization separation means is guided back to the beam splitting means and passes through the beam splitting means as it is.
A second light receiving element is provided on an optical path where a part of the one light beam that has been polarized and separated by the polarization separation means is reflected by the beam splitting means and reflected again by the polarization separation means, Optical information recording and reproducing, characterized in that a total reflection surface is provided that reflects the other beam after the polarization is separated by the separation means, and a third light receiving element is provided on the optical path of the beam reflected by the total reflection surface. Device. 2. A 1/2 wavelength plate, a beam splitting means, a polarized light separating means, and a total reflection surface are integrally formed, and the optical element formed by integrating these is used as a laser light source, a first light receiving element, and a second light receiving element. 2. The optical information recording and reproducing apparatus according to claim 1, wherein the light receiving element and the third light receiving element are fixedly disposed on an integrated member. 3. An optical information recording and reproducing apparatus that records, reproduces, and erases information by condensing light emitted from a laser light source by an objective lens and irradiating it onto the surface of an optical information recording medium, wherein the laser A diffraction grating, a beam splitting means, and a 1/2 wavelength plate are sequentially arranged on the optical path of the light emitted from the light source toward the objective lens, and the reflected light from the optical information recording medium is directed to the beam splitting means. A first light beam is provided on the optical path in which a part of one of the light beams after being polarized and separated by the polarization separation means is guided back to the beam splitting means and passes through the beam splitting means as it is. A second light receiving element is provided on an optical path where a part of the one light beam that has been polarized and separated by the polarization separation means is reflected by the beam splitting means and reflected again by the polarization separation means, Optical information recording and reproducing, characterized in that a total reflection surface is provided that reflects the other beam after the polarization is separated by the separation means, and a third light receiving element is provided on the optical path of the beam reflected by the total reflection surface. Device. 4. A diffraction grating, a 1/2 wavelength plate, a beam splitting means, a polarization separating means, and a total reflection surface are integrally formed,
Claim 3 characterized in that these integrally formed optical elements are fixedly disposed on a member in which the laser light source, the first light receiving element, the second light receiving element, and the third light receiving element are integrated.
The optical information recording and reproducing device described above.