JP2004144902A - Tilt sensor device - Google Patents

Tilt sensor device Download PDF

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Publication number
JP2004144902A
JP2004144902A JP2002308428A JP2002308428A JP2004144902A JP 2004144902 A JP2004144902 A JP 2004144902A JP 2002308428 A JP2002308428 A JP 2002308428A JP 2002308428 A JP2002308428 A JP 2002308428A JP 2004144902 A JP2004144902 A JP 2004144902A
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JP
Japan
Prior art keywords
light
tilt sensor
optical path
deflection
deflection angle
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP2002308428A
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Japanese (ja)
Inventor
Yasuhiro Miyazaki
宮崎 靖浩
Original Assignee
Olympus Corp
オリンパス株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by Olympus Corp, オリンパス株式会社 filed Critical Olympus Corp
Priority to JP2002308428A priority Critical patent/JP2004144902A/en
Publication of JP2004144902A publication Critical patent/JP2004144902A/en
Pending legal-status Critical Current

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Abstract

<P>PROBLEM TO BE SOLVED: To provide a tilt sensor device which is accurate, miniaturized, has a wide range of detection, detects the two-dimensional angle of deflection of an optical deflection element, and makes a stable angular control of the optical deflection element compatible with the miniaturization of the optical deflection element. <P>SOLUTION: The tilt sensor device 1 detects the angle of deflection of the optical deflection element 2, and is provided with: a light source 3 which emits light directed to a reflection face 2a for detecting the angle of deflection furnished on the optical deflection element 2; an optical path separation means 4 which passes the light emitted from the light source 3 and deflects and separates the light reflected from the reflection face 2a for detecting the angle of deflection; an optical detector 5 which receives the light emitted from the optical path separation means 4 and detects the angle of deflection of the optical deflection element 2 on the basis of the light-receiving position; and a light shielding member 6 which is arranged in optical path between the light source 3 and the optical detector 5 and shields light at the peripheral part of the light flux. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a tilt sensor device and a system including the tilt sensor device. In particular, the present invention relates to a tracking control device used for an optical pickup, a tilt sensor device as an optical switching means of an optical fiber used for optical communication, and a system including the tilt sensor device.
[0002]
[Prior art]
This type of tilt sensor device detects a relative angle between the optical axis of the beam emitted from the optical pickup to the recording medium and the recording surface of the recording medium, and emits a diffused light to the recording surface. Some include two light receiving elements that are arranged on both sides of the light emitting element and detect light reflected from the recording surface. This inclination sensor device detects the amount of inclination when the recording medium is inclined by calculating the difference between the amounts of reflected light detected by the two light receiving elements (see, for example, Patent Document 1). ).
[0003]
There is also a tilt sensor device that receives reflected light from a recording medium on a four-divided light receiving surface and detects a tilt in two directions by taking a difference (for example, see Patent Document 2).
Further, there is a tilt sensor device that detects the amount of tilt by detecting reflected light from a deflecting mirror through a beam splitter whose reflectance changes depending on the incident angle (for example, see Patent Documents 3 and 4).
[0004]
Further, for downsizing, an optical path splitting member for separating a forward path from the light source to the deflection angle detecting reflection surface and a return path for guiding the reflected light from the deflection angle detection reflection surface to the photodetector by a reciprocating path. A beam splitter may be used to bend the optical path compactly.
[0005]
[Patent Document 1]
Japanese Patent Publication No. 7-66554
[Patent Document 2]
JP-A-8-227552
[Patent Document 3]
JP-A-11-144273
[Patent Document 4]
JP-A-11-144274
[0006]
[Problems to be solved by the invention]
However, the method disclosed in Patent Document 1 has a problem that a wide range of detection cannot be performed because the size of the detector is limited, and only one-dimensional tilt detection can be performed.
Further, in the method of Patent Document 2, if the detection range is similarly widened, the size of the detector becomes large, so that there is a problem that the entire mechanical layout becomes large.
Further, in the methods of Patent Document 3 and Patent Document 4, the detection accuracy is deteriorated unless the characteristics of the reflection film of the beam splitter are improved. Similarly, if the detection range is widened, the entire mechanical layout becomes large. There's a problem.
[0007]
When an optical path separating member (such as a beam splitter) is used, the reflected light from the end face of the stop or the reflected light from the photodetector for taking out the light flux of an appropriate portion of the intensity distribution arranged near the light source is used. There is a problem that the light becomes harmful light and a detection error or the like or non-linearity of the deflection angle detection characteristic occurs.
[0008]
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and can detect a deflection angle of a light deflecting element in a two-dimensional direction with high accuracy, a small size, a wide detection range, and a stable light deflector. It is an object of the present invention to provide a tilt sensor device that can achieve both the angle control and the miniaturization that have been performed.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides the following means.
The invention according to claim 1 is a tilt sensor device for detecting a deflection angle of a light deflection element, wherein the light source emits light toward a deflection angle detection reflection surface provided in the light deflection element, and the light source And a light path separating member that transmits light from the light path and deflects and separates reflected light from the deflection angle detecting reflection surface, receives light from the light path separating member, and deflects the light deflecting element according to the light receiving position. Provided is a tilt sensor device including: a photodetector that detects a corner; and a light blocking member that is disposed in an optical path from the light source to the photodetector and blocks a peripheral portion of a light beam.
[0010]
According to this invention, the light emitted from the light source is transmitted through the optical path separating member and then reflected on the deflection angle detecting reflection surface of the optical deflector in a direction corresponding to the inclination angle of the deflection angle detection reflection surface. Is done. The reflected light is deflected by the optical path separating member, is separated from the incident optical path, and is received by the photodetector disposed in front of the separated optical path. Thus, the photodetector detects the deflection angle of the light deflection element according to the light receiving position. In this case, since the light shielding member is provided in the optical path from the light source to the photodetector, the light distributed around the light beam in the optical path is shielded by the light shielding member. This makes it possible for the photodetector to detect only light that is located near the center of the optical path. As a result, stray light that has an adverse effect on the detection accuracy of the deflection angle can be reduced, and the detection accuracy can be improved.
[0011]
According to a second aspect of the present invention, in the tilt sensor device according to the first aspect, the light shielding member is disposed between the light source and the optical path separating unit, and has a tapered opening gradually expanding toward the light source. Provided is a tilt sensor device which is an aperture having a tilt angle.
According to the present invention, of the light distributed around the light beam from the light source, the light that enters the regular light path when emitted from the light path separating means is transmitted to the light source side through a wide aperture. By reflecting the light on the tapered surface of the stop having the portion, the light can be removed from the regular optical path. As a result, it is possible to improve the detection accuracy by removing the peripheral light in which the amount of light reaching the photodetector tends to be unstable.
[0012]
According to a third aspect of the present invention, in the tilt sensor device according to the second aspect, another tilting member is provided between the optical path separating member and the deflection angle detecting reflection surface to block a peripheral portion of the light beam. A sensor device is provided.
According to this invention, of the light reflected from the tapered surface of the light shielding member disposed between the light source and the optical path separating means, returned to the normal optical path direction, and emitted from the optical path separating member, the light deflecting element By blocking the light toward the outer peripheral side of the deflection angle detecting reflection surface with another light shielding member, stray light can be removed, and the detection accuracy can be further improved.
[0013]
The invention according to claim 4 is an inclination sensor device for detecting a deflection angle of a light deflecting element, wherein the light source emits light toward a deflection angle detection amount reflecting surface provided in the direction of the light deflecting element; An optical path separating member for separating the light from the light source and the light from the deflection angle detecting reflection surface; and a light for receiving the light from the optical path separating member and detecting the deflection angle of the optical deflection element based on the light receiving position. Provided is a tilt sensor device including a detector and a quarter-wave plate disposed in an optical path from the light source to the photodetector.
[0014]
According to the present invention, the polarization direction of light entering the optical path separating member can be adjusted by operating the quarter-wave plate. As a result, it is possible to prevent the reflected light from the photodetector from being reflected again in the direction of the photodetector by the optical path separating member and returned, and to provide a small-sized tilt sensor device having a wide detection range and high detection accuracy. It is possible to do.
[0015]
The invention according to claim 5 provides the tilt sensor device according to claim 4, wherein the optical path separating means is a polarization beam splitter.
According to the present invention, by separating the optical path by the polarizing beam splitter, it is possible to more efficiently remove harmful light than a half mirror.
[0016]
The invention according to claim 6 provides the tilt sensor device according to claim 5, wherein the quarter-wave plate is disposed between the optical path separating member and the photodetector. .
According to the present invention, of the light reflected from the deflection angle detecting reflection surface, only the S-polarized light component is reflected by the polarizing beam splitter, converted into circularly polarized light by the 波長 wavelength plate, and then reaches the photodetector. Further, the light reflected by the photodetector is converted into P-polarized light by a 波長 wavelength plate, so that the light can pass through a polarization beam splitter. As a result, it is necessary to prevent light once detected by the photodetector from being reflected by the polarization beam splitter and from reaching the photodetector again, thereby preventing detection errors and non-linearity in deflection angle detection characteristics. Becomes possible.
[0017]
According to a seventh aspect of the present invention, in the tilt sensor device according to the fifth or sixth aspect, the quarter-wave plate is disposed between the optical path separating member and the deflection angle detecting reflection surface. A tilt sensor device.
According to this invention, when only the P-polarized light is transmitted from the light source side through the optical path separating member including the polarization beam splitter, the P-polarized light is converted into circularly polarized light by transmitting through the 1 / wavelength plate. Later, the light is reflected on the deflection angle detecting reflection surface, and can be converted into S-polarized light by transmitting through a quarter-wave plate again. Therefore, since only the S-polarized light reaches the polarization beam splitter, it is possible to efficiently reflect the light without loss of light amount and detect it by the photodetector.
[0018]
The invention according to claim 8 is the tilt sensor device according to any one of claims 4 to 7, wherein a stop is arranged in an optical path from the light source to the photodetector. I will provide a.
ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to block the light arrange | positioned at the periphery among the luminous flux emitted from the light source, and to improve detection accuracy.
[0019]
The invention according to claim 9 provides the tilt sensor device according to claim 8, wherein the diaphragm has a tapered opening gradually expanding toward the light source.
According to this invention, as in the invention according to the second aspect, it is possible to reduce stray light which adversely affects the detection accuracy of the deflection angle and improve the detection accuracy.
[0020]
According to a tenth aspect of the present invention, in the tilt sensor device according to any one of the first to ninth aspects, an optical element having a positive power is disposed in an optical path from the light source to the photodetector. An inclination sensor device is provided.
According to the present invention, it is possible to obtain an appropriate luminous flux diameter on the light receiving surface of the photodetector, and to shorten the optical path to reduce the size of the device.
[0021]
The invention according to claim 11 provides the tilt sensor device according to claim 10, wherein the optical element having the positive power is disposed between the light source and the optical path separating member.
According to the present invention, the diffused light emitted from the light source can be collimated by the optical element having the positive power, and the stray light deviating from the regular optical path can be prevented from being generated, so that the light can be transmitted efficiently.
[0022]
According to a twelfth aspect of the present invention, in the tilt sensor device according to the tenth aspect, the optical element having the positive power is disposed between the optical path separating member and the deflection angle detecting reflection surface. Provide equipment.
According to the present invention, it is possible to secure an appropriate luminous flux diameter on the light receiving surface.
[0023]
According to a thirteenth aspect of the present invention, in the tilt sensor device according to any one of the first to twelfth aspects, the optical path separating member is disposed between the light source and the deflection angle detecting reflection surface. An inclination sensor device is provided.
According to the present invention, the device can be made compact by disposing the optical path separating member in the middle of the optical path turned back on the deflection angle detecting reflection surface.
[0024]
According to a fourteenth aspect of the present invention, there is provided the tilt sensor device according to the thirteenth aspect, wherein the optical path separating member includes a prism having an optical medium before and after an optical path dividing surface.
According to the present invention, the optical path separating member can be configured at low cost, so that the product cost can be reduced and the device can be downsized.
[0025]
The invention according to claim 15 provides the tilt sensor device according to claim 13, wherein the optical path separating member is a parallel flat plate.
According to the present invention, since the optical path separation member can be manufactured with high dimensional accuracy, the detection accuracy can be increased with a simple configuration.
[0026]
According to a sixteenth aspect of the present invention, in the tilt sensor device according to any one of the first to fifteenth aspects, the photodetector is a two-divided element that calculates a difference signal in one direction. I will provide a.
According to the present invention, it is possible to improve the detection accuracy in one direction at low cost.
[0027]
According to a seventeenth aspect, in the tilt sensor device according to any one of the first to fifteenth aspects, the photodetector is a four-divided element that calculates a difference signal in each of two orthogonal directions. An inclination sensor device is provided.
According to the present invention, it is possible to inexpensively improve the detection accuracy in the two-dimensional direction.
[0028]
The invention according to claim 18 provides the tilt sensor device according to any one of claims 1 to 15, wherein the photodetector is a position detection light receiver (PSD).
According to the present invention, it is possible to achieve a wide detection range.
[0029]
The invention according to claim 19 provides the tilt sensor device according to any one of claims 1 to 15, wherein the photodetector is a solid-state imaging device (CCD).
According to the present invention, since light to be detected can be collected as an image, image processing can be performed after detection. As a result, harmful light components can be removed afterwards to improve detection accuracy.
[0030]
According to a twentieth aspect of the present invention, there is provided a tilt sensor device according to any one of the first to nineteenth aspects, and a deflection angle control means for controlling a deflection angle of the optical deflection element based on an output from the tilt sensor device. An optical signal switch system comprising:
According to the present invention, the deflection angle is controlled by the operation of the deflection angle control means based on the deflection angle of the optical deflection element detected with high accuracy, so that the switching of the optical signal can be performed accurately and reliably. It becomes.
[0031]
An invention according to claim 21 is a recording medium having a tilt sensor device according to any one of claims 1 to 19, and a recording surface capable of recording and / or reproducing an information signal by irradiating light. A recording / reproducing light source for irradiating the recording medium with a light beam for recording and / or reproducing the information signal, and deflecting the light beam from the recording / reproducing light source in a plane parallel to a recording surface of the recording medium. An information recording / reproducing system provided with an optical deflecting element.
[0032]
According to the present invention, the light emitted from the recording / reproducing light source is irradiated on the recording surface of the recording medium after being deflected by the optical deflecting element, and recording or reproducing or recording or reproducing the information signal included in the light on the recording surface. Both are done. In this case, since the deflection angle of the light deflecting element is accurately detected by the tilt sensor device, it is possible to perform recording on the recording surface or reproduction from the recording surface with high accuracy by using this. .
[0033]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a tilt sensor device according to an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the tilt sensor device 1 according to the present embodiment is a tilt sensor device 1 that detects a deflection angle of the light deflecting element 2 and includes a light source 3 and the light source 3 and the light deflecting element 2. A beam splitter (optical path separating member) 4 disposed between the reflection surface 2a for deflection angle detection provided; a photodetector 5 for detecting light reflected by the beam splitter 4; a light source 3 and a beam splitter 4 and a light-blocking member 6 disposed therebetween.
[0034]
The light source 3 is, for example, a laser diode, and is a point light source that emits diffused light that diffuses from one point.
The light deflecting element 2 is a rotating mirror having a reflecting surface 2b for reflecting a predetermined light beam on one surface thereof, and the reflecting surface 2a for detecting a deflection angle is provided on the back side of the reflecting surface 2b.
[0035]
The beam splitter 4 is, for example, an optical path splitting surface designed to have a P-polarized light transmittance of 100% and an S-polarized light reflectance of 100% on a 45 ° bonding surface where two triangular prisms 4a and 4b are bonded. 4c comprises a polarizing beam splitter. A 波長 wavelength plate 7 is provided integrally with the beam splitter 4 on the side of the deflection angle detecting reflection surface 2 a of the beam splitter 4.
A lens (optical element) 8 having a positive power is provided between the quarter-wave plate 7 and the deflection angle detecting reflection surface 2a.
[0036]
The photodetector 5 is, for example, a two-dimensional PSD (Position Sensitive Detector), and is configured to output a signal corresponding to a light irradiation position and a light irradiation amount.
The light-shielding member 6 is configured by a diaphragm having an opening 6b formed in a plate-like portion 6a arranged so as to block between the light source 3 and the beam splitter 4. The plate portion 6a is integrally formed with a chassis member 9 that supports the tilt sensor device 1 according to the present embodiment. As shown in FIG. 2, the opening 6 b is formed in a tapered shape that gradually expands toward the light source 3.
[0037]
The operation of the thus configured tilt sensor device 1 according to the present embodiment will be described below.
The linearly polarized light emitted from the light source 3 has a relatively flat intensity distribution near a spread angle of 0 °. Since the light shielding member 6 is provided adjacent to the light source 3, the light beam emitted from the light source 3 is passed through the opening 6b, so that the peripheral light distributed around the opening is blocked, and the central flat light is emitted. A light beam in a range having an intensity distribution is directed to the beam splitter 4.
[0038]
Since the beam splitter 4 is constituted by a polarization beam splitter, only the P-polarized light is transmitted 100% on the optical path splitting surface 4c. The P-polarized light transmitted through the beam splitter 4 is converted into, for example, clockwise circularly polarized light by passing through a 波長 wavelength plate 7 provided integrally with the beam splitter 4 at a subsequent stage. . Then, the light beam which has been collimated by passing through the lens 8 and has become substantially parallel light is applied to the deflection angle detecting reflection surface 2 a of the light deflecting element 2, and is directed in a direction corresponding to the inclination of the light deflecting element 2. It will be reflected.
[0039]
At this time, the light reflected on the deflection angle detecting reflection surface 2a is converted into circularly polarized light in the opposite direction, that is, counterclockwise circularly polarized light according to the inclination of the light deflecting element 2. In this state, the light is transmitted through the lens 8 again, converted into convergent light, and then converted into S-polarized light by the 波長 wavelength plate 7. Since the S-polarized light is reflected 100% on the optical path splitting surface 4c of the beam splitter 4, it is deflected by 90 ° on the 45 ° optical path splitting surface 4c and detected by the photodetector 5 disposed in front thereof. Become.
[0040]
That is, according to the tilt sensor device 1 according to the present embodiment, of the diffused light emitted from the light source 3, the ambient light emitted at a large angle with respect to the optical axis is blocked by the light shielding member 6. Therefore, it is possible to prevent unnecessary light from being detected by the photodetector 5.
[0041]
In addition, since the opening 6b of the light shielding member 6 is formed in a tapered shape gradually expanding toward the light source 3, the following effects are obtained.
That is, as shown in FIG. 3, when the taper angle of the opening 6b is 0 °, the peripheral light emitted from the light source 3 and reflected by the cylindrical surface of the opening 6b is reflected by the beam splitters 4, 1 The light passes through the / 4 wavelength plate 7 and the lens 8 and is irradiated on the deflection angle detecting reflection surface 2a. After being reflected on the deflection angle detection reflection surface 2a, the light is guided to the photodetector 5 without loss. At this time, an annular spot image 10 as shown in FIG. 4 is formed corresponding to only the peripheral light reflected by the cylindrical surface of the opening 6b among the light detected by the photodetector 5. Will be.
[0042]
However, since the spot image 10 is composed of unstable light whose light quantity is liable to fluctuate due to a change over time in the reflectance of the cylindrical surface of the opening 6b, the deflection angle of the light deflecting element 2 changes. In some cases, the output signal of the photodetector 5 may be changed. In such a case, the error of the output signal is increased and the detection accuracy is reduced, which is not preferable.
[0043]
Therefore, as shown in FIG. 1, by forming a tapered inner surface having an angle α gradually expanding toward the light source 3 in the opening 6 b of the light shielding member 6, as in the inclination sensor device 1 according to the present embodiment. By increasing the incident angle of the peripheral light reflected on the tapered inner surface of the light emitted from the light source 3 to the beam splitter 4, the peripheral light transmitted through the beam splitter 4 can be directed to the outside of the lens 8. it can. Accordingly, since the ambient light is removed from the path of the optical system, it is prevented from being detected by the photodetector 5, and the detection accuracy can be improved. The angle α may be set to a value that can remove ambient light to the maximum.
[0044]
By forming the light shielding member 6 integrally with the chassis member 9 that holds the components of the tilt sensor device 1 such as the light source 3 and the optical path separating member 4, space efficiency is improved, miniaturization and reduction in the number of parts are achieved. Can be achieved. Further, when the chassis member 9 is formed by injection molding using a mold member (not shown), the opening 6b is formed in a tapered shape that gradually expands toward the light source 3, that is, toward the outside of the chassis member 9. Therefore, the shape becomes advantageous for removal from the mold member formed so as to surround the chassis member 9 from the outside, and manufacturing can be facilitated.
[0045]
In order to further effectively prevent the peripheral light reflected by the inner surface of the stop provided on the light blocking member 6 from being detected by the photodetector 5, as shown in FIG. The second light blocking member 11 may be arranged between the lens 8 and the second light blocking member 11. The light blocking member 11 is, for example, formed in an annular shape as shown in FIG. 6, and blocks peripheral light transmitted through the beam splitter 4 to prevent the light from entering the lens 8. . Accordingly, the first light-blocking member 6 blocks the peripheral light that cannot be completely removed to the outside of the lens 8, and the detection accuracy in the photodetector 5 can be further improved.
The light-blocking member 11 in FIG. 5 can be integrally formed with the chassis member 9 by injection-molding a plastic that effectively absorbs and scatters light rays, thereby reducing the number of parts, reducing manufacturing costs, and It is also preferable from the viewpoint of reducing the size and weight.
[0046]
Next, a tilt sensor device according to a second embodiment of the present invention will be described below with reference to FIGS.
In the description of the present embodiment, portions having the same configuration as those of the tilt sensor device 1 according to the above-described first embodiment will be denoted by the same reference numerals, and description thereof will be omitted.
The tilt sensor device 20 according to the present embodiment differs from the tilt sensor device 1 according to the first embodiment in that a quarter-wave plate 21 is provided between the beam splitter 4 and the photodetector 5. ing.
[0047]
FIG. 8 shows, as a comparative example, an example of an optical path when the quarter wavelength plate 21 is not provided. The light transmitted from the light source 3 through the light-shielding member 6, the beam splitter 4, the quarter-wave plate 7, and the lens 8 and reflected on the deflection angle detecting reflection surface 2a of the light deflector 2 is returned to the lens 8, 1/4. By transmitting through the wave plate 7, the light is converted into S-polarized light and is incident on the beam splitter 4. After being reflected 100% on the optical path splitting surface 4 c of the beam splitter 4, the light is detected by the photodetector 5.
[0048]
However, when silicon is used as the light receiving surface material of the photodetector 5, the refractive index of silicon at a wavelength of 780 nm is set to about 3.7, and the refractive index of a resin layer provided on the surface for protecting the silicon layer. Is about 1.5, the reflectance of these two surfaces is approximately as follows according to the boundary condition with air.
(1.5-1) 2 / (1.5 + 1) 2+ (3.7-1.5) 2 / (3.7 + 1.5) 2 = 0.04 + 0.18 = 0.22
[0049]
The S-polarized light from the light deflecting element 2 that has entered the photodetector 5 is reflected at the light receiving surface of the photodetector 5 at the above-described reflectance. The light receiving surface of the photodetector 5 is not an optically perfect reflecting surface. Therefore, the reflected light becomes elliptically polarized light and is incident on the beam splitter 4 again. The light reflected by the beam splitter 4 passes through the 波長 wavelength plate 7, the lens 8, the deflection angle detecting reflection surface 2a, the lens 8 and the 波長 wavelength plate 7, and again on the optical path splitting surface 4c of the beam splitter 4. The light is reflected and re-enters the photodetector 5.
FIG. 9 is a diagram showing the positions of the spot images 22 and 23 on the light receiving surface of the photodetector 5. In addition to the spot image 22 due to the light beam to be detected, the light is reflected on the light receiving surface of the photodetector 5. A spot image 23 due to the stray light is formed.
[0050]
The amount of this stray light is equivalent to about 28% of the amount of light to be detected, assuming that the reflectance on the light receiving surface of the photodetector 5 is 0.22, and is very large disturbance light. When the inclination of the light deflecting element 2 is small, the distance between the two spot images 22 and 23 on the photodetector 5 is small, so that the influence on the position detection accuracy is small. Increases, the distance between the spot images 22 and 23 on the photodetector 5 increases, and the position detection accuracy decreases.
FIG. 10 shows a change in the output signal with respect to the deflection angle of the light deflection element 2. According to FIG. 10, the output signal increases as the inclination of the light deflecting element 2 increases, but if the inclination increases to a certain angle, the influence of stray light becomes maximum and linearity may be inconvenient. Understand.
[0051]
According to the tilt sensor device 20 according to the present embodiment, the S-polarized light reflected by the beam splitter 4 in the direction of the photodetector 5 passes through the 波長 wavelength plate 21 before being detected by the photodetector 5. As a result, for example, the light is converted into clockwise circularly polarized light, and then enters the photodetector 5. The light beam reflected by the photodetector 5 becomes left-handed circularly polarized light, is converted into P-polarized light by passing through the quarter-wave plate 21 again, and is incident on the beam splitter 4. Since the optical path splitting surface 4c of the beam splitter 4 has a transmittance of 100% with respect to the P-polarized light, the light is not reflected by the beam splitter 4 but is transmitted therethrough and irregularly reflected by the external chassis member 9 and the like. .
Therefore, it is possible to prevent the light reflected by the beam splitter 4 from becoming stray light and being detected again by the photodetector 5, and to further improve the detection accuracy of the photodetector 5.
[0052]
As described above, the light diffusely reflected by the external chassis member 9 after passing through the beam splitter 4 can be more effectively scattered and attenuated by roughening the surface of the chassis member 9. For example, there is a processing method in which an oxide film is formed on a metal surface by thermal deburring treatment, and a change in reflectance due to oxidation over time is accelerated to suppress a change with time thereafter. The thermal deburring process uses a mixed gas of hydrogen + oxygen or methane gas + oxygen as a fuel to ignite the high-pressure gas injected into the pressure vessel, instantaneously generating high heat energy, and using the energy to generate high heat energy on the surface and inside of the part. This is a processing method for burning and removing burrs instantaneously. According to this method, there is an effect of promoting a change in the reflectance of the metal surface. Further, as another means, by performing aging in an environment of high temperature and high humidity at the beginning, the oxidation of the surface can be promoted, and the same effect as above can be obtained.
[0053]
Although the two-dimensional PSD is used as the photodetector 5, a one-dimensional PSD, a two-division or four-division photodiode may be used instead. The use of a photodiode is preferable because the size and cost can be reduced as compared to a PSD.
[0054]
Further, in addition to the tapering of the opening 6b of the light shielding member 6 and the light shielding member 11 between the beam splitter 4 and the light deflecting element 2 in the first embodiment, the 波長 wavelength plate 21 in the second embodiment is also provided. It may be arranged in combination. This makes it possible to perform high-accuracy detection that eliminates the influence of stray light.
[0055]
Further, a 1 / wavelength plate or a に お け る wavelength plate may be arranged instead of the 波長 wavelength plate 7 in FIG. In this case, although a slight loss of light amount occurs as compared with the case of the quarter-wave plate 7, it is effective in that it has the effect of reducing the deterioration of accuracy due to stray light to some extent.
[0056]
Although a laser diode that emits P-polarized light is used as the light source 3, for example, an LED is used instead, and the light from the light source 3 is supplied between the light source 3 and the beam splitter 4. May be arranged.
[0057]
Further, the lens 8 disposed between the beam splitter 4 and the light deflecting element 2 may be omitted. The same effect can be achieved by arranging another lens (not shown) having a positive power between the light source 3 and the beam splitter 4.
[0058]
Further, although the beam splitter 4 in which the two triangular prisms 4a and 4b are joined is employed as the optical path separating member, a parallel plate-shaped polarization beam splitter (not shown) may be employed instead. Since the parallel-plate-shaped polarizing beam splitter can be manufactured with high dimensional accuracy, it can be assembled with high precision by directly bonding to the chassis member 9 or the like manufactured with high accuracy. Loss of light quantity can be minimized, and detection accuracy can be improved. As the optical path separating member, a wavelength selective filter or a HOE (Holographic Optical Element) may be employed instead of the beam splitter.
[0059]
Next, an optical signal switch system 100 including the tilt sensor devices 1 and 20 according to any of the first and second embodiments will be described with reference to FIG.
The optical signal switch system 100 according to the present embodiment includes an input side cable unit 105 including a plurality of input side cables 101, an output side cable unit 106 including a plurality of output side cables 109, and two optical switching devices 108. And
[0060]
A collimator unit 102 for collimating the diffused light 103 emitted from the output port 101a is disposed facing the output port 101a of the input side cable 101. Further, the entrances 109a of the output side cable 109 are also regularly arranged in a lattice matrix, and each of the entrances 109a focuses the transmitted parallel light 103 and forms an image on the entrance 109a. The unit 107 is disposed to face.
[0061]
The optical switching device 108 includes a plurality of light deflecting elements 2 regularly arranged in a lattice matrix, an inclination sensor device 1 arranged on the back side of each light deflecting element 2, and an output from the inclination sensor device 1. Deflection angle control means 61 for controlling the deflection angle of the light deflection element 2 based on the Each light deflecting element 2 is arranged corresponding to the collimator unit 102, and can deflect the parallel light 103 emitted from the collimator unit 102 in a direction corresponding to the deflection angle.
[0062]
The operation of the thus configured optical signal switch system 100 according to this embodiment will be described below.
The laser beam 103 transmitted inside one input-side cable 101 reaches the emission port 101a and is radiated from there to the outside of the input-side cable 101. The diffused light 103 emitted from the emission port 101a is collimated by the collimator unit 102, and is converted into parallel light having an appropriate thickness so as not to be shaken by dust or the like. It is emitted toward.
[0063]
The collimated light 103 emitted from the collimator unit 102 is reflected by the light deflecting element 2 of one of the optical switching devices 108 arranged corresponding to the collimator unit 102, and the other light switching device according to the deflection angle. The light is deflected in the direction of the specific light deflection element 2 at 108. Then, the parallel light 103 reflected by the light deflecting element 2 is incident on the image forming unit 107 arranged corresponding to the light deflecting element 2, thereby facing the image forming unit 107. An image is formed on the entrance 109 a of the output cable 109. Thus, the laser beam 103 incident on the output side cable 109 is transmitted inside the output side cable 109.
[0064]
That is, according to the optical signal switch system 100 according to the present embodiment, the laser emitted from one input side cable 101 by changing the deflection angle of the optical deflection element 2 provided in the two optical switching devices 108. The output side cable 109 that the light beam 103 reaches can be changed, whereby the switching of the optical signal is performed.
[0065]
For example, in FIG. 11, a laser beam 103A emitted from a specific input-side cable 101A is deflected toward an optical polarization element 2B corresponding to an output-side cable 109B by switching the deflection angle of an optical deflection element 2A. . The light deflecting element 2B is adjusted to a deflection angle corresponding to the incident angle of the laser beam 103A such that the laser beam 103A enters the output-side cable 109B.
[0066]
Since the exit port 101a and the entrance port 109a are regularly arranged, the deflection angles of the light deflecting elements 2A and 2B corresponding to the exit port 101a and the entrance port 109a depend on the positional relationship between the two optical switching devices 108. It is predetermined. Therefore, the deflection angle of the specific light deflecting element 2A of the light switching device 108 on the incident side is changed to switch the light deflecting element 2B of the light switching device 108 on the output side, which is the deflection destination of the laser beam 103A. By appropriately adjusting the deflection angle of the selected light deflecting element 2B, the switching of the optical signal can be performed.
[0067]
In order to perform such switching of the optical signal, the deflection angle of the optical deflection element 2 is detected by the above-described tilt sensor device 1 and the deflection of the optical deflection element 2 is performed via the deflection angle control means 61 shown in FIG. The actuator 2c for changing the angle is feedback-controlled.
[0068]
As shown in FIG. 13, the deflection angle control means 61 decodes a deflection angle control signal 201 for specifying a deflection angle, and generates a target level signal 204 corresponding to a target deflection angle of the optical deflection element 2. And a control unit 61b which receives a deviation between the detection level signal 203 from the inclination sensor device 1 and the target level signal 204 and generates a drive signal 202 for the actuator 2c.
[0069]
Next, an optical signal switching method will be described mainly with reference to FIGS. First, the input cable 101A and the output cable 109B of the switching laser beam 103A are specified. Then, the information is externally input to the deflection angle control means 61 of each optical switching device 108 by the deflection angle control signal 201.
[0070]
When the specific information of the input side cable 101A and the output side cable 109B is input to the deflection angle control means 61, the decoding means 61a generates a target level signal 204 corresponding to the target deflection angles of the light deflection elements 2A, 2B. Then, a deviation between the target level signal 204 and the detected level signal 203 based on the deflection angle detected by the tilt sensor device is calculated and input to the control unit 61b. The controller 61b adjusts the drive signal 202 so that the deflection angles of the optical deflecting elements 2A and 2B become closer to the target deflection angles by amplifying, differentiating, integrating, and the like, for example, to the actuator 2c. give feedback.
[0071]
As described above, since the feedback control is performed using the tilt sensor device 1 as the detecting means, the deflection angles of the light deflection elements 2A and 2B are corrected to the target deflection angles. That is, for example, even if a disturbance occurs and the deflection angle deviates from the target deflection angle, the deflection angle is immediately corrected to the target deflection angle according to the deviation amount. Therefore, real-time feedback control is realized by the optical switching device 108 including the deflection angle control unit 61 and the tilt sensor device 1.
[0072]
Furthermore, since the inclination sensor device 1 is configured to be compact, the optical switching device 108 can be reduced in size and space. Further, since the tilt sensor device 1 disposed behind the light deflecting element 2 is compact, the arrangement interval of the light deflecting elements 2 can be reduced. Therefore, the arrangement intervals of the optical cables 101 and 109 of the input-side cable unit 105 and the output-side cable unit 106 can be reduced, and each of them is made compact. As a result, there is an advantage that the number of switchable transmission paths can be increased without increasing the deflection angle of the optical deflection element 2.
[0073]
Further, according to the optical signal switching system 100 according to the present embodiment, stray light is removed in the tilt sensor device 1 and the deflection angle can be detected with high detection accuracy, so that accurate switching of the optical signal can be performed. it can.
[0074]
In the above description, an example in which one light deflecting element 2 is provided for each of the emission ports 101a of the input side cable unit 105 has been described. However, there are other uses for switching the transmission path other than switching the laser beam 103 individually. For example, this is a case of switching to a line for backup during maintenance of a transmission line. In this case, the entirety of the predetermined input side cable unit 105 is switched from one output side cable unit 106 to another output side cable unit 106. In such a case, switching is performed while maintaining the arrangement of the input-side cable units 105, so that only one optical deflection element 2 may be provided for the input-side cable units 105.
[0075]
Next, an embodiment of an information recording / reproducing system such as a pickup device including the tilt sensor device 1 according to the above-described embodiment will be described. FIG. 14 is a plan view showing a schematic configuration of the information recording / reproducing system 110 according to the present embodiment.
[0076]
The information recording / reproducing system according to the present embodiment includes, for example, a recording disk (recording medium) 112 such as an optical disk or a magneto-optical disk for recording / reproducing an information signal, and an intensity / pulse width according to the information signal. A semiconductor laser (light source) 3 that irradiates a laser beam (light beam) 115 with modulated light, an imaging lens 116 and an imaging lens unit 114 that image the laser beam 115, and an imaging lens that deflects the laser beam 115. In order to perform fine movement tracking control by changing the position of incidence on the unit 114, an optical system including the optical deflecting element 2 driven to be deflected by an actuator (not shown) and the tilt sensor device 1, and those optical systems An arm 113 that can be installed and moved in a direction parallel to and perpendicular to the recording surface of the recording disk 112;
The semiconductor laser 3 is connected to a laser driving unit 3b for modulating a laser beam 115 with an information signal.
The light deflection element 2 has a structure shown in FIG. The tilt sensor device 1 may be the tilt sensor 20 of the above-described second embodiment.
[0077]
Reference numeral 111 denotes a housing in which a recording disk 112 is disposed on a drive shaft 112a that is driven to rotate by a DC control motor or the like. The recording disk 112 is held rotatably around the drive shaft 112a.
[0078]
The recording disk 112 has a recording surface on at least one of its surfaces, on which one or both of optical signal recording and reproduction is possible. On the formatted recording disk 112, track signals are formed in the circumferential direction of the recording surface, and the recording position of the information signal is logically divided in the radial direction.
[0079]
The arm 113 is disposed above the recording surface, and is elastically supported vertically with respect to the recording disk 112. The arm 113 is rotatably supported by a rotation shaft 113a in a direction parallel to the recording surface of the recording disk 112. The arm 113 is rotatably driven around a rotation shaft 113a by a drive coil 117 such as an electromagnetic coil.
[0080]
The imaging lens 116 is configured to appropriately shape the laser beam 115 emitted from the semiconductor laser 3 into, for example, parallel light. The imaging lens unit 114 receives the laser beam 115 to form an image on a recording surface, receives reflected light from the recording surface, and outputs signal light corresponding to an information signal and focus detection for performing focus control. Each of the light receiving elements receives light and tracking detection light for performing tracking control.
[0081]
The operation of the thus configured information recording / reproducing system according to the present embodiment will be described below.
First, the recording surface of the recording disk 112 is irradiated with the laser beam 115, the reflected light is received by the imaging lens unit 114, a tracking signal is picked up, and information such as the position of the track and the amount of deviation from the track is collected. Based on the information, the rotational position of the arm 113 is coarsely controlled by the drive coil 117 to perform movement between tracks and follow the tracks.
[0082]
Further, in order to perform more precise tracking, the optical deflecting element 2 is tilted, the laser beam 115 is deflected, the incident position on the imaging lens unit 114 is shifted, and the radial imaging position on the recording surface is shifted. Move slightly. At this time, the tilt sensor device 1 detects the deflection angle of the light deflection element 2 and performs feedback control. For the feedback control, a method similar to the optical signal switching method described with reference to FIG. 13 can be employed.
[0083]
As described above, by configuring the information recording / reproducing system using the tilt sensor device 1 according to the present embodiment, first, the tilt sensor device 1 can be compactly configured. can do. Therefore, there is an advantage that the mechanical response characteristic can be improved. Secondly, a wide detection range of the tilt sensor device 1 can be ensured, so that a larger deflection angle can be taken. Thus, a predetermined incident position can be obtained even if the distance from the light deflection element 2 to the imaging lens unit 114 is short. As a result, the optical path length of the optical system on the arm 113 can be shortened. That is, there is an advantage that the size of the arm 113 can be reduced, and a more compact information recording / reproducing system having excellent mechanical response characteristics can be obtained.
Further, since the detection accuracy of the tilt sensor device 1 can be increased, there is an effect that information can be recorded and reproduced with high accuracy.
[0084]
【The invention's effect】
As described above, according to the tilt sensor device according to the present invention, stray light emitted from the light source is effectively removed so as not to be detected by the photodetector, so that the deflection angle of the light deflection element can be accurately determined. This has the effect of being able to be detected.
Further, according to the optical signal switch system of the present invention, it is possible to provide a compact system capable of switching accurately with an inclination sensor device having high detection accuracy.
Further, according to the information recording / reproducing system according to the present invention, it is possible to provide a compact system capable of recording / reproducing information with high accuracy by the tilt sensor device having high detection accuracy.
[Brief description of the drawings]
FIG. 1 is an optical path diagram showing a tilt sensor device according to a first embodiment of the present invention.
FIG. 2 is a longitudinal sectional view showing an opening shape of a light shielding member used in the tilt sensor device of FIG.
FIG. 3 is an optical path diagram in a case where a tapered surface is not formed in an opening in the inclination sensor device of FIG. 1;
FIG. 4 is a diagram showing a spot image due to ambient light detected by a photodetector of the tilt sensor device of FIG. 3;
FIG. 5 is an optical path diagram showing a modification of the tilt sensor device of FIG. 1;
FIG. 6 is a front view showing a shape of a second light shielding member constituting the inclination sensor device of FIG. 5;
FIG. 7 is an optical path diagram showing an inclination sensor device according to a second embodiment of the present invention.
8 is an optical path diagram showing a comparative example in the case where a quarter-wave plate does not exist in the tilt sensor device of FIG. 7;
FIG. 9 is a diagram showing a spot image on the photodetector in the case of FIG. 8;
FIG. 10 is a graph showing a relationship between a deflection angle of a light deflecting element and an output of a photodetector in the tilt sensor of FIG.
FIG. 11 is an explanatory diagram showing an optical signal switch system according to an embodiment of the present invention.
FIG. 12 is an explanatory diagram showing a configuration of a light deflecting element and its surroundings in the system of FIG. 11;
FIG. 13 is a block diagram showing deflection angle control means in the system of FIG. 11;
FIG. 14 is an explanatory diagram showing an information recording / reproducing system according to an embodiment of the present invention.
[Explanation of symbols]
1,20 tilt sensor device
2 Optical deflection element
2a Reflection surface for deflection angle detection
3 light source
4 Beam splitter (optical path separating member)
4a, 4b prism
4c Optical path splitting surface
5 Photodetector
6,11 Light shielding member
6b opening
7,21 quarter wave plate
8 Lens (optical element)
61 deflection angle control means
100 Optical signal switch system
110 Information recording and playback system
112 Recording disk (recording medium)

Claims (21)

  1. An inclination sensor device for detecting a deflection angle of a light deflection element,
    A light source that emits light toward a deflection angle detection reflection surface provided in the light deflection element,
    An optical path separating member that transmits light from the light source and deflects and separates reflected light from the deflection angle detecting reflection surface;
    A light detector that receives light from the optical path separating member and detects a deflection angle of the light deflection element based on the light receiving position;
    A light-shielding member disposed in an optical path from the light source to the photodetector and shielding a peripheral portion of the light beam.
  2. The tilt sensor device according to claim 1, wherein the light blocking member is a stop disposed between the light source and the optical path separating unit and having a tapered opening gradually expanding toward the light source.
  3. The tilt sensor device according to claim 2, further comprising another light blocking member that blocks a peripheral portion of the light beam between the optical path separation member and the deflection angle detection reflection surface.
  4. An inclination sensor device for detecting a deflection angle of a light deflection element,
    A light source that emits light toward a deflection angle detection amount reflection surface provided in the light deflection element direction,
    An optical path separating member that separates light from the light source and light from the deflection angle detecting reflection surface,
    A light detector that receives light from the optical path separating member and detects a deflection angle of the light deflection element based on the light receiving position;
    A tilt sensor device comprising: a 波長 wavelength plate disposed in an optical path from the light source to the light detector.
  5. The tilt sensor device according to claim 4, wherein the optical path separating unit is a polarization beam splitter.
  6. The tilt sensor device according to claim 5, wherein the quarter-wave plate is disposed between the optical path separating member and the photodetector.
  7. 7. The tilt sensor device according to claim 5, wherein the quarter-wave plate is disposed between the optical path separating member and the deflection angle detecting reflection surface. 8.
  8. The tilt sensor device according to any one of claims 4 to 7, wherein a stop is disposed in an optical path between the light source and the photodetector.
  9. 9. The tilt sensor device according to claim 8, wherein the stop has a tapered opening gradually expanding toward the light source.
  10. The tilt sensor device according to any one of claims 1 to 9, wherein an optical element having a positive power is arranged in an optical path from the light source to the photodetector.
  11. The tilt sensor device according to claim 10, wherein the optical element having the positive power is disposed between the light source and the optical path separating member.
  12. The tilt sensor device according to claim 10, wherein the optical element having the positive power is disposed between the optical path separating member and the deflection angle detecting reflection surface.
  13. The tilt sensor device according to any one of claims 1 to 12, wherein the optical path separating member is disposed between the light source and the deflection angle detecting reflection surface.
  14. 14. The tilt sensor device according to claim 13, wherein the optical path separating member includes a prism having an optical medium before and after the optical path dividing surface.
  15. 14. The tilt sensor device according to claim 13, wherein the optical path separating member is a parallel flat plate.
  16. The tilt sensor device according to any one of claims 1 to 15, wherein the photodetector is a two-divided element that calculates a difference signal in one direction.
  17. The tilt sensor device according to any one of claims 1 to 15, wherein the photodetector is a four-divided element that calculates a difference signal in each of two orthogonal directions.
  18. The tilt sensor device according to claim 1, wherein the light detector is a position detection light receiver (PSD).
  19. The tilt sensor device according to any one of claims 1 to 15, wherein the light detector is a solid-state imaging device (CCD).
  20. 20. An optical signal switch system comprising: the tilt sensor device according to claim 1; and a deflection angle control unit that controls a deflection angle of the light deflection element based on an output from the tilt sensor device.
  21. 20. A tilt sensor device according to any one of claims 1 to 19, a recording medium having a recording surface capable of recording and / or reproducing information signals by irradiating light, and the information medium being recorded on the recording medium. Information comprising a recording / reproducing light source for irradiating a light beam for recording and / or reproducing a signal, and a light deflecting element for deflecting a light beam from the recording / reproducing light source in a plane parallel to a recording surface of the recording medium. Recording and playback system.
JP2002308428A 2002-10-23 2002-10-23 Tilt sensor device Pending JP2004144902A (en)

Priority Applications (1)

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Country Link
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010038792A (en) * 2008-08-06 2010-02-18 High Energy Accelerator Research Organization Method for controlling drive shaft in super-precision shape measurement device of normal vector tracking type
JP2016181645A (en) * 2015-03-25 2016-10-13 日本オクラロ株式会社 Optical transmission module

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010038792A (en) * 2008-08-06 2010-02-18 High Energy Accelerator Research Organization Method for controlling drive shaft in super-precision shape measurement device of normal vector tracking type
JP2016181645A (en) * 2015-03-25 2016-10-13 日本オクラロ株式会社 Optical transmission module

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