JP2001124564A - Optical gyro and method using the same for detecting rotation direction - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical gyro element which avoids strong locking-in phenomenon by suppressing back scattering at a light extracting part, can operate with a low oscillation threshold and has a wide allowance range of an assembly error thereof. SOLUTION: A light 18 extracted from a rightward turn mode 16 by an extraction mirror 13 and a light 19 taken from a leftward turn mode 17 by a take mirror 12 form interference fringes in the vicinity of photodetectors 14 and 15. In order to suppress reflection at the plane of incidence of the photodetector so as not to combine with a laser oscillation mode, a normal of the plane of the photodetector is made different from the advancing direction of the light taken from an element. The two photodetectors 14 and 15 are set on an observation face, so that the interval between the centers of the photodetectors 14 and 15 become an (N/2+1/4) times (N is an integer) a pitch A of the interference fringe pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical gyro and a method for detecting a rotational direction using the optical gyro, and more particularly, to an optical gyro device for detecting rotation using a semiconductor ring laser, and its driving and signal processing.

[0002]

2. Description of the Related Art Conventionally, as a gyro for detecting the rotation of an object, that is, an angular velocity, a mechanical gyro having a rotor and a vibrator and an optical gyro are known. Since the optical gyro can be activated instantaneously and has a wide dynamic range,
It is bringing innovation in the gyro field. The optical gyro includes a ring laser gyro, an optical fiber gyro, a passive ring resonator gyro, and the like. A ring laser type gyro using a gas laser has already been put to practical use in aircraft and the like. Further, a semiconductor laser gyro integrated on a semiconductor substrate as a small and high-precision ring laser gyro is disclosed in, for example, Japanese Patent Application Laid-Open No. Hei 5-288556.

As such a signal processing of a laser gyro, there is a method of converting the oscillation frequency of an output signal into a voltage signal by a frequency-voltage conversion circuit. The frequency-voltage conversion circuit includes a circuit for processing an analog signal and a circuit for counting the number of pulses by binarizing the signal.

[0004]

However, the conventional ring laser type gyro cannot detect the direction of rotation from the output signal as it is, and applies a slight rotational vibration (dither) to the gyro.
The direction of rotation was detected from the correlation between dither and signal.

[0005] In a ring laser gyro that extracts light from a ring laser element and receives light with another element, backscattering at the light extraction section causes an optical difference between clockwise light and counterclockwise light. Due to the coupling, the lock-in phenomenon occurred in a region of small angular velocity. This is because the oscillation frequency is pulled into the frequency of one mode due to the coupling between the clockwise light and the counterclockwise light, and no signal is output.

Accordingly, a first object of the present invention is to provide a ring laser gyro that detects the direction of rotation even when no mechanical micro vibration (dither) is applied.

A second object of the present invention is to provide a ring laser gyro which prevents a lock-in phenomenon from occurring strongly by suppressing backscattering at a light extraction portion and operates at a low oscillation threshold. That is.

A third object of the present invention is to provide an optical gyro element which can be electrically corrected and has a wide allowable range of element assembly errors.

A fourth object of the present invention is to provide a ring laser gyro in which a lock-in phenomenon is not strongly generated by return light.

A fifth object of the present invention is to provide a ring laser gyro in which the sensitivity of the element is reduced and the S / N ratio is suppressed.

A sixth object of the present invention is to provide a ring laser gyro having an improved S / N and a gradual positional accuracy in assembly.

A seventh object of the present invention is to provide a ring laser gyro in which all components can be formed monolithically on a substrate and the direction of rotation can be detected.

An eighth object of the present invention is to provide a ring laser gyro capable of detecting a rotation direction without applying mechanical minute vibration (dither).

A ninth object of the present invention is to provide a ring laser gyro which can detect a rotation direction by signal processing without applying mechanical dither.

[0015] A tenth object of the present invention is to provide a ring laser gyro which can detect a rotation direction by signal processing without applying mechanical dither and is not affected by fluctuation of interference fringe pitch.

An eleventh object of the present invention is to provide a method for detecting the rotation direction of a ring laser gyro which can detect the rotation direction without applying mechanical dither.

A twelfth object of the present invention is to provide a method of detecting the rotation direction of a ring laser gyro which can detect the rotation direction by signal processing without applying mechanical dither and is not affected by the fluctuation of the interference fringe pitch. That is.

[0018]

An optical gyro according to the present invention for solving the above-mentioned problems includes an exciting means, a ring-shaped resonator, and a first optical output section for outputting a part of clockwise light. A semiconductor ring laser having a second light output unit for outputting a part of the counterclockwise light, and an overlapping position of the clockwise and counterclockwise light extracted from the first and second light output units And a plurality of light receiving elements placed in the same.

Further, according to the rotation direction detecting method of the present invention, the fluctuation period and the movement period of the interference fringe pattern formed at the position of the light receiving element by the light intensity signal from the plurality of light receiving elements using the optical gyro described above. The direction is detected, and the angular velocity and the rotation direction are obtained from this.

In the rotation direction detecting method according to the present invention, the speed and direction of the movement of the interference fringe pattern formed at the position of the array element are detected based on the light intensity signals from the plurality of light receiving elements, and the angular velocity is detected. And the direction of rotation.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to mathematical expressions.

[Embodiment 1] In Embodiment 1, the optical gyro includes an exciting unit, a ring-shaped resonator, a first optical output unit for outputting a part of clockwise light, and a counterclockwise light output unit. A semiconductor ring laser having a second light output unit for outputting a part thereof; and a plurality of clockwise and counterclockwise light beams extracted from the first and second light output units disposed at overlapping positions. It has a light receiving element.

In the above configuration, a clockwise rotation mode and a counterclockwise rotation mode exist independently in a ring resonator in which a gain is generated by current injection. When the element has no angular velocity with respect to the inertial system, there is no difference between the oscillation frequencies of the clockwise mode and the counterclockwise mode, and the laser oscillation is in the resonator mode with the gain peak wavelength of the active layer.

Output means for outputting a part of the clockwise light from the ring resonator outputs a part of the clockwise light, and output means for outputting a part of the counterclockwise light turns the counterclockwise light. Output part of the light,
The clockwise and counterclockwise light is superimposed and reached.

For the sake of simplicity, consider a case where the observation surface is far from the light output means and can be treated as parallel beams. It is assumed that the two beams are incident at an angle of ± ε / 2 with respect to the normal to the observation surface. Here, the plane defined by the two beams is referred to as an incident plane.

When the intersection of the incident surface and the observation surface is the X axis, and clockwise light enters from the positive direction of the X axis and counterclockwise light enters from the negative direction of the X axis, Is represented by the following equation.

I = I ₀ (1 + cos Φ) where Φ = 2πεX / λ + 2π (f1-f2) t where λ is the wavelength of light when the semiconductor laser gyro is stationary, and f1 and f2 are clocks, respectively. The oscillation frequency of the surrounding light and the oscillation frequency of the counterclockwise light. When the semiconductor laser gyro is stationary, the interference fringes do not change with time because f1 = f2. The pitch of the interference fringes is λ / ε
It can be seen that

Here, the semiconductor laser gyro has an angular velocity Ω
, The oscillation frequency of the first clockwise laser beam becomes Δf1 = 2SΩ / λ compared with the non-rotational case.
Decrease by L. Where S is the area surrounding the ring resonator,
L is the optical path length of the laser. At the same time, the oscillation frequency of the second laser light in the counterclockwise direction is ΔΔ
f2 = 2SΩ / λL. At this time, the light intensity distribution I oscillates at a beat frequency f2−f1 = 4SΩ / λL, and the interference fringe pattern moves in the positive direction of x.

When the laser gyro rotates counterclockwise, the light intensity distribution becomes equal to the beat frequency (f1-f2) =
Oscillating at 4 SΩ / λL, the interference fringes move in the negative x direction.

Even when the two lights are not parallel beams, the interference fringe pitch represented by the light intensity distribution I becomes an irregular interval, but the movement of the interference fringes according to the beat remains unchanged.

Therefore, by arranging a plurality of light receiving elements on the observation surface at intervals different from the pitch of the interference fringes and detecting light intensity vibrations having different phases, the absolute value of the angular velocity of rotation is known from the vibration frequency. The moving direction of the interference fringes can be detected from the phase difference of the vibration. Therefore, the ring laser gyro can detect the rotation direction.

[Second Embodiment] In the second embodiment, the first and second light output sections are reflection mirrors provided on a part of the waveguide section.

In the above configuration, the reflection mirror spatially divides the wavefront of the guided mode light, takes out the portion reaching the mirror surface out of the waveguide, and affects the guided mode light that does not reach the mirror surface. It functions as a wavefront splitting type optical splitter. At this time, since the backscattering is small, the coupling between the clockwise light and the counterclockwise light is suppressed, and the lock-in characteristics are not deteriorated. Also, since the insertion loss can be designed by the geometrical shape, the low oscillation threshold
An optical gyro having a low driving current can be obtained.

[Third Embodiment] In the third embodiment, the plurality of light receiving elements are a light receiving element group formed in an array or a CCD array.

In the above arrangement, signal processing such as interpolation can be performed by using two or more arrays of light receiving elements or a CCD array as the light receiving elements, and the pitch of interference fringes on the observation surface where the light receiving elements are located. Is different from the design, the moving direction of the interference fringes can be detected with high sensitivity by signal processing. That is, even if the position of the light receiving element deviates from the designed observation plane, it can be electrically corrected, and the allowable range of the error in assembling the element can be increased.

[Fourth Embodiment] In the fourth embodiment, the light receiving surfaces of the plurality of light receiving elements are not perpendicular to any of the two light beams incident on the light receiving elements.

In the above configuration, such an arrangement of the light receiving surface is such that the reflected light on the light receiving surface returns to the same optical path in the reverse direction and is coupled into the element, so that the optical path is formed between the clockwise light and the counterclockwise light. Prevents binding. That is, it is possible to prevent the lock-in phenomenon from being strongly generated by such an arrangement.

[Fifth Embodiment] In the fifth embodiment, the normal line of the light receiving surface of the plurality of light receiving elements is prevented from being a bisector of an angle formed by two light beams incident on the light receiving elements.

In the above configuration, by arranging the light receiving surface in this way, it is possible to prevent the light reflected on the light receiving surface from returning to the inside of the device as return light and being optically coupled with light in the same circuit direction.
This suppresses the formation of the external resonator mode due to the return light, and suppresses the reduction in the sensitivity of the element and the deterioration of the S / N.

[Embodiment 6] In Embodiment 6, a parallel plate made of a member transparent to laser light is provided.
An optical path conversion element using a Fresnel lens is provided on one side of the parallel plate, and a light receiving element is placed on the opposite side.

In the above configuration, the optical path conversion element converts each divergent light extracted from the ring laser into a parallel light and bends the traveling direction of the light to superimpose the two parallel lights on the observation surface on the back surface of the parallel plate. It causes interference.

Since the parallel lights are superimposed, the contrast of the interference fringes does not deteriorate much even when the observation surface is separated, and interference fringes having a uniform pitch are formed. By the former, S
/ N has been improved, and the latter has reduced the positional accuracy of installing the detector. Further, by making the quartz plate thicker, the angle formed by the two light beams forming the interference fringes could be reduced, and the pitch of the formed interference fringes could be increased. As a result, the light receiving area of the detector is increased and the S / N
And the positional accuracy of the assembly was moderated.

[Embodiment 7] In Embodiment 7, as the plurality of light receiving elements, the same layer configuration as that of the ring laser is used, or a laser element having the same layer configuration as the ring laser is used.

With the above configuration, the ring resonator laser, the optical element for changing the propagation direction of the output light, and the light receiving element have the same layer configuration, so that all the components can be formed monolithically on the substrate.

[Eighth Embodiment] In the eighth embodiment, the fluctuation period and the moving direction of the interference fringe pattern formed at the position of the light receiving element are detected based on the light intensity signals from the plurality of light receiving elements, and the angular velocity and the rotation are determined. I try to get directions.

In the above configuration, as can be seen from the above-described equations of the light intensity distributions I, Δf1, and Δf2, the angular velocity of the element can be obtained from the fluctuation cycle of the light intensity signal in each light receiving element. The direction of movement of the interference fringe pattern, that is, the direction of rotation, can be detected from the phase difference of the fluctuation of the light intensity signal in step (1).

Ninth Embodiment In the ninth embodiment, at least two intervals between the plurality of light receiving elements are different from an integral multiple of the pitch of the interference fringe pattern.

In the above configuration, the light intensity signals obtained from the plurality of light receiving elements provided at intervals different from the integral multiple of the interference fringe pitch change with time in the same oscillation cycle and have different signal phases. The direction of rotation can be detected from this phase difference.

More specifically, a case will be described as an example where two light receiving elements are placed so that the center interval is N / 2 + ／ times the pitch 倍 of the interference fringe pattern (N is an integer). Assuming that the x-coordinate of the position of the first light-receiving element is −Λ / 4 and the x-coordinate of the position of the second light-receiving element is 2Λ, from the above-described expression of the light intensity distribution I, the interference fringe pattern is obtained from the first light-receiving element It can be seen that a signal corresponding to sin (2π (f1-f2) t) is obtained from the second light receiving element as a signal corresponding to cos (2π (f1-f2) t). As a result, the second
When the light intensity at the first light-receiving element is increasing when the light intensity at the light-receiving element is close to the maximum, the interference fringe moves in the negative direction of x, and the first light-receiving element It can be seen that the interference fringes are moving in the positive x direction when the light intensity at is reduced.

[Tenth Embodiment] In the tenth embodiment, the movement of the interference fringe pattern formed at the position of the light receiving element group is performed by the light intensity signal from the array of light receiving element groups placed at the position where the light overlaps. The speed and direction are detected, and the angular speed and rotation direction are obtained from this.

In the above configuration, the interference fringe pattern is received by the array-shaped elements, and the intensity signal is subjected to signal processing to obtain a function representing the interference fringe pattern. By examining the time change, the speed and direction of the movement of the interference fringe pattern are detected, and the angular velocity and the rotation direction can be obtained. This is also effective when interference fringe patterns that are not equally spaced are formed. In addition, even when the element temperature changes, the oscillation wavelength of the laser fluctuates, and the interference fringe pitch fluctuates, the same signal processing can always be performed.

[Eleventh Embodiment] In the eleventh embodiment, the fluctuation period and the moving direction of the interference fringe pattern formed at the position of the light receiving element are detected based on the light intensity signals from the plurality of light receiving elements, and the angular velocity and the rotation are determined. I try to get directions.

In the above configuration, the light intensity signals obtained from the plurality of light receiving elements provided at intervals different from the integral multiple of the interference fringe pitch change with time in the same oscillation cycle and have different signal phases. The direction of movement of the interference fringe pattern can be obtained from this phase difference to detect the direction of rotation.

[Twelfth Embodiment] In a twelfth embodiment, the speed and direction of the movement of the interference fringe pattern formed at the position of the array element are detected based on the light intensity signals from the plurality of light receiving elements, and the angular velocity and the rotation direction are detected. I'm trying to get

In the above configuration, the interference fringe pattern is received by the array-shaped elements, and the intensity signal is subjected to signal processing to obtain a function representing the interference fringe pattern. By examining the time change, the speed and direction of the movement of the interference fringe pattern are detected, and the angular velocity and the rotation direction can be obtained. This is also effective when interference fringe patterns that are not equally spaced are formed. In addition, even when the element temperature changes, the oscillation wavelength of the laser fluctuates, and the interference fringe pitch fluctuates, the same signal processing can always be performed.

[0056]

FIG. 1A is a plan view of an optical gyro according to a first embodiment. Reference numeral 10 denotes an optical gyro according to the present embodiment, reference numeral 11 denotes a ring resonator type semiconductor laser device, reference numerals 12 and 13 denote light extraction mirrors provided on a part of a waveguide, and reference numerals 14 and 15 denote photodetectors. The ring resonator type semiconductor laser device has a clockwise rotation mode shown by 16 and a counterclockwise rotation mode shown by 17.

FIG. 1B shows the ring resonator type semiconductor laser device 11 and the photodetectors 14, 1 of the first embodiment.
5 is a sectional view of FIG. Ring resonator type semiconductor laser device 1
1 and the photodetectors 14 and 15 were produced as follows.

First, on the n-InP substrate 102,
Non-doped InGaAsP light guide layer 103 having a composition of 1.3 μm (thickness 0.15 μm), undoped InGaAsP active layer 104 having a composition of 1.55 μm (thickness 0.1 μm)
m) A non-doped InGaAsP light guide layer 105 (thickness: 0.15 μm) and a p-InP cladding layer 106 (thickness: 1.5 μm) having a composition of 1.3 μm and a p-InGaAs cap layer 107 were crystal-grown. Apply photoresist,
The mask pattern was exposed and developed to form a resist pattern having a waveguide shape and a mirror shape. A high mesa-shaped ridge waveguide having a height of 3 μm and a photodetector portion were formed by reactive ion etching using chlorine gas.

Next, Cr / Au was vapor-deposited on the ridge waveguide and the photodetector to form a p-electrode 108.

On the other hand, AuGe / Au was deposited on the lower side of the wafer to form an n-electrode 101. The alloy was formed in a hydrogen atmosphere, and the p- and n- electrodes were brought into ohmic contact.

Next, laser oscillation of the ring resonator type semiconductor device 11 will be described. Since the refractive index is different between the semiconductor layer and air, reflection occurs at the interface. If the refractive index of the semiconductor layer is 3.5, total reflection occurs when the angle between the laser beam and the normal to the interface between the semiconductor and air is 16.6 degrees or more. In the ring resonator type laser element 11, the waveguide and the semiconductor / laser are bent at the corner mirror at the bent portion of the waveguide.
The angle formed by the normal to the air interface is 45 degrees, which satisfies the condition of total reflection. In the mode of total reflection, the threshold gain is smaller by the mirror loss than in the other modes, so that the laser oscillates at a low injection current level. The concentration of the gain in the oscillation mode suppresses the oscillation in the other modes. The light extraction mirrors 12 and 13
Part of the guided mode light is extracted out of the waveguide by total internal reflection. The light folded by the mirror is emitted from the waveguide into the air, but in order to prevent reflection at this interface from being coupled as return light, the inclination of the mirror surface with respect to the length direction of the waveguide must be slightly reduced from 45 degrees. It is shifted to.

The semiconductor laser device 11 of this embodiment oscillated at a threshold of 15 mA.

In the ring resonator, clockwise rotation mode 1
6 and the counterclockwise rotation mode 17 exist independently.
When the optical gyro has no angular velocity with respect to the inertial system, there is no difference between the oscillation frequencies of the clockwise mode and the counterclockwise mode, and the laser oscillates at the gain peak wavelength of the active layer. When the optical gyro is rotating at a certain angular velocity, there is a difference between the oscillation frequency of the clockwise rotation mode 16 and the oscillation frequency of the counterclockwise rotation mode 17.

The light 18 extracted from the clockwise rotation mode 16 by the extraction mirror 13 and the extraction mirror 1
Light 1 extracted from the counterclockwise rotation mode 17 by 2
9 forms interference fringes near the photodetectors 14 and 15.

The photodetectors 14 and 15 are applied with a reverse bias, and can extract a current corresponding to the incident light. Further, in order to suppress the reflection at the incident surface of the photodetector from being coupled with the laser oscillation mode, the normal line of the incident surface of the photodetector is made different from the traveling direction of the light extracted from the element.

On the observation surface, two photo detectors 1
4 and 15, the distance between the centers is the pitch of the interference fringe pattern.
(N / 2 + ／) times (N is an integer). With this arrangement, the cos of the interference fringe pattern
(2π (f1-f2) t) signal and sin
Since a signal corresponding to (2π (f1−f2) t) is obtained, the moving direction of the interference fringe pattern, that is, the magnitude relationship between f1 and f2, can be determined by signal processing, and the rotation direction can be detected. The angular velocity of the rotation can be determined from the period of the vibration of the interference fringes. Alternatively, the moving speed of the interference fringe pattern Λ · (f1
−f2) shows the angular velocity of rotation.

When the optical gyro rotates clockwise at an angular velocity of 30 degrees per second due to camera shake or a change in the attitude of the automobile, the oscillation frequency f1 of the laser beam becomes 20.
The frequency increased by 0 Hz, and the oscillation frequency of f2 decreased by 200 Hz. The photodetectors 14 and 15 detected a signal of 400 Hz, and obtained a rotation speed and a rotation direction from this.

The photodetectors 14 and 15 may detect a change in impedance by applying a forward bias.

In this embodiment, InGa is used as a semiconductor material.
AsP / InP system was used, but GaAs system, ZnSe
A material such as an InGaN-based material that can cause laser oscillation by current injection may be used. Second Embodiment FIG. 2 is a plan view of an optical gyro according to a second embodiment. 20 is an optical gyro according to the second embodiment, 21 is a ring resonator type semiconductor laser device, and 22 and 2
Reference numeral 3 denotes a light extraction mirror provided on a part of the waveguide, and reference numeral 24 denotes an array-shaped photodetector, which is provided in contact with the cleavage end face of the substrate of the ring resonator type semiconductor laser device 21 so as to provide a light receiving portion above the substrate. It is fixed to. The ring resonator type semiconductor laser device 21 has a clockwise rotation mode indicated by 25 and a counterclockwise rotation mode indicated by 26.

The configuration and operation of the ring resonator type semiconductor laser device are the same as in the first embodiment.

The light 27 extracted from the clockwise rotation mode 25 by the extraction mirror 23 and the extraction mirror 2
2 extracted from the counterclockwise rotation mode 26 by
8 forms an interference fringe on the end face of the substrate of the optical gyro element.

The element spacing of the arrayed photodetector 24 is smaller than １ ／ of the interference fringe pitch determined by the angle of incidence on the light receiving surface and the laser wavelength. The interference fringes at the position of the substrate end surface are monitored by the photodetector 24, and the output is signal-processed to obtain an interference fringe pattern. The direction and speed of movement of this interference fringe pattern were detected. Thereby, the rotation direction and the angular velocity were obtained.

When the device is made of an AlGaAs material or the like and the oscillation wavelength is a wavelength at which a silicon CCD has sensitivity, the interference fringe pattern may be observed with an inexpensive CCD array device. [Third Embodiment] FIG. 3 is a perspective view of a third embodiment. 31 is a ring resonator type semiconductor laser device, 32 and 3
3 is light extracted from the ring resonator type semiconductor laser, 3
Reference numeral 4 denotes a quartz plate on which a Fresnel lens 35 is formed. Reference numeral 36 denotes a photodetector provided on the back surface of the quartz plate.

The configuration of the ring resonator type semiconductor laser is the same as that of the first or second embodiment. Part 32 of the clockwise laser light is extracted and part of the clockwise laser light is extracted. 33 are emitted from the substrate. The laser light is collimated by the Fresnel lens 35 on the quartz plate 34 to be parallel light, and the traveling direction is slightly bent so that these parallel lights overlap on the back surface of the quartz plate 34.

On the back surface of the quartz plate 34, interference fringes due to clockwise light and counterclockwise light are formed, as in the first and second embodiments.
The moving speed and moving direction of the interference fringes were detected by the two photodetectors 36 and 37, and the rotational speed and direction of the element could be known.

Compared with the previous embodiment, since the beam is collimated by the Fresnel lens, the contrast of the interference fringes is improved, and interference fringes having a uniform pitch are formed.
The former has improved the S / N, and the latter has loosened the positional accuracy of installing the detector. Also, by designing the optical path such as making the quartz plate thicker, the angle between the two light beams forming the interference fringes could be reduced, and the pitch of the formed interference fringes could be increased. Thus, the light receiving area of the detector can be increased and the positional accuracy can be reduced.

[0077]

According to the first embodiment of the present invention described above, an optical gyro capable of detecting the angular velocity and direction of rotation can be obtained.

According to the second embodiment of the present invention, an optical gyro having a low oscillation threshold without deteriorating the lock-in characteristic can be obtained.

According to the third embodiment of the present invention, even if the position of the light receiving element is deviated from the designed observation plane, it is possible to electrically correct the light receiving element, thereby increasing the allowable range of the element assembly error. A gyro that can be obtained.

Further, according to the fourth embodiment of the present invention, it is possible to obtain an optical gyro in which a lock-in phenomenon is not strongly generated by return light.

According to the fifth embodiment of the present invention, it is possible to obtain an optical gyro in which the formation of the external resonator mode due to the return light is suppressed and the sensitivity of the element is reduced and the S / N is suppressed from deteriorating.

According to the sixth embodiment of the present invention, the S / N
Thus, an optical gyro can be obtained in which the gyro is improved and the positional accuracy of the assembly is moderate.

According to the seventh embodiment of the present invention, an optical gyro having a small number of components and capable of detecting the angular velocity and the rotational direction of rotation can be obtained.

According to the eighth and ninth embodiments of the present invention, an optical gyro that can detect the direction of rotation from the phase difference between signals at a plurality of light receiving elements can be obtained.

According to the tenth embodiment of the present invention, the speed and direction of the movement of the interference fringe pattern are detected, and an optical gyro that can obtain the angular speed and the rotation direction can be obtained.

Further, according to the eleventh embodiment of the present invention, a method for detecting the rotation direction of the optical gyro, which can detect the rotation direction from the phase difference between the signals at the plurality of light receiving elements, is obtained.

According to the twelfth embodiment of the present invention, it is possible to detect a moving speed and a direction of an interference fringe pattern, and obtain a method of detecting a rotation direction of an optical gyro that can obtain an angular velocity and a rotation direction.

[Brief description of the drawings]

FIG. 1 is a plan view and a sectional view of an optical gyro according to a first embodiment.

FIG. 2 is a plan view of an optical gyro according to a second embodiment.

FIG. 3 is a perspective view of an optical gyro according to a third embodiment.

[Explanation of symbols]

10, 20 Optical gyro element 11, 21, 31 Ring resonator type semiconductor laser element 12, 13, 22, 23 Light extraction mirror 14, 15, 36 Photodetector 16, 25 Clockwise circling mode light 17, 26 Counterclockwise Circumferential mode light 24 Array photodetector 31 Ring resonator type semiconductor laser device 32, 33 Light extracted from ring resonator type semiconductor laser 34 Quartz plate 35 Fresnel lens

Claims (14)

[Claims] A first light output unit for outputting a part of clockwise light and a second light output unit for outputting a part of counterclockwise light; 1. An optical gyro comprising: a semiconductor ring laser having a plurality of light receiving elements disposed at positions where clockwise and counterclockwise light extracted from the first and second light output units overlap. 2. The optical gyro according to claim 1, wherein the first and second optical output sections are reflection mirrors provided on a part of a waveguide section. 3. The optical gyro according to claim 1, wherein the plurality of light receiving elements are light receiving element groups formed in an array. 4. An optical gyro according to claim 1, wherein said plurality of light receiving elements include a CCD array. 5. The optical gyro according to claim 1, wherein light receiving surfaces of the plurality of light receiving elements are not perpendicular to any of two light beams incident on the light receiving elements. 6. A normal line of a light receiving surface of the plurality of light receiving elements,
2. The optical gyro according to claim 1, wherein the angle does not become a bisector of an angle formed by two light beams incident on the light receiving element. 7. A parallel plate made of a member transparent to a laser beam, wherein an optical path conversion element using a Fresnel lens is provided on one surface of the parallel plate, and a light receiving element is placed on the opposite surface. The optical gyro according to claim 1, wherein: 8. The optical gyro according to claim 1, wherein the plurality of light receiving elements have the same layer configuration as a ring laser. 9. The optical gyro according to claim 1, wherein a laser element having the same layer configuration as a ring laser is used as the plurality of light receiving elements. 10. The method according to claim 1, wherein a fluctuation period and a moving direction of an interference fringe pattern formed at a position of the light receiving element are detected based on light intensity signals from the plurality of light receiving elements, and an angular velocity and a rotation direction are obtained from the detected fluctuation period and moving direction. The optical gyro according to claim 1. 11. The optical gyro according to claim 10, wherein at least two intervals between the plurality of light receiving elements are different from an integral multiple of a pitch of the interference fringe pattern. 12. The method according to claim 1, wherein a speed and a direction of movement of an interference fringe pattern formed at a position of the array element are detected based on a light intensity signal from the light receiving element group in the array, and an angular velocity and a rotation direction are obtained from the detected speed and direction. The optical gyro according to claim 3, wherein 13. A pumping means, a ring-shaped resonator, a first light output unit for outputting a part of clockwise light, and a second light output unit for outputting a part of counterclockwise light. Direction detecting method using a semiconductor gyro having a semiconductor ring laser and a plurality of light receiving elements placed at positions where clockwise and counterclockwise lights extracted from the first and second light output portions overlap each other A light intensity signal from the plurality of light receiving elements, detecting a fluctuation period and a moving direction of an interference fringe pattern formed at a position of the light receiving element, and obtaining an angular velocity and a rotation direction from the detected light. Gyro rotation direction detection method. 14. An excitation means, a ring-shaped resonator, a first light output unit for outputting a part of clockwise light, and a second light output unit for outputting a part of counterclockwise light. Direction using an optical gyro having a semiconductor ring laser having an array of light receiving elements arranged in a position where clockwise and counterclockwise light extracted from the first and second optical output portions overlaps A detection method, wherein light intensity signals from the plurality of light receiving elements detect a speed and a direction of movement of an interference fringe pattern formed at a position of an array element and obtain an angular velocity and a rotation direction from the detected speed and direction. A method for detecting the rotation direction of an optical gyro.