JP5263659B2 - Circulating optical path device and 3-axis ring laser gyro - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circulating optical path device capable of forming mutually-crossing three circulating optical paths in a space acquired by etching a silicon substrate. <P>SOLUTION: Light excited by an excitation light source 71 of a light source substrate 40 is condensed on a solid laser medium 51, and laser light is radiated from a light emission point 42 onto the first reflection surface substrate 20, and laser light is radiated in both directions in parallel with a reference plane 11 and a plane PL2 from the second light source 80 provided on the first reflection surface substrate 20, and reflected by utilizing a plurality of reflecting surfaces 21-28 on the first reflection surface substrate 20 and a reflecting surface 41 of the light source substrate 40, and three circulating optical paths LC1-LC3 are formed easily in mutually orthogonal planes. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a circulating optical path device for circulating laser light and a three-axis ring laser gyro using the same.

  Angular velocity sensors are used in many fields such as car navigation, camera shake correction, games, aircraft, rockets, and robots. Examples of the angular velocity sensor (gyro) include an optical gyro, a rotary gyro, and a vibration gyro. The vibrating gyroscope is described in Patent Document 1 and the like, and has recently been produced at low cost by MEMS (Micro Electro Mechanical Systems) technology. In these methods, an object is vibrated by a piezoelectric force or an electrostatic force, and a generated Coriolis force is detected to detect an angular velocity. MEMS vibratory gyros are small and low-cost, and are widely used in consumer equipment. However, since the vibration gyro has a large zero point offset, it is not suitable for detecting an absolute angle and is difficult to use for inertial navigation.

  When high-precision detection is required, such as on an aircraft, submarine, or rocket, an optical fiber gyro or ring laser gyro using the Sagnac effect is used. Optical fiber gyros are described in Patent Document 2, Patent Document 3, and the like. This optical fiber gyro splits and inserts laser light into both end faces of an optical fiber wound many times. When an angular velocity is applied about an axial direction perpendicular to the surface on which the optical fiber is wound, an optical path difference occurs in the separated light. A phase difference occurs between the two lights separated by this optical path difference. The angular velocity is obtained by detecting this phase difference. This optical fiber gyroscope needs to have a very long optical fiber and a large number of turns in order to increase the detection sensitivity of the optical path difference of light. Therefore, the problem is that it is sensitive to temperature changes.

  A ring laser gyro forms a laser resonator with a ring-shaped optical path by a plurality of mirrors, oscillates clockwise and counterclockwise laser light in this optical path, and detects the difference between the oscillation wavelengths of both laser lights. Detect angular velocity.

  These optical fiber gyros and ring laser gyros have good performance, but are relatively large and expensive, making them difficult to use in general consumer applications.

Further, Patent Document 4 discloses a configuration in which a high-precision optical gyro is easily formed by batch processing using MEMS technology. In this optical gyro, a circular optical path of a laser beam is formed by using anisotropic etching of silicon so that a highly accurate optical gyro can be easily formed by batch processing.
JP-A-10-227644 Japanese Examined Patent Publication No. 62-39836 Japanese Patent Publication No. 2-60127 Japanese Patent No. 3751553

  However, since the optical gyro shown in Patent Document 4 forms a circular optical path in a plane parallel to the substrate, it can only detect in one axis direction, and in order to detect in two axes, the direction is changed by 90 degrees. It is necessary to arrange another one, and the apparatus becomes large. Further, when forming a lens by lithography or the like, there is a problem that it is difficult to collimate the laser beam with respect to light parallel to the substrate surface. On the other hand, the inventors of this application laminated a silicon substrate having a (100) surface as a surface, and used a pyramidal inclined surface by anisotropic etching as a resonance surface, and was perpendicular to the substrate surface and perpendicular to each other. Have proposed a ring laser gyro that forms two circular optical paths and detects angular velocities in two axial directions.

  The present invention further provides a space obtained by etching a silicon substrate, and a reflective surface which is a highly accurate surface obtained by anisotropic etching, so that three orbits that easily cross each other in a plurality of intersecting surfaces can be obtained. It is an object of the present invention to provide an orbiting optical path device capable of forming an optical path and a triaxial ring laser gyro capable of detecting angular velocities in three axial directions.

  An orbiting optical path device of the present invention includes a base having a reference plane, one or more substrates stacked in parallel to the reference plane in a direction perpendicular to the reference plane of the base, and a plurality of light sources. The base has a normal line in a first plane perpendicular to the reference plane, and is inclined at a predetermined angle with respect to the reference plane. At least two reflecting surfaces that are perpendicular and each have a normal line in a second plane that intersects the first plane and is inclined at a predetermined angle with respect to the reference plane; and the reference plane A plurality of reflective surfaces having normal lines in a third plane parallel to the first plane, the one or more substrates having reflective surfaces parallel to the reference plane, and any one of the plurality of light sources. The light source of the part emits light in the first plane and the second plane. The light emitted from the light source is forward and backward in the two planes by a reflecting surface having a normal line in the first plane and the second plane and a reflecting surface parallel to the reference plane. Forming a first circular optical path and a second circular optical path that oscillate and laser oscillate, and the other light sources of the plurality of light sources are arranged to emit light in the third plane, the light source The light radiated from the laser beam circulates in the forward and reverse directions in the third plane by the plurality of reflecting surfaces to form a third optical path for laser oscillation.

  Further, in at least one of the circulating optical paths, the light emitting point of the light source that forms the circulating optical path is disposed on one reflecting surface that forms the circulating optical path, so that the circulating optical path is stably formed. Can do.

  Further, the substrate laminated in parallel to the reference plane is formed by a light source substrate having a light source that forms the first and second circular optical paths, and the number of components is reduced by sharing the light source, thereby simplifying the structure. It is characterized by doing.

  The light source is composed of a light-excited solid light source medium that emits light by irradiating light, and the substrate is a laminate of a substrate having a solid light source medium and an excitation light source substrate having an excitation light source that excites the solid light source medium. A plurality of excitation light sources disposed on the excitation light source substrate to excite different points on the solid light source medium to emit light from the plurality of different light emission points to form first to third optical paths, It is characterized by dispersing the heat source and avoiding local temperature rise.

  The third optical path is a triangular circuit formed by two reflecting surfaces having a normal line in a third plane parallel to the reference plane and a reflecting surface of the light source mounted on the substrate. It is characterized by increasing the optical path (optical path length / area) to improve detection sensitivity.

  The light source forming the third optical path is composed of a light-excited solid light source medium that emits light by irradiating light, is projected and stacked on the base, and is emitted from the excitation light source substrate stacked on the base. The structure is simplified by emitting laser light in a third plane when excited by the laser light and sharing the first and second optical paths, the light source and the excitation light source. .

  Further, the excitation light source substrate is disposed on the opposite side of the substrate having the solid light source medium with the base interposed therebetween, and it is easy to take out part of the laser light that circulates in the forward and reverse directions in each of the circulating optical paths while dispersing the heat source. It is characterized by.

  The three-axis ring laser gyro of the present invention is a laser beam that circulates in the forward and reverse directions in each of the circulating optical path device and the first circulating optical path, the second circulating optical path, and the third circulating optical path formed by the circulating optical path device. Interference fringe generating means for extracting a part and interfering to generate an interference fringe, interference fringe detecting means for detecting a change in the interference fringe in each circulating optical path generated by the interference fringe generating means, and the interference fringe detection And calculating means for calculating angular velocities about three axes on the basis of the change in interference fringes in each optical path detected by the means.

  According to the present invention, a substrate having a reference plane has at least two reflecting surfaces each having a normal line in a first plane perpendicular to the reference plane and inclined at a predetermined angle with respect to the reference plane; At least two reflecting surfaces that are perpendicular to the plane and each have a normal in a second plane intersecting the first plane and inclined at a predetermined angle with respect to the reference plane; A plurality of reflecting surfaces having normal lines are provided in a parallel third plane, and the substrate laminated in parallel to the reference plane of the substrate is provided with a reflecting surface parallel to the reference plane. By reflecting the laser beam by using, three circular optical paths can be easily formed in planes orthogonal to each other.

  In addition, by forming a plurality of reflecting surfaces provided on the base in a space obtained by etching a silicon substrate with a surface obtained by anisotropic etching, it is possible to accurately form a plurality of reflecting surfaces intersecting each other. It is possible to stably form the three circular optical paths.

  Furthermore, a part of the laser light that circulates in the forward and reverse directions in each of the first, second, and third optical paths formed by the optical circuit device of the present invention is extracted and interfered to generate interference fringes. By calculating the angular velocities around the three axes based on the generated interference fringe changes, the angular velocities around the three axes can be detected stably.

  1A and 1B show the configuration of an orbiting optical path device according to the present invention. FIG. 1A is a plan sectional view of an orbiting optical path device 10 cut along an aa plane in FIG. 1B, and FIG. Sectional drawing and (c) are cc sectional views of (a). For example, the size of the circulating optical path device 10 is about several millimeters in the vertical and horizontal directions in FIGS.

  As shown in FIG. 1, the circulating optical path device 10 includes a first reflecting surface substrate 20, a spacer substrate 30, and a light source substrate 40. The first reflecting surface substrate 20 has a reference plane 11 on one surface, and a spacer substrate 30 is laminated on the reference plane 11.

  As shown in the perspective views of FIGS. 1 and 2, the first reflecting surface substrate 20 is formed in a parallel plate shape, and has four regular quadrangular pyramids at the corners of the quadrangular prism with the thickness direction at the center as the depth direction. A hole 29 in a state of being overlapped with each other is penetrated from the reference plane 11 side, and an opening area of the through hole 29 is formed to be large on the reference plane 11 side. In this through hole 29, reference numerals 21, 22, 23, and 24 indicate the wall surfaces of four regular quadrangular pyramid holes, and reference numerals 25, 26, 27, and 28 indicate the wall surfaces of the hole of the quadrangular prism, all of the same space. Is formed. Since these wall surfaces 21 to 28 are used as reflecting surfaces, the wall surfaces 21 to 28 are hereinafter referred to as reflecting surfaces 21 to 28. A plane PL1 shown in FIG. 1 (a) intersects perpendicularly with respect to the reference plane 11, and the reflecting surfaces 21 and 22, which are wall surfaces of holes formed in a regular quadrangular pyramid, are normal to the plane PL1. And inclined with a predetermined acute angle with respect to the reference plane 11. Further, the plane PL2 shown in FIG. 1A intersects the reference plane 11 and the plane PL1 perpendicularly, and the reflecting surfaces 23 and 24, which are the walls of a regular quadrangular pyramid hole formed on the plane PL2, are on the plane PL2. The reference plane 11 is inclined at a predetermined acute angle. The reflecting surfaces 25 to 28 that are the wall surfaces of the holes of the quadrangular columns are formed with normal lines parallel to the reference plane 11.

  The first reflecting surface substrate 20 is a silicon substrate, and a hole 29 in a state in which a regular quadrangular pyramid and a quadrangular prism are overlapped is easily formed with high accuracy using anisotropic etching. That is, as shown in the perspective view of FIG. 2, the first reflecting surface substrate 20 appears by anisotropic etching of a silicon substrate having a silicon (110) surface (hereinafter referred to as a silicon (110) substrate). The planes perpendicular to the reference plane 11 and the reflection planes 21 and 22 that use the (111) plane, are inclined ± 54.7 degrees with respect to the reference plane 11, and have normals parallel to the plane PL1 perpendicular to the reference plane 11 Reflecting surfaces 23 and 24 having normal lines parallel to PL2 and reflecting surfaces 25 to 28 inclined by 90 degrees with respect to the reference plane 11 are formed. The reflecting surfaces 21 to 28 are preferably subjected to, for example, gold plating in order to sufficiently increase the reflectance.

  The spacer substrate 30 is a substrate for setting a predetermined interval between the first reflecting surface substrate 20 and the light source substrate 40, and square holes are formed in the thickness direction. A plane portion facing the first reflecting surface substrate 20 of the light source substrate 40 provided on the opposite side of the first reflecting surface substrate 20 across the spacer substrate 30 is a reflecting surface 41. The reflecting surface 41 is a reference surface. It is formed in parallel with the plane 11.

  The light source substrate 40 includes a second reflective surface substrate 50, a glass substrate 60, and an excitation light source substrate 70 that are stacked. The second reflecting surface substrate 50 has a thin parallel plate shape, and a solid laser medium 51 such as YAG or YVO4, which is excited by irradiating excitation light, is applied to the bottom substrate 52 as shown in the sectional view of FIG. The reflective film 53 is formed between them. The reflection film 53 is a film that reflects at the wavelength of the light generated by the solid-state laser medium 51 and transmits at the wavelength of the excitation light emitted from the excitation light source substrate 70, and reflects incident light having an incident angle of 19.4 degrees. The ratio is set so as to increase, and the reflection surface 41 of the light source substrate 40 is formed. The bottom substrate 52 also transmits the excited wavelength light, and an antireflection film 54 is formed on the surface thereof. The excitation light source substrate 70 is provided with a surface-emitting excitation light source 71. The laser light emitted from the excitation light source 71 is condensed on the solid laser medium 51 of the second reflecting surface substrate 50 by the microlens 61 formed on the glass substrate 60 to become a light emitting point 42 that excites the light. As this excitation light source 71, a semiconductor laser element or the like may be mounted. Thus, by providing the light emitting point 42 on the second reflecting surface substrate 50, the installation error of the light emitting point 42 can be reduced.

  The size of the square-shaped hole in the spacer substrate 30 is formed to be slightly smaller than the size of the hole in the state where the regular quadrangular pyramid and the quadrangular prism formed in the first reflecting surface substrate 20 are overlapped with each other in the reference plane 11. The second light source 80, which is a semiconductor laser element, is mounted on the edge portion of the spacer substrate 30 corresponding to the position of the reflecting surface 21 on the plane PL1. The second light source 80 emits light from both end faces of the chip, and antireflection films are formed on both end faces so that there is no reflection at the end faces. As shown in FIGS. Laser light is emitted in both directions parallel to the plane PL2. Microlenses 81a and 81b are mounted in the vicinity of both end surfaces of the second light source 80 that emit laser light, and the divergence angle of the laser light emitted from the second light source 80 is adjusted. The second light source 80 and the microlenses 81a and 81b are mounted on the upper surface of the spacer substrate 30 by an appropriate method.

  In the circulating optical path device 10 formed as described above, the light excited by the excitation light source 71 of the light source substrate 40 is condensed on the solid laser medium 51 and emitted from the light emitting point 42 toward the first reflecting surface substrate 20 side. As shown in FIG. 1C, a part of the emitted laser light is repeatedly reflected on the reflecting surface 21 and the reflecting surface 22 of the first reflecting surface substrate 20 and the reflecting surface 41 of the light source substrate 40. As a result, laser oscillation occurs in the forward and reverse directions, and a triangular first circular optical path LC1 is formed in the plane PL1. Further, another part of the laser light emitted at the same time is reflected by the reflecting surface 23 and the reflecting surface 24 of the first reflecting surface substrate 20 and the reflecting surface 41 of the light source substrate 40 as shown in FIG. By repeating reflection, laser oscillation is performed in the forward and reverse directions, and a triangular second circulating optical path LC2 is formed in the plane PL2.

  Further, when laser light is emitted from the second light source 80 in the vertical direction in FIG. 1A, the laser light emitted from the second light source 80 to the reflection surface 25 side of the first reflection surface substrate 20 is The divergence angle is adjusted by the macro lens 81a, the light is sequentially reflected by the reflection surface 25, the reflection surface 27, the reflection surface 26, and the reflection surface 28, and returns to the second light source 80 through the micro lens 81b. The laser light emitted from the second light source 80 to the reflecting surface 28 side of the first reflecting surface substrate 20 is adjusted in divergence angle by the microlens 81 b, and the reflecting surface 28, the reflecting surface 26, the reflecting surface 27, and the reflecting surface 25. Are sequentially reflected and returned to the second light source 80 via the microlens 81a, and a third circular light path LC3 having a drum shape that oscillates in the forward and reverse directions and oscillates is formed in the plane PL3 parallel to the reference plane 11. be able to.

  In this way, the light excited by the excitation light source 71 of the light source substrate 40 is condensed on the solid-state laser medium 51 to emit laser light from the light emitting point 42, and from the second light source 80 to the reference plane 11 and the plane PL2. Laser light is radiated in both parallel directions and reflected by using the plurality of reflecting surfaces 21 to 28 of the first reflecting surface substrate 20 and the reflecting surface 41 of the light source substrate 40, so that three orbits are formed in a plane orthogonal to each other. The optical paths LC1 to LC3 can be easily formed.

  In addition, the microlenses 81a and 81b are provided in the circulating optical path LC3 of the laser light emitted from the second light source 80 to adjust the divergence angle of the laser light. The second light source travels around the circulating optical path LC3 in the forward and reverse directions. The divergence angle is adjusted so that the wavefront shape of the laser beam returning to 80 improves the laser oscillation efficiency. By adjusting the divergence angle of this laser beam, the laser oscillation in the second light source 80 is adjusted. Efficiency can be increased. Note that laser oscillation is possible without adjusting the divergence angle of the laser beam, and it is not necessary to adjust the divergence angle of the laser beam.

  In the above description, the first reflecting surface substrate 20 is formed in a parallel plate shape. However, the shape of the surface opposite to the reference plane 11 does not affect the formation of the circular optical paths PL1 to PL3. Need not be flat and may have an appropriate shape.

  In addition, in order to generate and generate interference fringes by taking out a part of the laser light that circulates in the forward and reverse directions in the first and second optical paths PL1 and PL2, the circular optical paths PL1 and PL2 are set in the forward and reverse directions. A part of the laser light that circulates around the light source substrate 40 may be performed on the light source substrate 40 side.

  In the circulating optical path device 10, a spacer substrate 20 is provided between the first reflecting surface substrate 20 and the light source substrate 40 to form a space for the first circulating optical path PL1 and the second circulating optical path PL2. You may form the space for 1st optical path PL1 and 2nd optical path PL2 without providing.

  FIG. 4A is a plan sectional view of the circulating optical path device 10a, and FIG. 4B is a BB sectional view of FIG. 4A, with respect to the circulating optical path device 10a having no spacer substrate 20. 4) which is a sectional view taken along the line C-C of FIG. 4 and FIG. 5 which is a perspective view of the first reflecting surface substrate 20. FIG.

  As shown in FIGS. 4B, 4C, and 5, the first reflecting surface substrate 20 of the circulating optical path device 10a is formed to be thick, and the hole 29 that forms the reflecting surfaces 21 to 28 is formed deeply. doing. The hole 29 uses a silicon (110) substrate as the first reflecting surface substrate 20, utilizes the (111) plane that appears by anisotropic etching, is inclined ± 54.7 degrees with respect to the reference plane 11, and Reflecting surfaces 21 to 24 having normal lines on two mutually orthogonal planes PL1 and PL2 perpendicular to the plane 11 and reflecting surfaces 25 to 28 inclined by 90 degrees with respect to the reference plane 11 are formed.

  Further, the second reflecting surface substrate 50 of the light source substrate 40 is formed of a laser medium with a part protruding at a position corresponding to the edge portion of the reflecting surface 21 of the first reflecting surface substrate 20 on the plane PL1. A third light source 82 that emits laser light in both directions parallel to the plane 11 and the plane PL2 is formed. The excitation light source substrate 70 is provided with an excitation light source 71 for forming the light emission point 42, and an excitation light source 83 for emitting laser light incident on the third light source 82 is provided. A microlens 84 that condenses the laser light emitted from the excitation light source 83 to the third light source 82 is provided together with the microlens 61 that condenses the emitted laser light at the light emitting point 42.

  The second reflecting surface substrate 50 of the light source substrate 40 is directly bonded to the first reflecting surface substrate 20 in which the holes 29 for forming the reflecting surfaces 21 to 28 are deeply formed, and the holes formed deep in the first reflecting surface substrate 20. 29 forms a space for the first circulating optical path PL1 and the second circulating optical path PL2.

  Similarly to the circular optical path circuit 10, the circular optical path device 10a is configured such that the laser light excited at the light emission point 42 by the laser light emitted from the excitation light source 71 is, as shown in FIG. The reflection surfaces 21 and 22 facing each other and the reflection surface 41 of the light source substrate 40 are repeatedly reflected to form the first circular optical path LC1 in the plane PL1, and the first reflection as shown in FIG. 4B. The second reflecting optical path LC2 is formed in the plane PL2 by repeating reflection on the reflecting surface 23 and the reflecting surface 24 of the surface substrate 20 and the reflecting surface 41 of the light source substrate 40. Also, one laser beam excited by the third light source 82 by the laser light emitted from the excitation light source 83 is reflected on the reflection surface 25, the reflection surface 27, the reflection surface 26, and the reflection as shown in FIG. The other laser beam is sequentially reflected by the surface 28, and the other laser beam is sequentially reflected by the reflecting surface 28, the reflecting surface 26, the reflecting surface 27, and the reflecting surface 25 to form the third circular optical path LC3 in the plane PL3 parallel to the reference plane 11. To do.

  As described above, the three optical paths LC1 to LC3 can be formed in a plane orthogonal to each other with a simple configuration in which the first reflecting surface substrate 20 and the light source substrate 40 are joined.

  In the circulating optical path devices 10 and 10a, the case where the light source substrate 40 in which the second reflective surface substrate 50, the glass substrate 60, and the excitation light source substrate 70 are stacked is used as the light source substrate 40. The glass substrate 60 and the excitation light source substrate 70 may be separated.

  A circular optical path device 10b in which the second reflecting surface substrate 50 is separated from the glass substrate 60 and the excitation light source substrate 70, a plan sectional view of the circular optical path device 10b, FIG. 6 (a), and a BB sectional view of FIG. 6 (b) and FIG. 6 (c) which is a cross-sectional view taken along the line C-C of FIG. 6 (a).

  As shown in FIG. 5, the circulating optical path device 10 b is formed with a large thickness, and the opening area of the hole 29 that penetrates the first reflecting surface substrate 20 that deeply forms the hole 29 that forms the reflecting surfaces 21 to 28. The second reflecting surface substrate 50 is bonded to the reference plane 11 side having a large thickness, and the glass substrate 60 and the example light source substrate 70 are disposed on the surface of the first reflecting surface substrate 20 opposite to the surface where the second reflecting surface substrate 50 is bonded. Are stacked.

  On the second reflecting surface substrate 50, a third light source 82 made of a laser medium is formed by projecting a part at a predetermined distance from the center of the hole 29 of the first reflecting surface substrate 20 on the plane PL1. ing. As shown in FIG. 7B, a reflective film 85 is formed on the side surface of the third light source 82 that is orthogonal to the reference plane 11 and opposite to the reflective surface 21 side. An antireflection film 86 is formed. In addition, the excitation light source substrate 70 is provided with an excitation light source 71 that forms a light emitting point 42 on the second reflecting surface substrate 50 and an excitation light source 83 that emits laser light incident on the third light source 82, which are shifted in position. The substrate 60 is provided with a microlens 84 that condenses the laser light emitted from the excitation light source 83 to the second light source 82 together with the microlens 61 that condenses the laser light emitted from the excitation light source 71 to the light emitting point 42. ing.

  The laser light emitted from the excitation light source 71 provided on the excitation light source substrate 70 by the circulating optical path device 10b passes through the microlens 61 formed on the glass substrate 60 and the hole 29 of the first reflecting surface substrate 20, and is second reflected. The light is condensed on the solid laser medium 51 of the surface substrate 50, and the laser light is excited from the light emitting point 42. As shown in FIGS. 6C and 7A, a part of the laser light excited at the light emitting point 42 is obtained by reflecting the reflecting surface 21, the reflecting surface 22 and the second reflecting surface 21 of the first reflecting surface substrate 20. FIG. 6B shows another part of the laser beam excited by the light emission point 42 by repeatedly reflecting the reflection film 53 of the reflecting surface substrate 50 to form the first circular optical path LC1 in the plane PL1. As described above, the second reflecting optical path LC2 is formed in the plane PL2 by repeating reflection by the reflecting surfaces 23 and 24 and the reflecting film 53 of the second reflecting surface substrate 50 facing each other on the first reflecting surface substrate 20.

  Further, the laser light emitted from the excitation light source 83 provided on the excitation light source substrate 70 passes through the micro lens 84 formed on the glass substrate 60 and the hole 29 of the first reflection surface substrate 20, and the second reflection surface substrate 50. The light is condensed on the second light source 82 a and the laser light is excited from the third light source 82. The laser light excited by the third light source 82 is radiated in the direction of the reflecting surface 21 in parallel with the reference plane 11, and part of the emitted laser light is shown in FIGS. 6 (a) and 7 (b). As described above, reflection is repeated by the reflection surfaces 25 and 28 of the first reflection surface substrate 20 and the reflection film 85 of the third light source 82. By setting the reflectivity of the reflecting surfaces 25 to 28 that repeat this reflection sufficiently high and supplying power with excitation light, the light emitted from the third light source 82 in two directions circulates in the forward and reverse directions. The third oscillation optical path LC3 having a drum shape is formed in a plane PL3 parallel to the reference plane 11 by laser oscillation. If a solid-state laser is used as the third light source 82 that forms the third circular optical path LC3, a thermal lens is formed at the condensing point of the excitation light, so that a microlens for adjusting the divergence angle of the laser light becomes unnecessary. Yes.

  In this way, the second reflective surface substrate 50 is separated from the glass substrate 60 and the excitation light source substrate 70 and provided on both surfaces of the first reflective surface substrate 20, and heat generated by the excitation light sources 71 and 83 provided on the excitation light source substrate 70. By dispersing the heat generated by the light emitting point 42 of the second reflecting surface substrate 50 and the third light source 82, it is possible to prevent the temperature from rising locally. In addition, a part of the laser light that circulates in the forward and reverse directions on each of the circulating optical paths LC <b> 1 to LC <b> 3 can be easily extracted from the second reflecting surface substrate 50.

  In addition, the excitation light source 71 and the excitation light source 83 are arranged at different positions on the excitation light source substrate 70, and the positions of the light emitting point 42 and the third light source 82 of the second reflecting surface substrate 50 are also the positions of the excitation light source 71 and the excitation light source 83. Accordingly, the heat generated by the excitation light sources 71 and 83, the light emitting point 42, and the third light source 82 can be dispersed, and a local temperature rise can be further prevented.

  Further, as shown in the plan cross-sectional view of FIG. 8A, the BB cross-sectional view of FIG. 8B, and the CC cross-sectional view of FIG. 8C, the excitation light source 71 of the excitation light source substrate 70 is connected to the first circular optical path. Even if the two light emitting points 42a and 42b are formed on the second reflecting surface substrate 50 by separating them into the excitation light source 71a that forms LC1 and the excitation light source 71b that forms the second circular optical path LC2, the same triangle as described above. The first circular optical path LC1 and the second circular optical path LC2 can be formed, and the heat source can be further dispersed by separating the excitation light source 71 into the excitation light source 71a and the excitation light source 71b. Therefore, the temperature rise can be further reduced.

  In this way, by using the circular optical path devices 10, 10a, and 10b that form the three circular optical paths LC1 to LC3 in planes orthogonal to each other, it is possible to realize a three-axis gyro sensor that detects the angular velocity in the three-axis direction. it can.

  FIG. 9 shows a configuration of a three-axis gyro sensor using, for example, the circulating optical path device 10b, (a) is a plan layout diagram of the three-axis gyro sensor, (b) is a cross-sectional view along line BB in (a), and (c). FIG. 4 is a cross-sectional view taken along line CC in FIG. As shown in the figure, the three-axis gyro sensor 100 includes a circulating optical path device 10c, an interference fringe generation unit 110, an interference fringe detection unit 120, and a calculation unit 130.

  The reflection film 53 provided between the bottom substrate 52 of the second reflection surface substrate 50 and the laser medium 51 of the circulating optical path device 10b reflects a part of the laser light oscillated by the excitation light source 71 and transmits a part thereof. On the second reflecting surface substrate 50, a third light source 82 made of a laser medium is formed by projecting a part of the second reflecting surface substrate 50 at a predetermined distance from the center of the hole 29 of the first reflecting surface substrate 20 on the plane PL1. Has been. A reflection film 85 is formed on the side surface of the third light source 82 that is orthogonal to the reference plane 11 and opposite to the reflection surface 21 side, and an antireflection film 86 is formed on the side surface on the reflection surface 21 side. The reflection film 85 reflects a part of the laser light oscillated by the third light source 82 and transmits a part thereof. In addition, the excitation light source 71 that forms the light emission point 42 on the second reflection surface substrate 50 of the excitation light source substrate 70 has a reflection surface 24 of a predetermined distance from the plane PL1 on the plane PL2, as shown in FIG. 8A. An excitation light source 83 that is provided at a position apart to the side and emits laser light incident on the third light source 82 of the second reflective surface substrate 50 corresponds to the third light source 82 provided on the second reflective surface substrate 50. The excitation light source 71 and the excitation light source 83 are arranged so as not to be in a straight line.

  The interference fringe generation unit 110 includes a first prism substrate 111 and a second prism substrate 112. The first prism substrate 111 is provided on the opposite surface of the second reflective surface substrate 50 of the circular optical path device 10b to the first reflective surface substrate 20, and is formed with the first circular optical path LC1 formed by the circular optical path device 10c. A part of the laser light that circulates around the second optical path LC2 is extracted and interfered to generate interference fringes. The first prism substrate 111 is formed in a parallel plate shape, and a prism end surface 113a composed of an inclined surface inclined by a minute angle α, for example, an angle of 91 ° with respect to an angle of 90 ° with respect to the parallel upper and lower surfaces of two orthogonal side surfaces. 113b. For example, corner portions 115a and 115b having an apex angle of 91 degrees are formed as the prism end surface 114 opposite to the joint surface between the prism end surfaces 113a and 113b and the first reflecting surface substrate 20. The first prism substrate 111 has a corner portion 115a in the vicinity of the optical axis of the laser beam corresponding to one of the triangular hypotenuses forming the triangular first circular optical path LC1 generated by the circular optical path device 10c. It is arranged so that the corner portion 115b is in the vicinity of the optical axis of the laser beam corresponding to one of the triangular hypotenuses forming the triangular second optical path LC2 generated by the circular optical path device 10c. . For example, the laser beam that is incident on the reflecting film 53 of the second reflecting surface substrate 50 from the reflecting surface 22 of the first reflecting surface substrate 20 of the circulating optical path device 10b and is transmitted through the reflecting film 53 is disposed near the corner 115a. Then, the laser light incident on the reflective film 53 of the second reflective surface substrate 50 from the reflective surface 24 of the first reflective surface substrate 20 of the circulating optical path device 10b and transmitted through the reflective film 53 is incident near the corner 115b. Has been placed.

  The second prism substrate 112 is located at a predetermined distance from the reflective film 85 on the side surface opposite to the reflective surface 21 side of the second light source 82a of the second reflective surface substrate 50 bonded to the first reflective surface substrate 20. And a part of the laser light that circulates around the third circular optical path LC2 formed by the circular optical path device 10b is extracted and interfered to generate interference fringes. The second prism substrate 112 is formed in a parallel plate shape, and one side surface has a prism end surface 116 which is an inclined surface inclined by an angle of 45 degrees with respect to the parallel upper and lower surfaces, and the side surface opposite to the prism end surface 116 is The prism end surface 117a is composed of an inclined surface that is inclined by a minute angle α, for example, an angle of 91 ° with respect to an angle of 90 ° with respect to two parallel side surfaces sandwiching the side surface and the prism end surface 116. The prism end surface 117a and the prism end surface 117b opposite to the second light source 82a form a corner portion 118 having an apex angle of 91 degrees, for example. The second prism substrate 111 is arranged so that the corner portion 118 is in the vicinity of the optical axis of the laser beam corresponding to one of the triangular hypotenuses forming the third circulating optical path LC3 generated by the circulating optical path device 10b. . For example, the laser beam incident on the reflection film 85 of the third light source 82 from the reflection surface 25 of the first reflection surface substrate 20 of the circulating optical path device 10 b and transmitted through the reflection film 85 is arranged near the corner portion 118. ing.

  The interference fringe detection means 120 includes a detection substrate 121, an LC1 detection unit 122a, an LC2 detection unit 122b, and an LC3 detection unit 122c provided with the detection substrate 121. The LC1 detection unit 122a detects a change in the interference fringes of the laser light that circulates around the first circulation optical path LC1 generated by the first prism substrate 111, and the LC1 detection unit 122a of the first circulation optical path LC1 generated by the circulation optical path device 10b. The position on the optical axis of the laser beam corresponding to the triangular hypotenuse, for example, the reflection film 53 is incident on the reflection film 53 of the second reflection surface substrate 50 from the reflection surface 21 of the first reflection surface substrate 20 of the circular optical path device 10b. It arrange | positions so that the laser beam which permeate | transmitted may inject. The LC2 detection unit 122b detects a change in the interference fringes of the laser light that circulates in the second circular optical path LC2 generated by the first prism substrate 111. The LC2 detection unit 122b includes a second optical path LC2 generated by the circular optical path device 10b. A position on the optical axis of the laser beam corresponding to the triangular hypotenuse, for example, the reflection film 53 is incident on the reflection film 53 of the second reflection surface substrate 50 from the reflection surface 23 of the first reflection surface substrate 20 of the circular optical path device 10b. It arrange | positions so that the laser beam which permeate | transmitted may inject. The LC3 detector 122c detects a change in the interference fringes of the laser light that circulates around the third circular optical path LC3 generated by the second prism substrate 112. For example, the reflection of the first reflecting surface substrate 20 of the circular optical path device 10b. Laser light incident on the reflective film 85 of the third light source 82 from the surface 28 and transmitted through the reflective film 85 is incident on and reflected by the prism end surface 116 inclined at an angle of 45 degrees of the second prism substrate 112. Are arranged to be.

  The calculation means 130 is configured to detect interference fringes of laser light that circulates in the first and second optical paths LC1 and LC2 detected by the LC1 detector 122a, the LC2 detector 122b, and the LC3 detector 122c. The angular velocity around the three axes is calculated from the change.

  FIG. 9C and FIG. 10 show the processing for generating the interference fringes of the laser light that circulates around the first circular optical path LC1 by the first prism substrate 111 of the interference fringe generating means 110 of the three-axis gyro sensor 100 and obtaining the angular velocity. This will be described with reference to the partial cross-sectional view of FIG.

  Part of the laser light that circulates in the first circular optical path LC1 in the circular optical path device 10b passes through the reflective film 53 provided between the bottom substrate 52 of the second reflective surface substrate 50 and the laser medium 51, thereby generating interference fringes. 110 enters the first prism substrate 111. Since the laser light in the first circular optical path LC1 incident on the first prism substrate 111 oscillates in both the forward and reverse directions, the laser beam travels in two directions in the first prism substrate 111, and the first circular optical path LC1 travels in the opposite direction. The laser light that circulates clockwise and enters the reflection film 53 of the second reflection surface substrate 50 from the reflection surface 21 of the first reflection surface substrate 20 and passes through the reflection film 53 is transmitted through the first prism substrate 111 and LC1. The light enters the detector 122a. On the other hand, the laser light that circulates counterclockwise around the first optical path LC1 and enters the reflective film 53 of the second reflective surface substrate 50 from the reflective surface 22 of the first reflective surface substrate 20 and passes through the reflective film 53 is The light enters the corner portion 115a of the first prism substrate 111, is reflected by both the prism end surface 114 and the prism end surface 113a, returns slightly shifted from the incident light path to the corner portion 115a, and the reflective film 53 of the second reflective surface substrate 50. And enters the LC1 detector 122a.

  Since the laser beams incident on the LC1 detection unit 122a in this way are coherent, they interfere with each other to generate interference fringes. The light and darkness of the interference fringes is detected by the LC1 detector 122a, and the calculation means 130 performs a predetermined calculation to calculate the angular velocity.

  That is, the laser light that circulates around the first circulatory optical path LC1 circulates in the forward and reverse directions, and oscillates with the optical path length as the resonance length. In this state, when the entire first optical path LC1 is rotated about an axis orthogonal to the drawing, the Sagnac effect causes a deviation between the clockwise laser oscillation wavelength and the counterclockwise oscillation wavelength. The angular velocity can be obtained by detecting this shift as a beat frequency.

For example, the appearance of the interference fringes 140 generated in FIG. 11 is schematically shown. FIG. 11A shows the state (reference state) of the interference fringe 140 in a state where the angular velocity is zero, and FIGS. 11B and 11C show the first circular optical path LC1 in FIG. 10C. The state of the interference fringes 140 when the clockwise and counterclockwise rotations are generated around the axis orthogonal to is shown. As shown in FIG. 11, depending on whether the rotation direction is clockwise or counterclockwise, the interference fringe 140 shifts from the reference state to the right or left, and the shift amount corresponds to the beat frequency and corresponds to the rotation angular velocity. Proportional.
That is, the calculated angular velocity Ω is the beat frequency f, the triangular area formed by the first circular optical path LP1 in one plane S, the optical path length of the first circular optical path LC1 L, and the wavelength of the laser light. If λ is given by the following equation.
Ω = L ・ λ ・ f / 4S
Here, since the beat frequency f is obtained from the amount of displacement of the interference fringes 140, the angular velocity can be calculated by inputting the output of the LC1 detector 122a to the calculation means 130 and performing a predetermined calculation.

  Similarly, the interference velocity fringes of the laser light that circulates on the second circular optical path LC2 can be generated on the first prism substrate 111 to obtain the angular velocity.

  Next, a process for generating an interference fringe of laser light that circulates in the third circular optical path LC3 and obtaining an angular velocity will be described with reference to a plan layout diagram of FIG. 10B and a partial sectional view of FIG.

  Part of the laser light that circulates in the third optical path LC3 in the optical path device 10b passes through the reflection film 85 of the third light source 82 and enters the second prism substrate 112 of the interference fringe generation unit 110. Since the laser light of the third circular optical path LC3 incident on the second prism substrate 112 oscillates in both the forward and reverse directions, it travels in the second prism substrate 112 in two directions. The laser light that circulates counterclockwise around the third optical path LC3, reflects off the reflecting surface 28, and passes through the reflective film 85 of the second light source 82a enters the second prism 112 and is inclined by 40 degrees. The light is reflected by the prism end face 116 and changed in direction by 90 degrees to enter the LC3 detector 122c. On the other hand, the laser light that circulates around the third optical path LC3 in the clockwise direction, is reflected by the reflecting surface 25, and passes through the reflective film 85 of the second light source 82a is incident on the corner portion 118 of the second prism substrate 112. Reflected by both the prism surface 117b and the prism surface 117a, slightly deviated from the incident light path to the corner portion 118, returned to the reflective film 85 of the second light source 82a, reflected by the reflective film 85, and angled 90 by the prism end surface 116. The direction of the light is changed and incident on the LC3 detector 122c to generate interference fringes. The light and dark state of the interference fringes is detected by the LC1 detector 122c, and a predetermined calculation is performed by the calculation means 130 to calculate the angular velocity in the axial direction orthogonal to the third circulating optical path LC3.

  In this way, the angular velocity in the triaxial direction can be detected using the circulating optical path device 10b.

  In the above description, the three-axis gyro sensor 100 using the orbiting optical path device 10b has been described, but a three-axis gyro sensor can also be formed using the orbiting optical path devices 10 and 10a.

It is a block diagram of the circumference optical path apparatus of this invention. It is a perspective view which shows the structure of the 1st reflective surface board | substrate of a circumference optical path apparatus. It is sectional drawing which shows the structure of the light source board | substrate of a circumference optical path apparatus. It is a block diagram of the 2nd circumference optical path apparatus of this invention. It is a perspective view which shows the structure of the 1st reflective surface board | substrate of a 2nd circumference optical path apparatus. It is a block diagram of the 3rd circumference optical path apparatus of this invention. It is a fragmentary sectional view which shows the excitation state of the laser beam which forms the circumference optical path LC1 and the circumference optical path LC3 in a 3rd circumference optical path apparatus. It is another block diagram of the 3rd circumference optical path device. It is a block diagram of the 3-axis gyro sensor of this invention. It is a block diagram of an interference fringe production | generation means and an interference fringe detection means. It is a schematic diagram which shows the interference fringe produced | generated with the 3-axis gyro sensor.

Explanation of symbols

10: Circulating optical path device 11: Reference plane 20: First reflecting surface substrate
21-28; reflective surface, 29; hole, 30; spacer substrate, 40; light source substrate,
41; reflective surface, 50; second reflective surface substrate, 51; solid-state laser medium, 52; bottom substrate,
53; reflection film, 54; antireflection film, 60; glass substrate, 61; microlens,
70; excitation light source substrate, 71; excitation light source, 80; second light source,
81; microlens, 82; third light source, 83; excitation light source,
84; micro lens, 100; three-axis gyro sensor, 110 interference fringe generating means,
111; first prism substrate; 112; second prism substrate; 120; interference fringe detection means;
121; detection substrate, 122a; LC1 detection unit, 122b; LC2 detection unit,
122c; LC3 detection unit, 130; calculation means, LC1 to LC3;

Claims (8)

A substrate having a reference plane, one or more substrates stacked in parallel to the reference plane in a direction perpendicular to the reference plane of the substrate, and a plurality of light sources,
The substrate has a normal line in a first plane perpendicular to the reference plane, and has at least two reflecting surfaces formed at a predetermined angle with respect to the reference plane, and is perpendicular to the reference plane. And at least two reflecting surfaces each having a normal line in a second plane intersecting the first plane and inclined at a predetermined angle with respect to the reference plane, and the reference plane A plurality of reflective surfaces having normals in a third parallel plane;
The one or more substrates have a reflective surface parallel to the reference plane;
One of the plurality of light sources is arranged to emit light in the first plane and the second plane, and the light emitted from the light source is coupled to the first plane and the first plane. First and second circular optical paths that oscillate in the forward and reverse directions in the two planes by a reflective surface having a normal line in two planes and a reflective surface parallel to the reference plane are formed. And
The other light sources of the plurality of light sources are arranged to emit light in the third plane, and the light emitted from the light sources is forward and backward in the third plane by the plurality of reflection surfaces. A circular optical path device characterized by forming a third circular optical path that circulates and laser-oscillates. Wherein at least one round optical path among the round optical path, the light emitting point of the light source to form a round optical path, according to claim 1, characterized in that it is arranged on one of the reflective surfaces forming a round optical path Circulating optical path device. 3. The circulating optical path device according to claim 1, wherein the substrate stacked in parallel to the reference plane is a light source substrate having a light source that forms the first and second circulating optical paths. The light source comprises a light-excited solid light source medium that emits light when irradiated with light,
The substrate includes a substrate having the solid light source medium and an excitation light source substrate having an excitation light source that excites the solid light source medium, and a plurality of excitation light sources arranged on the excitation light source substrate are used on the solid light source medium. circulation according to any one of claims 1 to 3, characterized in that from the first by emitting light from different light emitting points to excite the different points to form a third round optical path Optical path device. The third orbiting optical path is a triangular orbiting optical path formed by two reflecting surfaces having a normal line in a third plane parallel to a reference plane and a reflecting surface of a light source mounted on the substrate. The circulating optical path device according to any one of claims 1 to 4 , wherein The light source of the third round optical path is composed of a light-excited solid light source medium that emits light by irradiating light, is projected and stacked on the base, and is emitted from an excitation light source substrate stacked on the base 6. The circulating optical path device according to claim 5 , wherein the circulating optical path device emits laser light in the third plane when excited by light. The excitation light source substrate, round optical path device according to any one of claims 4 to 6, characterized in that it is arranged on the side opposite to the substrate having the solid-state light source medium across said substrate. A circulating optical path device according to any one of claims 1 to 7 ,
Interference fringe generation for generating interference fringes by extracting and interfering a part of the laser light that circulates in the forward and reverse directions in the first and second rounding optical paths and the third rounding optical path formed by the rounding optical path device. Means,
Interference fringe detecting means for detecting a change in interference fringes in each of the circulating optical paths generated by the interference fringe generating means;
A three-axis ring laser gyro comprising: an arithmetic unit that calculates an angular velocity about three axes based on a change in interference fringes in each of the circulating optical paths detected by the interference fringe detection unit.

Images