JP2009150793A - Interference fringe generator, ring laser gyro, and ring laser gyro forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an interference fringe generator, a ring laser gyro, and a method for forming a ring laser gyro, which can be detected in a biaxial direction with a simple configuration.
A ring laser gyro according to the present invention includes a plate-like prism substrate that is stacked in parallel to a reference plane in a direction orthogonal to a reference plane of a base body, and has forward and reverse directions oscillated in a circular optical path. Each part of the laser light enters the flat prism from the incident surface of the flat prism, and one of the forward and reverse laser beams is reflected by the two reflecting surfaces of the flat prism, An interference fringe is generated by being overlapped with the laser beam at a minute angle, and a change in the interference fringe is detected by the detecting means.
[Selection] Figure 1

Description

  The present invention relates to an interference fringe generator, a ring laser gyro, and a ring laser gyro forming method, and more particularly to a configuration of a ring laser gyro having a simple configuration that is applied to an angle sensor.

  Angular velocity sensors are applied in many fields such as car navigation, camera shake correction, games, aircraft, rockets, and robots. The angular velocity sensor (gyro) includes an optical gyro, a rotary gyro, and a vibration gyro. Among them, the vibration type gyro is described in Patent Document 1 and the like, and has recently been produced at low cost by the MEMS technology. These are devices that vibrate an object with piezoelectric power and electrostatic force and detect the generated Coriolis force to detect the 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.

  In addition, when high-precision detection is required such as mounted 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 Literature 2, Patent Literature 3, and the like. An 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 wound surface, 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. However, since this optical fiber gyroscope needs to make the fiber very long, that is, to wind a lot in order to detect the optical path difference of light, it is problematic that it is sensitive to temperature change.

  On the other hand, a ring laser gyro forms a laser resonator having a ring-shaped optical path by a plurality of mirrors, oscillates a clockwise and counterclockwise laser in this optical path, and detects the difference between the oscillation wavelengths of both laser beams. Thus, the angular velocity is detected. However, this ring laser gyro also has good performance, but is relatively large and expensive, so it is difficult to use it for general consumer use.

Therefore, Patent Document 4 proposes a configuration in which a high-precision optical gyro is easily formed by batch processing using MEMS technology. The optical gyro proposed in Patent Document 4 is formed by using anisotropic etching of silicon in a circular optical path of a ring laser gyro. Therefore, a more accurate optical gyro can be easily formed by batch processing. However, since the optical gyro of Patent Document 4 forms a circulating optical path in a plane parallel to the substrate, it can only detect in one axial direction. In order to detect in the biaxial direction, it is necessary to change the 90 deg direction and arrange another one, which increases the size of the apparatus. 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. Therefore, by stacking silicon substrates (100) and using a pyramidal inclined surface by anisotropic etching as a resonance surface, two circular optical paths perpendicular to the substrate surface and perpendicular to each other are formed to detect the angular velocity in the biaxial direction. Possible ring laser gyros have been proposed.
JP-A-10-227644 Japanese Examined Patent Publication No. 62-39836 Japanese Patent Publication No. 2-60127 Japanese Patent No. 3,751,553

  However, when the ring laser gyro is constructed, it is necessary to form interference fringes of the oscillation light around both sides and detect the movement thereof, and the lasers around both sides generated in the two-way circular optical paths perpendicular to the substrate and perpendicular to each other. In order to extract light effectively, it is necessary to arrange a triangular prism on each axis, which makes the configuration complicated and difficult to manufacture.

  The present invention is for solving these problems, and provides an interference fringe generator, a ring laser gyro, and a method for forming a ring laser gyro, which can be detected in a biaxial direction with a simple configuration. With the goal.

  In order to solve the above problems, an interference fringe generator according to the present invention includes a base having a reference plane, one or more substrates stacked in parallel to the reference plane in a direction orthogonal to the reference plane, and a light source And a flat prism substrate laminated in parallel to the reference plane in a direction perpendicular to the reference plane. Further, in the base body and / or the substrate and / or the prism substrate, three or more reflecting surfaces that reflect light from the light source have a normal line of the reflecting surface in a plane orthogonal to the reference plane, and the reference surface. It is formed to be parallel to the plane or inclined at a predetermined angle. Further, the light source is arranged so as to emit light in a plane, and a circular optical path is formed in which the light emitted from the light source circulates in the forward and reverse directions in the plane by three or more reflecting surfaces to oscillate. The angle formed between the first reflecting surface of the flat prism and the second reflecting surface adjacent to the first reflecting surface is shifted from 90 degrees, and the forward and reverse laser light oscillated in the circulating optical path. A part of each of the light beams enters the flat prism from the incident surface of the flat prism, and one of the forward and reverse laser beams is reflected by the first reflective surface and the second reflective surface of the flat prism. Are overlapped in a state where they cross each other at a small angle with respect to the laser beam in the other direction to generate interference fringes. Accordingly, an interference fringe generator having a simple configuration is provided in which laser resonators generated in two circular optical paths orthogonal to the substrate are formed, and a part of the laser beams on both sides in the circular optical path are extracted and interfered with each other. Can do.

  In addition, the interference fringe generator 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 orthogonal to the reference plane, a light source, and orthogonal to the reference plane. And a flat prism substrate laminated in parallel with the reference plane. Further, on the base body and / or the substrate and / or the prism substrate, three or more reflecting surfaces that reflect light from the light source have normal lines of the reflecting surfaces in two planes orthogonal to the reference plane and orthogonal to each other. And are formed so as to be parallel to the reference plane or inclined at a predetermined angle. Further, the light source is arranged to emit light in the first plane and the second plane, and the light emitted from the light source circulates in the forward and backward directions in the first plane by the reflection surfaces of three or more light sources. The second circulation in which the first circulation optical path for laser oscillation is formed and the light emitted from the light source circulates in the forward and reverse directions in the second plane by the reflection surfaces of the three or more light sources. An optical path is formed. The angle formed between the first reflecting surface of the flat prism and the second reflecting surface adjacent to the first reflecting surface is shifted from 90 degrees, and the forward and reverse laser light oscillated in the circulating optical path. A part of each of the light beams enters the flat prism from the incident surface of the flat prism, and one of the forward and reverse laser beams is reflected by the first reflective surface and the second reflective surface of the flat prism. Are superimposed on the laser beam in the other direction at a slight angle to generate a first interference fringe. Further, the normal line of the third reflecting surface adjacent to the first reflecting surface and the second reflecting surface of the flat prism is in a plane including the second circulating optical path and in a direction parallel to the reference plane. A part of each of the forward and reverse laser beams which are inclined by a minute angle and oscillate in the second circular optical path is incident from the surface where the flat prism and the first circular optical path are in contact with each other. One of the laser beams reflects the end face of the flat prism and the surface facing the first optical path, and is overlapped with the laser beam in the other direction at a minute angle to generate a second interference fringe. To do. Therefore, it is possible to provide an interference fringe generator capable of detecting angular velocities in two orthogonal directions using a single light source with a simple configuration.

  Furthermore, the interference fringe generator 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 orthogonal to the reference plane, two light sources, and a reference plane. A flat prism substrate that is stacked in parallel to the reference plane in a direction orthogonal to each other. Further, in the base body and / or the substrate and / or the prism substrate, three or more reflecting surfaces for reflecting light from each light source are normal to the reflecting surface in two planes orthogonal to the reference plane and orthogonal to each other. Are formed so as to be parallel to the reference plane or inclined at a predetermined angle. Further, the first light source is arranged to emit light in the first plane, and the second light source is arranged to emit light in the second plane, and is emitted from the first light source. The reflected light for three or more first light sources circulates in the first plane in the forward and reverse directions to form a first optical path for laser oscillation, and the light emitted from the second light source A second orbiting optical path that oscillates in the forward and reverse directions in the second plane is formed by three or more reflecting surfaces for the second light source. The angle formed between the first reflecting surface of the flat prism and the second reflecting surface adjacent to the first reflecting surface is shifted from 90 degrees, and the forward and reverse laser light oscillated in the circulating optical path. A part of each of the light beams enters the flat prism from the incident surface of the flat prism, and one of the forward and reverse laser beams is reflected by the first reflective surface and the second reflective surface of the flat prism. Are superimposed on the laser beam in the other direction at a slight angle to generate a first interference fringe. Further, the normal line of the third reflecting surface adjacent to the first reflecting surface and the second reflecting surface of the flat prism is in a plane including the second circulating optical path and in a direction parallel to the reference plane. A part of each of the forward and reverse laser beams which are inclined by a minute angle and oscillate in the second circular optical path is incident from the surface where the flat prism and the first circular optical path are in contact with each other. One of the laser beams reflects the end face of the flat prism and the surface facing the first optical path, and is overlapped with the laser beam in the other direction at a minute angle to generate a second interference fringe. To do. Therefore, it is possible to provide an interference fringe generator capable of detecting angular velocities in two orthogonal directions with a simple configuration using two light sources.

  The light source, the first light source, or the second light source is disposed between the flat prism and the base or substrate that forms a circular optical path, and most of the oscillated laser light is reflected on the flat prism side of the light source. In addition, a reflective / transmissive film that partially transmits is formed. Therefore, by arranging the detection surface on the light source side, the electrical wiring can be concentrated in one place, and the configuration can be simplified.

  Further, a reflection film for reflecting the oscillated laser beam is formed on the outer periphery of the flat prism. Therefore, the reflectance at the prism surface that forms the interference fringes can be improved.

  Further, a ring laser gyro as another invention includes the interference fringe generating device, and a detection substrate having a detection means for detecting a change in the interference fringe in a direction perpendicular to the reference plane and parallel to the reference plane is laminated. The present invention is characterized in that it has a calculation means for calculating the angular velocity based on the detected change in interference fringes. Therefore, the movement of the formed interference fringes can be detected, and the angular velocity signal can be obtained with a simple configuration.

  Furthermore, a ring laser gyro as another invention has the interference fringe generator, and a detection means for detecting the interference fringe is provided on a part of the substrate constituting the interference fringe generator, and the detected interference It is characterized by having a calculation means for calculating the angular velocity based on the change in fringes. Therefore, it is possible to provide a low-cost ring laser gyro with a reduced number of components.

  According to another method for forming a ring laser gyro as another invention, the first and second end faces of the flat prisms constituting the interference fringe generator are formed by laminating and bonding the substrates constituting the ring laser gyro. The whole is characterized in that it is formed by dicing at a slight angle from the perpendicular to the reference surface. Therefore, the inclined end face of the prism that forms the interference fringes can be easily formed at low cost.

  Furthermore, since the diced end surface is polished, the reflectance and the wavefront accuracy can be improved.

  The ring laser gyro of the present invention has a flat prism substrate laminated in parallel to the reference plane in a direction perpendicular to the reference plane of the substrate, and each of forward and reverse laser beams oscillated in a circular optical path. Part of the light enters the flat prism from the incident surface of the flat prism, and one of the laser beams in the forward and reverse directions is reflected by the two reflecting surfaces of the flat prism, and against the laser light in the other direction Then, the interference fringes are generated by being overlapped at a minute angle, and the change of the interference fringes is detected by the detecting means. Therefore, it is possible to detect the angular velocity with a simple configuration.

  FIG. 1 is a diagram showing a configuration of a ring laser gyro according to a first embodiment of the present invention. (A) of the figure is a cross-sectional view of the ring laser gyro according to the present embodiment, (b) of the figure is a cross-sectional view taken along the line AA ′ in (a) of the figure, and (c) of FIG. It is a BB 'line sectional view in (b). In addition, exemplifying the size of the ring laser gyro shown in FIG. 1, the vertical and horizontal sizes in FIGS. 1A to 1C are about several mm.

  A ring laser gyro 10 according to the present embodiment shown in FIG. 1A mainly includes an orbiting optical path device including a bottom substrate 11, a reflecting surface substrate 12, and a spacer substrate 13, and further includes a prism in the orbiting optical path device. It has an interference fringe generator configured to include the substrate 14, and further includes a detection device configured to include a detection substrate 15 having a detection unit described later in the interference fringe generator. The bottom substrate 11 is provided with a light source 16 and lenses 17 and 18. Further, the bottom substrate 11 is a base body and has a reference plane 19. The reflecting surface substrate 12 has a thin parallel plate shape, and a regular quadrangular pyramidal hole is formed through the center of the reflecting surface substrate 12 in the depth direction. The regular quadrangular pyramidal hole of the reflecting surface substrate 12 has four wall surfaces. have. Among these wall surfaces, two of the four wall surfaces shown in FIG. 1A are used as the reflecting surfaces 20 and 21. The spacer substrate 13 is a substrate for setting a predetermined distance between the reflecting surface substrate 12 and the prism substrate 14, and a square hole is formed in the thickness direction as shown in FIG. Has been drilled. The size of the square-shaped hole is slightly larger than the size of the bottom surface of the hole on the regular quadrangular pyramid formed in the reflecting surface substrate 12. Further, the lower planar portion of the prism substrate 14 provided on the spacer substrate 13 in FIG.

  The light source 16 is a semiconductor laser element in the present embodiment. In FIG. 1A, the light source 16 emits laser light parallel to the reference plane 19 in the horizontal direction in the drawing. The semiconductor laser element of the light source 16 in the present embodiment emits light from both end faces of the chip, and antireflection films are formed on both end faces so that there is no reflection on the end faces. The lenses 17 and 18 are mounted in the vicinity of both end surfaces of the light source 16 and adjust the divergence angle of the laser light emitted from the light source 16. That is, the lenses 17 and 18 are divergence angle adjusting means for adjusting the divergence angle of light emitted from the light source 16. The light source 16 and the lenses 17 and 18 are mounted on the upper surface of the bottom substrate 11 forming the reference plane 19 by an appropriate method. The laser beam emitted from the light source 16 is divergent, and the beam diameter of the laser beam that follows the circulating optical path varies depending on the position. However, since the drawing becomes complicated, such a change in the beam diameter is shown in FIG. It has not been. The same applies to the following drawings.

  1 (b) and 1 (c), there is a plane 25 on which a circular optical path is formed. This plane 25 is orthogonal to the reference plane 19 as shown in FIGS. 1 (b) and 1 (c). The plane 25 is parallel to the drawing in FIG. 1A, and all of the reflection surfaces 20, 21, and 24 are parallel to the plane 25 whose normal is one plane. The normals of the surfaces 21, 22, and 24 are included in the surface. The plane 25 which is one plane includes laser light emitted from the light source 16 which is a semiconductor laser element, and optical axes of lenses 17 and 18 serving as divergence angle adjusting means for adjusting the divergence angle of these laser lights. It is a plane orthogonal to the reference plane 19.

  Accordingly, when laser light is emitted from the light source 16 in the left-right direction of FIG. 1A, the emitted laser light is adjusted by the lenses 17 and 18 and reflected by the reflecting surfaces 20, 21, and 24. . Laser light (solid arrow) emitted from the light source 16 toward the reflecting surface 20 is adjusted in divergence angle by the lens 17, sequentially reflected by the reflecting surfaces 20, 24, and 21, and returns to the light source 16 through the lens 18. Laser light (dotted arrow) emitted from the light source 16 toward the reflecting surface 21 is adjusted in divergence angle by the lens 18, sequentially reflected by the reflecting surfaces 21, 24, and 20, and returns to the light source 16 through the lens 17.

  In this way, the laser light emitted from the light source 16 in the above two directions circulates in the forward and reverse directions to form a circulating optical path in the plane 25 that is one plane. The circular optical path has a triangular shape as shown in FIG. 1A, and the optical paths in the quasi-reverse direction are the same. The adjustment of the divergence angle by the lenses 17 and 18 is performed so that the wavefront shape of the laser light that circulates in the forward and reverse directions on the circulating optical path and returns to the light source 16 becomes a surface shape that improves the laser oscillation efficiency.

  Here, in order to detect the angular velocity, the beat frequency is obtained by detecting the movement of the interference fringes by causing the laser beams in the forward and reverse directions generated in the above-described circulating optical path to interfere with each other. The reflecting surface 24 of the prism substrate 14 that forms the circulating optical path is a reflecting / transmitting surface that reflects part of the light and transmits the remaining light, and also serves as the prism incident surface 26. Since the laser oscillates in both the forward and reverse directions in the circulating optical path, the laser beam passes through the prism incident surface 26 and travels in the prism substrate 14 in two directions. That is, part of the laser light emitted from the light source 16 toward the reflecting surface 20 and transmitted through the lens 17 is transmitted through the prism incident surface 26 and is incident on the second prism reflecting surface 28 of the prism substrate 14. On the other hand, part of the laser light emitted from the light source 16 toward the reflecting surface 21 and transmitted through the lens 18 is transmitted through the prism incident surface 26 and incident on the corner portion 29 of the prism substrate 14, and the incident optical path to the corner portion 29. Is slightly deviated from the light beam, returns to the prism incident surface 26, is reflected here, and then enters the second prism reflection surface 28. Actually, the light is reflected by both surfaces of the corner portion 26 (for example, 91 degrees) slightly shifted from 90 degrees, that is, the light is reflected by both the first prism reflecting surface 27 and the second prism reflecting surface 28. Since the light beams are slightly deviated from the optical path, the two light beams overlap each other with a minute angle in the traveling direction.

  In this way, the two light beams overlap on the upper surface of the prism substrate 14 constituting the interference fringe generator in the ring laser gyro 10 of the first embodiment shown in FIG. 1, but these are coherent with the laser light, so that they are mutually coherent. Interference occurs to produce interference fringes. That is, the interference fringe generator in the ring laser gyro 10 of the first embodiment shown in FIG. 1 is parallel to the reference plane 19 in the direction perpendicular to the reference plane 19 and the bottom base 11 having the reference plane 19. The reflective surface substrate 12, the spacer substrate 13, the prism substrate 14, the detection substrate 15, and the light source 16 are stacked, and the one or more reflective surface substrates 12 and the prism substrate 14 have three or more reflective surfaces 20, 21, 24 has a normal line in a plane 25 orthogonal to the reference plane 19, is formed parallel to the reference plane 19 or inclined at a predetermined angle, and the light source 16 is arranged to emit light into the plane 25. . Then, the light emitted from the light source 16 circulates in the forward / reverse direction in the plane 25 which is one plane by the three or more reflecting surfaces 20, 21, 24 to form a circulating optical path, and the forward / reverse light emitted from the circulating optical path. The laser beam in the direction is incident on the prism substrate 14 which is a flat prism laminated on the reference plane 19. Further, one of the forward and reverse laser beams is reflected by the first prism reflecting surface 27 and the second prism reflecting surface 28 of the prism substrate 14 whose angle formed between them is deviated from 90 degrees. It is overlapped with the other laser beam in a state of crossing at a minute angle to generate interference fringes.

  Here, FIG. 2 shows the state of interference fringes generated by the interference fringe generator in the ring laser gyro 10 of the first embodiment. The interference fringes in (a) in the figure are the interference fringe state (reference state) when the angular velocity is 0, and (b) and (c) in FIG. It shows the state of interference fringes when clockwise or counterclockwise rotation occurs around an orthogonal axis. Depending on whether the rotation direction is clockwise or counterclockwise, the interference fringes shift from the reference state to the right or left, and the amount of shift corresponds to the beat frequency described above and is proportional to the angle of rotation. Here, in the place where the interference fringes are generated, the detection substrate 15 on which the detection unit 30 for detecting the brightness of the interference fringes is formed is stacked on the prism substrate 14.

  Therefore, according to the ring laser gyro 10 according to the first embodiment having such a configuration, the laser light that circulates in the circular optical path is clockwise and counterclockwise as shown in FIG. In other words, the laser beam oscillates in the forward and reverse directions, and laser oscillation occurs with the optical path length as the resonance length. In this state, when the entire rotating optical path is rotated around an axis orthogonal to the drawing, the Sagnac effect causes a deviation between the clockwise laser oscillation wavelength and the counterclockwise oscillation wavelength. This deviation is detected as a beat frequency by the detection unit 30 provided on the detection substrate 15 constituting the detection device in the ring laser gyroscope 10 in the first embodiment, and the angular velocity is obtained by performing a predetermined calculation based on the detection result. Can be calculated.

Incidentally, the calculated angular velocity Ω is as follows, where f is the beat frequency, S is the area of the triangle formed by the circulating optical path in one plane, L is the optical path length of the circulating optical path, and λ is the wavelength of the laser beam. It is given by the formula.
Ω = L · λ · f / (4 · S) (1)
Since the beat frequency f is determined by the amount of displacement of the interference fringes, the angular velocity can be calculated by inputting the output of the detection unit 30 to a calculation means (not shown) such as a computer and calculating the above equation (1).

  Note that according to the above equation (1), the angular velocity Ω is inversely proportional to the area S of the circulating optical path. Therefore, the shape of the circulating optical path is preferably a shape that increases its area. Further, by setting the number of reflecting surfaces for forming one circular optical path to 4 or 6, it is possible to form a circular or hexagonal circular optical path having a large area. A detailed configuration when the circular optical path is a quadrangular shape or a hexagonal shape will be described later.

  As described above, the ring laser gyro 10 according to the first embodiment shown in FIG. 1 takes out and interferes with a part of the laser light that circulates in the forward and reverse directions on the circulating optical path, and the light source 16, the reflective substrate 12, and the spacer substrate. 13 includes an orbiting optical path device that includes 13, an interference fringe generator that includes the orbiting optical path device and the prism substrate 14 and generates an interference fringe, and a detection unit 30 that detects a change in the interference fringe. It has a detection device having a substrate 15 and a calculation means (such as a computer (not shown)) for calculating an angular velocity based on the detected change in interference fringes.

  Incidentally, the lenses 17 and 18 as the divergence angle adjusting means adjust the divergence angle so that the wavefront shape of the laser light that circulates in the forward and backward directions on the circulating optical path and returns to the light source as described above improves the laser oscillation efficiency. By using these, it is known that the efficiency of laser oscillation in the light source 16 can be increased, but laser oscillation is possible without using a divergence angle adjusting means, and a circular optical path can be formed. Therefore, the divergence angle adjusting means is not essential for the circulating optical path device of the present invention.

  Further, since the spacer substrate 13 is for forming a space for the circular optical path, the depth of the regular quadrangular pyramid hole formed in the reflecting surface substrate 12 is sufficiently deep so that the spacer substrate 13 is not interposed. The prism substrate 14 can also be bonded directly on the reflecting surface substrate 12.

  Further, in the first embodiment shown in FIG. 1, the shape of the surface opposite to the reference plane 19 in the bottom substrate 11 constituting the base body has no influence on the formation of the circular optical path, so that it is opposite to the reference plane 19. The portion does not need to be a plane and can have an appropriate shape. Similarly, since the shape of the detection substrate 15 on the side where the detection unit 30 is not formed does not affect the formation of the circulating optical path, this portion does not need to be a flat surface and can be an appropriate shape. The surface opposite to the reference plane of the bottom substrate 11 is set to be a plane, and a light source for forming another circulating optical path in which light circulates in a plane parallel to the reference plane 19, and three or more reflecting surfaces And can be formed. Further, the reflecting surfaces 20 and 21 are preferably plated with gold so that the laser beam can be easily reflected.

  In the circling optical path device shown in FIG. 1, in order to form a hole having a regular quadrangular pyramid-like slope on the reflecting surface substrate 12 as described above, the following may be performed. That is, a silicon substrate is used as the reflecting surface substrate 12, and the surface (the surface on the side where the spacer substrate 13 is provided in FIG. 1A is defined as the (100) plane in the silicon crystal, with respect to the (100) plane. When etching by anisotropic wet etching is performed, the (111) plane is exposed, and a regular pyramid-shaped hole can be easily and reliably formed.The (111) plane thus formed is used as a reflective surface. However, the inclination angle formed by the reflecting surface with respect to the reference plane 19 is accurately ± 54.7 degrees.

  In the first embodiment shown in FIG. 1, the reflecting surface substrate 12 is obtained by etching a silicon substrate as described above, and a hole for forming a space for a circulating optical path on the surface where a large opening is formed. A spacer substrate 13 having a through hole is laminated and bonded, and a prism substrate 14 having a reflection surface 24 formed on the lower surface is further laminated and bonded.

  As described above, the bottom substrate 11 and the reflective surface substrate 12 may be a single substrate, and a truncated quadrangular pyramid hole may be formed on one surface of the substrate. In this case, the substrate may be silicon. When forming a slope to be a reflective surface by anisotropic wet etching as a substrate, it is necessary to make the bottom surface of the hole a smooth surface parallel to the reference plane in order to mount the light source 16 and the lenses 17 and 18. Such a bottom portion is not always easy to form. Accordingly, as shown in FIG. 1, a hole having a truncated quadrangular pyramid shape is formed in the reflecting surface member so as to penetrate the reflecting surface substrate 12, and this portion is a bottom surface having a flat plane as a reference plane 19. It is preferable that the light source 16 and the lenses 17 and 18 of the semiconductor laser element are mounted on the bottom surface with the reference plane 19 as the bottom surface of the hole, which is covered with the substrate 11. The semiconductor laser element as the light source 16 may be mounted on a fixed base. Further, if the position of the reflecting surface 24 of the prism substrate 14 is shifted, an accurate circular optical path device cannot be formed. Therefore, an electrostatic actuator or the like is provided to finely adjust the reflecting surface 24 in the vertical direction in FIG. May be.

  FIG. 3 is a cross-sectional view showing a configuration of a ring laser gyro according to the second embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same components. In the ring laser gyro 40 of the second embodiment shown in the same figure, a glass substrate 41 is laminated between the reflecting surface substrate 12 and the spacer substrate 13, and on one side parallel to the reference plane 19 of the glass substrate 41, Microlenses 42 and 43 serving as divergence angle adjusting means are formed. According to the ring laser gyro 40 of the present embodiment having such a configuration, the laser light beams emitted from the light source 16 which is a semiconductor laser element in the left-right direction in the figure are reflected by the reflecting surfaces 20 and 21, respectively. The divergence angle is adjusted by the lenses 42 and 43, passes through the glass substrate 41, is reflected by the reflecting surface 24 of the prism substrate 14, is reflected by the reflecting surfaces 20 and 21 through the microlenses 42 and 43, and returns to the light source 16. A circular optical path for laser oscillation is formed. The thickness or the like of the spacer substrate 13 is adjusted in consideration of the thickness or the like of the glass substrate 41 so that the above-described circulation optical path device is formed.

  In the first embodiment shown in FIG. 1, since the optical axes of the lenses 17 and 18 are parallel to the reference plane, it is generally difficult to form them on the surface of the bottom substrate 11, and the lenses formed separately. 17 and 18 are retrofitted on the reference plane 19 of the bottom substrate 11, and a precise mounting process is required. In the second embodiment shown in FIG. 3, the optical axes of the microlenses 42 and 43 are provided. Is orthogonal to the surface of the glass substrate 41. Therefore, forming the microlenses 42 and 43 on the surface of the glass substrate 41 can be easily realized by a combination of photolithography technology and etching, making it easy to manufacture the circulating optical path device. It is. The circulating optical path is formed in one plane orthogonal to the reference plane (a plane parallel to the drawing of FIG. 3).

  FIG. 4 is a cross-sectional view showing a configuration of a ring laser gyro according to the third embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same components. The ring laser gyro 50 according to the present embodiment shown in the figure uses a surface-emitting light source 51. The surface-emitting light source mentioned here is not the edge-emitting semiconductor laser element used in the first and second embodiments, but emits light from the surface of the substrate, such as a VCSEL. However, unlike a general surface emitting laser, the light source itself has a reflection mirror for defining the resonance length only on one side, so that a resonance wavelength depending on the optical path length can be obtained. It shall be comprised as follows. In the present embodiment, the divergence angle is widened because it is configured to emit in the direction of two sides of the triangular optical path. 4 is formed of two (111) surfaces, which are anisotropic etching surfaces of the reflective surface substrate 12 of the silicon substrate, and one surface of the reflection / transmission surface 53 of the light source substrate 52. . In the first and second embodiments, the surface on which the light source is mounted, that is, the joint surface between the bottom substrate 11 and the reflecting surface substrate 12 is used as the reference plane 19. In the third embodiment, the reflecting surface substrate 12 is used. The larger surface of the etched opening is the reference plane 19. Since the reflection / transmission surface 53 of the light source substrate 52 is partially reflected and partially transmitted, a part of the forward and reverse laser beams oscillated by reflection in the circulation optical path is extracted from the reflection / transmission surface 53 to the outside of the circulation optical path. It is. The light source substrate 52 itself is made of a material that transmits laser light. The prism substrate 14 is laminated on the light source substrate 52.

  According to the present embodiment having such a configuration, the clockwise laser beam (solid arrow) in the drawing passes through the light source substrate 52 in the circulating optical path in FIG. 4 and the second prism reflection surface of the prism substrate 14. After being reflected at 28, the light enters the detection unit 30. Further, the counterclockwise laser beam (dotted arrow) in the drawing in the circular optical path in FIG. 4 is transmitted through the light source substrate 52 and reflected by the corner portion 29 of the prism substrate 14. Strictly speaking, the first prism reflection surface 27 and the second prism reflection surface 28 are reflected. The incident direction is changed by changing a minute angle direction, reflected by the reflection / transmission surface 53 of the light source substrate 52, and then incident on the detection unit 30 so as to overlap with the clockwise laser beam. Since the clockwise and counterclockwise laser beams cross each other at a minute angle, interference fringes with a predetermined interval are formed in the detection unit 30, and the beats of the clockwise and counterclockwise laser beams when the entire apparatus rotates. The frequency is observed by the movement of the interference fringes. Further, the angular velocity is calculated by calculation by a calculation means (computer or the like) not shown.

  As described above, in the third embodiment, the detection unit 30 is formed on the surface of the light source substrate 52, and the wiring to be supplied to the light source 51 and the detection wiring can be combined on the same substrate. Further, the first prism reflection surface 27 and the second prism reflection surface 28 of the prism substrate 14 are formed with reflection films so that light can propagate efficiently. Furthermore, a laser crystal (solid laser such as YAG or YVO4) may be excited by another light source such as an LD or a VCSEL, and light may be emitted from the surface of the laser crystal.

  FIG. 5 is a cross-sectional view showing a configuration of a ring laser gyro according to the fourth embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 4 denote the same components. The ring laser gyro 60 of the present embodiment shown in the figure is an example in which dicing is performed obliquely. Here, an example using the ring laser gyro according to the third embodiment is shown. It is necessary to prepare a prism substrate 14 having an inclined end surface and affix the prism substrate 14 to a substrate that forms a circular optical path. After all of them are bonded together as shown in FIG. A first prism reflection surface 27 inclined on the substrate 14 may be formed. In this way, batch production is possible, productivity is improved, and a low-cost name device can be provided. If the surface accuracy sufficient to use the dicing surface 61 as an optical surface cannot be obtained, the first prism reflection surface 27 may be polished after dicing.

  FIG. 6 is a diagram showing a configuration of a ring laser gyro according to the fifth embodiment of the present invention. (A) of the figure is a sectional view of the ring laser gyro according to the present embodiment, (b) of the figure is a sectional view taken along the line CC ′ in (a) of the figure, and (c) of the figure is the figure. It is a DD 'line sectional view in (b). In the figure, the same reference numerals as those in FIG. 4 denote the same components. The ring laser gyro 70 according to the present embodiment shown in the figure includes a triangular first circular optical path 71-1 formed in the plane 25 shown in FIG. And a triangular second optical path 71-2 formed in the plane 72 shown. In the present embodiment, a light source for forming the first circulating optical path 70-1 and a light source for forming the second circulating optical path 70-2 are used in common as the light source 51. The light source 51 is positioned on the axis of a regular quadrangular pyramid formed in the reflecting surface substrate 12. The laser light emitted from the light source 51 forms a triangular first circular optical path 71-1 in the plane 25 which is one plane orthogonal to the reference plane 19, and also in the plane 71 orthogonal to the reference plane 19. A triangular second optical path 71-2 is formed. The plane 25 and the plane 72 are both orthogonal to the reference plane 19 and orthogonal to each other.

  In addition, for the laser light in the first circulating optical path 71-1 in the plane 25, the reflecting surfaces 20, 21 and the reflection / transmission surface 53 constitute three reflecting surfaces that reflect and circulate the laser light. For the laser light in the second circulating optical path 71-2 in the plane 72, the reflecting surfaces 22, 23 and the reflecting / transmitting surface 53 constitute three reflecting surfaces that circulate by reflecting the laser light. Yes. That is, the reflection / transmission surface 53 of the light source substrate 52 is commonly used in two sets of three reflection surfaces forming two circular optical paths. In this way, the first and second circular optical paths 71-1 and 71-2 are formed in the planes 25 and 71, which are the first and second planes that are orthogonal to the reference plane 19 and orthogonal to each other. The laser light circulates in the forward and reverse directions in the first and second circulating optical paths 71-1 and 71-2.

  By using two circular optical paths as in this embodiment, a part of the forward and reverse laser light that circulates around each circular optical path is extracted and caused to interfere with each other, and interference fringes are detected to detect two orthogonal directions. A ring laser gyro capable of detecting the angular velocity of the laser beam can be configured. That is, as shown in FIG. 6A, two adjacent first and third prism reflecting surfaces 27 and 72 of the prism substrate 14 are formed with a slight angle with respect to the reference plane 19. Therefore, interference fringes generated in the two orthogonal first and second circular optical paths 71-1 and 71-2 are formed on the second prism reflection surface 28. This can be taken out using the detection unit 30-1 and the detection unit 30-2 on the detection substrate 15. An angular velocity can be calculated based on the detected movement of interference fringes using a calculation means (computer or the like) not shown.

  FIG. 7 is a diagram showing a configuration of a ring laser gyro according to the sixth embodiment of the present invention. 4A is a cross-sectional view, and FIG. 4B is a cross-sectional view taken along the line E-E ′ of FIG. In the figure, the same reference numerals as those in FIG. 6 denote the same components. The ring laser gyro 80 of the present embodiment shown in the figure includes a first hexagonal circular optical path 81-1 formed in the plane 25 shown in FIG. And a hexagonal second circular optical path 81-2 formed in the plane 82 shown in FIG. Specifically, the ring laser gyro 80 according to the present embodiment is arranged on the detection substrate 15 in a direction orthogonal to the reference plane 19 (the surface above the detection substrate 15), in parallel with the reference plane 19. The first reflection surface substrate 83, the glass substrate 84, the light source substrate 52, the glass substrate 85, the second reflection surface substrate 86, and the upper surface substrate 87 are stacked. The first reflecting surface substrate 83 and the second reflecting surface substrate 86 have the same configuration. For example, like the reflecting surface substrate 12 used in FIG. 1, the first reflecting surface substrate 83 and the second reflecting surface substrate 86 are different from a silicon substrate having a (100) surface. In the isotropic wet etching, a regular quadrangular pyramid-shaped hole having an inclined surface ((111) surface) having an inclination angle of ± 54.7 degrees with respect to the reference plane is formed. Further, a small diameter portion of a regular quadrangular pyramidal hole formed in the first reflecting surface substrate 83 and the second reflecting surface substrate 86 includes a reference plane 19 that is the upper surface of the detection substrate 15, and a lower surface of the upper substrate 87. 88 is exposed. In the present embodiment, the reference plane 19 that is the upper surface of the detection substrate 15 and the lower surface 88 of the upper substrate 87 are also used as the reflection surface. The light source substrate 52 is provided with a first light source 51-1 of a surface-emitting type laser light source element in the substrate, and emits laser light from two surfaces parallel to the reference plane of the light source substrate 52. ing. The first light source 51-1 of the laser light source element is different from a general surface emitting laser, and does not have a reflection mirror (reflection film) for defining a resonance length in the light source itself. A resonance wavelength depending on the circulation optical path length is obtained. Further, on the glass substrates 84 and 85, the micro lenses 89 and 90 are formed so that the optical axes are common and the first light source 51-1 of the laser light source element is located on the optical axes.

  Laser light (solid arrow) emitted from the first light source 51-1 of the laser light source element downward in FIG. 7A is transmitted through the glass substrate 84, and the divergence angle is adjusted by the microlens 89. After being reflected by the reflecting surface 20 of the first reflecting surface substrate 83, it is reflected by the prism incident surface 91 (also formed as a reflecting / transmitting surface) of the prism substrate 14, enters the reflecting surface 21, and is reflected. 7 (a), the light beam is directed upward, and sequentially passes through the glass substrate 84, the light source substrate 52, and the glass substrate 85, and reflects the reflecting surface 21-1 of the second reflecting surface substrate 86 and the lower surface of the upper surface substrate 87. 88 (which is formed as a reflecting surface) sequentially, and further reflected by the reflecting surface 20-1 of the second reflecting surface substrate 86 to become a light beam directed downward in FIG. Glass substrate 85, light source substrate 52 Transmission to return to the first light source 51-1 of the laser light source device. In this way, the first circular optical path 81-1 having a hexagonal shape is formed. That is, the laser light (solid arrow) radiated downward from FIG. 7A from the first light source 51-1 of the laser light source element circulates in the counterclockwise direction on the first circulation optical path 81-1, and the laser Laser light (dotted arrow) emitted from the first light source 51-1 of the light source element upward in FIG. 7A circulates in the clockwise direction on the first circulation optical path 81-1, contrary to the above. To do. Also in this embodiment, it is preferable that each reflecting surface that reflects the laser light is subjected to gold plating so that the laser light can be easily reflected.

  FIG. 7B shows a state in which the positional relationship between the first reflecting surface substrate 83, the reference plane 19 of the detection substrate 15, and the microlens 89 is viewed from above in FIG. 7A. This relationship is the same as the positional relationship between the second reflecting surface substrate 86, the upper surface substrate 87, and the microlens 90. Since the first light source 51-1 of the laser light source element is on the optical axis of the microlenses 89 and 90, the first circulating optical path 81-1 is formed in the one plane 25 perpendicular to the reference plane 19. The The lower surface 88 of the upper substrate 87 and the prism incident surface 91 may be configured to be finely movable in a direction perpendicular to the reference plane 19 so that an accurate optical path for the laser light to circulate can be formed.

  In order to configure a ring laser gyro using such a circular optical path, a part of the forward and reverse laser light oscillated on the prism incident surface 91 of the reflection / transmission surface of the prism substrate 14 is incident on the prism substrate 14, Interference fringes can be generated by reflecting the laser light at the corner 29 and then superimposing it with the other. The detection unit 30-1 on the detection board 15 detects the movement of the interference fringes, and can calculate the angular velocity based on the detected movement of the interference fringes using a calculation unit (computer or the like) not shown. .

  Further, the second circulating optical path 81-2 of the ring laser gyro 80 according to the present embodiment will be described. The light source substrate 52 includes a second light source 51-2 as shown in FIG. , The reflecting surface 22, the prism incident surface 91, the reflecting surface 23, the reflecting surface 23-1, the lower surface 88 of the upper substrate 87, and the reflecting surface 22-1 form a second optical path 81-2 to cause laser oscillation and detection. The movement of the interference fringes can be detected by the detection unit 30-2 on the substrate 15, and the angular velocity can be calculated based on the detected movement of the interference fringes using a calculation unit (computer or the like) not shown. Therefore, according to the present embodiment, it is possible to detect the angular velocity in the biaxial direction.

  The ring laser gyro of the present invention as described above can be applied to an angular velocity sensor that has a simple configuration and can detect biaxial directions.

  The present invention is not limited to the above embodiments, and it goes without saying that various modifications and substitutions are possible as long as they are described in the scope of the claims.

It is a figure which shows the structure of the ring laser gyro which concerns on the 1st Embodiment of this invention. It is a figure which shows the mode of the interference fringe produced | generated by the interference fringe generator in the ring laser gyro of 1st Embodiment. It is sectional drawing which shows the structure of the ring laser gyro which concerns on the 2nd Embodiment of this invention. It is sectional drawing which shows the structure of the ring laser gyro which concerns on the 3rd Embodiment of this invention. It is sectional drawing which shows the structure of the ring laser gyro which concerns on the 4th Embodiment of this invention. It is a figure which shows the structure of the ring laser gyro which concerns on the 5th Embodiment of this invention. It is a figure which shows the structure of the ring laser gyro which concerns on the 6th Embodiment of this invention.

Explanation of symbols

10, 40, 50, 60, 70, 80; ring laser gyro,
11: Bottom substrate, 12: Reflective surface substrate, 13: Spacer substrate,
14; prism substrate, 15; detection substrate, 16, 51; light source,
17, 18; lens, 19; reference plane, 20 to 24; reflecting surface,
25, 72, 82; plane, 26, 91; prism incident surface,
27; first prism reflecting surface; 28; second prism reflecting surface;
29; Corner part, 30, 30-1, 30-2; Detection part,
41; Glass substrate, 42, 43, 89, 90; Microlens,
52; light source substrate; 53; reflection / transmission surface; 61; dicing surface;
71-1, 81-1; first circular optical path;
71-2, 81-2; second circulating optical path; 83; first reflecting surface substrate;
84; glass substrate, 85; glass substrate, 86; second reflecting surface substrate,
87; upper substrate, 88; lower surface.

Claims (10)

A substrate having a reference plane, one or more substrates stacked in parallel to the reference plane in a direction orthogonal to the reference plane, a light source, and in a direction orthogonal to the reference plane, relative to the reference plane And a flat prism substrate laminated in parallel,
In the base body and / or the substrate and / or the prism substrate, three or more reflecting surfaces that reflect light from the light source have a normal line of the reflecting surface in a plane orthogonal to the reference plane. And formed so as to be parallel or inclined at a predetermined angle to the reference plane,
The light source is arranged to emit light in the plane;
The light emitted from the light source circulates in the forward and reverse directions in the plane by the three or more reflecting surfaces to form a circulating optical path for laser oscillation,
The forward-reverse laser beam oscillated in the circular optical path, wherein the angle formed between the first reflecting surface of the flat prism and the second reflecting surface adjacent to the first reflecting surface is shifted from 90 degrees. A part of each of the laser beams enters the flat prism from the incident surface of the flat prism, and either one of the laser beams in the forward and reverse directions is reflected by the first reflecting surface of the flat prism and the An interference fringe generator, wherein the interference fringe is generated by being reflected from the second reflecting surface and superposed in a state of being crossed by a minute angle with respect to laser light in the other direction. A substrate having a reference plane, one or more substrates stacked in parallel to the reference plane in a direction orthogonal to the reference plane, a light source, and in a direction orthogonal to the reference plane, relative to the reference plane And a flat prism substrate laminated in parallel,
In the base body and / or the substrate and / or the prism substrate, three or more reflecting surfaces for reflecting light from the light source are arranged in two planes orthogonal to the reference plane and perpendicular to each other. Each having a normal line and being parallel to the reference plane or inclined at a predetermined angle,
The light source is arranged to emit light in a first plane and a second plane;
Light radiated from the light source forms a first circular optical path in which the light radiated from the light source circulates in the forward and backward directions in the first plane by three or more reflecting surfaces of the light source and oscillates. Forming a second circulating optical path that oscillates in the forward and reverse directions in the second plane by the reflecting surface of the light source of 3 or more,
The forward-reverse laser beam oscillated in the circular optical path, wherein the angle formed between the first reflecting surface of the flat prism and the second reflecting surface adjacent to the first reflecting surface is shifted from 90 degrees. A part of each of the laser beams enters the flat prism from the incident surface of the flat prism, and either one of the laser beams in the forward and reverse directions is reflected by the first reflecting surface of the flat prism and the Reflecting the second reflecting surface and overlapping the laser beam in the other direction at a slight angle to generate a first interference fringe,
The normal line of the third reflecting surface adjacent to the first reflecting surface and the second reflecting surface of the flat prism is in a plane including the second circulating optical path and in a direction parallel to the reference plane. A part of each of the forward and reverse laser beams which are inclined by a minute angle and oscillate in the second circular optical path is incident from the surface where the flat prism and the first circular optical path are in contact, and the forward and reverse laser lights The second laser beam is reflected on the end face of the flat prism and the surface facing the first optical path, and is overlapped with the laser beam in the other direction so as to intersect at a minute angle. An interference fringe generating apparatus characterized by generating interference fringes.   The light source is disposed between the flat prism and the base or substrate that forms the circular optical path, and most of the oscillated laser light is reflected and partially transmitted to the flat prism side of the light source. An interference fringe generator according to claim 1, wherein a reflection / transmission film is formed. A base having a reference plane, one or more substrates stacked in parallel to the reference plane in a direction orthogonal to the reference plane, two light sources, and a direction orthogonal to the reference plane A flat prism substrate laminated in parallel with
In the base body and / or the substrate and / or the prism substrate, three or more reflecting surfaces that reflect light from the respective light sources have the reflecting surfaces in two planes orthogonal to the reference plane and orthogonal to each other. Are formed so as to be parallel to the reference plane or inclined at a predetermined angle, respectively.
A first light source is disposed to emit light in a first plane, and a second light source is disposed to emit light in a second plane;
The light emitted from the first light source forms a first circulating optical path for laser oscillation by revolving in the forward and reverse directions in the first plane by three or more reflecting surfaces for the first light source; and The light emitted from the two light sources forms a second circulating optical path that oscillates in the forward and reverse directions in the second plane by three or more reflecting surfaces for the second light source;
The forward-reverse laser beam oscillated in the circular optical path, wherein the angle formed between the first reflecting surface of the flat prism and the second reflecting surface adjacent to the first reflecting surface is shifted from 90 degrees. A part of each of the laser beams enters the flat prism from the incident surface of the flat prism, and either one of the laser beams in the forward and reverse directions is reflected by the first reflecting surface of the flat prism and the Reflecting the second reflecting surface and overlapping the laser beam in the other direction at a slight angle to generate a first interference fringe,
The normal line of the third reflecting surface adjacent to the first reflecting surface and the second reflecting surface of the flat prism is in a plane including the second circulating optical path and in a direction parallel to the reference plane. A part of each of the forward and reverse laser beams which are inclined by a minute angle and oscillate in the second circular optical path is incident from the surface where the flat prism and the first circular optical path are in contact, and the forward and reverse laser lights The second laser beam is reflected on the end face of the flat prism and the surface facing the first optical path, and is overlapped with the laser beam in the other direction so as to intersect at a minute angle. An interference fringe generating apparatus characterized by generating interference fringes.   The first light source and the second light source are disposed between the flat prism and the base or substrate forming the circular optical path, and are disposed on the flat prism side of the first light source and the second light source. 6. The interference fringe generator according to claim 5, further comprising a reflection / transmission film that reflects most of the oscillated laser light and transmits a part thereof.   The interference fringe generator according to claim 1, wherein a reflection film that reflects the oscillated laser beam is formed on an outer periphery of the flat prism.   A detection substrate having the interference fringe generator according to any one of claims 1 to 6 and having detection means for detecting a change in the interference fringes in a direction perpendicular to the reference plane and parallel to the reference plane is laminated. A ring laser gyro comprising a calculating means for calculating an angular velocity based on a detected change in interference fringes.   The interference fringe generator according to any one of claims 1 to 6, wherein a detection means for detecting the interference fringe is provided on a part of a substrate constituting the interference fringe generator, and the detected interference A ring laser gyro comprising a calculating means for calculating an angular velocity based on a change in fringes. A ring laser gyro forming method for forming the ring laser gyro according to claim 7 or 8,
The first and second end faces of the plate-like prism constituting the interference fringe generator are diced diagonally from the vertical to the reference surface by a minute angle after the substrates constituting the ring laser gyro are laminated and joined. A ring laser gyro forming method, characterized in that the ring laser gyro is formed.   The ring laser gyro forming method according to claim 9, wherein the diced end face is polished.

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