Passive laser gyroscope mode matching method and device based on concave mirror

Abstract

The invention relates to the technical field of passive laser gyroscopes, and discloses a mode matching device of a passive laser gyroscope, which comprises a light source, a beam splitter, a plane mirror, a mode matching component, an annular resonant cavity, a beam combining interference component and a signal detection component. Compared with the prior art, the mode matching assembly with the multiple concave mirrors is adopted to replace an existing mode matching assembly formed by multiple cylindrical lenses for mode matching, the concave mirrors can adjust the meridian plane and the sagittal plane of the light beam at the same time, and compared with the mode matching assembly formed by the cylindrical lenses, fewer elements are used; the influence degree of wavefront distortion can be improved; and due to the reduction of elements, the structure in the mode matching assembly is more compact, and the occupied space of the device is reduced. The invention also provides a mode matching method of the passive laser gyroscope, which can adapt to a mode matching assembly formed by combining a plurality of concave mirrors, and effectively reduce the influence of wavefront distortion.

Description

Technical Field

[0001] This invention relates to the field of laser gyroscope technology, and in particular to a passive laser gyroscope mode matching method and apparatus based on a concave mirror. Background Technology

[0002] A laser gyroscope is a high-precision, high-stability instrument based on the Sagnac effect for measuring the angular velocity or angular displacement of an object. It has wide applications in inertial navigation, geodesy, rotational seismology, and fundamental physics. Its principle involves injecting two laser beams, one propagating clockwise and the other counterclockwise, into a ring resonant cavity. As the cavity rotates one revolution, the two beams, traveling in opposite directions, resonate at different frequencies within the cavity. The angular velocity of the cavity is obtained by measuring the frequency difference between these two beams; this frequency difference is called the Sagnac frequency. The relationship between the Sagnac frequency and the angular velocity is: Based on the presence or absence of a gain medium within the cavity, laser gyroscopes can be classified into active and passive laser gyroscopes. Passive laser gyroscopes lack a gain medium within the cavity and require external laser injection. The mode matching step in using a passive laser gyroscope involves matching the optical field mode of the externally injected laser beam with the eigenmode within the ring resonant cavity. Specifically, by adding suitable optical elements in front of the ring resonant cavity, the size and shape of the incident light spot, as well as the wavefront curvature radius, are altered to match the eigenmode of the ring resonant cavity, thereby achieving the resonant transverse electromagnetic fundamental mode within the ring resonant cavity. Maximize energy.

[0003] Most existing mode-matching schemes for passive laser gyroscopes employ cylindrical lenses to adjust the characteristics of the incident light. Due to the structural limitations of cylindrical lenses, they can only alter the beam characteristics in the axial direction, having no effect on the beam in the vertical direction. Therefore, two sets of cylindrical lenses are needed to control the size, shape, and wavefront curvature radius of the incident light from the meridional and sagittal planes respectively, thus achieving mode matching. This mode-matching scheme typically requires control in both the meridional and sagittal planes, requiring at least four cylindrical lenses in two sets for each optical path, meaning the entire system requires at least eight cylindrical lenses for control. Since each optical element undergoes surface unevenness during manufacturing, altering the propagation path and phase of the light wave, these minute errors accumulate, leading to wavefront distortion. In other words, the more optical elements the beam passes through, the greater the degree of wavefront distortion.

[0004] The technical problem that needs to be solved is how to reduce the use of optical components while achieving pattern matching in both the meridional and sagittal planes and obtaining higher pattern matching efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a passive laser gyroscope mode matching device based on a concave mirror to solve the technical problems of the large number of optical elements causing the beam to be greatly affected by wavefront distortion and the inability to achieve mode matching simultaneously on the meridional and sagittal planes.

[0006] Based on this, the present invention provides a passive laser gyroscope mode matching device based on a concave mirror, which includes a light source, a beam splitter, a mode matching component, a ring resonant cavity, a beam combining interference component, and a signal detection component. The light source is used to output the original light to the beam splitter. The beam splitter is used to receive the original light and split it into a first incident light and a second incident light. The pattern matching component includes a first concave mirror group and a second concave mirror group. The first concave mirror group is used to receive the first incident light and adjust the beam waist size and beam waist position of the first incident light. The second concave mirror group is used to receive the second incident light and adjust the beam waist size and beam waist position of the second incident light. The annular resonant cavity is used to receive the first incident light and the second incident light after adjusting the waist size and waist position. The first incident light and the second incident light resonate within the annular resonant cavity so that the first incident light and the second incident light after adjusting the waist size and waist position match the waist size and waist position of the eigenmode of the annular resonant cavity. The beam combining interference component is used to receive the second and third emitted light and combine them to form a fourth emitted light. The signal detection component is used to receive the first emitted light to detect the optical power of the first emitted light, and the signal detection component is also used to receive the fourth emitted light to detect the Sagnac frequency of the laser gyroscope.

[0007] In some embodiments of this application, a plane mirror is included, which is used to receive a second incident light and change the path of the second incident light to transmit the second incident light to the second concave mirror group.

[0008] In some embodiments of this application, the first concave mirror group includes a first concave mirror and a second concave mirror, and the first incident light is sequentially incident on the first concave mirror and the second concave mirror. The first concave mirror and the second concave mirror are used to adjust the waist size and waist position of the first incident light. The second concave mirror group includes a third concave mirror and a fourth concave mirror, and the second incident light is sequentially incident on the third concave mirror and the fourth concave mirror. The third concave mirror and the fourth concave mirror are used to adjust the waist size and waist position of the second incident light.

[0009] In some embodiments of this application, the annular resonant cavity includes a first cavity mirror, a second cavity mirror, a third cavity mirror, and a fourth cavity mirror. The first cavity mirror is used to receive the first incident light and reflect the first incident light to the third cavity mirror. The second cavity mirror is used to receive the second incident light and reflect the second incident light to the fourth cavity mirror. The third cavity mirror is used to receive the first incident light and reflect the first incident light to the fourth cavity mirror so that the first incident light is transmitted clockwise within the annular resonant cavity via the fourth cavity mirror, the second cavity mirror, and the first cavity mirror in sequence. The third cavity mirror is also used to output a first outgoing light. The fourth cavity mirror is used to receive the second incident light and reflect the second incident light to the third cavity mirror so that the second incident light is transmitted counterclockwise within the annular resonant cavity via the third cavity mirror, the first cavity mirror, and the second cavity mirror in sequence. The fourth cavity mirror is also used to output a second outgoing light and a third outgoing light.

[0010] In some embodiments of this application, the beam combining interference component includes a first beam combining mirror, a second beam combining mirror, and a beam combiner. The first beam combining mirror is used to receive the second emitted light and transmit the second emitted light to the beam combiner. The second beam combining mirror is used to receive the third emitted light and transmit the third emitted light to the beam combiner. The beam combiner is used to combine the second emitted light and the third emitted light into a fourth emitted light and transmit it to the signal detection component.

[0011] In some embodiments of this application, the signal detection component includes a first photodetector and a second photodetector. The first photodetector is used to receive a first emitted light to detect the optical power of the first emitted light, and the second photodetector is used to receive the fourth emitted light to detect the Sagnac frequency of the passive laser gyroscope.

[0012] Another objective of this application is to provide a mode matching method for a passive laser gyroscope using the aforementioned concave mirror-based passive laser gyroscope mode matching device, comprising the following steps: S1. The light source outputs the original light to the beam splitter. After receiving the original light, the beam splitter splits the original light into the first incident light and the second incident light. S2. The first concave mirror group of the pattern matching component receives the first incident light and adjusts the waist size and waist position of the first incident light; the second concave mirror group of the pattern matching component receives the second incident light and adjusts the waist size and waist position of the second incident light. S3. The ring resonant cavity receives the first incident light and the second incident light after adjusting the beam waist size and beam waist position, and forms the first outgoing light, the second outgoing light and the third outgoing light; S4. The beam combining interference component receives the second and third outgoing beams output from the ring resonant cavity and combines them to form the fourth outgoing beam; S5. The signal detection component receives the first emitted light output from the ring resonant cavity and measures the optical power of the first emitted light. The signal detection component receives the fourth emitted light output from the beam combining interference component and detects the Sagnac frequency of the passive laser gyroscope. S6. Adjust the setting positions of the first concave mirror group and the second concave mirror group to change the beam waist size and beam waist position of the first incident light and the second incident light. Repeat steps S3 to S5 to obtain the change in the optical power of the first outgoing light. S7. Adjust the positions of the first concave mirror group and the second concave mirror group to change the waist size and waist position of the first incident light and the second incident light. Repeat steps S3 to S5 to obtain the Sagnac frequency change of the passive laser gyroscope.

[0013] In some embodiments of this application, in step S2, the first concave mirror group includes a first concave mirror and a second concave mirror, the first concave mirror receives the first incident light and transmits the first incident light to the second concave mirror, and the second concave mirror group includes a third concave mirror and a fourth concave mirror, the third concave mirror receives the second incident light and transmits the second incident light to the fourth concave mirror. In step S3, the annular resonant cavity includes a first cavity mirror, a second cavity mirror, a third cavity mirror, and a fourth cavity mirror. The first cavity mirror receives the first incident light emitted from the second concave mirror and transmits the first incident light to the third cavity mirror, so that the first incident light is transmitted clockwise in the annular resonant cavity in the order of the first cavity mirror, the third cavity mirror, the fourth cavity mirror, the second cavity mirror, and the first cavity mirror. The second cavity mirror receives the second incident light emitted from the fourth concave mirror and transmits the second incident light to the fourth cavity mirror, so that the second incident light is transmitted counterclockwise in the annular resonant cavity in the order of the second cavity mirror, the fourth cavity mirror, the third cavity mirror, the first cavity mirror, and the second cavity mirror. In step S4, the beam combining interference component includes a first reflector, a second beam combining reflector, and a beam combiner. The first beam combining reflector receives the second emitted light output from the ring resonant cavity and transmits the second emitted light to the beam combiner. The second beam combining reflector receives the third emitted light output from the ring resonant cavity and transmits the third emitted light to the beam combiner. The beam combiner combines the second emitted light and the third emitted light into a fourth emitted light and transmits it to the signal detection component. In step S5, the signal detection component includes a first photodetector and a second photodetector. The first photodetector receives the first emitted light output from the ring resonant cavity and measures the optical power of the first emitted light. The second photodetector receives the fourth emitted light and detects the Sagnac frequency of the passive laser gyroscope. In steps S6 and S7, the positions of the first concave mirror, the second concave mirror, the third concave mirror, and the fourth concave mirror are adjusted to change the waist size and waist position of the first incident light and the second incident light.

[0014] In some embodiments of this application, in steps S6 and S7, the parameters of the sagittal and meridional planes of each incident light at any position are defined as... ,but The size of satisfies the following formula: in, For any position along the direction of light transmission, This is the waist position of the Gaussian beam. The radius of the light spot is the waist. The wavelength of light This is within the Rayleigh range.

[0015] In some embodiments of this application, in steps S6 and S7, the optical elements through which each incident light passes are defined as an optical system, and a transformation matrix is ​​established for the coordinate parameter transformation relationship of the incident light before and after passing through the optical system: Then through the optical system before and after The relationship between the parameters can be expressed by the following formula: in, The Gaussian beam before passing through the optical system parameter, After passing through the optical system parameter.

[0016] This invention provides a passive laser gyroscope mode matching device based on a concave mirror, which has the following advantages compared with the prior art: This application provides a passive laser gyroscope mode matching device based on concave mirrors, including a light source, a beam splitter, a mode matching component, a ring resonant cavity, a beam combining interference component, and a signal detection component. The light source is used to output original light to the beam splitter, and the beam splitter is used to receive and process the original light to form a first incident light and a second incident light. The mode matching component includes a first concave mirror group and a second concave mirror group. The first concave mirror group is used to receive the first incident light and adjust the beam waist size and beam waist position of the first incident light. The second concave mirror group is used to receive the second incident light and adjust the beam waist size and beam waist position of the second incident light. The ring resonant cavity is used to receive the first incident light and the second incident light and output a first outgoing light, a second outgoing light, and a third outgoing light. The beam combining interference component is used to receive the second outgoing light and the third outgoing light to synthesize a fourth outgoing light. The signal detection component is used to receive the first outgoing light to detect the optical power of the first outgoing light. The signal detection component is also used to receive the fourth outgoing light to detect the Sagnac frequency of the laser gyroscope.

[0017] Based on the above structure, in use, the light emitted by the light source enters the beam splitter, which splits the emitted light into a first incident light and a second incident light. The first incident light is directly transmitted to the first concave mirror, while the second incident light is reflected by the plane mirror and transmitted to the third concave mirror. The first incident light that hits the first concave mirror is reflected by the first concave mirror to the second concave mirror, and then transmitted to the first cavity mirror via the second concave mirror. The second incident light that hits the third concave mirror is reflected by the third concave mirror to the fourth concave mirror, and then transmitted to the second cavity mirror via the fourth concave mirror. The beam of light that hits the first cavity mirror is reflected by the first cavity mirror and travels along the third cavity mirror, the fourth cavity mirror, and the second cavity mirror. The beam of light emitted from the first cavity mirror then travels clockwise through the second cavity mirror, passing through the fourth, third, and first cavity mirrors before returning to the second cavity mirror to form a beam of light that travels counterclockwise within the ring resonant cavity. A portion of the beam within the ring resonant cavity exits through the opening of the ring resonant cavity and is emitted to the signal detection component. The first photodetector measures the optical power of the first emitted light. The first and second beam combiner mirrors reflect the second and third emitted lights so that they reach the beam combiner and combine to form the fourth emitted light. The second photodetector receives the fourth emitted light and detects the Sagnac frequency of the passive laser gyroscope.

[0018] The present invention also provides a mode matching method for a passive laser gyroscope, which can be adapted to a mode matching component formed by combining multiple concave mirrors, effectively reducing the influence of wavefront distortion. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the pattern matching device for a prior art passive laser gyroscope. Figure 2 This is a schematic diagram of the structure of a passive laser gyroscope mode matching device according to some embodiments of the present invention; Figure 3 This is a schematic diagram illustrating pattern matching of a passive laser gyroscope according to some embodiments of the present invention; Figure 4 This is a flowchart illustrating the pattern matching method for a passive laser gyroscope according to some embodiments of the present invention.

[0020] In the diagram, 1 is the light source; 2 is the beam splitter; 3 is the plane mirror; 4 is the pattern matching component; 41 is the first concave mirror; 42 is the second concave mirror; 43 is the third concave mirror; 44 is the fourth concave mirror; 5 is the ring resonator; 51 is the first cavity mirror; 52 is the second cavity mirror; 53 is the third cavity mirror; 54 is the fourth cavity mirror; 6 is the beam combining interference component; 61 is the first beam combining mirror; 62 is the second beam combining mirror; 63 is the beam combiner; 7 is the signal detection component; 71 is the first photodetector; 72 is the second photodetector. 100, Light source; 200, Beam splitter; 300, Plane mirror; 400, Pattern matching assembly; 401, First cylindrical lens; 402, Second cylindrical lens; 403, Third cylindrical lens; 404, Fourth cylindrical lens; 405, Fifth cylindrical lens; 406, Sixth cylindrical lens; 407, Seventh cylindrical lens; 408, Eighth cylindrical lens; 5, Ring resonator; 501, First cavity mirror; 502, Second cavity mirror; 503, Third cavity mirror; 504, Fourth cavity mirror; 6, Beam combining interference assembly; 601, First beam combining mirror; 602, Second beam combining mirror; 603, Beam combiner; 7, Signal detection assembly; 701, First photodetector; 702, Second photodetector. Detailed Implementation

[0021] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0022] like Figure 1As shown, the mode matching device of the prior art passive laser gyroscope uses cylindrical lenses to fabricate the mode matching component 400. Specifically, the mode matching device of the passive laser gyroscope includes a light source 100, a beam splitter 200, a plane mirror 300, a mode matching component 400, a ring resonator 500, a beam combining interference component 600, and a signal detection component 700. The light source 100 outputs the original light into the beam splitter 200. The beam splitter 200 receives the original light emitted from the light source 100 and splits it into two incident beams. The plane mirror 300 is disposed beside the light source 100 to change the path of the laser beam emitted from the light source 100, ensuring that the laser beam enters the mode matching component 400. The two incident beams emitted from the beam splitter 200 are respectively injected into the mode matching component 400. The cylindrical lens group of the mode matching component 400 is used to receive the incident light and adjust the relative positions of different cylindrical lenses or keep the positions of the cylindrical lenses unchanged. Rotating cylindrical lenses alters the sagittal beam waist size and position, as well as the meridional beam waist size and position. Multiple cylindrical lenses adjust the incident light as it enters the annular resonant cavity 500, where resonance occurs to achieve the operation of the passive laser gyroscope. Furthermore, the mode matching assembly 400 includes a first cylindrical lens 401, a second cylindrical lens 402, a third cylindrical lens 403, a fourth cylindrical lens 404, a fifth cylindrical lens 405, a sixth cylindrical lens 406, a seventh cylindrical lens 407, and an eighth cylindrical lens 408. Light beams transmitted along the first cylindrical lens 401, second cylindrical lens 402, third cylindrical lens 403, and fourth cylindrical lens 404 propagate clockwise after entering the annular resonant cavity 500, while light beams transmitted along the fifth cylindrical lens 405, sixth cylindrical lens 406, seventh cylindrical lens 407, and eighth cylindrical lens 408 propagate counterclockwise after entering the annular resonant cavity 500.Correspondingly, the ring resonator 500 includes a first cavity mirror 501, a second cavity mirror 502, a third cavity mirror 503, and a fourth cavity mirror 504. Two beams reflected from the pattern matching component 400 enter the ring resonator 500 through the first cavity mirror 501 and the second cavity mirror 502, respectively, and are reflected by the first cavity mirror 501 and the second cavity mirror 502 into the third cavity mirror 503 and the fourth cavity mirror 504. The third cavity mirror 503 and the fourth cavity mirror 504 reflect the beams and transmit a portion of the beams to the outside of the ring resonator 500. The signal detection component 700 is used to detect the outgoing light to identify the ring resonator 500. In the pattern matching state within 0, the signal detection component 700 includes a first photodetector 701 and a second photodetector 702. The first photodetector 701 is used to detect the optical power of the transmitted light. The beam combining interference component 600 includes a first beam combining mirror 601, a second beam combining mirror 602, and a beam combiner 603. The beam emitted from the fourth lens is reflected by the first beam combining mirror 601 and the second beam combining mirror 602 and enters the beam combiner 603, and finally forms a beam that enters the second photodetector 702. The second photodetector 702 is used to measure the Sagnac frequency of the passive laser gyroscope. In practical use, the light source 100 emits a beam that enters the beam splitter 200. The beam splitter 200 splits the beam emitted by the light source 100 into two beams, which are respectively directed to the first cylindrical lens 401 and the fifth cylindrical lens 405. The beam directed to the first cylindrical lens 401 passes through the first cylindrical lens 401, the second cylindrical lens 402, the third cylindrical lens 403, and the fourth cylindrical lens 404 and is directed to the first cavity mirror 501, forming a clockwise propagating beam within the annular resonant cavity 500. The beam directed to the fifth cylindrical lens 405 passes through the fifth cylindrical lens 405, the sixth cylindrical lens 406, the seventh cylindrical lens 407, and the eighth cylindrical lens 408, and is directed to the second cavity mirror 502, forming a counterclockwise propagating beam within the annular resonant cavity 500. Adjusting the first cylindrical lens 401 and the second cylindrical lens 402 can achieve meridional mode matching of the clockwise optical path. Adjusting the third cylindrical lens 403 and the fourth cylindrical lens 404... 4. Sagittal plane mode matching of the clockwise optical path can be completed. Adjusting the fifth cylindrical lens 405 and the sixth cylindrical lens 406 can complete the meridional plane mode matching of the counterclockwise optical path. Adjusting the seventh cylindrical lens 407 and the eighth cylindrical lens 408 can complete the sagittal plane mode matching of the counterclockwise optical path. Further, part of the beam is transmitted to the signal detection component 700 through the third cavity mirror 503 and the fourth cavity mirror 504. The transmitted light power emitted from the third cavity mirror 503 is measured by the first photodetector 701, and the mode matching efficiency between the mode matching component 400 and the ring resonator 500 is calculated. The multiple beams emitted from the fourth cavity mirror 504 are reflected by the first beam combiner mirror 601 and the second beam combiner mirror 602 so that they reach the beam combiner 603 to complete the beam combining. The Sagnac frequency of the laser gyroscope is detected by the second photodetector 702.

[0023] like Figures 2 to 3As shown, unlike existing technologies, this application provides a passive laser gyroscope mode matching device based on a concave mirror, including a light source 1, a beam splitter 2, a plane mirror 3, a mode matching component 4, a ring resonator 5, a beam combining interference component 6, and a signal detection component 7. The light source 1 is used to output the original light 8 to the mode matching component 4. The beam splitter 2 is used to process the original light 8 so that the original light 8 forms a first incident light 81 and a second incident light 82. The plane mirror 3 is used to receive the second incident light 82 and change the path of the second incident light 82 to transmit the second incident light 82 to the mode matching component 4. The mode matching component 4 includes a first concave mirror group and a second concave mirror group. The first concave mirror group is used to receive the first incident light 81 and adjust the beam waist of the first incident light 81. Regarding the size and waist position, the second concave mirror group is used to receive the second incident light 82 and adjust the waist size and waist position of the second incident light 82. Specifically, the first concave mirror group includes a first concave mirror 41 and a second concave mirror 42, which are used to receive the first incident light 81 and adjust the waist size and waist position of the first incident light 81. The second concave mirror group includes a third concave mirror 43 and a fourth concave mirror 44, which are used to receive the second incident light 82 and adjust the waist size and waist position of the second incident light 82. The annular resonant cavity 5 is used to receive the first incident light 81 and the second incident light 82 and output the first emitted light 83, the second emitted light 84, and the third emitted light 85. The resonant cavity 5 includes a first cavity mirror 51, a second cavity mirror 52, a third cavity mirror 53, and a fourth cavity mirror 54. The first cavity mirror 51 receives a first incident light 81 and reflects it to the third cavity mirror 53. The second cavity mirror 52 receives a second incident light 82 and reflects it to the fourth cavity mirror 54. The third cavity mirror 53 receives the first incident light 81 and reflects it to the fourth cavity mirror 54 to ensure clockwise transmission of the first incident light 81 within the ring resonant cavity 5. The third cavity mirror 53 also outputs a first outgoing light 83. The fourth cavity mirror 54 receives the second incident light 82 and reflects it to the third cavity mirror 53 to ensure counterclockwise transmission of the second incident light 82 within the ring resonant cavity 5. 4 is also used to output the second emitted light 84 and the third emitted light 85. The beam combining interference component 6 is used to receive the second emitted light 84 and the third emitted light 85 to combine them into a fourth emitted light 86. The beam combining interference component 6 includes a first beam combining mirror 61, a second beam combining mirror 62, and a beam combiner 63. The first beam combining mirror 61 is used to receive the second emitted light 84 and transmit it to the beam combiner 63. The second beam combining mirror 62 is used to receive the third emitted light 85 and transmit it to the beam combiner 63. The beam combiner 63 is used to combine the second emitted light 84 and the third emitted light 85 into a fourth emitted light 86 and transmit it to the signal detection component 7. The signal detection component 7 is used to receive the first emitted light 83 to detect the optical power of the first emitted light 83.The signal detection component 7 is also used to receive the fourth emitted light 86 to detect the Sagnac frequency of the laser gyroscope. The signal detection component 7 includes a first photodetector 71 and a second photodetector 72. The first photodetector 71 is used to receive the first emitted light 83 to detect the optical power of the first emitted light 83, and the second photodetector 72 is used to receive the fourth emitted light 86 to detect the Sagnac frequency of the passive laser gyroscope.

[0024] Based on the above structure, in use, the light source 1 emits a primary light 8 which enters the beam splitter 2. The beam splitter 2 splits the primary light 8 emitted from the light source 1 into a first incident light 81 and a second incident light 82. The first incident light 81 is directly transmitted to the first concave mirror 41, while the second incident light 82 is reflected by the plane mirror 3 and transmitted to the third concave mirror. The first incident light 81 that hits the first concave mirror 41 is reflected by the first concave mirror 41 to the second concave mirror 42, and then transmitted to the first cavity mirror 51. The second incident light 82 that hits the third concave mirror 43 is reflected by the third concave mirror 43 to the fourth concave mirror 44, and then transmitted to the second cavity mirror 52. The beam of light that hits the first cavity mirror 51 is reflected by the first cavity mirror 51 and then transmitted along the third cavity mirror 53 and the fourth cavity mirror 52. 4. The beam transmitted clockwise through the second cavity mirror 52 and then through the first cavity mirror 51 forms a beam transmitted clockwise within the ring resonant cavity 5. The beam transmitted to the second cavity mirror 52 passes through the fourth cavity mirror 54, the third cavity mirror 53 and the first cavity mirror 51 and then through the second cavity mirror 52 to form a beam transmitted counterclockwise within the ring resonant cavity 5. Part of the beam in the ring resonant cavity 5 exits through the opening of the ring resonant cavity 5 and is emitted to the signal detection component 7. The first photodetector 71 measures the optical power of the first emitted light 83. The first beam combiner mirror 61 and the second beam combiner mirror 62 reflect the second emitted light 84 and the third emitted light 85 so that they reach the beam combiner 63 to synthesize the fourth emitted light 86. The second photodetector 72 receives the fourth emitted light 86 and detects the Sagnac frequency of the passive laser gyroscope. Thus, this application uses multiple concave mirrors to replace the cylindrical lenses in existing pattern matching assemblies for pattern matching. The concave mirrors can simultaneously adjust the meridional and sagittal planes of the beam. Compared with the pattern matching assembly formed by the cylindrical lens, the pattern matching and assembly of this application uses fewer components, which can improve the degree of influence of wavefront distortion. Moreover, due to the reduction of components, the internal structure of the pattern matching assembly is more compact, reducing the space occupied by the device.

[0025] It should be noted that since the first emitted light 83 only shows the beam pattern in a certain direction (clockwise or counterclockwise propagation) within the ring resonant cavity 5, to further improve the accuracy of the measurement, this application can also consider setting an opening in the ring resonant cavity 5 to collect the optical power of another emitted light when measuring the optical power. The optical power of the two beams can be combined and compared to calculate the mode matching efficiency of the laser gyroscope. Specifically, the mode matching efficiency is the transmitted light power divided by the incident light power.

[0026] In addition, this application also provides a mode matching method for a passive laser gyroscope using the above-mentioned mode matching device based on a concave mirror, which includes the following steps: S1. The light source 1 emits the original light 8 to the beam splitter 2. After receiving the original light 8, the beam splitter 2 disperses the original light 8 into the first incident light 81 and the second incident light 82. S2. The first concave mirror 41 receives the first incident light 81 and transmits it to the second concave mirror 42. The second concave mirror 42 receives the first incident light 81 and transmits it to the first cavity mirror 51. The third concave mirror 43 receives the second incident light 82 and transmits it to the fourth concave mirror 44. The fourth concave mirror 44 receives the second incident light 82 and transmits it to the second cavity mirror 52. S3. After receiving the first incident light 81, the first cavity mirror 51 transmits the first incident light 81 to the third cavity mirror 53, so that the first incident light 81 is transmitted clockwise in the ring resonant cavity 5 in the order of the first cavity mirror 51, the third cavity mirror 53, the fourth cavity mirror 54, the second cavity mirror 52, and the first cavity mirror 51. After receiving the second incident light 82, the second cavity mirror 52 transmits the second incident light 82 to the fourth cavity mirror 54, so that the second incident light 82 is transmitted counterclockwise in the ring resonant cavity 5 in the order of the second cavity mirror 52, the fourth cavity mirror 54, the third cavity mirror 53, the first cavity mirror 51, and the second cavity mirror 52. S4. The first photodetector 71 receives the first emitted light 83 output from the ring resonant cavity 5 and measures the optical power of the first emitted light 83. S5. The first beam combiner mirror 61 receives the second emitted light 84 output from the ring resonant cavity 5 and transmits the second emitted light 84 to the beam combiner 63. The second beam combiner mirror 62 receives the third emitted light 85 output from the ring resonant cavity 5 and transmits the third emitted light 85 to the beam combiner 63. The beam combiner 63 combines the second emitted light 84 and the third emitted light 85 into a fourth emitted light 86 and transmits it to the second photodetector 72. The second photodetector 72 receives the fourth emitted light 85 and detects the Sagnac frequency of the passive laser gyroscope. S6. Adjust the positions of the first concave mirror 41, the second concave mirror 42, the third concave mirror 43, and the fourth concave mirror 44, and repeat steps S3 to S5 to obtain the change in optical power of the first emitted light 83. S7. Adjust the positions of the first concave mirror 41, the second concave mirror 42, the third concave mirror 43, and the fourth concave mirror 44, and repeat steps S3 to S5 to obtain the Sagnac frequency change of the passive laser gyroscope.

[0027] Specifically, in steps S6 and S7 of this application, for the first incident light 81, the position of the second concave mirror 42 is kept unchanged, the first concave mirror 41 is finely adjusted, and the first photodetector 71 continuously collects the light power of the transmitted light until the light power reaches its maximum. Then, the position of the first concave mirror 41 is kept unchanged, the second concave mirror 42 is finely adjusted, and the first photodetector 71 continues to collect the light power of the transmitted light until the light power reaches its maximum. Similarly, for the second incident light 82, the position of the third concave mirror 43 is kept unchanged while the position of the fourth concave mirror 44 is adjusted, or the position of the fourth concave mirror 44 is kept unchanged while the position of the third concave mirror 43 is adjusted. Through continuous iterative adjustment of the two optical paths, the transmitted light power obtained by the entire system is maximized, so that the laser gyroscope reaches the optimal mode matching state.

[0028] It should be further explained that if the parameters of the meridional plane and the sagittal plane of the incident light at any position are defined as q, then the magnitude of q satisfies the following formula: in, For in position The radius of curvature of the beam at that location. For in position The expression for the spot radius at that location is as follows: Simplifying the above formula, we get: in, For any position along the direction of light transmission, This is the waist position of the Gaussian beam. The radius of the light spot is the waist. The wavelength of light Within the Rayleigh range, for (0 units away from the waist) Parameter values; The coordinate parameter transformation relationship of a paraxial ray before and after passing through an optical system formed by any optical element can be expressed by the following formula: in, This is the transformation matrix of the optical system for paraxial rays.

[0029] It should be noted that the optical system here refers to the integration of optical elements into which incident light enters; it can be a single optical element or a collection of several optical elements.

[0030] If the transformation matrix of the paraxial ray through the optical system is known, then the transformation matrix before and after passing through the optical system is... The relationship between the parameters can be expressed by the following formula: in, The Gaussian beam before passing through the optical system parameter, After passing through the optical system parameter.

[0031] Taking the position of the laser emitted from the light source as the origin, the laser wavelength of the incident light is defined as... The beam waist position is defined as The beam waist radius in the meridional plane at the beam waist is defined as The radius of the waist of the sagittal beam is defined as For the beam waist position when it exits the optical system but has not yet entered the optical system, then... The q-parameter of the meridional plane is denoted as , The q-parameter of the sagittal surface is denoted as , Given that the beam waist of the five cavity modes of a square ring resonator in a passive laser gyroscope is located at the center of each side, the beam waist radius of the meridional cavity mode is defined as... The waist radius of the sagittal cavity mode is defined as .like Figure 3 As shown, the distance between the light source 1 and the first concave mirror 41 is defined as... The distance between the first concave mirror 41 and the second concave mirror 42 is defined as The distance between the second concave mirror 42 and the first cavity mirror 51 inside the ring resonant cavity 5 is defined as... The refractive index of each cavity mirror in the square ring resonant cavity is The radius of curvature of each endoscope is The side length of the ring resonant cavity 5 is Then, regarding the beam waist position after the light emitted from the light source is injected into the annular resonant cavity 5 at an incident angle of 45°, The q-parameter of the meridional plane is denoted as , The q-parameter of the sagittal surface is denoted as .

[0032] Regarding meridian noodles: from to At this location, the transmission transformation matrix of the optical system on the meridional plane is: Known in place The parameters are: Then in place The parameters are: The result obtained here Complex number expressions; For the sagittal plane: from to At this location, the transmission transformation matrix of the sagittal plane of the optical system is: Known in place The parameters are: Then in place The parameters are: The result obtained here Complex number expressions; because , ,make real part imaginary part , real part imaginary part Four independent constraints were derived, and the system of equations was solved to obtain the radius of curvature of each concave mirror. And the off-axis angle (the angle of incidence when incident light enters a concave mirror). .

[0033] At this point, the initial placement and rotation angle of each concave mirror are determined based on the radius of curvature and off-axis angle of the concave mirror. Subsequently, by continuously fine-tuning the placement of each concave mirror, the optical power of the first emitted light is maximized to achieve mode matching between the propagation of the incident light in the mode matching component and the propagation of the incident light in the ring resonant cavity.

[0034] In summary, the embodiments of the present invention provide a passive laser gyroscope mode matching device based on concave mirrors. It uses multiple concave mirrors to replace multiple cylindrical lenses in existing mode matching components for mode matching. The concave mirrors in the first and second concave mirror groups can simultaneously adjust the meridional and sagittal planes of the beam. Compared with the mode matching component formed by cylindrical lenses, the mode matching and component of this application uses fewer components, which can improve the degree of influence of wavefront distortion. Moreover, due to the reduction of components, the internal structure of the mode matching component is more compact, reducing the space occupied by the device.

[0035] The present invention also provides a mode matching method for a passive laser gyroscope, which can be adapted to a mode matching component formed by combining multiple concave mirrors, effectively reducing the influence of wavefront distortion.

[0036] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A passive laser gyroscope mode matching device based on a concave mirror, characterized in that, It includes a light source (1), a beam splitter (2), a mode matching component (4), a ring resonator (5), a beam combining interference component (6), and a signal detection component (7). The light source (1) is used to output the original light (8) to the beam splitter (2). The beam splitter (2) is used to receive the original light (8) and split the original light (8) into a first incident light (81) and a second incident light (82). The pattern matching component (4) includes a first concave mirror group and a second concave mirror group. The first concave mirror group is used to receive the first incident light (81) and adjust the waist size and waist position of the first incident light (81). The second concave mirror group is used to receive the second incident light (82) and adjust the waist size and waist position of the second incident light (82). The annular resonant cavity (5) is used to receive the first incident light (81) and the second incident light (82) after adjusting the waist size and waist position. The first incident light (81) and the second incident light (82) resonate in the annular resonant cavity (5) so that the first incident light (81) and the second incident light (82) after adjusting the waist size and waist position match the waist size and waist position of the intrinsic mode of the annular resonant cavity (5). The beam combining interference component (6) is used to receive the second emitted light (84) and the third emitted light (85) and combine them to form the fourth emitted light (86). The signal detection component (7) is used to receive the first emitted light (83) to detect the optical power of the first emitted light (83), and the signal detection component (7) is also used to receive the fourth emitted light (86) to detect the Sagnac frequency of the laser gyroscope.

2. The passive laser gyroscope mode matching device based on a concave mirror according to claim 1, characterized in that, Includes a plane mirror (3), which is used to receive the second incident light (82) and change the path of the second incident light (82) to transmit the second incident light (82) to the second concave mirror group.

3. The passive laser gyroscope mode matching device based on a concave mirror according to claim 1, characterized in that, The first concave mirror group includes a first concave mirror (41) and a second concave mirror (42). The first incident light (81) is incident on the first concave mirror (41) and the second concave mirror (42) in sequence. The first concave mirror (41) and the second concave mirror (42) are used to adjust the waist size and waist position of the first incident light (81). The second concave mirror group includes a third concave mirror (43) and a fourth concave mirror (44). The second incident light (82) is incident on the third concave mirror (43) and the fourth concave mirror (44) in sequence. The third concave mirror (43) and the fourth concave mirror (44) are used to adjust the waist size and waist position of the second incident light (82).

4. The passive laser gyroscope mode matching device based on a concave mirror according to claim 1, characterized in that, The annular resonant cavity (5) includes a first cavity mirror (51), a second cavity mirror (52), a third cavity mirror (53), and a fourth cavity mirror (54). The first cavity mirror (51) is used to receive the first incident light (81) and reflect the first incident light (81) to the third cavity mirror (53). The second cavity mirror (52) is used to receive the second incident light (82) and reflect the second incident light (82) to the fourth cavity mirror (54). The third cavity mirror (53) is used to receive the first incident light (81) and reflect the first incident light (81) to the fourth cavity mirror (54) so ​​that the first incident light (81) in the annular resonant cavity (51) is reflected in the fourth cavity mirror (54). The light is transmitted clockwise through reflections by the fourth cavity mirror (54), the second cavity mirror (52), and the first cavity mirror (51) in sequence. The third cavity mirror (53) is also used to output the first outgoing light (83). The fourth cavity mirror (54) is used to receive the second incident light (82) and reflect the second incident light (82) to the third cavity mirror (53) so that the second incident light (82) is transmitted counterclockwise through reflections by the third cavity mirror (53), the first cavity mirror (51), and the second cavity mirror (52) in sequence within the annular resonant cavity (5). The fourth cavity mirror (54) is also used to output the second outgoing light (84) and the third outgoing light (85).

5. The passive laser gyroscope mode matching device based on a concave mirror according to claim 1, characterized in that, The beam combining interference component (6) includes a first beam combining mirror (61), a second beam combining mirror (62), and a beam combiner (63). The first beam combining mirror (61) is used to receive the second emitted light (84) and transmit the second emitted light (84) to the beam combiner (63). The second beam combining mirror (62) is used to receive the third emitted light (85) and transmit the third emitted light (85) to the beam combiner (63). The beam combiner (63) is used to combine the second emitted light (84) and the third emitted light (85) into a fourth emitted light (86) and transmit it to the signal detection component (7).

6. The passive laser gyroscope mode matching device based on a concave mirror according to claim 5, characterized in that, The signal detection component (7) includes a first photodetector (71) and a second photodetector (72). The first photodetector (71) is used to receive the first emitted light (83) to detect the optical power of the first emitted light (83), and the second photodetector (72) is used to receive the fourth emitted light (86) to detect the Sagnac frequency of the passive laser gyroscope.

7. A mode matching method for a passive laser gyroscope using the mode matching device based on a concave mirror as described in any one of claims 1-6, comprising the following steps: S1. The light source (1) emits the original light (8) to the beam splitter (2). The beam splitter (2) receives the original light (8) and then splits the original light (8) into the first incident light (81) and the second incident light (82). S2. The first concave mirror group of the pattern matching component (4) receives the first incident light (81) and adjusts the waist size and waist position of the first incident light (81). The second concave mirror group of the pattern matching component (4) receives the second incident light (82) and adjusts the waist size and waist position of the second incident light (82). S3, the ring resonant cavity (5) receives the first incident light (81) and the second incident light (82) adjusted by the waist size and waist position, and forms the first outgoing light (83), the second outgoing light (84) and the third outgoing light (85). S4. The beam combining interference component (6) receives the second outgoing light (84) and the third outgoing light (85) output from the ring resonator (5) and combines them to form the fourth outgoing light (86). S5. The signal detection component (7) receives the first outgoing light (83) output from the ring resonant cavity (5) and measures the optical power of the first outgoing light (83). The signal detection component (7) receives the fourth outgoing light (86) output from the beam combining interference component (6) and detects the Sagnac frequency of the passive laser gyroscope. S6. Adjust the setting position of each concave mirror in the first concave mirror group and the second concave mirror group, and change the incident angle of the first incident light (81) and the second incident light (82) to adjust the waist size and waist position of the first incident light (81) and the second incident light (82). Repeat steps S3 to S5 to obtain the change in optical power of the first outgoing light (83). S7. Adjust the setting position of each concave mirror in the first concave mirror group and the second concave mirror group to change the waist size and waist position of the first incident light (81) and the second incident light (82). Repeat steps S3 to S5 to obtain the Sagnac frequency change of the passive laser gyroscope.

8. The mode matching method for a passive laser gyroscope according to claim 7, characterized in that, In step S2, the first concave mirror group includes a first concave mirror (41) and a second concave mirror (42). The first concave mirror (41) receives the first incident light (81) and transmits the first incident light (81) to the second concave mirror (42). The second concave mirror group includes a third concave mirror (43) and a fourth concave mirror (44). The third concave mirror (43) receives the second incident light (82) and transmits the second incident light (82) to the fourth concave mirror (44). In step S3, the annular resonant cavity (5) includes a first cavity mirror (51), a second cavity mirror (52), a third cavity mirror (53), and a fourth cavity mirror (54). The first cavity mirror (51) receives the first incident light (81) emitted from the second concave mirror (42) and transmits the first incident light (81) to the third cavity mirror (53), so that the first incident light (81) travels along the first cavity mirror (51), the third cavity mirror (53), the fourth cavity mirror (54), and the second cavity mirror (52). The first cavity mirror (51) is transmitted clockwise in the ring resonant cavity (5). The second cavity mirror (52) receives the second incident light (82) emitted from the fourth concave mirror (44) and transmits the second incident light (82) to the fourth cavity mirror (54), so that the second incident light (82) is transmitted counterclockwise in the ring resonant cavity (5) in the order of the second cavity mirror (52), the fourth cavity mirror (54), the third cavity mirror (53), the first cavity mirror (51), and the second cavity mirror (52). In step S4, the beam combining interference component (6) includes a first reflector (61), a second beam combining reflector (62), and a beam combiner (63). The first beam combining reflector (61) receives the second outgoing light (84) output from the ring resonant cavity (5) and transmits the second outgoing light (84) to the beam combiner (63). The second beam combining reflector (62) receives the third outgoing light (85) output from the ring resonant cavity (5) and transmits the third outgoing light (85) to the beam combiner (63). The beam combiner (63) combines the second outgoing light (84) and the third outgoing light (85) into a fourth outgoing light (86) and transmits it to the signal detection component (7). In step S5, the signal detection component (7) includes a first photodetector (71) and a second photodetector (72). The first photodetector (71) receives the first emitted light (83) output from the ring resonant cavity (5) and measures the optical power of the first emitted light (83). The second photodetector (72) receives the fourth emitted light (85) and detects the Sagnac frequency of the passive laser gyroscope. In steps S6 and S7, the positions of the first concave mirror (41), the second concave mirror (42), the third concave mirror (43), and the fourth concave mirror (44) are adjusted to change the waist size and waist position of the first incident light (81) and the second incident light (82).

9. The mode matching method for a passive laser gyroscope according to claim 6, characterized in that, In steps S6 and S7, the parameters of the sagittal and meridional planes of each incident light at any position are defined as follows: ,but The size of satisfies the following formula: in, For any position along the direction of light transmission, This is the waist position of the Gaussian beam. The radius of the light spot is the waist. The wavelength of light This is within the Rayleigh range.

10. The mode matching method for a passive laser gyroscope according to claim 7, characterized in that, In steps S6 and S7, the optical elements through which each incident light passes are defined as an optical system, and a transformation matrix is ​​established for the coordinate parameter transformation relationship of the incident light before and after passing through the optical system: Then through the optical system before and after The relationship between the parameters can be expressed by the following formula: in, The Gaussian beam before passing through the optical system parameter, After passing through the optical system parameter.

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