Laser gyro resonant cavity structure with improved temperature stability and laser gyro

Abstract

The present invention relates to a laser gyroscope resonant cavity structure and a laser gyroscope with improved temperature stability, belonging to the technical field of laser gyros. The resonant cavity structure includes a gas storage hole, a discharge region capillary, and a non-discharge region capillary. Multiple gas storage holes are spaced apart within the resonant cavity of the resonant cavity structure, and adjacent gas storage holes are connected via the discharge region capillary and / or the non-discharge region capillary to form a closed optical path. The discharge region capillary is connected to the discharge hole arranged within the resonant cavity. The diameter of the non-discharge region capillary is larger than that of the discharge region capillary. This invention reduces the flow of gain gas within the laser gyroscope resonant cavity capillary and the temperature gradient of the laser gyroscope resonant cavity, thereby reducing the impact of temperature field changes on the laser gyroscope's zero bias.

Description

Technical Field

[0001] The present invention relates to the technical field of laser gyros, and in particular to a laser gyro resonant cavity structure and a laser gyro capable of improving temperature stability. Background Art

[0002] Ring laser gyros, as angular motion sensors, are core components of inertial navigation systems and are widely used in aviation, navigation, aerospace, and guidance. The output of a laser gyro is angular velocity. Due to factors such as the processing technology, the output angular velocity of a laser gyro often deviates from the input angular velocity by a certain amount, generally referred to as zero bias. This bias also changes with temperature.

[0003] Because inertial navigation systems often operate within a wide temperature range and in environments with complex temperature fluctuations, it is crucial that the laser gyro's bias does not experience large and irregular changes with temperature. Irregular and large fluctuations in bias can cause large errors in the laser gyro's output, increasing the navigation error of the entire inertial navigation system and reducing navigation accuracy.

[0004] The design and manufacture of laser gyros involve multiple fields, including optics, mechanics, electronics, algorithms, and materials, making it a complex systems engineering project. Each subsystem of a laser gyro will experience fluctuations within the temperature range of -40°C to 70°C, leading to unstable temperature performance. Furthermore, during the mass production of laser gyros, process stability and fluctuations will lead to differences in the laser gyro's temperature characteristics.

[0005] One of the important reasons why the laser gyroscope's zero bias changes with temperature is that the flow of the gain gas in the laser gyroscope has large and unstable changes under different temperature field environments, and the asymmetric expansion of the Langmuir flow and the gain gas causes temperature errors, which affects the frequency difference between the forward and reverse beams in the laser gyroscope, and thus causes changes in the zero bias. Summary of the Invention

[0006] In order to reduce the influence of temperature on the laser gyro zero bias, the present invention provides a laser gyro resonant cavity structure and a laser gyro with improved temperature stability, which can reduce the flow of gain gas in the laser gyro resonant cavity capillary and reduce the influence of temperature field changes on the laser gyro zero bias.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A laser gyro resonant cavity structure with improved temperature stability, the resonant cavity structure comprising a gas storage hole, a discharge region capillary, and a non-discharge region capillary;

[0009] A plurality of gas storage holes are arranged at intervals in the resonant cavity of the resonant cavity structure, and adjacent gas storage holes are connected through the discharge region capillary and / or the non-discharge region capillary to form a closed optical path, and the discharge region capillary is connected to the discharge hole arranged in the resonant cavity; and the diameter of the non-discharge region capillary is larger than the diameter of the discharge region capillary.

[0010] Furthermore, the diameter ratio of the capillary tube in the discharge region to the capillary tube in the non-discharge region is 1:2 to 1:4.

[0011] Furthermore, the inner tube wall roughness Ra value of the capillary tube in the discharge area and the capillary tube in the non-discharge area is not less than 0.5 μm.

[0012] Furthermore, a graphene patch is attached to the surface of the resonant cavity structure.

[0013] Furthermore, the Langmuir flow of the gain gas in the resonant cavity structure is inversely proportional to the equivalent relative molecular mass M of the gain gas.

[0014] Furthermore, the gain gas is a helium-neon mixed gas, and the ratio of helium to neon gas is 14:1 to 29:1.

[0015] Furthermore, the resonant cavity structure is composed of an expansion coefficient of (0±0.05)×10 -6 / ℃ made of microcrystalline glass.

[0016] Furthermore, the resonant cavity structure also includes an aperture; the two gas storage holes on one side of the resonant cavity are connected by two discharge area capillaries, and the two discharge area capillaries are connected through the through hole of the aperture; one discharge hole is located outside the aperture and is respectively connected to the two discharge area capillaries.

[0017] Furthermore, the resonant cavity structure further includes a getter hole; the getter hole is arranged in the resonant cavity on one side thereof and is communicated with the capillary in the non-discharge region.

[0018] The present invention also discloses a laser gyroscope, which includes any one of the above-mentioned laser gyroscope resonant cavity structures for improving temperature stability.

[0019] Beneficial effects of the present invention:

[0020] The present invention discloses a laser gyroscope resonant cavity structure and a laser gyroscope with improved temperature stability. The structure reduces the error introduced by temperature by reducing the flow of gain gas in the laser gyroscope resonant cavity capillary, thereby reducing the influence of temperature on the laser gyroscope zero bias.

[0021] The present invention optimizes the structure of the capillary in the resonant cavity structure and expands the flow area of ​​the gain gas in the capillary through the non-discharge area capillary, which can not only increase the gas storage capacity of the gain gas in the capillary but also slow down the flow of the gain gas, thereby reducing the influence of temperature on the zero bias of the laser gyroscope and helping to extend the service life of the laser gyroscope.

[0022] The present invention increases the flow resistance of the tube wall to the gain gas and reduces the flow speed of the gain gas by increasing the roughness of the inner tube wall of the capillary tube in the discharge area and the capillary tube in the non-discharge area.

[0023] The present invention can accelerate the heat conduction of the resonant cavity structure through the graphene patch, thereby balancing the temperature difference and ensuring the temperature balance of the resonant cavity structure.

[0024] The present invention can also reduce the gain gas flow rate by adopting the gain gas whose Langmuir flow is inversely proportional to the equivalent relative molecular mass M. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the laser gyro resonant cavity structure for improving temperature stability according to the present invention;

[0026] Figure 2 This is a schematic diagram of the resonant cavity structure during testing of the laser gyroscope of the present invention.

[0027] Among them: 1-discharge hole, 2-aperture, 3-gas storage hole, 4-getter hole, 5-discharge area capillary, 6-non-discharge area capillary, 7-heating resistor. DETAILED DESCRIPTION

[0028] The following embodiments are further described in detail with reference to the accompanying drawings and examples. The following embodiments are only used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0029] Terms such as "upper," "lower," "left," "right," "inner," "outer," "front," "back," "head," and "tail" in this application are based on the directions or positions shown in the accompanying drawings. The corresponding positions may vary depending on the drawings, and should not be construed as limiting the scope of protection.

[0030] In the present invention, the terms "installed," "connected," "connected," "connected," "fixed," etc. should be understood in a broad sense. For example, they may refer to fixed connection, detachable connection, integral connection, mechanical connection, electrical connection, or mutual communication. They may be directly connected or indirectly connected through an intermediate medium. They may refer to internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0031] This embodiment describes a laser gyroscope resonant cavity structure and a laser gyroscope with improved temperature stability. It is a cavity solution for reducing the flow of gain gas in the laser gyroscope capillary, which can improve the temperature stability of the laser gyroscope and thus extend the service life of the laser gyroscope.

[0032] The resonant cavity structure is composed of an expansion coefficient of (0±0.05)×10 -6 / ℃ made of glass-ceramics, such as Figure 1 As shown, the resonant cavity structure includes a discharge hole 1, an aperture 2, a gas storage hole 3, a getter hole 4, a discharge region capillary 5, and a non-discharge region capillary 6.

[0033] The resonant cavity structure is axisymmetric, with multiple gas reservoirs 3 spaced apart within it. This embodiment illustrates four gas reservoirs 3 located at the four corners. The axes of the gas reservoirs 3 are typically arranged along the diagonals of the resonant cavity. The diameters of the gas reservoirs 3 are significantly larger than those of the discharge region capillary 5 and the non-discharge region capillary 6, increasing the amount of gain gas stored within the resonant cavity. The gas reservoirs 3, the discharge region capillary 5, and the non-discharge region capillary 6 form a closed optical path.

[0034] The specific configuration of the closed optical path includes, but is not limited to, the following structure: two gas storage holes 3 on the front side of the resonant cavity are connected by a non-discharge region capillary 6. A getter hole 4 is installed along the front-to-back axis of the resonant cavity and communicates with the non-discharge region capillary 6. The getter in the getter hole 4 absorbs impurities to purify the gain gas in the resonant cavity, thereby improving the lifespan of the laser gyroscope. Two gas storage holes 3 on the rear side of the resonant cavity are connected by two discharge region capillaries 5. These two discharge region capillaries 5 are connected through a through hole in the aperture 2. The through hole is centered on the front-to-back axis of the resonant cavity and the opening size of the through hole is adjustable. The aperture 2 through hole, gas storage holes 3, discharge region capillaries 5, and non-discharge region capillaries 6 together form a gain gas circuit. The aperture 2 is used to filter out stray light in the gain gas circuit, ensuring that the laser beam passes through the gain gas circuit and preventing stray light from affecting the accuracy of the laser gyroscope. Outside the aperture 2, the discharge hole 1 is connected to the two discharge region capillaries 5, serving as the cathode of the laser circuit. The two gas storage holes 3 on the left and right sides of the resonant cavity are respectively connected through capillaries consisting of a discharge area capillary 5 and a non-discharge area capillary 6, and the non-discharge area capillary 6 and the discharge area capillary 5 are arranged in front and behind. Two discharge holes 1 on the left and right sides of the resonant cavity are respectively set in the resonant cavity along the left and right axes of the resonant cavity and are respectively connected to the discharge area capillary 5, serving as the anode of the laser circuit.

[0035] The gain region is within the discharge region capillary 5, while the non-discharge region capillary 6 is within the non-gain region. This embodiment optimizes the diameter ratio of the discharge region capillary 5 to the non-discharge region capillary 6, making the diameter of the non-discharge region capillary 6 larger than the diameter of the discharge region capillary 5. This increases the storage capacity of the gain gas within the resonant cavity and changes the gas flow velocity in the gain region, thereby reducing temperature errors. Preferably, the diameter ratio of the discharge region capillary 5 to the non-discharge region capillary 6 is 1:2 to 1:4.

[0036] In this embodiment, the inner walls of the discharge region capillary tube 5 and the non-discharge region capillary tube 6 have a certain degree of roughness. The greater the roughness, the greater the flow resistance to the gain gas, reducing the flow velocity of the gain gas. Preferably, the capillary inner wall roughness Ra is no less than 0.5 μm. Raised structures may also be provided on the inner wall to increase the roughness and thus the airflow resistance.

[0037] In order to solve the problem of unequal temperatures on the two arms of the resonant cavity, this embodiment pastes graphene patches on the surface of the resonant cavity structure to accelerate the heat conduction of the resonant cavity structure, balance the temperature difference, and ensure the temperature balance of the resonant cavity structure.

[0038] The Langmuir flow of the gain gas in the resonant cavity structure of this embodiment is inversely proportional to the gain gas's equivalent relative molecular mass, M. Increasing the gain gas's relative molecular mass reduces the gain gas flow rate. Langmuir flow tests were conducted using helium-neon gas as the gain gas, with different ratios of helium-neon gas as an example, as shown in Table 1 below.

[0039] Table 1 Langmuir flow tests at different ratios

[0040] Helium-neon filling ratio Langmuir flow bias 14:1 14° / h 19:1 10° / h 29:1 6° / h 39:1 5° / h 49:1 4° / h

[0041] Using the resonant cavity structure of this embodiment in a laser gyro can significantly reduce bias fluctuations in variable temperature environments. Temperature sensitivity testing can be performed using test equipment to detect the impact on bias. Typical test equipment includes an optical platform, a laser gyro test bench, a host computer, a counterweight, a temperature-controlled power supply, a heating resistor (Pt1000), and a temperature recorder. The test method is as follows:

[0042] 1. Before the test, fill the closed optical path in the resonant cavity structure with a predetermined ratio of helium-neon gas. The discharge hole 1 above the aperture 2 is connected to the cathode of the laser circuit power supply, and the two discharge holes 1 on the left and right are connected to the anode of the laser circuit power supply respectively. At the same time, Figure 2 As shown, at the junction of the anode discharge hole 1 and the discharge region capillary 5 of the left or right arm of the resonant cavity structure (i.e. Figure 2 A heating resistor 7 is attached above the points X and C shown;

[0043] 2. Place the resonant cavity structure on the laser gyro test bench, and connect the heating resistor 7 to the temperature-controlled power supply through a wire; turn on the laser circuit, generate laser light in the closed optical path, and excite the helium-neon gas, which generates fluctuations and the laser light circulates in the closed optical path; turn on the temperature-controlled power supply to control the heating resistor 7 to heat until one arm of the resonant cavity structure is heated to a predetermined temperature (so that the temperature difference between the two arms of the resonant cavity reaches a preset temperature difference, such as the 10°C temperature difference used in the test in Table 2), and use a temperature recorder to record the temperature data of the two arms of the resonant cavity structure and the zero bias data test until the zero bias curve stabilizes and stops.

[0044] 3. Take the difference ΔBs between the maximum and minimum values ​​of the laser gyro zero bias in multiple tests and calculate the temperature difference sensitivity. Temperature difference sensitivity: Wherein, the difference between the maximum and minimum values ​​of the laser gyro zero bias ΔBs, the temperature difference sensitivity S ΔT , the test results are shown in Table 2 below:

[0045] Table 2 Temperature sensitivity test results

[0046] serial number Sensitivity Conventional cavity 1 0.035° / h / ℃ Conventional cavity 2 0.040° / h / ℃ Optimized cavity 1 0.007° / h / ℃ Optimized cavity 2 0.010° / h / ℃

[0047] Tests show that, compared with a conventional resonant cavity structure having a capillary tube of the same diameter, the zero bias fluctuation of the resonant cavity structure of the laser gyro of this embodiment is reduced by about 2.5 times within the temperature range of -40°C to 70°C.

[0048] Note: The temperature difference sensitivity of the laser gyro resonant cavity is used to evaluate the laser gyro's resistance to temperature fluctuations in a variable temperature environment. The temperature difference sensitivity is defined as the change in the 100-second mean value of the zero bias when the temperature difference between the two arms of the resonant cavity increases by 1°C: Where ΔT is the temperature difference between the left and right arms of the resonant cavity.

[0049] Although the principles of the present invention have been described in detail above in conjunction with the preferred embodiments of the present invention, those skilled in the art should understand that the above embodiments are merely illustrative of the present invention and are not intended to limit the scope of the present invention. The details in the embodiments do not constitute a limitation on the scope of the present invention. Without departing from the spirit and scope of the present invention, any obvious changes such as equivalent transformations and simple substitutions based on the technical solution of the present invention fall within the scope of protection of the present invention.

Claims

1. A laser gyro resonant cavity structure with improved temperature stability, characterized in that: The resonant cavity structure comprises a gas storage hole (3), a discharge region capillary (5), and a non-discharge region capillary (6); A plurality of gas storage holes (3) are arranged at intervals in the resonant cavity of the resonant cavity structure, and adjacent gas storage holes (3) are connected through the discharge region capillary (5) and / or the non-discharge region capillary (6) to form a closed optical path, and the discharge region capillary (5) is connected to the discharge hole (1) arranged in the resonant cavity; and the diameter of the non-discharge region capillary (6) is larger than the diameter of the discharge region capillary (5).

2. The laser gyro resonant cavity structure for improving temperature stability according to claim 1, wherein: The diameter ratio of the discharge region capillary (5) to the non-discharge region capillary (6) is 1:2 to 1:

4.

3. The laser gyro resonant cavity structure with improved temperature stability according to claim 1 or 2, characterized in that: The inner tube wall roughness Ra value of the discharge region capillary tube (5) and the non-discharge region capillary tube (6) is not less than 0.5 μm.

4. The laser gyro resonant cavity structure for improving temperature stability according to claim 1, characterized in that: A graphene patch is attached to the surface of the resonant cavity structure.

5. The laser gyro resonant cavity structure for improving temperature stability according to claim 1, characterized in that: The Langmuir flow of the gain gas in the resonant cavity structure is inversely proportional to the equivalent relative molecular mass M of the gain gas.

6. The laser gyro resonant cavity structure for improving temperature stability according to claim 5, characterized in that: The gain gas is a helium-neon mixed gas, and the ratio of helium-neon gas is 14:1 to 29:

1.

7. The laser gyro resonant cavity structure for improving temperature stability according to claim 1, characterized in that: The resonant cavity structure is composed of an expansion coefficient of (0±0.05)×10 -6 / ℃ made of microcrystalline glass.

8. The laser gyro resonant cavity structure for improving temperature stability according to claim 1, characterized in that: The resonant cavity structure further includes an aperture (2); two gas storage holes (3) on one side of the resonant cavity are connected via two discharge region capillaries (5), and the two discharge region capillaries (5) are connected via a through hole of the aperture (2); one discharge hole (1) is located outside the aperture (2) and is respectively connected to the two discharge region capillaries (5).

9. The laser gyro resonant cavity structure for improving temperature stability according to claim 1, characterized in that: The resonant cavity structure further comprises a getter hole (4); the getter hole (4) is arranged in the resonant cavity on one side thereof and is communicated with the non-discharge region capillary (6).

10. A laser gyroscope, characterized in that: The laser gyro comprises the laser gyro resonant cavity structure for improving temperature stability according to any one of claims 1 to 9.

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