Total reflection prism type laser gyroscope device

Abstract

The total reflection prism type laser gyroscope device comprises a laser gyroscope body, the laser gyroscope body comprises an annular cavity and a plurality of prisms, the periphery of the annular cavity is provided with a first prism, a second prism, a third prism and a fourth prism respectively, each prism is provided with an incident plane, a total reflection plane and an emergent plane, and the incident plane, the total reflection plane and the emergent plane are arranged in parallel. Light rays can enter from the incident plane and are emitted from the emergent plane after being reflected by the total reflection plane, a light path hole is formed in the annular cavity between every two adjacent prisms, and the light rays in the annular laser body sequentially pass through the prisms and the light path holes at intervals to form a loop. A high-frequency oscillator is mounted at the position of the light path hole between the first prism and the second prism; the stability of the laser gyroscope can be improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of laser gyroscopes, and more specifically, to a total reflection prism laser gyroscope device. Background Art

[0002] At present, the main countries in the world that develop and produce LG (laser gyroscope) are the United States, Britain, Germany, France, Japan and Russia. Among the companies and research institutions directly engaged in the development, production and application of LG, the most powerful ones are Honeywell and Litton in the United States. The level of these two companies, especially Honeywell, represents the level of LG technology in the world. In terms of production capacity, no company in the world can compare with Honeywell. By 1991, the company had produced more than 50,000 sets of LG, which is more than four times the total output of all other companies in the world. At present, the world's LG mainly comes from Honeywell, and a considerable part comes from Litton.

[0003] The performance of LG mainly depends on the ring laser, and the ring laser can only be used for LG under certain conditions. The stable operation of the ring resonator should usually meet the following four conditions: ① The ring resonator must be a stable cavity; ② The paired reverse traveling modes must be maintained in the ring laser; ③ The reverse traveling mode should operate in a single transverse mode and a single longitudinal mode; ④ The operating wavelength of the ring laser should be conducive to photoelectric detection. Summary of the invention

[0004] The present invention is to provide a total reflection prism laser gyro device which can improve the stability of the laser gyro.

[0005] In order to achieve the above objectives, the technical solutions adopted in this disclosure are as follows:

[0006] A total reflection prism laser gyro device, comprising a laser gyro body, the laser gyro body comprising a ring cavity and a plurality of prisms, characterized in that a first prism, a second prism, a third prism and a fourth prism are respectively arranged around the ring cavity, the first prism, the second prism, the third prism and the fourth prism are all quadrilaterals, each of the prisms has an incident plane, a total reflection plane and an exit plane, light can enter from the incident plane, and be emitted from the exit plane after being reflected from the total reflection plane, an optical path hole is arranged in the ring cavity between two adjacent prisms, and light in the laser gyro body passes through the prisms and the optical path holes in sequence and at intervals to form a loop, and a high-frequency oscillator is installed at the optical path hole between the first prism and the second prism;

[0007] A double-layer magnetic shielding cover is installed on each of the prisms.

[0008] Optionally, the prism is a right-angled trapezoid.

[0009] Optionally, a light-combining prism is further installed outside the total reflection plane of the second prism, and a gap is provided between the light-combining prism and the second prism.

[0010] Optionally, the cross-section of the light-combining prism is triangular.

[0011] Optionally, a first aperture assembly is disposed in the optical path hole between the first prism and the second prism, and a second aperture assembly is disposed in the optical path hole between the third prism and the fourth prism.

[0012] Optionally, the output light of the second prism is input into an oscilloscope after passing through a beam expander and a rotating mirror.

[0013] Optionally, the cross-section of the light path hole is elliptical.

[0014] Optionally, the incident point position of the incident plane of the first prism is in the shape of an arc, and the incident point position of the exit plane of the second prism is in the shape of an arc.

[0015] Optionally, the incident point position of the total reflection plane of the first prism and the incident point position of the total reflection plane of the second prism are both arc-shaped.

[0016] The present invention provides a first prism, a second prism, a third prism and a fourth prism which are respectively arranged around a ring cavity, and each prism has an incident plane, a total reflection plane and an exit plane, so that light can enter from the incident plane, be reflected from the total reflection plane and then be emitted from the exit plane, and the light passes through the prisms and light path holes in sequence at intervals to form a loop; a novel prism arrangement of a four-prism laser gyroscope is provided, and each prism is provided with a double-layer magnetic shielding cover to reduce the influence of an external magnetic field on the total reflection prism and keep the prism clean. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 It is a schematic structural diagram of the total reflection prism laser gyro device disclosed in the present invention.

[0019] Figure 2 It is a schematic diagram of the structure of the optical path in the laser gyro ring cavity in the present disclosure.

[0020] Figure 3 Schematic diagram of the structure of a single prism in the present invention.

[0021] Figure 4 Schematic diagram of the structure of the light path in a single prism in the present disclosure.

[0022] Figure 5 It is a schematic diagram of the structure of the detection optical path of the total reflection prism laser gyro device in the present invention. DETAILED DESCRIPTION

[0023] The preferred embodiments of the present disclosure are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present disclosure can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present disclosure.

[0024] See also Figure 1 , Figure 2 As shown, a total reflection prism laser gyro device includes a laser gyro body filled with He-Ne gas for vacuum sealing. The laser gyro body includes a ring cavity 1 and a plurality of prisms. The ring cavity 1 is surrounded by a first prism 21, a second prism 22, a third prism 23 and a fourth prism 24. The first prism 21, the second prism 22, the third prism 23 and the fourth prism 24 are all quadrilaterals. The four prisms are sealed with a cover to keep the surface clean and reduce the influence of the external magnetic field on the TRP. The prism can be a quadrilateral structure. Fused quartz can be selected as the TRP material. At 25°C, its refractive index is n=1.457. Figure 4 As shown, each of the prisms has an incident plane 201, a total reflection plane 202 and an exit plane 203, and light 4 can enter from the incident plane 201, and be emitted from the exit plane 203 after being reflected from the total reflection plane 202. An optical path hole 3 is provided in the ring cavity 1 between two adjacent prisms, and light 4 in the laser gyro body passes through the prisms and the optical path hole 3 in sequence to form a loop, and a high-frequency oscillator 5 is installed at the optical path hole 3 between the first prism 21 and the second prism 22; each of the prisms is installed with a double-layer magnetic shielding cover to reduce the influence of the external magnetic field on the total reflection prism and keep the prism clean.

[0025] In another embodiment of the present disclosure, a light-combining prism 6 is also installed outside the total reflection plane 202 of the second prism 22, and a gap is provided between the light-combining prism 6 and the second prism 22, so that there is a "wedge-shaped" gap of the wavelength order between the working surfaces of the two prisms, forming a prism coupler with a "wedge-shaped" gap, through which the sampled output light can be obtained. This coupling method is similar to the prism coupling in the flat waveguide. Specifically, the cross-section of the light-combining prism 6 is a triangle.

[0026] A first aperture 7 assembly is provided in the optical path hole 3 between the first prism 21 and the second prism 22, and a second aperture 8 assembly is provided in the optical path hole 3 between the third prism 23 and the fourth prism 24. They are used to limit the 0.6328 μm high-order transverse mode and 1.15 μm laser used in this embodiment, respectively, so that the resonant cavity maintains single transverse mode oscillation. Minimum diffraction zero deviation can also be obtained.

[0027] See also Figure 5 As shown, the output light of the second prism 22 passes through the beam expander 9 and the rotating mirror 10 and then is input into the oscilloscope 11. After the sampling light is expanded by the beam expander 9, it is projected onto the rotating mirror 10 driven by the motor, and then, after reflection, it is projected onto a photoelectric detector with a small aperture, and then, after being amplified by the electronic circuit, it is connected to the oscilloscope 11 to display the waveform.

[0028] The cross section of the optical path hole 3 is elliptical. The actual TRP ring cavity works with elliptically polarized light. The ellipticity is proportional to the sum of the stresses in the prism and the non-coplanarity of the resonant cavity. The external electromagnetic field interferes with the elliptically polarized light, which can cause electromagnetic non-reciprocity in the reverse traveling wave.

[0029] The incident point position of the incident plane 201 of the first prism 21 is in the shape of an arc, and the incident point position of the exit plane 203 of the second prism 22 is in the shape of an arc.

[0030] In order to stabilize the resonant cavity, the small right-angled surface of the incident plane 201 of the first prism 21 through which light passes is ground into a spherical surface with a curvature radius of R.

[0031] See also Figure 2 , Figure 4 As shown in the figure, the light is incident on the TRP (Total Reflection Prism) surface at the Brewster angle, so astigmatism occurs when it is refracted on the TRP surface. Therefore, it is necessary to consider the light transformation matrix of the light in the meridian plane (the main section of the prism) and the sagittal plane (the plane composed of the meridian plane normal and the optical axis) respectively. The light transformation matrix used in the TRP ring cavity. These matrices are obtained when the light is incident on the TRP surface at the Brewster angle.

[0032]

[0033] In the table, n is the refractive index of the prism, and R1 is the small right-angle surface through which the first type of TRP passes light ( Figure 2 The curvature radius of the surface at No. 4, 5 and No. 16, 17 in the middle), R2 is the TRP slope ( Figure 2 The radius of curvature of the surface at number 3 and number 18).

[0034] The ABCD matrix method is usually used to study the stability of the TRP ring cavity. Select a point z of the ring cavity as the starting point, rotate around the ring cavity once, and invert the product of the transformation matrix of the light passing through in sequence to obtain the surrounding matrix T z . The wrapping matrix T z Written as

[0035]

[0036] Using the ABCD law, the stability condition of the laser resonant cavity is

[0037]

[0038] Assume that the length of the capillary filled with gain medium is L1, the optical path length of the light in each TRP is L2, the length of the vacuum capillaries on both sides is L3, the length of the capillary filled with dry air is L4, and the length of the optical path from the large right angle surface of TRP to the inclined surface is ( Figure 2 The distance between number 2 (18) and number 3 (19) is h1, and the length from the small right angle surface to the inclined surface ( Figure 2 The distance between number 3 (18) and number 4 (17) is h2, the refractive index of the prism is n, and the small right-angle surface ( Figure 2 , the curvature radius of the surface at positions 4, 5 and positions 16, 17 is R (mm).

[0039] Usually, the total encircling matrix of the meridional ray and the sagittal ray is different. To ensure the stability of the TRP ring cavity, the meridional and sagittal rays must meet the stability requirements at the same time. Therefore, the ABCD matrix of the meridional plane and the sagittal plane are calculated respectively. When actually designing the TRP ring cavity, the stability of the cavity is controlled by changing the radius of curvature R (mm). Since the analytical form of the ABCD matrix is ​​very complicated, it needs to be calculated by computer.

[0040] The following example takes the prism as a right-angle trapezoid; Figure 3 The geometric relations are:

[0041] L2=L-L1cosα,h2=L2 / sinθ1

[0042] The total length of light traveling through the right-angle prism is

[0043]

[0044] Given the geometric parameters of the TRP ring cavity, the stability of the TRP ring cavity is studied. The so-called geometric parameters of the TRP ring cavity refer to the shape of the cavity, the radius of curvature of the surface of each TRP light-passing area, the geometric dimensions of each side of the ring cavity, and the parameters of each optical element in the cavity.

[0045] Optical cavity length L <![CDATA[L1]]> <![CDATA[L2]]> <![CDATA[L3]]> <![CDATA[L4]]> <![CDATA[h1]]> <![CDATA[h2]]> The refractive index of TRP is n 282.5 55.0 11.8 50.0 59.0 7.1 4.7 1.45738

[0046] The geometric structure parameter table of the TRP ring cavity is given. The ABCD matrix of the quadrangular TRP ring cavity is derived, and using the parameters in Table 3-2, the stability condition of the meridian light of the TRP ring cavity can be calculated as:

[0047] R>165.5, or 45.188 <R<62.165,

[0048] The sagittal ray stability condition is:

[0049] R>55.679 or 16.080 <R<22.610

[0050] The present invention provides a first prism 21, a second prism 22, a third prism 23 and a fourth prism 24 around a ring cavity, and each prism has an incident plane 201, a total reflection plane 202 and an exit plane 203. Light 4 can enter from the incident plane 204, and be emitted from the exit plane 203 after being reflected from the total reflection plane 202. Light 4 passes through the prisms and the optical path holes 3 in sequence and at intervals to form a loop. A novel prism setting of a four-prism laser gyroscope is provided. At the same time, the incident point position of the incident plane 201 of the first prism 21 is an arc shape, and the incident point position of the exit plane of the second prism 202 is an arc shape, which can improve the stability of the laser gyroscope.

[0051] According to the above principle, in order to further improve the stability of the laser gyro, the incident point position of the total reflection plane 202 of the first prism 21 and the incident point position of the total reflection plane 202 of the second prism 22 are both arc-shaped.

[0052] Although the embodiments of the present disclosure are described in conjunction with the accompanying drawings, the patent owner may make various variations or modifications within the scope of the appended claims. As long as they do not exceed the protection scope described by the claims of the present disclosure, they should be within the protection scope of the present disclosure.

Claims

1. A total reflection prism laser gyro device, comprising a laser gyro body, wherein the laser gyro body comprises a ring cavity and a plurality of prisms, characterized in that: The first prism, the second prism, the third prism and the fourth prism are respectively arranged around the ring cavity, the first prism, the second prism, the third prism and the fourth prism are all quadrilaterals, each of the prisms has an incident plane, a total reflection plane and an exit plane, light can enter from the incident plane, and be emitted from the exit plane after being reflected from the total reflection plane, and an optical path hole is arranged in the ring cavity between two adjacent prisms, and the light in the laser gyro body passes through the prisms and the optical path holes in sequence to form a loop, and a high-frequency oscillator is installed at the optical path hole between the first prism and the second prism; A double-layer magnetic shielding cover is installed on each of the prisms.

2. The total reflection prism laser gyro device according to claim 1, characterized in that: The prism is a right-angle trapezoid.

3. The total reflection prism laser gyro device according to claim 1, characterized in that: A light-combining prism is also installed outside the total reflection plane of the second prism, and a gap is provided between the light-combining prism and the second prism.

4. The total reflection prism laser gyro device according to claim 3, characterized in that: The cross section of the light-combining prism is a triangle.

5. The total reflection prism laser gyro device according to claim 4, characterized in that: A first aperture assembly is arranged in the optical path hole between the first prism and the second prism, and a second aperture assembly is arranged in the optical path hole between the third prism and the fourth prism.

6. The total reflection prism laser gyro device according to claim 1, characterized in that: The output light of the second prism is input into the oscilloscope after passing through the beam expander and the rotating mirror.

7. The total reflection prism laser gyro device according to claim 1, characterized in that: The cross section of the optical path hole is elliptical.

8. The total reflection prism laser gyro device according to claim 1, characterized in that: The incident point position of the incident plane of the first prism is in the shape of an arc, and the incident point position of the exit plane of the second prism is in the shape of an arc.

9. The total reflection prism laser gyro device according to claim 1, characterized in that: The incident point position of the total reflection plane of the first prism and the incident point position of the total reflection plane of the second prism are both arc-shaped.

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