Detection light pressure electro-reflector and position detector module to realize optical path pointing closed loop method

Abstract

A method for achieving a closed-loop optical path pointing using a detection light pressurized electro-reflector and a position detector module. This method uses a pressurized electro-reflector to adjust the angle of the light beam and verifies the correctness of the angle adjustment by detecting the position of the light beam through position detection. This method can change the three-dimensional coordinate position where the light beam hits the position detector, ultimately achieving orthogonality between the detection light path and the pumping light path, that is, perpendicularity between the pumping light path and the detection light path. This method not only allows the detection light to be directed to the exact center of the gas chamber, which is the optimal point, but also allows the pumping light path and the detection light path to be orthogonal by adjusting the pressurized electro-reflector of the detection light path even when the pump beam has already hit the optimal point of the gas chamber.

Description

Technical Field

[0001] The present invention relates to the technical field of SERF-coupled magnetometers, and more specifically to a method for achieving a closed-loop optical path pointing system using a detection light piezoelectric mirror and a position detector module. This method adjusts the angle of the piezoelectric mirror to change the three-dimensional coordinate position at which the light beam strikes the position detector, ultimately achieving orthogonality between the detection light path and the pumping light path, that is, perpendicularity between the pumping light path and the detection light path. This method not only allows the detection light to be directed to the exact center of the gas chamber, which is the optimal point, but also allows the pumping light path and the detection light path to be orthogonal by adjusting the piezoelectric mirror in the detection light path even when the pumping light beam has already struck the optimal point in the gas chamber. Background Art

[0002] SERF inertial measurement (using SERF coupled magnetometer, SERF is spin-exchange relaxation-free) is sensitive to the change of electron spin polarization caused by measuring the external rotation, and has high measurement accuracy and stability because its atomic spin ensemble has self-compensation ability for the change of external magnetic field. The detection system is the output end of the entire SERF inertial measurement system, and its performance is directly related to the performance of the entire system. The detection system is based on measuring electron spin polarization, so the stability of the SERF inertial measurement system is closely related to the stability of electron spin polarization. The stability of atomic spin polarization is related to the pump light power in the longitudinal direction and is affected by the detection light power in the transverse direction. The non-ideal linear polarization of the detection light directly acts on the electron spin, and the detection light pumping effect caused becomes one of the important factors that restrict the system sensitivity and stability improvement. Therefore, the orthogonality of pumping and detection light restricts the improvement of system sensitivity. In view of this, the inventor has completed the present invention. Summary of the Invention

[0003] In response to the defects or shortcomings of the prior art, the present invention provides a method for realizing a closed-loop optical path pointing by using a detection light pressurized electric reflector and a position detector module. The pressurized electric reflector is used to adjust the angle of the light beam, and the correctness of the angle adjustment is verified by detecting the position of the light beam through position detection. This method can change the three-dimensional coordinate position where the light beam hits the position detector by adjusting the angle of the pressurized electric reflector, and ultimately achieve the state where the detection light path is orthogonal to the pumping light path, that is, the pumping light path is perpendicular to the detection light path. This method can not only make the detection light hit the exact center of the air chamber, and the exact center of the air chamber is the optimal point, but also, when the pumping light beam has hit the optimal point of the air chamber, the pumping light path and the detection light path can be orthogonal by adjusting the pressurized electric reflector of the detection light path.

[0004] The technical solutions of the present invention are as follows:

[0005] The method for detecting light-induced pressure electro-reflective mirror and position detector module to realize light path pointing closed loop is characterized by comprising the following steps:

[0006] Step 1: a pressurized electric reflector is provided on the detection light incident side of the air chamber in the SERF coupled magnetometer system, and a beam splitter is provided on the detection light exiting side of the air chamber, the reflective side of the beam splitter is connected to a position detector, and the position detector is connected to the optical path pointing control end of the pressurized electric reflector through a first electric control, the pressurized electric reflector reflects the detection light through a lens, a collimating lens and the air chamber in sequence and then enters the beam splitter, the transmission side of the beam splitter is connected to a second polarization beam splitter through a third λ / 2 plate, the reflective side of the second polarization beam splitter is connected to a first input end of a differential circuit through a second photodetector, the transmission side of the second polarization beam splitter is connected to a second input end of the differential circuit through a third photodetector, and the output end of the differential circuit is used for SERF coupled magnetometer signal output;

[0007] Step 2: Turn on the pump laser and the detection laser in the SERF-coupled magnetometer system, and adjust the SERF-coupled magnetometer system to enter a normal working state;

[0008] Step 3, obtain the position of the detection light through the position detector, and the first electronic control adjusts the angle of the pressurized electric reflector according to the beam position of the detection light, so that the detection light hits the center of the gas chamber and the detection light and the pumping light are orthogonal to each other in the center of the gas chamber.

[0009] The detection light passes through the gas cell in the opposite direction of the y-axis, and the pumping light passes through the gas cell in the same direction as the x-axis.

[0010] The air chamber is located in an oven, the oven is located in a ferrite, the ferrite is located in a second layer of permalloy, and the second layer of permalloy is located in a first layer of permalloy.

[0011] The pumping laser is sequentially connected to the third Glan prism, the second liquid crystal phase retarder, the fourth Glan prism, the fourth λ / 2 plate, the third polarization beam splitter prism, the fifth λ / 2 plate, the reflector and the gas chamber; the third polarization beam splitter prism is sequentially connected to the second liquid crystal phase retarder through the fourth photodetector and the second electric control; the detection laser is sequentially connected to the first λ / 2 plate, the first Glan prism, the first liquid crystal phase retarder, the second Glan prism, the second λ / 2 plate, the first polarization beam splitter prism and the pressurized electric reflector; the first polarization beam splitter prism is sequentially connected to the first liquid crystal phase retarder through the first photodetector and the third electric control.

[0012] Step 3 includes the following formula:

[0013]

[0014] Mtot =M d (d3)M f (f2,x2)M d (d2)M f (f1,x1)M d (d1)

[0015] Where x is the distance formed by the light beam offset from the center of the cell without any lens, which is called the offset; θ is the angle of the light beam relative to the central axis of the cell; θ0 is the initial angle between the light propagation angle and the central axis of the cell; x0 is the initial distance offset from the center of the cell; M tot is the total transformation matrix; M d It is a matrix calculation to calculate the propagation distance of light; M d (d3) is the matrix calculation about d3; M d (d2) is the matrix calculation about d2; M d (d1) is the matrix calculation about d1; d1 is the distance between the pressure electric reflector and the lens; f1 is the focal length of the lens, d2 is the distance between the lens and the collimating lens, f2 is the focal length of the collimating lens; d3 is the distance between the collimating lens and the gas chamber; M f It is a matrix calculation, x1 is the offset under lens conditions, and x2 is the offset under collimating lens conditions.

[0016] Step 3 includes the following formula:

[0017]

[0018] Among them, M d (d) is the matrix calculation about d, d is the beam path length, M f (f,x) is the matrix calculation about f and x, where f is the focal length of the lens and x is the lens offset.

[0019] Step 3 includes the following formula:

[0020]

[0021] d2=f1+f2

[0022] d tot =d1+d2+d3

[0023] where d tot is the total beam path length.

[0024] The technical effects of the present invention are as follows: The detection light piezoelectric mirror and position detector module implement a closed-loop optical path pointing method. The position detector determines the three-dimensional position of the detection light and feeds it back to the piezoelectric mirror. The piezoelectric mirror is used to adjust the angle of the light beam, and the position detector verifies the correctness of the angle adjustment by detecting the position of the light beam. This method is not only important for finding the center point of the light beam passing through the gas cell, but also achieves orthogonality between the pump and detection beams without changing the direction of the pump beam.

[0025] The advantages of the present invention over the prior art are: This article proposes a method for realizing a closed-loop optical path pointing by combining a detection light pressurized electric reflector and a position detector module. This method obtains the position of the detection light through the position detector, and feeds it back to the pressurized electric reflector, and autonomously adjusts the angle of the pressurized electric reflector, thereby finding the optimal point for light to pass through the gas chamber and making the pumping and detection orthogonal. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the structure of the SERF coupled magnetometer system involved in the light-piezoelectric reflector and position detector module to realize the closed-loop optical path pointing method of the present invention. SERF is spin-exchange relaxation-free.

[0027] Figure 2 The present invention is a flow chart of a method for implementing a light path pointing closed loop method using a light-pneumatic electric reflector and a position detector module. Figure 2 The method includes step 1, installing a pressurized electric reflector and a position detector module consisting of a lens, a collimating lens and a position detector; step 2, turning on the pumping and detection lasers, and adjusting the device to enter a normal working state; step 3, obtaining the position of the detection light through the position detector; step 4, feeding back to the pressurized electric reflector through the electronic control system, and automatically adjusting the angle of the pressurized electric reflector.

[0028] The reference numerals are as follows: 1-detection laser; 2-first λ / 2 plate; 3-first Glan prism; 4-first liquid crystal phase retarder; 5-second Glan prism; 6-second λ / 2 plate; 7-first polarization beam splitter; 8-first photodetector; 9-pressure electro-reflecting mirror; 10-lens; 11-collimating lens; 12-first layer of Permalloy; 13-second layer of Permalloy; 14-ferrite; 15-oven; 16-beam splitter; 17-position detector; 18-first electro-reflecting mirror Control; 19-third λ / 2 plate; 20-second polarization beam splitter; 21-second photodetector; 22-third photodetector; 23-differential circuit; 24-pump laser; 25-third Glan prism; 26-second liquid crystal phase retarder; 27-second electric control; 28-fourth photodetector; 29-fourth Glan prism; 30-fourth λ / 2 plate; 31-third polarization beam splitter; 32-fifth λ / 2 plate; 33-gas chamber; 34-reflector; 35-third electric control. DETAILED DESCRIPTION

[0029] Below is the attached figure ( Figure 1-Figure 2 ) and Examples illustrate the present invention.

[0030] Figure 1 It is a structural diagram of a SERF-coupled magnetometer system involved in the method of realizing a light path pointing closed loop by detecting a light-pressurized electro-reflector and a position detector module of the present invention. Figure 2 This is a flow chart of the method for implementing the light path pointing closed loop method of the present invention by detecting the light pressure electro-reflector and the position detector module. Figures 1 to 2As shown, the detection light pressurized electric reflector and the position detector module realize the light path pointing closed loop method, which includes the following steps: Step 1, setting a pressurized electric reflector on the detection light incident side of the air chamber in the SERF coupled magnetometer system, and setting a beam splitter prism on the detection light exit side of the air chamber, the reflection side of the beam splitter prism is connected to the position detector, and the position detector is connected to the light path pointing control end of the pressurized electric reflector through a first electric control, the pressurized electric reflector reflects the detection light through the lens, the collimating lens and the air chamber in sequence and then enters the beam splitter prism, the transmission side of the beam splitter prism is connected to the second polarization beam splitter prism through a third λ / 2 plate, and the reflection side of the second polarization beam splitter prism is connected to the second polarization beam splitter prism. The transmission side of the second polarization splitter is connected to the first input end of the differential circuit through the second photodetector, the transmission side of the second polarization splitter is connected to the second input end of the differential circuit through the third photodetector, and the output end of the differential circuit is used for SERF coupled magnetometer signal output; step 2, turning on the pump laser and the detection laser in the SERF coupled magnetometer system, and adjusting the SERF coupled magnetometer system to enter a normal working state; step 3, obtaining the position of the detection light through the position detector, and the first electronic control adjusting the angle of the pressurized electric reflector according to the beam position of the detection light, so that the detection light hits the center of the gas chamber, and the detection light and the pump light are orthogonal at the center of the gas chamber.

[0031] The detection light passes through the air chamber along the x-axis, while the pumping light passes through the air chamber along the x-axis. The air chamber is located within an oven, which is located within a ferrite layer. The ferrite layer is located within a second layer of permalloy, which is located within a first layer of permalloy. The pumping laser is sequentially connected to a third Glan prism, a second liquid crystal retarder, a fourth Glan prism, a fourth λ / 2 plate, a third polarization beam splitter, a fifth λ / 2 plate, a reflector, and the air chamber. The third polarization beam splitter is sequentially connected to the second liquid crystal retarder via a fourth photodetector and a second electric control. The detection laser is sequentially connected to a first λ / 2 plate, a first Glan prism, a first liquid crystal retarder, a second Glan prism, a second λ / 2 plate, a first polarization beam splitter, and the piezoelectric reflector. The first polarization beam splitter is sequentially connected to the first liquid crystal retarder via a first photodetector and a third electric control.

[0032] Step 3 includes the following formula:

[0033]

[0034] M tot =M d (d3)M f (f2,x2)M d (d2)M f (f1,x1) M d(d1)

[0035] Where x is the distance formed by the light beam offset from the center of the cell without any lens, which is called the offset; θ is the angle of the light beam relative to the central axis of the cell; θ0 is the initial angle between the light propagation angle and the central axis of the cell; x0 is the initial distance offset from the center of the cell; M tot is the total transformation matrix; M d It is a matrix calculation to calculate the propagation distance of light; M d (d3) is the matrix calculation about d3; M d (d2) is the matrix calculation about d2; M d (d1) is the matrix calculation about d1; d1 is the distance between the pressure electric reflector and the lens; f1 is the focal length of the lens, d2 is the distance between the lens and the collimating lens, f2 is the focal length of the collimating lens; d3 is the distance between the collimating lens and the gas chamber; M f It is a matrix calculation, x1 is the offset under lens conditions, and x2 is the offset under collimating lens conditions.

[0036] Step 3 includes the following formula:

[0037]

[0038] Among them, M d (d) is the matrix calculation about d, d is the beam path length, M f (f,x) is the matrix calculation about f and x, where f is the focal length of the lens and x is the lens offset.

[0039] Step 3 includes the following formula:

[0040]

[0041] d2=f1+f2

[0042] d tot =d1+d2+d3

[0043] where d tot is the total beam path length.

[0044] The spin-exchange relaxation-free (SERF) coupled magnetometer, derived from a SERF integrated magnetometer composed of the electron spins of alkali metal atoms and the nuclear spins of noble gas atoms, also has the potential to be used as a miniaturized gyroscope for inertial navigation, making it a key development direction for the next generation of miniaturized, high-precision inertial navigation technology. SERF-coupled magnetometer measurement systems for inertial navigation require high bias stability. However, optical detection errors caused by laser misalignment are a major factor limiting improvements in bias stability. To improve the bias stability of SERF atomic spin inertial measurement systems, a closed-loop optical path pointing method combining a piezoelectric mirror with a position detector module was proposed. By adjusting the angle of the piezoelectric mirror, this method changes the three-dimensional coordinate position at which the beam strikes the position detector, ultimately achieving orthogonality between the detection and pump paths. This method can not only make the detection light hit the exact center of the gas chamber, which is the optimal point, but also when the pumping beam has hit the optimal point of the gas chamber, the pumping light path and the detection light path can be orthogonal by adjusting the pressurized electric reflector of the detection light path.

[0045] Figure 1 The position detector module is used to find the optimal point where the light beam passes through the center of the gas cell. The position detector module consists of three parts: a lens 10 mounted on a three-axis translation stage, a fixed collimating lens 11 for guiding the light beam, and a three-axis position detector 17. To the left of the first lens is a piezoelectric mirror 22. The position detector module determines the position of the detection light and feeds it back to the piezoelectric mirror.

[0046] The detection light pressurized electric reflector and the position detector module realize the closed loop of light path pointing. In the detection laser module, the position of the detection light, that is, the three-dimensional coordinates of the light, is obtained by the position detector and fed back to the pressurized electric reflector.

[0047] Since the pressurized electric mirror is used to adjust the angle of the light beam, the three-dimensional coordinate position of the light beam is monitored by a position detector to verify the correctness of the angle adjustment. The position detector is placed on the side of the split light beam of the prism. The angle of the pressurized electric mirror is adjusted according to the position of the light beam detected by the position detector until the deviation of the position detector does not produce any translation on the detector. This method can not only make it possible to hit the detection light at the exact center of the gas chamber, which is the optimal point, but also, when the pumping beam has hit the optimal point of the gas chamber, by adjusting the pressurized electric mirror of the detection light path, it is possible to achieve orthogonality between the pumping light path and the detection light path.

[0048] The position detector module is used to find the optimal point at which the beam passes through the center of the gas cell. The position detector module consists of three components: a lens mounted on a three-axis translation stage, a fixed collimating lens used to guide the beam, and a position detector that determines the three axes. To the left of the first lens is a piezoelectric mirror. The distance x and the offset angle θ of the piezoelectric mirror, lens, and collimating lens from the exact center of the gas cell must be calculated using the beam propagation matrix:

[0049]

[0050] Where x is the distance formed by the light beam offset from the center of the cell without any lens, which is called the offset; θ is the angle of the light beam relative to the central axis of the cell; θ0 is the initial angle between the light propagation angle and the central axis of the cell; x0 is the initial distance offset from the center of the cell; M tot is the total transformation matrix, calculated as:

[0051] M tot =M d (d3)M f (f2,x2)M d (d2)M f (f1,x1)M d (d1)

[0052] Where M d It is a matrix calculation to calculate the propagation distance of light; d1 is the distance between the pressurized electric reflector and the lens; f1 is the focal length of the lens, d2 is the distance between the lens and the collimating lens, f2 is the focal length of the collimating lens; d3 is the distance between the collimating lens and the gas chamber.

[0053] Light propagation distance M d (d) is given by the matrix operator,

[0054]

[0055] Then for a lens with focal length f and offset x, its matrix operator is

[0056]

[0057] The amount of light beam offset between the lens and the collimator lens is determined by the set of distances d1, d2, and d3 between the lenses, that is, the total length of the beam path is affected by d tot =d1+d2+d3, and the distance between the two lenses is also constrained by the focal length of the lenses: d2=f1+f2. This allows the beam offset to be centered in the air cell by adjusting the distance between the lenses. The distance formula for the pressure point reflector, lens, collimating lens, and air cell is:

[0058]

[0059] d3=d tot -d2

[0060] The position of the detection beam is fixed on the unit using a position detector and fed back to the pressurized electric reflector. Under the feedback, the horizontal angle, horizontal position and vertical position of the pumping light are determined to make the pumping light orthogonal to the detection light. The lenses currently used are f1 = 100mm and f2 = 250mm. At the position d1 = 50mm, d2 = 352mm, d3 = 564mm, d tot =966mm.

[0061] Any content not described in detail in this specification is prior art known to those skilled in the art. It should be noted that the above description is intended to help those skilled in the art understand the present invention, but does not limit the scope of protection of the present invention. Any equivalent substitution, modification, improvement, and / or simplification of the above description that does not depart from the essence of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A light path pointing closed-loop method is realized by detecting a light-pneumatic electric reflector and a position detector module, characterized in that: The following steps are involved: Step 1: a pressurized electric reflector is provided on the detection light incident side of the air chamber in the SERF coupled magnetometer system, and a beam splitter is provided on the detection light exiting side of the air chamber, the reflective side of the beam splitter is connected to a position detector, and the position detector is connected to the optical path pointing control end of the pressurized electric reflector through a first electric control, the pressurized electric reflector reflects the detection light through a lens, a collimating lens and the air chamber in sequence and then enters the beam splitter, the transmission side of the beam splitter is connected to a second polarization beam splitter through a third λ / 2 plate, the reflective side of the second polarization beam splitter is connected to a first input end of a differential circuit through a second photodetector, the transmission side of the second polarization beam splitter is connected to a second input end of the differential circuit through a third photodetector, and the output end of the differential circuit is used for SERF coupled magnetometer signal output; Step 2: Turn on the pump laser and the detection laser in the SERF-coupled magnetometer system, and adjust the SERF-coupled magnetometer system to enter a normal working state; Step 3, obtain the position of the detection light through the position detector, and the first electronic control adjusts the angle of the pressurized electric reflector according to the beam position of the detection light, so that the detection light hits the center of the gas chamber and the detection light and the pumping light are orthogonal to each other in the center of the gas chamber.

2. The method for realizing a closed-loop optical path pointing by using a detection light-piezoelectric reflector and a position detector module according to claim 1, characterized in that: The detection light passes through the gas cell in the opposite direction of the y-axis, and the pumping light passes through the gas cell in the same direction as the x-axis.

3. The method for realizing a closed-loop optical path pointing by using a detection light-pneumatic electro-reflector and a position detector module according to claim 1, characterized in that: The air chamber is located in an oven, the oven is located in a ferrite, the ferrite is located in a second layer of permalloy, and the second layer of permalloy is located in a first layer of permalloy.

4. The method for realizing a closed-loop optical path pointing by using a detection light-pneumatic electro-reflector and a position detector module according to claim 1, characterized in that: The pumping laser is sequentially connected to the third Glan prism, the second liquid crystal phase retarder, the fourth Glan prism, the fourth λ / 2 plate, the third polarization beam splitter prism, the fifth λ / 2 plate, the reflector and the gas chamber; the third polarization beam splitter prism is sequentially connected to the second liquid crystal phase retarder through the fourth photodetector and the second electric control; the detection laser is sequentially connected to the first λ / 2 plate, the first Glan prism, the first liquid crystal phase retarder, the second Glan prism, the second λ / 2 plate, the first polarization beam splitter prism and the pressurized electric reflector; the first polarization beam splitter prism is sequentially connected to the first liquid crystal phase retarder through the first photodetector and the third electric control.

5. The method for realizing a closed-loop optical path pointing by using a detection light-piezoelectric reflector and a position detector module according to claim 1, characterized in that: Step 3 includes the following formula: M tot =M d (d3)M f (f2,x2)M d (d2)M f (f1,x1)M d (d1) Where x is the distance formed by the light beam offset from the center of the cell without any lens, which is called the offset; θ is the angle of the light beam relative to the central axis of the cell; θ0 is the initial angle between the light propagation angle and the central axis of the cell; x0 is the initial distance offset from the center of the cell; M tot is the total transformation matrix; M d It is a matrix calculation to calculate the propagation distance of light; M d (d3) is the matrix calculation about d3; M d (d2) is the matrix calculation about d2; M d (d1) is the matrix calculation about d1; d1 is the distance between the pressure electric reflector and the lens; f1 is the focal length of the lens, d2 is the distance between the lens and the collimating lens, f2 is the focal length of the collimating lens; d3 is the distance between the collimating lens and the gas chamber; M f It is a matrix calculation, x1 is the offset under lens conditions, and x2 is the offset under collimating lens conditions.

6. The method for realizing a closed-loop optical path pointing by using a detection light-pneumatic electro-reflector and a position detector module according to claim 1, characterized in that: Step 3 includes the following formula: Among them, M d (d) is the matrix calculation about d, d is the beam path length, M f (f,x) is the matrix calculation about f and x, where f is the focal length of the lens and x is the lens offset.

7. The method for realizing a closed-loop optical path pointing by using a detection light-pneumatic electro-reflector and a position detector module according to claim 5, characterized in that: Step 3 includes the following formula: d2=f1+f2 d tot =d1+d2+d3 where d tot is the total beam path length.

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