Normal-stable Raman laser reflector vibration isolation system and control method

Abstract

The invention discloses a normal-stable Raman laser reflector vibration isolation system, which comprises a Raman laser reflector and a reflector which are arranged above a vibration isolation table, and a four-quadrant photoelectric detector arranged above the reflector, the piezoelectric ceramic is arranged between the vibration isolation table and the Raman laser reflector and is used for controlling the posture of the Raman laser reflector; the piezoelectric ceramic and the four-quadrant photoelectric detector are respectively connected with a normal feedback control module; the invention further discloses a control method. According to the invention, the problem of normal drift of the Raman laser reflector caused by attitude drift of the vibration isolation table in the cold atom interferometer is solved, and the environmental vibration adaptability of the cold atom interferometer is improved; by improving the normal stability of the Raman laser reflector, the long-term drift of the measurement result of the cold atom interferometer is greatly reduced, and the measurement precision is improved.

Description

Technical Field

[0001] This invention relates to the field of cold atom interferometry precision measurement technology, specifically to a normal-stabilized Raman laser reflector vibration isolation system and its normal feedback control method. Background Technology

[0002] Cold atom interferometry has developed rapidly in the past 20 years and has been widely used in precision measurement physics and fundamental physics research, achieving fruitful results in the measurement of inertial quantities such as gravitational acceleration, gravitational gradient, and angular velocity.

[0003] The basic working principle of cold atom interferometer for measuring inertial quantities is as follows: the temperature of the atomic cluster is cooled to the micro Kelvin level using a laser; then, the cold atomic cluster is interfered with using a π / 2-π-π / 2 Raman laser; the atomic cluster is then irradiated with a probe light to make it emit fluorescence, and the fluorescence emitted by the atomic cluster is collected and focused onto a photodetector, thereby realizing the detection of the atomic interference result; finally, the phase of the atomic interference fringes is extracted, and the inertial quantity to be measured is calculated.

[0004] As the core component for manipulating the quantum states of cold atom clusters, the normal stability of the Raman laser mirror directly affects the measurement accuracy and long-term stability of the cold atom interferometer.

[0005] To improve the adaptability of cold atom interferometers to complex vibration environments, Raman laser mirrors are typically placed on vibration isolation tables. The vibration isolation tables themselves exhibit attitude drift, causing instability in the normal orientation of the Raman laser mirrors, which affects the measurement accuracy and long-term stability of the cold atom interferometer. Summary of the Invention

[0006] One of the objectives of this invention is to provide a normal-stabilized Raman laser mirror vibration isolation system to overcome the problem of normal drift of the Raman laser mirror placed on the vibration isolation platform, which in turn affects the measurement accuracy and long-term stability of the cold atom interferometer.

[0007] The technical solution adopted by this invention to solve its technical problem is: a normal-stabilized Raman laser reflector vibration isolation system, including a Raman laser reflector and a reflector disposed above a vibration isolation platform, and a four-quadrant photodetector disposed above the reflector. The four-quadrant photodetector is used to detect the direction of the Raman laser reflected from the Raman laser reflector. It also includes a piezoelectric ceramic disposed between the vibration isolation platform and the Raman laser reflector for attitude control of the Raman laser reflector. The piezoelectric ceramic and the four-quadrant photodetector are respectively connected to a control module for normal feedback of the Raman laser reflector. The normal feedback control module receives and processes the Raman laser direction information output by the four-quadrant photodetector and drives the piezoelectric ceramic to adjust the normal direction of the Raman laser reflector.

[0008] The described normal-stabilized Raman laser reflector vibration isolation system has a fixed relative position between its four-quadrant photodetector and the reflector, and the reflector allows partial reflection of the Raman laser to pass through.

[0009] The second objective of this invention is to provide a control method for a normally stabilized Raman laser mirror vibration isolation system, comprising the following steps:

[0010] S10, Initial position calibration of the Raman laser mirror:

[0011] S20, Feedback Control:

[0012] S201, the four-quadrant photodetector detects the position of the reflected Raman laser spot and inputs it into the normal feedback control module. The normal feedback control module compares the real-time measured direction of the reflected Raman laser with the initial direction of the reflected Raman laser and performs digital PID calculations while waiting for the atomic interference process to end.

[0013] S202, waiting for the atomic interference process to end;

[0014] S203 employs a digital PID algorithm to feedback control the piezoelectric ceramic, achieving active stabilization control of the Raman laser reflector's normal direction: the digital PID algorithm performs PID calculations on the error signal, and the calculation result drives the piezoelectric ceramic in the form of voltage. Then, the normal feedback control module feeds back to control the piezoelectric ceramic, adjusting the normal direction of the Raman laser reflector.

[0015] S30 sequentially cycles through the three steps S201 to S203, always maintaining the reflected Raman laser pointing in line with the initial calibration pointing, thereby achieving active stabilization control of the Raman laser reflector normal on the vibration isolation platform and improving the measurement accuracy and long-term stability of the cold atom interferometer.

[0016] The beneficial effects of this invention are as follows: a four-quadrant photodetector is used to measure the change in the pointing of the Raman laser, and then a normal feedback control module is used to drive the piezoelectric ceramic to adjust the normal of the Raman laser reflector placed on the vibration isolation platform, so that the incident Raman laser and the reflected Raman laser keep coincident, thereby achieving stable control of the normal of the Raman laser reflector and solving the change in the normal of the Raman laser reflector caused by the change in the attitude of the vibration isolation platform itself. The cold atom interferometer introduced is used to measure drift, thereby improving the measurement accuracy and long-term stability of the cold atom interferometer. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention;

[0018] Figure 2 The present invention relates to a method for measuring the normal direction of a Raman laser reflector and for feedback control.

[0019] The labels in the attached figures are as follows: 10—four-quadrant photodetector, 20—reflector, 30—Raman laser reflector, 40—piezoelectric ceramic, 50—vibration isolation table, 60—normal feedback control module. Detailed Implementation

[0020] The present invention will now be described in further detail with reference to the accompanying drawings.

[0021] like Figure 1 As shown, this invention discloses a normal-stabilized Raman laser reflector vibration isolation system. This system can accurately detect changes in the normal of the Raman laser reflector and lock the normal of the Raman laser reflector at the initial calibration position. This method effectively solves the problem of normal drift of Raman laser reflectors placed on vibration isolation platforms, improving the measurement accuracy and long-term stability of cold atom interferometers. It includes a Raman laser reflector 30 and a reflector 20 positioned above the vibration isolation platform 50, and a four-quadrant photodetector 10 positioned above the reflector 20. The four-quadrant photodetector 10 detects the direction of the Raman laser reflected from the Raman laser reflector 30. It also includes a piezoelectric ceramic 40 positioned between the vibration isolation platform 50 and the Raman laser reflector 30 for attitude control of the Raman laser reflector 30. The Raman laser reflector 30 is placed on the vibration isolation platform 50 via the piezoelectric ceramic 40, which can be used to adjust the normal direction of the Raman laser reflector 30. The input Raman laser, after being reflected by the reflector 20, is directed towards the Raman laser reflector 30 and reflected back along its original path. Since the reflector 20 can transmit a portion of the Raman laser, a portion of the reflected Raman laser will illuminate the four-quadrant photodetector 10. The four-quadrant photodetector 10 can acquire the directional changes of the reflected Raman laser. The Raman laser reflector 30 is fixed on the vibration isolation table 50 by the piezoelectric ceramic 40. The vibration isolation is used to isolate the Raman laser reflector 30 from the influence of environmental vibrations.

[0022] To address the impact of vibration isolation table attitude drift on the measurement accuracy and long-term stability of the cold atom interferometer, the piezoelectric ceramic 40 and the four-quadrant photodetector 10 are respectively connected to a normal feedback control module 60 for normal feedback of the Raman laser reflector 30. This module drives the piezoelectric ceramic 40 to adjust the normal of the Raman laser reflector 30, achieving active feedback control of the normal. The normal feedback control module 60 receives and processes the Raman laser pointing information output by the four-quadrant photodetector 10 and drives the piezoelectric ceramic 40 to adjust the normal direction of the Raman laser reflector 30. The relative positions of the four-quadrant photodetector 10 and the reflector 20 remain fixed, and the reflector 20 allows partial reflection of the Raman laser to pass through.

[0023] Figure 2 The diagram shows a flowchart of the normal feedback control of a Raman laser mirror. The present invention discloses a control method for a normal-stabilized Raman laser mirror vibration isolation system, which includes the following steps.

[0024] The first step is to adjust the incident Raman laser and the reflected Raman laser to coincide, and record the initial direction of the reflected Raman laser at this time through the four-quadrant photodetector 10, thus completing the initial position calibration of the Raman laser reflector 30 (S10).

[0025] The second step is the feedback control stage (S20). The four-quadrant photodetector 10 detects the direction of the reflected Raman laser beam and inputs it into the normal feedback control module 60 (S201). The normal feedback control module 60 compares the real-time measured direction of the reflected Raman laser with the initial direction of the reflected Raman laser, performs digital PID calculations, and waits for the atomic interference process to end (S202). Then, the normal feedback control module 60 feeds back to control the piezoelectric ceramic 40 to adjust the normal of the Raman laser reflector 30 (S203).

[0026] By sequentially cycling through the three steps S201 to S203, the direction of the reflected Raman laser is always kept consistent with the initial calibration direction, thereby achieving active stabilization control of the normal direction of the Raman laser reflector 30 on the vibration isolation table 50 and improving the measurement accuracy and long-term stability of the cold atom interferometer.

[0027] Those skilled in the art will readily understand that the above description is merely a preferred use case of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A normal-stable Raman laser mirror isolation system, characterized in that: The application relates to a Raman laser mirror (30) and a mirror (20) arranged above a vibration isolation table (50), and a four-quadrant photodetector (10) arranged above the mirror (20), and a piezoelectric ceramic (40) arranged between the vibration isolation table (50) and the Raman laser mirror (30) for attitude control, wherein the piezoelectric ceramic (40) and the four-quadrant photodetector (10) are respectively connected with a control module (60), the normal feedback control module (60) receives and processes the Raman laser pointing information output by the four-quadrant photodetector (10), and drives the piezoelectric ceramic (40) to adjust the normal direction of the Raman laser mirror (30).

2. The normal stable Raman laser mirror isolation system according to claim 1, characterized in that, The relative position between the four-quadrant photodetector (10) and the mirror (20) is fixed, and the mirror (20) allows part of the reflected Raman laser to pass through.

3. A method of controlling a Raman laser mirror isolation system as claimed in claim 1, characterized in that The application comprises the following steps: S10, initial position calibration of the Raman laser mirror (30); S20, feedback control: S201, the four-quadrant photodetector (10) detects the position of the reflected Raman laser spot and inputs the normal feedback control module (60), and the normal feedback control module (60) compares the reflected Raman light pointing information collected by the four-quadrant photodetector (10) with the initial calibration pointing information to obtain an error signal; S202, waiting for the end of the atomic interference process; S203, feedback control of the piezoelectric ceramic (40) by using a digital PID algorithm to realize active stable control of the normal direction of the Raman laser mirror (30): the error signal is subjected to PID operation by using a digital PID algorithm, and the operation result drives the piezoelectric ceramic (40) in the form of voltage to realize stable control of the normal direction of the Raman laser mirror (30); S30, sequentially circulating S201-S203 to keep the reflected Raman laser pointing consistent with the initial calibration pointing, and realizing active stable control of the normal direction of the Raman laser mirror (30) on the vibration isolation table (50).

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