Apparatus and method for adjusting the transmission properties of a light beam in an alkali atom cell

Abstract

The application relates to a device and a method for adjusting the transmission performance of a light beam in an alkali metal atom cell. The device comprises a detection system and a cell assembly. The cell assembly comprises a fiber input light source, an alkali metal atom cell, a mounting frame and an adjusting mechanism. The alkali metal atom cell is configured to be filled with alkali metal atoms and buffer gas. The alkali metal atom cell is connected to the adjusting mechanism through the mounting frame. The detection system comprises a detection piece for detecting the light spot morphology of the light beam emitted by the fiber input light source after passing through the alkali metal atom cell. The adjusting mechanism is configured to move the mounting frame to adjust the position of the alkali metal atom cell. The light spot morphology of the light beam after passing through the alkali metal atom cell can be detected in real time by the detection piece. The placement position of the alkali metal atom cell can be adjusted by the adjusting mechanism to adjust the light spot morphology of the light beam after passing through the alkali metal atom cell, thereby improving the transmission performance of the light beam in the alkali metal atom cell.

Description

Technical Field

[0001] This application relates to the fields of quantum sensing, optics, biomedicine and life sciences, and in particular to a device and method for adjusting the transmission performance of a light beam in an alkali metal atom gas cell. Background Technology

[0002] Based on the Spin-Exchange Relaxation-Free (SERF) principle, SERF atomic magnetometers have become a key technology in fields such as biomagnetic imaging (e.g., magnetoencephalography, magnetocardiography), fundamental physics research (e.g., dark matter detection), and inertial navigation due to their superior performance in detecting extremely weak magnetic fields. The core principle of the SERF magnetometer is to highly polarize alkali metal atoms (e.g., rubidium, potassium) through optical pumping and measure their Larmor precession frequency in a near-zero magnetic field environment, thereby retrieving information about the external magnetic field. However, its sensitivity is limited by the stability of atomic spin polarization and the signal-to-noise ratio of the probe light, both of which are closely related to the beam transmission performance within the alkali metal atom gas cell.

[0003] The core sensing unit of the SERF atomic magnetometer, the alkali metal atomic gas cell, is typically on the millimeter scale. Due to the short optical path, the effective volume for light-atomic interaction is limited, resulting in insufficient signal strength. Currently, alkali metal atomic gas cells have attracted much attention due to their compact size and enhanced light-atomic interaction. However, beam transmission within these cells is susceptible to diffraction losses, interface scattering, and mode mismatch, leading to poor optical performance, such as uneven intensity distribution, polarization degradation, and reduced transmission efficiency. This, in turn, reduces the uniformity of atomic spin polarization and the signal-to-noise ratio of magnetic field measurements. Summary of the Invention

[0004] Therefore, it is necessary to provide an apparatus and method for adjusting the transmission performance of a light beam in an alkali metal atom gas cell, so as to improve the optical performance of the light beam passing through the alkali metal atom gas cell.

[0005] This application provides a device for adjusting the transmission performance of a light beam in an alkali metal atom gas cell, the device comprising a detection system and a gas cell assembly; The gas chamber assembly includes an optical fiber input light source, an alkali metal atom gas chamber, a mounting frame, and an adjustment mechanism. The alkali metal atom gas chamber is configured to be filled with alkali metal atoms and a buffer gas, and is connected to the adjustment mechanism via the mounting frame. The detection system includes a detection element for detecting the spot morphology of the light beam emitted from the optical fiber input light source after passing through the alkali metal atom gas chamber. The adjustment mechanism is configured to drive the mounting frame to move, and the alkali metal atom gas chamber moves with the mounting frame until the spot morphology is a Gaussian spot with highly concentrated but unevenly distributed light beam energy.

[0006] In one embodiment, there are two optical fiber input light sources, the transmission directions of the two optical fiber input light sources are orthogonal, and each optical fiber input light source corresponds to one detection element.

[0007] In one embodiment, the air chamber assembly further includes an optical fiber bracket, with each optical fiber input light source corresponding to one optical fiber bracket, and the optical fiber input light source is mounted on the corresponding optical fiber bracket.

[0008] In one embodiment, the adjustment mechanism is a three-dimensional displacement platform, and the alkali metal atom gas chamber can move along the X, Y and Z directions under the drive of the three-dimensional displacement platform; And / or, the detection system further includes a host computer, the detection device is a spot analyzer, and the host computer is configured to receive spot test parameters of the spot morphology output by the spot analyzer; And / or, the alkali metal atom gas chamber is a cube or a cuboid, and the side length of the alkali metal atom gas chamber is 2mm to 20mm; And / or, the alkali metal atom gas chamber is made of high borosilicate silicon; And / or, the gas chamber assembly further includes a heating element for heating the alkali metal atom gas chamber.

[0009] In one embodiment, the device further includes a base, an optical fiber collimator, and an optical lens. The base is a non-magnetic base. The gas cell assembly, the optical fiber collimator, and the optical lens are all disposed on the base. The optical fiber collimator and the optical lens are both located between the optical fiber input light source and the alkali metal atom gas cell. The optical fiber collimator is used to collimate the light source generated by the optical fiber input light source, and the optical lens is used to adjust the light beam emitted through the optical fiber collimator unit. And / or, the base is provided with a six-degree-of-freedom fine-tuning platform for adjusting the position of the fiber collimator.

[0010] In one embodiment, the device further includes a sensitivity detection unit that performs magnetic field sensitivity measurements based on the alkali metal atom gas cell.

[0011] This application also provides a method for adjusting a device for adjusting the transmission performance of a light beam in an alkali metal atom gas cell, wherein the device is the device described in any of the above embodiments, and the adjustment method includes the following steps: In the gas chamber assembly, the detection system detects in real time the spot morphology of the light beam emitted from the fiber optic input light source after passing through the alkali metal atom gas chamber. The position of the alkali metal atom gas chamber is adjusted in real time by the adjustment mechanism. When the spot morphology is a Gaussian spot with highly concentrated but unevenly distributed light beam energy, the alkali metal atom gas chamber is fixed by the mounting bracket.

[0012] In one embodiment, the method further includes: The optical lens is fixed at a predetermined position on the base of the device; The fiber collimator is fixed at the entrance of the base, and the optical lens is located between the fiber collimator and the alkali metal atom gas cell. The gas chamber assembly after fixing the alkali metal atom gas chamber is fixed on the base. The inlet position is located between the optical fiber input light source and the optical lens, and is close to the optical fiber input light source. The magnetic field sensitivity of the alkali metal atom gas cell was measured using a sensitivity detection unit.

[0013] In one embodiment, the operating temperature of the alkali metal atom gas chamber is 120°~160°; And / or, the sensitivity detection unit performs magnetic field sensitivity measurement on the alkali metal atom gas cell within a permalloy magnetic shielding barrel.

[0014] In one embodiment, there are two optical fiber input light sources, and the transmission directions of the two optical fiber input light sources are orthogonal to each other. If the two beams of light passing through the alkali metal atom gas cell at the same time have overlapping morphologies, the position of the alkali metal atom gas cell will be offset. Then, the position of the alkali metal atom gas cell will be adjusted by an adjustment mechanism until the two beams of light passing through the alkali metal atom gas cell at the same time do not overlap, and the alkali metal atom gas cell will be adjusted into place.

[0015] Compared with the prior art, the device and method for adjusting the transmission performance of the beam in the alkali metal atom gas cell provided in this application have at least the following advantages: the beam spot morphology after passing through the alkali metal atom gas cell can be detected in real time by the detection system, and the placement position of the alkali metal atom gas cell can be adjusted by the adjustment mechanism according to the beam spot morphology, so as to adjust the beam spot morphology to present a better quality (highly concentrated but unevenly distributed beam energy) after passing through the alkali metal atom gas cell, thereby improving the transmission performance of the beam in the alkali metal atom gas cell. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a partial structural schematic diagram of a device according to an embodiment of this application; Figure 2 This is a system diagram of an alkali metal atom gas cell, a sensitivity detection unit, and a spot analyzer according to an embodiment of this application; Figure 3 This is a schematic diagram of the structure of a detection system according to an embodiment of this application; Figure 4 This is a light spot morphology image detected by the first light spot analyzer in one embodiment of this application; Figure 5 This is a spot morphology image detected by the second spot analyzer in one embodiment of this application; Figure 6 This is a morphology image of the light spot detected by the first light spot analyzer in the comparative example of this application; Figure 7 This is a spot morphology image detected by the second spot analyzer in the comparative example of this application; Figure 8 This is a flowchart of an adjustment method according to an embodiment of this application.

[0018] Explanation of reference numerals in the attached figures: 1. Detection system; 11. Spot analyzer; 111. First spot analyzer; 112. Second spot analyzer; 12. Host computer; 2. Gas chamber assembly; 21. Fiber optic input light source; 22. Alkali metal atom gas chamber; 23. Mounting bracket; 24. Three-dimensional displacement platform; 25. Fiber optic support; 3. Base; 31. Six-degree-of-freedom fine-tuning platform; 4. Fiber optic collimator; 5. Optical lens; 6. Sensitivity detection unit. Detailed Implementation

[0019] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0020] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or there may be an intermediate component. When a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be an intermediate component present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," "side," "top," "bottom," and similar expressions used in this application's specification are merely for describing various exemplary structural parts and elements of this application. However, their use herein is for illustrative purposes only and is determined based on the exemplary orientations shown in the accompanying drawings, and does not represent the only possible implementation. Since the embodiments disclosed in this application can be arranged in different orientations, these terms indicating orientation are for illustrative purposes only and should not be considered as limitations. For example, "upper" and "lower" are not necessarily limited to directions opposite to or consistent with the direction of gravity.

[0021] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0022] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature and the second feature are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0023] It should be noted that "axial arrangement" means that the overall arrangement direction is along the axial direction, including but not limited to axial extension, and may form an angle with the axial direction. "Intersecting angles" refers to angles other than 0° and 180°, which can be understood as intersections.

[0024] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items.

[0025] This application discloses a device for adjusting the transmission performance of a light beam in an alkali metal atom gas cell. For example... Figures 1-3 As shown, the device includes a detection system 1 and a gas chamber assembly 2. The gas chamber assembly 2 includes an optical fiber input light source 21, an alkali metal atom gas chamber 22, a mounting bracket 23, and an adjustment mechanism. The alkali metal atom gas chamber 22 is configured to be filled with alkali metal atoms and a buffer gas. In other words, the alkali metal atom gas chamber 22 contains only alkali metal atoms and a buffer gas, and does not contain optical components or detectors.

[0026] The alkali metal atomic gas chamber 22 is connected to the adjustment mechanism via the mounting bracket 23. The detection system 1 includes a detection element used to detect the spot morphology of the light beam emitted from the fiber optic input light source 21 after passing through the alkali metal atomic gas chamber 22. The adjustment mechanism is configured to drive the mounting bracket 23 to move, thereby adjusting the position of the alkali metal atomic gas chamber 22. In other words, the adjustment mechanism is driven to the mounting bracket 23 to move the mounting bracket 23. Since the alkali metal atomic gas chamber 22 is located on the mounting bracket 23, the alkali metal atomic gas chamber 22 moves together with the mounting bracket 23, thereby achieving the adjustment of the position of the alkali metal atomic gas chamber 22.

[0027] It is understandable that the detection device of the detection system 1 can detect the spot morphology of the beam after passing through the alkali metal atom gas cell 22 in real time. According to the spot morphology, the placement position of the alkali metal atom gas cell 22 can be adjusted by the adjustment mechanism to adjust the beam to present a better spot morphology after passing through the alkali metal atom gas cell 22, thereby improving the transmission performance of the beam in the alkali metal atom gas cell 22.

[0028] It should be noted that a high-quality Gaussian beam morphology refers to a beam with highly concentrated but unevenly distributed energy. The "high concentration" in "high energy concentration" refers to a beam waist radius between 0.2 mm and 1.5 mm and a beam quality factor < 1.1. That is, when the alkali metal atom gas cell 22 is properly positioned, the beam morphology after passing through the alkali metal atom gas cell 22 is a Gaussian beam with highly concentrated but unevenly distributed energy.

[0029] It should be noted that the alkali metal atom gas chamber 22 is rectangular or cubic, and the side length of the alkali metal atom gas chamber 22 is 2mm to 20mm. For illustrative purposes, the side length can be 2mm, 20mm, or any value between 2mm and 20mm, such as 5mm, 10mm, 15mm, etc. Furthermore, the material of the alkali metal atom gas chamber 22 can be high borosilicate silicon.

[0030] The fiber optic input light source 21 can be one or more; schematically, it can be two, three, or more. In other words, it is suitable for one beam of light to pass through the alkali metal atom gas chamber 22, and also suitable for multiple beams of light to pass through the alkali metal atom gas chamber 22 simultaneously. This embodiment is illustrated using two fiber optic input light sources 21 as an example.

[0031] like Figure 1 As shown, the transmission directions of the two fiber optic input light sources 21 are orthogonal within the alkali metal atom gas cell 22, and the two transmission directions are transmission direction X and transmission direction Y (not shown in the figure). It should be noted that... Figure 1 In the schematic diagram, one fiber optic input light source 21 is located to the left of the alkali metal atom gas chamber 22, with the rightward direction being the transmission direction X. The other fiber optic input light source 21 is located behind the alkali metal atom gas chamber 22, with the forward direction being the transmission direction Y. Other arrangements can also be used, as long as the transmission directions of the two fiber optic input light sources 21 are orthogonal within the alkali metal atom gas chamber 22. Each fiber optic input light source 21 corresponds to a detection system 1. Thus, each detection system 1 can detect the spot morphology of the light beam emitted from the corresponding fiber optic input light source 21 after passing through the alkali metal atom gas chamber 22.

[0032] The gas chamber assembly 2 also includes a fiber optic bracket 25, with one fiber optic bracket 25 corresponding to each fiber optic input light source 21. The fiber optic input light source 21 is mounted on the corresponding fiber optic bracket 25. It can be understood that the fiber optic bracket 25 can reliably support the fiber optic input light source 21, improving the stability of the fiber optic input light source 21.

[0033] The device also includes a base 3, an optical fiber collimator 4, and an optical lens 5. The gas cell assembly 2, the optical fiber collimator 4, and the optical lens 5 are all mounted on the base 3, with the optical fiber collimator 4 and the optical lens 5 positioned between the optical fiber input light source 21 and the alkali metal atom gas cell 22. Specifically, the optical fiber input light source 21, the optical fiber collimator 4, the optical lens 5, and the alkali metal atom gas cell 22 are arranged sequentially. That is, the optical fiber collimator 4, the optical lens 5, and the alkali metal atom gas cell 22 are arranged sequentially along the beam path emitted from the optical fiber input light source 21. The optical fiber collimator 4 is used to collimate the light source generated by the optical fiber input light source 21, and the optical lens 5 is used to adjust the beam emitted through the optical fiber collimator 4 unit. It should be noted that the base 3 is a non-magnetic base 3, which supports the gas cell assembly 2, the optical fiber collimator 4, and the optical lens 5.

[0034] Understandably, the non-magnetic base 3 does not generate an additional magnetic field. Since the alkali metal atom gas cell 22 is extremely sensitive to magnetic fields, the non-magnetic base 3 can ensure that the alkali metal atom gas cell 22 is in an environment without additional magnetic fields, providing a basic guarantee for the magnetic field measurement of the alkali metal atom gas cell 22.

[0035] Specifically, the base 3 is equipped with a six-degree-of-freedom fine-tuning platform 31 for adjusting the position of the fiber optic collimator 4. Thus, the position of the fiber optic collimator 4 can be adjusted via the six-degree-of-freedom fine-tuning platform 31 to ensure that the fiber optic collimator 4 has no pitch deviation. Furthermore, by fine-tuning the six-degree-of-freedom platform, the light spot after passing through the alkali metal atom gas cell 22 can be observed to gradually converge from a distorted, elliptical, or speckled pattern to a rounded, symmetrical Gaussian light spot. Once a high-quality Gaussian light spot is achieved, the fiber optic collimator 4 can be fixed.

[0036] It should be noted that the six-degree-of-freedom fine-tuning platform 31 adopts the existing six-degree-of-freedom fine-tuning platform 31 structure. As long as it can realize the adjustment of the fiber collimator 4 in the entire spatial attitude (translation along the three coordinate axes X, Y, and Z and rotation around these three axes), it will not be described in detail in this embodiment.

[0037] In this embodiment, the adjustment mechanism is a three-dimensional displacement platform 24. The alkali metal atom gas chamber 22 can move along the X, Y, and Z directions under the drive of the three-dimensional displacement platform 24. It should be noted that the three-dimensional displacement platform 24 adopts the existing structure of a three-dimensional displacement platform. As long as it can realize the movement of the alkali metal atom gas chamber 22 in three dimensions, it is sufficient. This embodiment will not elaborate further.

[0038] like Figure 3 As shown, the detection system 1 also includes a host computer 12, and the detection device is a spot analyzer 11. The host computer 12 is configured to receive the spot test parameters of the spot morphology output by the spot analyzer 11. In other words, the spot analyzer 11 can detect the spot morphology of one or more fiber optic input light sources 21 passing through the alkali metal atomic gas cell 22, and can output its spot test parameters to the host computer 12. When two fiber optic input light sources 21 are set, the two spot analyzers 11 detect the spot morphology of the corresponding fiber optic input light source 21 passing through the alkali metal atomic gas cell 22, and both output the corresponding spot test parameters to the host computer 12.

[0039] In particular, such as Figure 2 As shown, the device provided in this application also includes a sensitivity detection unit 6, which performs magnetic field sensitivity measurements based on the alkali metal atom gas cell 22. It is understood that the adjusted beam shape (Gaussian beam) only ensures beam quality. The sensitivity detection unit 6 verifies the interaction effect between the beam and the alkali metal atoms, i.e., the sensitivity measured based on the alkali metal atom gas cell 22. When the sensitivity meets the requirements, it indicates that the device is in a position with good performance. It should be noted that the sensitivity detection unit 6 can be any existing sensitivity detection device, which will not be described further in this embodiment.

[0040] It should be noted that the gas chamber assembly 2 also includes a heating element (not shown) for heating the alkali metal atom gas chamber 22. The heating element ensures that the working temperature of the alkali metal atom gas chamber 22 is at the required temperature. Indicatively, the heating element can be electrically heated or laser heated, as long as it can heat the alkali metal atom gas chamber 22. In this embodiment, the working temperature of the alkali metal atom gas chamber 22 is 120°C to 160°C. Indicatively, the working temperature can be 120°C, 160°C, or any value within the range of 120°C to 160°C, such as 130°C, 150°C, etc.

[0041] This application provides a method for adjusting the above-mentioned device, such as... Figures 1-3 and Figure 8 As shown, the adjustment method includes the following steps: Step S1, in the air chamber assembly 2, as follows Figure 1 As shown, the detection system 1 detects the spot morphology of the light beam emitted from the fiber optic input light source 21 after passing through the alkali metal atom gas chamber 22 in real time. The position of the alkali metal atom gas chamber 22 is adjusted in real time by the adjustment mechanism. When the spot morphology is a Gaussian spot with highly concentrated but unevenly distributed light beam energy, the mounting frame 23 fixes the alkali metal atom gas chamber 22, that is, the alkali metal atom gas chamber 22 and the mounting frame 23 are fixedly connected together.

[0042] It should be noted that when the alkali metal atom gas chamber 22 moves together with the mounting frame 23, in one embodiment, the alkali metal atom gas chamber 22 can move relative to the mounting frame 23, that is, the alkali metal atom gas chamber 22 is not fixed to the mounting frame 23. Preferably, after the alkali metal atom gas chamber 22 is adjusted to the position, it is fixed to the mounting frame 23, that is, the alkali metal atom gas chamber 22 and the mounting frame 23 do not move relative to each other. This is to prevent the alkali metal atom gas chamber 22 from shifting on the mounting frame 23 and to ensure the reliability of the position of the alkali metal atom gas chamber 22. There are various ways to fix the alkali metal atom gas chamber 22. Non-magnetic screws or bolts can be used to fix the alkali metal atom gas chamber 22, or non-magnetic clips can be used to fix the alkali metal atom gas chamber 22. In this embodiment, the mounting frame 23 has a limiting hole for limiting the alkali metal atom gas chamber 22. The alkali metal atom gas chamber 22 is fixed to the mounting frame 23 by filling the limiting hole with glue and curing it.

[0043] Specifically, a detailed explanation will be given using two fiber optic input light sources 21 as an example. In the gas chamber assembly 2, the two fiber optic input light sources 21 are respectively mounted on corresponding fiber optic brackets 25. The transmission directions of the two fiber optic input light sources 21 are orthogonal to each other. The spot analyzers 11 in the two detection systems 1 can detect the spot morphology of each fiber optic input light source 21 after passing through the alkali metal atom gas chamber 22, and output the corresponding spot test parameters to the host computer 12.

[0044] If the morphologies of the two beams of light passing through the alkali metal atom gas cell 22 overlap, it indicates that the position of the alkali metal atom gas cell 22 is off, and its position needs to be adjusted. The position of the alkali metal atom gas cell 22 can be adjusted using an adjustment mechanism to prevent the two beams of light passing through it from overlapping, and to ensure that both beams exhibit high-quality Gaussian spots in the corresponding spot analyzer 11. This means the Gaussian spot energy is highly concentrated but unevenly distributed. At this point, the alkali metal atom gas cell 22 is properly adjusted. See [link to details] for further information. Figure 4 and Figure 5 As shown. The two spot analyzers 11 are the first spot analyzer 111 and the second spot analyzer 112, respectively. The spot morphology detected by the first spot analyzer 111 is shown in [reference needed]. Figure 4 The spot morphology detected by the second spot analyzer 112 is shown in [reference]. Figure 5 .

[0045] At this point, the alkali metal atom gas chamber 22 is properly positioned (i.e., adjusted to the correct position), and its position can be fixed, thus completing the assembly of the gas chamber assembly 2. It should be noted that the diameter of the two light spots can be 1.5 mm. If the alkali metal atom gas chamber 22 is not adjusted using the above method, the spot morphology quality detected by the two spot analyzers 11 is poor. (See [reference needed]). Figure 6 and Figure 7 As shown. The spot morphology detected by the first spot analyzer 111 is shown in [reference needed]. Figure 6 The spot morphology detected by the second spot analyzer 112 is shown in [reference]. Figure 7 .

[0046] It should be pointed out that, Figures 4-7 The two vertical dashed lines in the diagram represent the two directions defined by the corresponding spot analyzer 11, namely direction X and direction Y.

[0047] Step S2: Fix the optical lens 5 at a predetermined position on the base 3. Specifically, a limiting part for installing the optical lens 5 is provided at the predetermined position on the base 3. Illustratively, the optical lens 5 can be fixed to the limiting part by adhesive, or it can be fixed to the limiting part by clamping, such as by providing a clamping groove for holding the optical lens 5. It can be understood that directly fixing the optical lens 5 to the predetermined position on the base 3 allows for quick and accurate installation of the optical lens 5, overcoming the errors caused by traditional manual installation relying on operator experience, such as installation tilt and positional offset.

[0048] Step S3: Fix the fiber collimator 4 at the entrance of the base 3, and the optical lens 5 is located between the fiber collimator 4 and the alkali metal atom gas chamber 22. Specifically, during the installation of the fiber collimator 4, the fiber collimator 4 can be fixed at the entrance of the base 3, the laser (i.e., the fiber input light source 21) is turned on, and a Gaussian beam is output through the fiber collimator 4. The beam passes through the installed optical lens 5.

[0049] In addition, to ensure that the fiber collimator 4 has no pitch deviation, the spot shape modulated by the optical lens 5 is usually acquired in real time by the spot analyzer 11. Based on the spot analysis results, the spatial pose of the fiber collimator 4 is dynamically adjusted by the six-degree-of-freedom fine-tuning platform 31 until a Gaussian spot of good quality appears on the spot analyzer 11. At this time, the fiber collimator 4 is in a suitable position and is fixed at the entrance position of the base 3.

[0050] Then, in step S4, the assembled air chamber assembly 2 (i.e., the air chamber assembly 2 adjusted in step S1) is installed on the base 3. The aforementioned inlet position is located between the fiber optic input light source 21 and the optical lens 5, and is close to the corresponding fiber optic input light source 21.

[0051] It should be noted that an optical lens 5 and an optical fiber collimator 4 are provided between each optical fiber input light source 21 and the alkali metal atom gas chamber 22. That is, the light beam emitted from each optical fiber input light source 21 enters the alkali metal atom gas chamber 22 after passing through the corresponding optical fiber collimator 4 and optical lens 5 in sequence.

[0052] On the base 3, the fiber optic input light source 21, the fiber optic collimator 4, the optical lens 5, and the alkali metal atom gas cell 22 are all positioned to detect a Gaussian spot with good quality.

[0053] S5. The sensitivity of the magnetic field based on the alkali metal atom gas cell 22 is measured using the sensitivity detection unit 6. Specifically, the sensitivity detection unit 6 performs the magnetic field sensitivity measurement based on the alkali metal atom gas cell 22 inside the permalloy magnetic shielding barrel.

[0054] The sensitivity is improved when the position of the alkali metal atom gas cell 22 is adjusted using the above adjustment method compared to the unadjusted position. Thus, the improvement in sensitivity can be used to demonstrate the effectiveness of the adjustment method of this application in improving the transmission performance of the light beam in the alkali metal atom gas cell 22.

[0055] Since the size of the alkali metal atom gas cell 22 is 2mm to 20mm, the above-described device and adjustment method can improve the optical performance of the beam passing through the alkali metal atom gas cell 22 at the millimeter scale, such as obtaining a high-quality light spot morphology.

[0056] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0057] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the patent protection scope of this application should be determined by the appended claims.

Claims

1. A device for adjusting the transmission performance of a light beam in an alkali metal atom gas cell, characterized in that, The device includes a detection system (1) and a gas chamber assembly (2); The gas chamber assembly (2) includes an optical fiber input light source (21), an alkali metal atom gas chamber (22), a mounting frame (23), and an adjustment mechanism. The alkali metal atom gas chamber (22) is configured to be filled with alkali metal atoms and buffer gas. The alkali metal atom gas chamber (22) is connected to the adjustment mechanism through the mounting frame (23). The detection system (1) includes a detection element for detecting the spot morphology of the light beam emitted by the optical fiber input light source (21) after passing through the alkali metal atom gas chamber (22). The adjustment mechanism is configured to drive the mounting frame (23) to move. The alkali metal atom gas chamber (22) moves with the mounting frame (23) until the spot morphology is a Gaussian spot with highly concentrated but unevenly distributed light beam energy. There are two optical fiber input light sources (21), and the transmission directions of the two optical fiber input light sources (21) are orthogonal. Each optical fiber input light source (21) corresponds to one detection device. When the two light spots of the two optical fiber input light sources (21) pass through the alkali metal atom gas cell (22) at the same time, there is an overlap. Then the position of the alkali metal atom gas cell (22) is shifted. Then the position of the alkali metal atom gas cell (22) is adjusted by the adjustment mechanism until the two light beams passing through the alkali metal atom gas cell (22) at the same time do not overlap. Then the alkali metal atom gas cell (22) is adjusted into place.

2. The apparatus according to claim 1, characterized in that, The air chamber assembly (2) also includes an optical fiber bracket (25), with each optical fiber input light source (21) corresponding to one optical fiber bracket (25), and the optical fiber input light source (21) is mounted on the corresponding optical fiber bracket (25).

3. The apparatus according to claim 1, characterized in that, The adjustment mechanism is a three-dimensional displacement platform (24), and the alkali metal atom gas chamber (22) can move along the X, Y and Z directions under the drive of the three-dimensional displacement platform (24); And / or, the detection system (1) further includes a host computer (12), the detection device is a spot analyzer (11), and the host computer (12) is configured to receive the spot test parameters of the spot morphology output by the spot analyzer (11); And / or, the alkali metal atom gas chamber (22) is a cube or a cuboid, and the side length of the alkali metal atom gas chamber (22) is 2mm~20mm; And / or, the material of the alkali metal atom gas chamber (22) is high borosilicate silicon; And / or, the gas chamber assembly (2) further includes a heating element for heating the alkali metal atom gas chamber (22).

4. The apparatus according to claim 1, characterized in that, The device also includes a base (3), an optical fiber collimator (4), and an optical lens (5). The base (3) is a non-magnetic base (3). The gas chamber assembly (2), the optical fiber collimator (4), and the optical lens (5) are all located on the base (3). The optical fiber collimator (4) and the optical lens (5) are both located between the optical fiber input light source (21) and the alkali metal atom gas chamber (22). The optical fiber collimator (4) is used to collimate and output the light source generated by the optical fiber input light source (21). The optical lens (5) is used to adjust the beam emitted through the optical fiber collimator (4) unit. And / or, the base (3) is provided with a six-degree-of-freedom fine-tuning platform (31) for adjusting the position of the fiber collimator (4).

5. The apparatus according to any one of claims 1 to 4, characterized in that, The device further includes a sensitivity detection unit (6) which performs magnetic field sensitivity measurements based on the alkali metal atom gas cell (22).

6. A method for adjusting the transmission performance of a light beam in an alkali metal atom gas cell, characterized in that, The device is the device according to any one of claims 1 to 5, and the adjustment method includes the following steps: In the gas chamber assembly (2), the detection system (1) detects in real time the spot morphology of the light beam emitted by the fiber input light source (21) after passing through the alkali metal atom gas chamber (22), and adjusts the position of the alkali metal atom gas chamber (22) in real time through the adjustment mechanism. When the spot morphology is a Gaussian spot with highly concentrated but unevenly distributed light beam energy, the alkali metal atom gas chamber (22) is fixed by the mounting bracket (23).

7. The adjustment method according to claim 6, characterized in that, The method further includes: The optical lens (5) is fixed at a set position on the base (3) in the device; The fiber collimator (4) is placed at the entrance of the base (3), and the optical lens (5) is located between the fiber collimator (4) and the alkali metal atom gas cell (22). The gas chamber assembly (2) after fixing the alkali metal atom gas chamber (22) is fixed on the base (3). The inlet position is located between the fiber input light source (21) and the optical lens (5), and is close to the fiber input light source (21). The magnetic field sensitivity measurement based on the alkali metal atom gas cell (22) is performed using the sensitivity detection unit (6).

8. The adjustment method according to claim 7, characterized in that, The working temperature of the alkali metal atom gas chamber (22) is 120°~160°; And / or, the sensitivity detection unit (6) performs magnetic field sensitivity measurement based on the alkali metal atom gas cell (22) inside the permalloy magnetic shielding barrel.

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