A cooling optical path device suitable for an atomic gravimeter

Abstract

The utility model relates to atomic gravity meter technical field especially is applicable to cooling light path device of atomic gravity meter. The device includes vacuum cavity, reflection subassembly and first reflector, receives laser in vacuum cavity, and laser passes vacuum cavity in horizontal direction and first emission to reflection subassembly, and reflection subassembly will laser propagation direction from horizontal direction conversion to vertical direction, and secondly injects vacuum cavity, the top of vacuum cavity is provided with first reflector in horizontal direction, so that laser returns along the original light path and thirdly injects vacuum cavity, and laser passes vacuum cavity and emits to reflection subassembly again, and laser propagates along the original light path and makes the propagation direction from vertical direction conversion for horizontal direction, and fourthly injects vacuum cavity, wherein, the direction of laser twice horizontal injection vacuum cavity is opposite direction, and the direction of twice vertical injection vacuum cavity is opposite direction, to form two pairs of opposite laser, is used for cooling atom group, reduces the device quantity to realize miniaturization and reduces the light intensity demand.

Description

Technical Field

[0001] This utility model relates to the field of atomic gravimeter technology, and in particular to a cooling optical path device suitable for atomic gravimeters. Background Technology

[0002] To construct an atomic gravimeter system, three pairs of counter-projection lasers and a pair of anti-Helmholtz coils are needed to form a magneto-optical trap. The three pairs of counter-projection lasers include two pairs of horizontal counter-projection lasers and one pair of vertical counter-projection lasers, with the two pairs of horizontal counter-projection lasers arranged orthogonally.

[0003] The existing methods for fabricating two pairs of horizontally opposed lasers include the following two, see below. Figure 1 In the diagram, the arrows represent the direction of light propagation. Scheme 1 uses four collimators 901 arranged in a crosshair to form two opposing laser beams. Since the laser emitted from collimators 901 is generally linearly polarized, a quarter-wave plate 902 is needed to adjust the laser to left-hand circular polarization. A quarter-wave plate 902 is also set between each collimator 901 and the vacuum cavity 90. Because the collimator 901 is large in size, and the larger the spot required for the cooling optical path, the larger the size of the collimator 901 becomes, resulting in a large atomic gravimeter that cannot be miniaturized. In addition, assuming that the light intensity required for one cooling beam is 20mW, the total light intensity required by Scheme 1 is 80mW, which greatly increases the burden of light intensity.

[0004] See Figure 2In the diagram, the solid line represents the optical path of the laser entering the vacuum cavity 91, and the dashed line represents the optical path of the laser reflecting back to the vacuum cavity 91. The arrows indicate the direction of light propagation. Scheme 2 uses only one collimator 910, followed by a polarization beam splitter 911. The polarization beam splitter 911 splits the laser into two beams: a transmitted beam and a reflected beam. A quarter-wave plate 912 is positioned along the optical path propagation direction of the transmitted laser. After passing through the quarter-wave plate 912, the transmitted laser enters the vacuum cavity 91. On the opposite side, a quarter-wave plate 912 and a reflector 913 are sequentially positioned along the optical path propagation direction to complete optical path reflection and polarization state conversion, forming a pair of opposing laser beams. A half-wave plate 914 and a polarization beam splitter 911 are sequentially positioned along the optical path propagation direction of the reflected laser. After entering the polarization beam splitter 911, the reflected laser... The laser beam is reflected a second time. A half-wave plate 914 and a polarization beam splitter 911 are sequentially arranged along the propagation direction of the reflected light path. After the reflected laser enters the polarization beam splitter 911, it is reflected a third time. A quarter-wave plate 912 is arranged along the propagation direction of the reflected light path. The reflected laser passes through the quarter-wave plate 912, and the laser polarization state is converted to a left-handed circular polarization and enters the vacuum cavity 91. On the opposite side, a quarter-wave plate 912 and a reflector 913 are sequentially arranged along the propagation direction of the light path to complete the light path reflection and polarization state conversion, forming a second pair of opposing laser beams. The structure of the second scheme for horizontal light path fabrication is complex, and the large number of components inevitably increases the instability of the light path. In addition, assuming that the light intensity required for a cooling beam is 20mW, the total light intensity required for the second scheme is 40mW, which is still a large light intensity burden.

[0005] Therefore, overcoming the shortcomings of the existing technology is an urgent problem to be solved in this technical field. Utility Model Content

[0006] The technical problem to be solved by this utility model is that existing horizontal cooling optical path fabrication schemes have problems such as large size, inability to achieve device miniaturization, and large light intensity burden, or large number of devices and complex structure leading to optical path instability.

[0007] The present invention adopts the following technical solution: This invention provides a cooling optical path device suitable for an atomic gravimeter, comprising a vacuum cavity 1, a reflective component 2, and a first reflector 3; The vacuum cavity 1 receives a laser beam, which passes through the vacuum cavity 1 in a horizontal direction and is first emitted to the reflector 2. The reflector 2 converts the direction of laser propagation from horizontal to vertical and then enters the vacuum cavity 1 for the second time. A first reflector 3 is horizontally arranged above the vacuum cavity 1, so that the laser returns along the original optical path and enters the vacuum cavity 1 for the third time. The laser passes through the vacuum cavity 1 and exits again to the reflector 2. The laser propagates along the original optical path so that the propagation direction changes from the vertical direction to the horizontal direction, and enters the vacuum cavity 1 for the fourth time. The laser is incident on the vacuum cavity 1 horizontally twice in opposite directions, and vertically twice in opposite directions, to form two pairs of opposing laser beams for cooling atomic clusters 4.

[0008] Furthermore, the reflective component 2 includes a second reflector 20, a third reflector 21, and a fourth reflector 22, all of which are tilted so that the laser beam is reflected and propagated among them.

[0009] Furthermore, the second reflector 20 is set at a preset angle, so that after the laser is reflected by the second reflector 20, the laser propagation direction changes from the horizontal direction to the vertical direction and is emitted onto the third reflector 21 set below the second reflector 20.

[0010] Furthermore, the third reflector 21 is set at a preset angle, so that after the laser is reflected by the third reflector 21, the laser propagation direction changes from the vertical direction to the horizontal direction and is emitted onto the fourth reflector 22 set to the left of the third reflector 21.

[0011] Furthermore, the fourth reflector 22 is set at a preset angle, so that after the laser is reflected by the fourth reflector 22, the laser propagation direction changes from the horizontal direction to the vertical direction and is emitted into the vacuum cavity 1 set above the fourth reflector 22.

[0012] Furthermore, a second waveplate 7 is disposed between the fourth reflecting mirror 22 and the vacuum cavity 1. The second waveplate 7 is used to convert the laser polarization state into left-hand circular polarization and transmit it into the vacuum cavity 1.

[0013] Furthermore, a third waveplate 8 is disposed between the first reflector 3 and the vacuum cavity 1. The third waveplate 8 is used to convert the laser polarization state into left-hand circular polarization and transmit it into the vacuum cavity 1.

[0014] Furthermore, the second waveplate 7 and the third waveplate 8 are made of crystals with different thicknesses, so that the angle of change of the polarization direction of the laser is different.

[0015] Furthermore, the device also includes a collimator 5 disposed on one side of the vacuum cavity 1, which collimates the laser and initially incident it into the vacuum cavity 1.

[0016] Furthermore, a first waveplate 6 is disposed between the collimator 5 and the vacuum cavity 1. The first waveplate 6 is used to change the polarization state of the laser, so that the polarization state of the laser is changed to left-hand circular polarization.

[0017] The advantages of this invention are as follows: only one collimator is needed to achieve two pairs of horizontal laser beams, which reduces the size of the atomic gravimeter and facilitates the miniaturization of the device; the optical path scheme involves fewer components, has a simple structure, and high optical path stability; furthermore, the laser light intensity emitted by the collimator is only the intensity of a cooling light beam, which greatly reduces the demand for cooling light intensity. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments of this utility model will be briefly described below. Obviously, the drawings described below are merely some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of an existing cooling optical path device provided by this utility model; Figure 2 This is a schematic diagram of the structure of an existing cooling optical path device provided by this utility model; Figure 3 This is a schematic diagram of a cooling optical path device suitable for an atomic gravimeter provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of a reflective component and a vacuum cavity provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of a collimator and vacuum cavity provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of the structure of a collimator, a first wave plate, and a vacuum cavity provided in an embodiment of this utility model; Figure 7 This is a schematic diagram of the optical path of the first and second laser incident vacuum cavity provided by an embodiment of the present invention; Figure 8 This is a schematic diagram of the optical path of the third and fourth laser incident vacuum cavity provided in an embodiment of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0021] Unless the context otherwise requires, throughout the specification and claims, the term "comprising" is interpreted as openly inclusive, meaning "including, but not limited to." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemplary embodiment," "example," "specific example," or "some examples" are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this disclosure. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics mentioned may be included in any suitable manner in any one or more embodiments or examples; that is, although they may be incorporated into embodiments or examples using the above terms for reasons such as order and position, it does not limit them to be incorporated in combination by a single embodiment or example.

[0022] In the description of this utility model, 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 indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this disclosure, unless otherwise stated, "a plurality of" means two or more. Furthermore, for example, the description may use the prefix "A" or "B" to describe the same type of nouns as two independent entities. In this case, the features defined with "A" and "B" are used only to distinguish between similar entities and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features.

[0023] In describing some embodiments, the terms "coupled," "coupled," and "connected," and their derivative expressions, may be used. For example, the term "connected" may be used in describing some embodiments to indicate that two or more components have direct physical or electrical contact with each other. Similarly, the term "coupled" may be used in describing some embodiments to indicate that two or more components have direct physical or electrical contact. However, the terms "connected" or "coupled" may also refer to two or more components that do not have direct contact with each other but still cooperate or interact with each other, such as "optical coupling" or "wireless connection." The embodiments disclosed herein are not necessarily limited to the scope of this invention.

[0024] Furthermore, the technical features involved in the various embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0025] Example 1: Embodiment 1 of this utility model provides a cooling optical path device suitable for atomic gravimeters, see reference. Figure 3 The device includes a vacuum cavity 1, a reflecting component 2, and a first reflecting mirror 3. The vacuum cavity 1 receives a laser beam, which passes horizontally through the vacuum cavity 1 and exits for the first time to the reflecting component 2. The reflecting component 2 converts the laser propagation direction from horizontal to vertical, and the laser then enters the vacuum cavity 1 a second time. The first reflecting mirror 3 is horizontally positioned above the vacuum cavity 1, causing the laser to return along its original optical path and enter the vacuum cavity 1 a third time. The laser then passes through the vacuum cavity 1 and exits again to the reflecting component 2. The laser propagates along its original optical path, converting its propagation direction from vertical to horizontal, and then enters the vacuum cavity 1 a fourth time. The directions of the two horizontal laser beams entering the vacuum cavity 1 are opposite to each other, and the two vertical laser beams entering the vacuum cavity 1 are also opposite to each other, forming two pairs of opposing laser beams used to cool the atomic cluster 4.

[0026] Miniaturization is achieved by reducing the number of components required for the optical path fabrication scheme, thereby reducing the size of the atomic gravimeter. The reduction in the number of components also improves the stability of the optical path and greatly reduces the demand for cooling light intensity.

[0027] like Figure 3 As shown, Figure 3 The solid line represents the optical path of the laser entering vacuum cavity 1 for the first and second times, and the dashed line represents the optical path of the laser entering vacuum cavity 1 for the third and fourth times. The arrows indicate the direction of light propagation. It should be noted that... Figure 3 The non-overlapping of the two pairs of light paths in a two-way laser beam is merely for the convenience of describing the direction of light propagation; it does not represent the actual propagation path of the light. In reality, the light paths of two-way laser beams are completely overlapped, and... Figure 3 The optical path shown is only for the purpose of describing the present invention and is not intended to require the present invention to be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the present invention.

[0028] In one embodiment, the reflecting component 2 receives the first emitted laser beam, wherein the propagation direction of the laser beam is horizontal and perpendicular to the boundary of the vacuum cavity 1. The laser beam undergoes multiple reflections within the reflecting component 2, causing it to enter the vacuum cavity 1 perpendicularly from the other side of an adjacent vacuum cavity 1. The polarization directions of the laser beam entering the vacuum cavity 1 for the first and second times are consistent. A first reflecting mirror 3 is disposed on the opposite side of the second laser beam entry point. The first reflecting mirror 3 is parallel to the boundary of the vacuum cavity 1, ensuring that the propagation direction of the laser beam exiting the vacuum cavity 1 for the second time is perpendicular to the first reflecting mirror 3. The first reflecting mirror 3 can reflect the laser beam and allow it to enter the vacuum cavity 1 for the third time along the original optical path. In practical applications, the reflective surface of the first reflecting mirror 3 is coated with a high-reflectivity reflective film to achieve total internal reflection.

[0029] Due to the reversibility of the optical path, after the laser enters the vacuum cavity 1 for the third time, it will return to the reflective component 2 along the original optical path. After multiple reflections along the original optical path in the emitting component, it will return to the end from which it was first emitted and enter the vacuum cavity 1 for the fourth time along the original optical path. The polarization direction of the laser entering the vacuum cavity 1 for the four times is consistent. The optical paths of the two horizontal entries into the vacuum cavity 1 coincide but are opposite in direction, and the optical paths of the two vertical entries into the vacuum cavity 1 coincide but are opposite in direction, so as to form two pairs of cooling optical paths.

[0030] To form a beam path for directed projection, refer to... Figure 4 The reflecting component 2 includes a second reflecting mirror 20, a third reflecting mirror 21, and a fourth reflecting mirror 22. The second reflecting mirror 20, the third reflecting mirror 21, and the fourth reflecting mirror 22 are all tilted so that the laser is reflected and propagated among the three.

[0031] In one embodiment, the second reflector 20 is inclined at 45 degrees to one side of the vacuum cavity 1, and the fourth reflector 22 is inclined at 45 degrees to the other side of the vacuum cavity 1. The second reflector 20 and the fourth reflector 22 are parallel to each other. The third reflector 21 is perpendicular to the second reflector 20 and the fourth reflector 22 and is disposed between the second reflector 20 and the fourth reflector 22. This allows the laser to be reflected by the second reflector 20 to the third reflector 21 after it first exits the vacuum cavity 1. The third reflector 21 can reflect the laser to the fourth reflector 22, and the fourth reflector 22 can reflect the laser to a vertical direction and enter the vacuum cavity 1 a second time. In practical applications, the reflective surfaces of the second reflector 20, the third reflector 21, and the fourth reflector 22 are all coated with a high-reflectivity reflective film to achieve total internal reflection.

[0032] To change the direction of the light path, please refer to [further details]. Figure 4The second reflector 20 is set at a preset angle, so that after the laser is reflected by the second reflector 20, the direction of laser propagation changes from horizontal to vertical and is emitted onto the third reflector 21 set below the second reflector 20.

[0033] In one embodiment, since the angle between the second reflector 20 and the vacuum cavity 1 is 45 degrees, the light path of the laser initially exiting the vacuum cavity 1 is horizontal. As a result, after the laser is reflected by the second reflector 20, the light path of the laser changes from horizontal to vertical and exits to the third reflector 21.

[0034] Continue reading Figure 4 Furthermore, the third reflector 21 is set at a preset angle, so that after the laser is reflected by the third reflector 21, the laser propagation direction changes from the vertical direction to the horizontal direction and is emitted onto the fourth reflector 22 set to the left of the third reflector 21.

[0035] In one embodiment, since the third reflector 21 is perpendicular to the second reflector 20, the angle between the laser and the third reflector 21 when the laser is incident on the third reflector 21 is 45 degrees, so that after the laser is reflected by the third reflector 21, the laser's optical path changes from the vertical direction to the horizontal direction and exits to the fourth reflector 22.

[0036] Continue reading Figure 4 Furthermore, the fourth reflector 22 is set at a preset angle, so that after the laser is reflected by the fourth reflector 22, the laser propagation direction changes from the horizontal direction to the vertical direction and is emitted into the vacuum cavity 1 set above the fourth reflector 22.

[0037] In one embodiment, since the fourth reflector 22 is perpendicular to the third reflector 21, the angle between the laser and the fourth reflector 22 when the laser is incident on the fourth reflector 22 is 45 degrees, so that after the laser is reflected by the fourth reflector 22, the laser's optical path changes from the horizontal direction to the vertical direction and exits into the vacuum cavity 1.

[0038] See Figure 5To ensure that the laser light initially incident on the vacuum cavity 1 is collimated, the device further includes a collimator 5 disposed on one side of the vacuum cavity 1. The collimator 5 collimates the laser light and initially incidents it on the vacuum cavity 1. In this embodiment, only one collimator 5 is needed to achieve two pairs of horizontal laser beams. The laser light intensity emitted by the collimator 5 is only the intensity of a single cooling light beam. Assuming that the intensity required for a single cooling light beam is 20mW, the total light intensity required in this embodiment is 20mW, greatly reducing the demand for cooling light intensity. The collimator 5 is disposed on the opposite side of the second reflector 20, and the collimator 5 is parallel to a set of sides of the vacuum cavity 1, so that the laser light initially incident on the second reflector 20 when it exits the vacuum cavity 1.

[0039] See Figure 6 In an atomic gravimeter system, the laser used for cooling the optical path must be incident on the vacuum cavity 1 with a left-handed circular polarization. To adjust the polarization direction of the laser, a first waveplate 6 is disposed between the collimator 5 and the vacuum cavity 1. The first waveplate 6 is used to change the polarization state of the laser, so that the polarization state of the laser changes to left-handed circular polarization. In one embodiment, the first waveplate 6 is set as a quarter-wave plate. The collimated laser is incident perpendicularly on the first waveplate 6, and the polarization state of the laser changes to left-handed circular polarization and is incident on the vacuum cavity 1 for the first time.

[0040] See Figure 7 Furthermore, a second waveplate 7 is disposed between the fourth reflecting mirror 22 and the vacuum cavity 1. The second waveplate 7 is used to convert the polarization state of the laser into a left-handed circular polarization and transmit it into the vacuum cavity 1. In one embodiment, after the laser exits the vacuum cavity 1 for the first time, it enters the second reflecting mirror 20. Since the angle between the second reflecting mirror 20 and the laser is 45 degrees, the polarization state of the laser is converted to a right-handed circular polarization when the laser exits the second reflecting mirror 20. Since the angle between the laser and the third reflecting mirror 21 and the fourth reflecting mirror 22 is 45 degrees when the laser enters them, the polarization state of the laser is converted to a right-handed circular polarization after two conversions and is perpendicularly incident on the second waveplate 7. The second waveplate 7 is set as a half-waveplate. The laser passes perpendicularly through the second waveplate 7, and the polarization state of the laser is converted to a left-handed circular polarization and enters the vacuum cavity 1 for the second time.

[0041] Continue reading Figure 7 Furthermore, a third waveplate 8 is disposed between the first reflector 3 and the vacuum cavity 1. The third waveplate 8 is used to convert the laser polarization state into left-hand circular polarization and transmit it to the vacuum cavity 1.

[0042] In one embodiment, the laser exits the vacuum cavity 1 for the second time and is perpendicularly incident on the third waveplate 8. After being reflected by the first reflecting mirror 3, the laser is again perpendicularly incident on the third waveplate 8. The third waveplate 8 is set as a quarter-wave plate. Due to the reciprocity of the third waveplate 8, the polarization state of the laser remains unchanged after passing through the third waveplate 8 twice. The laser is then incident on the vacuum cavity 1 for the third time with a left-handed circular polarization state.

[0043] Because the angles between the first reflecting mirror 3 and the fourth reflecting mirror 22 and the vacuum cavity 1 are different, and the second waveplate 7 and the third waveplate 8 are made of crystals with different thicknesses, the angles at which the polarization direction of the laser changes are different. In one embodiment, the second waveplate 7 is set as a half-waveplate, and the third waveplate 8 is set as a quarter-waveplate, so that when the laser passes through the second waveplate 7 and the third waveplate 8, the polarization state can be converted into a left-handed circular polarization to enter the vacuum cavity 1 and form a cooling optical path.

[0044] Example 2: Based on the optical paths of the first and second laser incident on vacuum cavity 1 described in Embodiment 1, Embodiment 2 of this utility model provides a detailed description of the optical paths of the third and fourth laser incident on vacuum cavity 1.

[0045] See Figure 8 In one embodiment, after being reflected by the first reflector 3, the laser returns to the fourth reflector 22 along the original optical path. Specifically, the laser is perpendicularly incident on the third waveplate 8 and enters the vacuum cavity 1 for the third time with a left-hand circular polarization state. The laser exits the vacuum cavity 1 for the third time and is perpendicularly incident on the second waveplate 7. After passing through the second waveplate 7, the laser polarization state is converted to a right-hand circular polarization state and enters the fourth reflector 22.

[0046] Continue reading Figure 8 In one embodiment, after the laser enters the fourth reflecting mirror 22, it will return to the second reflecting mirror 20 along the original optical path. Specifically, since the fourth reflecting mirror 22 and the third reflecting mirror 21 are perpendicular to each other, the angle between the laser entering the fourth reflecting mirror 22 and the fourth reflecting mirror 22 is 45 degrees. This causes the laser to be reflected by the fourth reflecting mirror 22, and the laser's optical path changes from the vertical direction to the horizontal direction, and then exits to the third reflecting mirror 21.

[0047] Furthermore, since the third reflector 21 and the fourth reflector 22 are perpendicular to each other, the angle between the laser and the third reflector 21 when the laser is incident on the third reflector 21 is 45 degrees. This causes the laser light path to change from the horizontal direction to the vertical direction after being reflected by the third reflector 21, and then exit to the second reflector 20.

[0048] Furthermore, since the second reflector 20 and the third reflector 21 are perpendicular to each other, the angle between the laser and the second reflector 20 when the laser is incident on the second reflector 20 is 45 degrees. This causes the laser's optical path to change from vertical to horizontal after being reflected by the second reflector 20, and the laser's polarization state to change to left-handed circular polarization after three reflections and then incident on the vacuum cavity 1 for the fourth time.

[0049] With the aforementioned device, the horizontal optical paths of the laser entering the vacuum cavity 1 for the first and fourth times coincide but are opposite in direction, and the vertical optical paths of the laser entering the vacuum cavity 1 for the second and third times coincide but are opposite in direction, thus forming two pairs of cooling optical paths; the optical path scheme involves only one collimator, which greatly reduces the volume of the atomic gravimeter and reduces the requirement for cooling light intensity.

[0050] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A cooling optical path device suitable for an atomic gravimeter, characterized in that, It includes a vacuum cavity (1), a reflective assembly (2), and a first reflector (3); The vacuum cavity (1) receives a laser beam. The laser beam passes through the vacuum cavity (1) in a horizontal direction and is emitted to the reflector (2) for the first time. The reflector (2) changes the direction of laser beam propagation from horizontal to vertical and then enters the vacuum cavity (1) for the second time. A first reflector (3) is horizontally arranged above the vacuum cavity (1), so that the laser returns along the original optical path and enters the vacuum cavity (1) for the third time. The laser passes through the vacuum cavity (1) and exits again to the reflector (2). The laser propagates along the original optical path so that the propagation direction changes from the vertical direction to the horizontal direction and enters the vacuum cavity (1) for the fourth time. The laser is incident horizontally into the vacuum cavity (1) twice in opposite directions, and vertically into the vacuum cavity (1) twice in opposite directions, to form two pairs of opposing laser beams for cooling atomic clusters (4).

2. The cooling optical path device for an atomic gravimeter according to claim 1, characterized in that, The reflective assembly (2) includes a second reflector (20), a third reflector (21) and a fourth reflector (22). The second reflector (20), the third reflector (21) and the fourth reflector (22) are all tilted so that the laser is reflected and propagated among the three.

3. The cooling optical path device for an atomic gravimeter according to claim 2, characterized in that, The second reflector (20) is set at a preset angle so that after the laser is reflected by the second reflector (20), the direction of laser propagation changes from horizontal to vertical and is emitted onto the third reflector (21) set below the second reflector (20).

4. The cooling optical path device for an atomic gravimeter according to claim 3, characterized in that, The third reflector (21) is set at a preset angle so that after the laser is reflected by the third reflector (21), the direction of laser propagation changes from vertical to horizontal and is emitted onto the fourth reflector (22) set to the left of the third reflector (21).

5. The cooling optical path device for an atomic gravimeter according to claim 4, characterized in that, The fourth reflector (22) is set at a preset angle so that after the laser is reflected by the fourth reflector (22), the laser propagation direction changes from the horizontal direction to the vertical direction and is emitted into the vacuum cavity (1) set above the fourth reflector (22).

6. The cooling optical path device for an atomic gravimeter according to claim 2, characterized in that, A second waveplate (7) is disposed between the fourth reflector (22) and the vacuum cavity (1). The second waveplate (7) is used to convert the laser polarization state into left-hand circular polarization and transmit it to the vacuum cavity (1).

7. The cooling optical path device for an atomic gravimeter according to claim 6, characterized in that, A third waveplate (8) is provided between the first reflector (3) and the vacuum cavity (1). The third waveplate (8) is used to convert the laser polarization state into left-hand circular polarization and transmit it to the vacuum cavity (1).

8. The cooling optical path device for an atomic gravimeter according to claim 7, characterized in that, The second waveplate (7) and the third waveplate (8) are set as crystals with different thicknesses, so that the angle of change of the polarization direction of the laser is different.

9. The cooling optical path device for an atomic gravimeter according to claim 1, characterized in that, It also includes a collimator (5) disposed on one side of the vacuum cavity (1), which collimates the laser and first incident it into the vacuum cavity (1).

10. The cooling optical path device for an atomic gravimeter according to claim 9, characterized in that, A first waveplate (6) is provided between the collimator (5) and the vacuum cavity (1). The first waveplate (6) is used to change the polarization state of the laser, so that the polarization state of the laser is changed to left-hand circular polarization.

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