High aspect ratio light beam generation device for atom interference
By combining optical elements such as fiber collimators and deformable prisms, high aspect ratio beams were generated, solving the problems of low energy utilization and severe diffraction effects in existing technologies, and improving the measurement accuracy and stability of atomic interferometers.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-23
- Publication Date
- 2026-04-03
Smart Images
Figure CN121784981A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of quantum precision measurement technology, and more specifically to a high aspect ratio beam generating device for atomic interference. Background Technology
[0002] As an advanced quantum precision measurement tool, the atomic interferometer demonstrates enormous application potential in fields such as inertial navigation, resource exploration, geophysics, and fundamental physics research due to its high precision and long-term stability. The physical basis of atomic interferometry is the interaction between Raman laser pulses and atoms (usually atomic beams), achieving interference effects by manipulating the internal population of the atoms. In this process, the contrast of the atomic interference fringes directly determines the measurement accuracy, and the level of contrast greatly depends on the efficiency of the interaction between the atoms and the Raman light field.
[0003] However, achieving high-efficiency interaction in atomic beam-based interferometers faces two key challenges: First, the atomic beam exhibits a certain velocity distribution along the Raman light propagation direction, causing atoms at different velocities to experience different Doppler detunings, thus reducing the overall efficiency of Raman transitions; Second, commonly used Raman laser spots have a Gaussian distribution, while the atomic beam has a specific spatial size in a plane perpendicular to its direction of motion. This results in atoms at different transverse positions of the atomic beam experiencing inconsistent light intensities, leading to uneven atomic transition probabilities and ultimately causing a decrease in the contrast of the interference fringes.
[0004] To solve the above problems, precise wavefront shaping of the Raman beam is necessary. Ideal beam shaping must meet three stringent conditions simultaneously: (1) In the direction of atomic beam motion (e.g., the X-axis), the beam must be compressed to the order of hundreds of micrometers to match the sheet-like shape of the atomic beam and enhance the interaction intensity; (2) In the transverse direction perpendicular to the atomic beam motion (e.g., the Y-axis), the beam must be fully expanded so that its spot size is much larger than the size of the atomic beam, thereby ensuring that the atoms in the entire atomic beam cross section experience uniform light intensity; (3) The beam must also be constructed into a through-beam configuration that can strictly return along the original path, and the waist of the reflected beam must be precisely coincident with the waist of the incident beam to form a high-quality standing wave field, which is a prerequisite for achieving high-precision atomic interference.
[0005] Currently, the conventional technique for beam shaping is the use of an aperture. This method allows the laser beam to pass through an aperture with a specific shape and size, achieving the desired energy distribution by blocking unwanted portions of the beam. However, this blocking-based principle has inherent and serious drawbacks: extremely low energy utilization, with most of the light energy wasted due to obstruction by the aperture. This not only places excessive demands on the output power of the pre-stage laser but also increases the system's power consumption and thermal management burden. Furthermore, when the aperture size is comparable to the laser wavelength, it induces significant diffraction effects, damaging the beam wavefront quality and making the final beam shape uncontrollable, failing to meet the high beam quality requirements of atomic interference.
[0006] Therefore, there is an urgent need in this field for a new beam generating device that can efficiently generate Raman beams with high aspect ratio, controllable spot shape, and precise alignment of the incident and reflected beam waists without relying on aperture blocking, so as to fundamentally overcome the problems of large energy loss, severe diffraction effect and insufficient alignment accuracy of existing technologies. Summary of the Invention
[0007] In view of the problems of low energy utilization, severe diffraction effect and poor beam alignment accuracy in the existing technology, the present invention provides a high aspect ratio beam generation device for atomic interference that is compact, stable and has high energy utilization.
[0008] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: The present invention provides a high aspect ratio beam generating device for atomic interference, comprising a laser, an optical fiber collimator, a pair of deformable prisms, a first plano-convex cylindrical lens, a second plano-convex cylindrical lens, and a plane mirror; The laser is connected to the fiber collimator via an optical fiber; The fiber collimator, the deformable prism pair, the first plano-convex cylindrical lens, the second plano-convex cylindrical lens, and the plane mirror are arranged sequentially along the optical path; wherein the centers of the first plano-convex cylindrical lens, the second plano-convex cylindrical lens, and the plane mirror are located on the same optical axis. The laser emitted from the laser is collimated by the fiber collimator to form a Gaussian beam; the deformable prism is used to unidirectionally expand the Gaussian beam in a first direction; the first plano-convex cylindrical lens is used to focus the expanded beam in a second direction to form a high aspect ratio spot; the second plano-convex cylindrical lens is used to collimate the focused beam; the plane mirror is used to reflect the collimated beam, so that the reflected beam returns along the original optical path and is refocused by the second plano-convex cylindrical lens, so that the reflected beam coincides with the beam waist of the incident beam to form a standing wave beam. The first direction is orthogonal to the second direction.
[0009] Furthermore, based on the above scheme, the laser is a Raman laser.
[0010] Furthermore, the diameter of the beam emitted from the fiber collimator The following relationship must be satisfied:
[0011] Where λ is the laser wavelength. The mode field diameter of the optical fiber is denoted as . This is the focal length of the fiber optic collimator.
[0012] Furthermore, the deformable prism pair includes two deformable prisms arranged at a preset angle, and the beam expansion ratio of the deformable prism pair in the first direction is [missing information]. ; in, Let θ be the magnification of a single deformable prism, n be the refractive index of the prism material, and θ be the prism apex angle.
[0013] Furthermore, the magnification of a single deformable prism for the beam in a plane for:
[0014] in, The width of the beam incident on the deformable prism. The width of the beam cross-section emitted from the deformable prism.
[0015] Furthermore, the focal length of the first plano-convex cylindrical lens is The diameter of the light spot focused by the first plano-convex cylindrical lens in the second direction is It satisfies the following relationship:
[0016] in, λ is the beam quality factor of the laser, λ is the laser wavelength, and D is the incident beam width.
[0017] Furthermore, the aspect ratio of the high aspect ratio spot formed by the first plano-convex cylindrical lens focusing the expanded beam in the second direction is not less than 156:1.
[0018] Furthermore, the convex surface of the second plano-convex cylindrical lens is positioned facing the laser.
[0019] Furthermore, the distance from the second plano-convex cylindrical lens to the focused spot is equal to the distance from the first plano-convex cylindrical lens to the focused spot.
[0020] Furthermore, the surface flatness of the planar reflector is better than λ / 10, and it is coated with a high-reflectivity film corresponding to the laser wavelength, where λ is the laser wavelength.
[0021] Compared with the prior art, the technical solution of this application has the following beneficial technical effects: The high aspect ratio beam generating device for atomic interference provided in this application achieves efficient redistribution of beam energy, rather than simple rejection, through unidirectional beam expansion in the first direction using a deformable prism and independent focusing in the second direction using a first plano-convex cylindrical lens. This fundamentally avoids energy loss caused by obstruction and wavefront distortion caused by pinhole diffraction, thus resolving the inherent contradiction between energy efficiency and beam quality. Specifically, it includes: 1. High system stability: By using an optical fiber collimator as the laser input interface, the mechanical vibration and temperature fluctuation of the front-end laser are effectively isolated from the interference of the subsequent optical path, thereby significantly improving the long-term operational stability and anti-environmental interference capability of the entire device.
[0022] 2. Compact and reliable structure: The core of the optical path of the device consists of only a few stable optical elements (such as deformable prism pairs, cylindrical lenses, etc.), and the overall structure is simple, which not only reduces the complexity of the system and the difficulty of assembly and adjustment, but also enhances mechanical stability and reliability.
[0023] 3. Precise and controllable beam shaping: Through the synergistic effect of deformable prisms and plano-convex cylindrical lenses, independent and precise control of the beam in two orthogonal dimensions (one-dimensional beam expansion and one-dimensional focusing) is achieved, which can efficiently generate Raman beams with preset high aspect ratios; it can flexibly output light spots with different aspect ratios, and the controllability of the light spot shape is excellent, which can meet diverse application needs.
[0024] 4. High adjustment tolerance and ease of use: Since the plane mirror reflects a parallel beam of light collimated by the second plano-convex cylindrical lens, changes in the axial distance between the mirror and the lens will not affect the final imaging quality of the reflected light spot. This characteristic gives users great flexibility in adjustment and reduces the difficulty of system installation and maintenance.
[0025] Compared with the method of beam shaping using apertures, the present invention adopts the principle of unobstructed active optical transformation, which avoids laser energy loss caused by obstruction, significantly improves energy utilization efficiency, reduces dependence on high-power lasers, and is conducive to the miniaturization and low power consumption of the equipment. Attached Figure Description
[0026] To more clearly illustrate the technical solution of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0027] Figure 1 This is a schematic diagram of the optical path structure of a high aspect ratio beam generating device according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the beam-expanding principle of a pair of deformable prisms in one embodiment of the present invention; Figure 3 This is a schematic diagram of the shape of the incident light spot at the focal point and its two-dimensional light intensity distribution in the X and Y directions, according to an embodiment of the present invention. Figure 3 (a) is the spot where the incident light focuses; Figure 3 (b) is a two-dimensional light intensity distribution diagram of the X-direction section at the incident light spot; Figure 3 (c) is a two-dimensional light intensity distribution diagram of the Y-direction section at the incident light spot; Figure 4 This is a schematic diagram of the shape of the reflected light spot at the focal point and its two-dimensional light intensity distribution in the X and Y directions, according to an embodiment of the present invention; wherein... Figure 4 (a) is the spot where the reflected light is focused; Figure 4 (b) is a two-dimensional light intensity distribution diagram of the X-direction section at the reflected light spot; Figure 4 (c) is a two-dimensional light intensity distribution diagram of the Y-direction section at the reflected light spot; Explanation of the labels in the diagram: 01. Laser; 02. Fiber optic collimator; 03. Deformation prism pair; 04. First plano-convex cylindrical lens; 05. Second plano-convex cylindrical lens; 06. Plane mirror. Detailed Implementation
[0028] The specific embodiments of the present invention will be described in detail below. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of protection of the present invention.
[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.
[0030] The present invention provides a high aspect ratio beam generating device for atomic interference, comprising a laser 01, an optical fiber collimator 02, a pair of deformable prisms 03, a first plano-convex cylindrical lens 04, a second plano-convex cylindrical lens 05, and a plane mirror 06. Laser 01 is connected to fiber collimator 02 via optical fiber.
[0031] The diameter of the beam emitted from fiber collimator 02 The following relationship must be satisfied:
[0032] Where λ is the laser wavelength. The mode field diameter of the optical fiber is denoted as . This is the focal length of fiber optic collimator 02.
[0033] Preferably, laser 01 is a Raman laser 01.
[0034] Specifically, the Raman laser 01 operates at a wavelength of 852 nm and has a beam quality factor M² of 1.1. Its emitted laser beam is input to the fiber collimator 02 via a single-mode fiber (mode field diameter D0 is 5.5 ± 0.5 μm). The focal length f0 of the fiber collimator 022 is 11 mm. According to the formula D0′ = (λ f0) / (π D0), the diameter D0′ of its emitted collimated Gaussian beam is approximately 2.16 mm, and the divergence angle is 0.25 mrad.
[0035] The fiber collimator 02, the deformable prism pair 03, the first plano-convex cylindrical lens 04, the second plano-convex cylindrical lens 05, and the plane mirror 06 are arranged sequentially along the optical path; wherein the centers of the first plano-convex cylindrical lens 04, the second plano-convex cylindrical lens 05, and the plane mirror 06 are located on the same optical axis.
[0036] The laser emitted from laser 01 is collimated by fiber collimator 02 to form a Gaussian beam.
[0037] The beam emitted from Raman laser 01 is coupled into fiber collimator 02 via fiber optic coupling. When the waist of the incident Gaussian beam is located at the back focal plane of fiber collimator 02, the size of the waist of the emitted Gaussian beam will reach its maximum value, and the collimation effect of the Gaussian beam is optimal at this time.
[0038] The deformable prism pair 03 is used to unidirectionally expand the Gaussian beam in the first direction (YZ plane); the first plano-convex cylindrical lens 04 is used to focus the expanded beam in the second direction to form a high aspect ratio spot; the second plano-convex cylindrical lens 05 is used to collimate the focused beam; and the plane mirror 06 is used to reflect the collimated beam, causing the reflected beam to return along the original optical path and be refocused by the second plano-convex cylindrical lens 05, so that the reflected beam coincides with the beam waist of the incident beam, forming a standing wave beam; wherein, the first direction and the second direction are orthogonally arranged. In this embodiment, the first direction is the Y-axis direction, and the second direction is the X-axis direction.
[0039] By employing a deformable prism pair 03 and optimizing its physical parameters, the output beam can be made parallel to the input beam. In an optional embodiment, the deformable prism pair 03 includes two deformable prisms set at a preset angle. The beam expansion ratio of the deformable prism pair 03 in the first direction is [missing information]. ; in, Let θ be the magnification of a single deformable prism, n be the refractive index of the prism material, and θ be the prism apex angle.
[0040] Furthermore, the magnification of a single deformable prism for the beam in the plane is [missing information]. for:
[0041] in, The width of the beam incident on the deformable prism. The width of the beam cross-section emitted from the deformable prism.
[0042] Specifically, the collimated beam then enters the deformable prism pair 03, which consists of two identical prisms placed at a specific angle. The prism material has a refractive index n of 1.5 and a vertex angle θ of 15°. According to its magnification formula M(n,θ) = cosθ / cos[arcsin(n sinθ)] and beam expansion ratio [M(n,θ)]², this embodiment can achieve approximately 6 times beam expansion in the Y-axis direction (first direction). After beam expansion, the beam width in the Y-direction becomes approximately 12.96 mm, while the width in the X-direction (second direction) remains unchanged at 2.16 mm, forming an elliptical beam spot.
[0043] Furthermore, optionally, the focal length of the first plano-convex cylindrical lens 04 is... The diameter of the light spot focused by the first plano-convex cylindrical lens 04 in the second direction is... It satisfies the following relationship:
[0044] in, λ is the beam quality factor of laser 01, λ is the laser wavelength, and D is the incident beam width.
[0045] The aspect ratio of the high aspect ratio light spot formed by focusing the expanded beam of light in the second direction by the first plano-convex cylindrical lens 04 is not less than 156:1.
[0046] Specifically, the expanded beam is incident on the first plano-convex cylindrical lens 04 (its plane faces the laser 01). The focal length f1 of this lens is 150mm, used to focus the beam in the X-axis direction. According to the focused spot formula w0= (4 M² f1λ) / (π D), where D is the beam width in the X direction of 2.16mm, the calculated X-direction spot diameter w0 at the focal point is approximately 0.083mm.
[0047] At this point, the spot size in the Y direction remains 12.96 mm, thus forming a high aspect ratio spot with an aspect ratio of approximately 156:1 (12.96 / 0.083) at the beam waist. The two-dimensional light intensity distribution diagrams of the incident light spot at the focal point and its cross-sections in the X and Y directions, obtained after calculation and simulation design, are shown below. Figure 3 .
[0048] The convex surface of the second plano-convex cylindrical lens 05 is positioned facing the laser 01; the distance from the second plano-convex cylindrical lens 05 to the focused spot is equal to the distance from the first plano-convex cylindrical lens 04 to the focused spot.
[0049] Specifically, the diverging beam continues to be transmitted to the second plano-convex cylindrical lens 05 (whose convex surface faces the laser 01). This lens also has a focal length of 150mm and is symmetrically placed with respect to the focusing spot with respect to the first plano-convex cylindrical lens 04, thereby collimating the diverging beam back into a parallel beam. After collimation, the beam width in the X direction is restored to 2.16mm, and in the Y direction it remains 12.96mm.
[0050] Furthermore, the surface flatness of the plane mirror 06 is better than λ / 10, and it is coated with a high-reflectivity film corresponding to the laser wavelength, where λ is the laser wavelength.
[0051] Specifically, the collimated parallel light is ultimately incident perpendicularly onto the plane mirror 06, whose surface flatness is better than λ / 10 and is coated with a dielectric film that highly reflects light at a wavelength of 852nm. The reflected light returns strictly along its original path, and after passing through the second plano-convex cylindrical lens 05 again, it is focused, with the focal point precisely coinciding with the focal point of the incident light, thus forming a high-quality Raman standing-wave beam. The shape of its reflected spot is consistent with that of the incident spot. The two-dimensional light intensity distribution diagrams of the reflected light spot at the focal point and its cross-sections in the X and Y directions, obtained through simulation design, are shown below. Figure 4 As shown.
[0052] In summary, the high aspect ratio beam generating device provided in this invention is not a simple improvement on existing technologies, but rather a completely new technical approach. It comprehensively and synergistically achieves high energy efficiency, high beam quality, high stability, and high ease of operation, with overall performance significantly superior to aperture-based beam shaping methods. This device can stably and reliably generate the ideal Raman light field required for atomic interferometry, providing crucial technical support for improving the measurement accuracy and practicality of atomic interferometers, and possesses promising application prospects and industrial value.
[0053] In the description of this specification, references to terms such as "specific example" or "some examples" refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example that are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.
[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A high aspect ratio beam generating device for atomic interference, characterized in that, It includes a laser, a fiber collimator, a pair of deformable prisms, a first plano-convex cylindrical lens, a second plano-convex cylindrical lens, and a plane mirror; The laser is connected to the fiber collimator via an optical fiber; The fiber collimator, the deformable prism pair, the first plano-convex cylindrical lens, the second plano-convex cylindrical lens, and the plane mirror are arranged sequentially along the optical path; wherein the centers of the first plano-convex cylindrical lens, the second plano-convex cylindrical lens, and the plane mirror are located on the same optical axis. The laser emitted from the laser is collimated by the fiber collimator to form a Gaussian beam; the deformable prism is used to unidirectionally expand the Gaussian beam in a first direction; the first plano-convex cylindrical lens is used to focus the expanded beam in a second direction to form a high aspect ratio spot; the second plano-convex cylindrical lens is used to collimate the focused beam; the plane mirror is used to reflect the collimated beam, so that the reflected beam returns along the original optical path and is refocused by the second plano-convex cylindrical lens, so that the reflected beam coincides with the beam waist of the incident beam to form a standing wave beam. The first direction is orthogonal to the second direction.
2. The apparatus according to claim 1, characterized in that, The laser is a Raman laser.
3. The apparatus according to claim 1, characterized in that, The diameter of the beam emitted from the fiber collimator The following relationship must be satisfied: Where λ is the laser wavelength. The mode field diameter of the optical fiber is denoted as . This is the focal length of the fiber optic collimator.
4. The apparatus according to claim 1, characterized in that, The deformable prism pair includes two deformable prisms arranged at a preset angle, and the beam expansion ratio of the deformable prism pair in the first direction is [missing information]. ; in, Let θ be the magnification of a single deformable prism, n be the refractive index of the prism material, and θ be the prism apex angle.
5. The apparatus according to claim 1, characterized in that, The magnification of a beam in a plane by a single deformable prism for: in, The width of the beam incident on the deformable prism. The width of the beam cross-section emitted from the deformable prism.
6. The apparatus according to claim 5, characterized in that, The focal length of the first plano-convex cylindrical lens is The diameter of the light spot focused by the first plano-convex cylindrical lens in the second direction is It satisfies the following relationship: in, λ is the beam quality factor of the laser, λ is the laser wavelength, and D is the incident beam width.
7. The apparatus according to claim 1, characterized in that, The first plano-convex cylindrical lens focuses the expanded beam in the second direction to form a high aspect ratio spot with an aspect ratio of not less than 156:
1.
8. The apparatus according to claim 1, characterized in that, The convex surface of the second plano-convex cylindrical lens is positioned facing the laser.
9. The apparatus according to claim 8, characterized in that, The distance from the second plano-convex cylindrical lens to the focused spot is equal to the distance from the first plano-convex cylindrical lens to the focused spot.
10. The apparatus according to claim 1, characterized in that, The surface flatness of the planar reflector is better than λ / 10, and it is coated with a high-reflectivity film corresponding to the laser wavelength, where λ is the laser wavelength.