Implementation method of light and small optical system of helium optical pump quantum magnetic measurement system

Abstract

The invention provides an implementation method for a light and small optical system of a helium optical pump quantum magnetic measurement system, and relates to the technical field of design and analysis of high-precision magnetic measurement optical systems, the light and small optical system mainly comprises a collimation optical system and a focusing optical system, the collimation optical system uses light emitted by a helium lamp or a laser as input, and the focusing optical system is used for focusing on the light and small optical system; parameters of the collimation optical system are designed by taking the sectional dimension of the atomic gas chamber and the length of the atomic gas chamber as constraints, so that the atomic gas chamber is filled with collimated light spots as much as possible, and light loss caused by incidence of light to the wall of the gas chamber in the process of penetrating through the atomic gas chamber is avoided, so that the signal amplitude of a magnetic resonance signal is ensured, and the measurement accuracy of the magnetic resonance signal is improved. The focusing optical system takes light penetrating through the atomic gas chamber as input, and the size of a photosensitive surface of the photoelectric detector as a constraint to design parameters of the focusing optical system, so that the size of a focused light spot is within the range of the photosensitive surface of the photoelectric detector, and full receiving of a photomagnetic detection signal is effectively realized.

Description

Technical Field

[0001] This invention relates to the field of high-precision magnetic measurement optical system design and analysis technology, and in particular to a method for realizing a lightweight optical system of a helium optical pump quantum magnetic measurement system. Background Technology

[0002] The helium optically pumped quantum magnetic field measurement system utilizes an optical field to manipulate the quantum state of helium atoms in a magnetic field. Through precise analysis of atomic energy levels, it achieves high-precision magnetic field measurement, forming an important component of quantum precision magnetic field measurement. Compared to other types of optically pumped quantum magnetic field measurement systems, the helium optically pumped quantum magnetic field measurement system has advantages such as high sensitivity and a large measurement bandwidth, and can be widely used in geophysical exploration, military reconnaissance, and biomedical research. The main working process of the helium optically pumped quantum magnetic field measurement system is as follows:

[0003] 1. Helium atoms in the atomic gas chamber transition to a metastable state under high-frequency excitation discharge, and then undergo Zeeman splitting in an external magnetic field, thus completing the preparation of the quantum state.

[0004] 2. By irradiating the helium atoms in the gas cell with collimated polarized light, the helium atoms in the metastable state absorb energy and undergo directional transitions, thereby changing the distribution of helium atoms between Zeeman levels and causing the atoms to become polarized.

[0005] 3. Polarized atoms undergo Larmor precession under the influence of an external magnetic field. When the frequency of the applied radio frequency field equals the Larmor precession frequency, magnetic resonance occurs, depolarizing the helium atoms and allowing them to reabsorb the light signal, thus altering the light intensity transmitted through the gas cell. This light signal is then focused onto a photodetector at the back end by a focusing optical system. The magnetic field is measured by detecting changes in the light signal.

[0006] As can be seen from the above process, in a helium optically pumped quantum magnetic measurement system, the atomic gas cell and the corresponding optical system have a crucial impact on the performance of the magnetic measurement system. Traditional optical system implementation methods have the following problems:

[0007] 1. Insufficient consideration was given to the matching between the collimated beam aperture and the atomic gas cell, resulting in a large optical system size or low utilization of helium atoms in the gas cell. Ideally, the magnetic measurement performance would be optimal when the collimated beam completely fills the entire gas cell, without wasting optical energy.

[0008] 2. Traditional helium-pumped quantum magnetic measurement systems use a single lens for collimation and focusing, which makes it difficult to achieve optimal beam collimation and a small focused spot size, resulting in low beam utilization. In this situation, to improve the system's signal-to-noise ratio, the following two solutions are often employed:

[0009] (1) Increasing the size of the atomic gas chamber and the receiving area of ​​the photodetector can improve the utilization rate of the beam, but this method will lead to an increase in the system volume and weight.

[0010] (2) Increase the power of the light source to increase the beam density and improve the signal-to-noise ratio of the magnetic resonance signal. However, this method will lead to an increase in system power consumption. At the same time, due to the increase in optical power, the heading difference of the magnetic measurement system will also be further increased.

[0011] Clearly, the two methods mentioned above limit the application of helium optical pump quantum magnetic measurement systems in scenarios with strict requirements for miniaturization and power consumption. Summary of the Invention

[0012] To address the application requirements and current challenges of lightweight helium optically pumped quantum magnetic measurement systems, this invention proposes a method for realizing a lightweight optical system for such systems. This method uses an atomic gas cell and a photodetector as constraints and fully considers the beam deflection caused by optical devices, achieving efficient beam utilization and a lightweight, miniaturized optical system design. The system boasts advantages of being lightweight, miniaturized, precise, and efficient, providing strong technical support for the application of lightweight, miniaturized, and low-power helium optically pumped quantum magnetic measurement systems.

[0013] The objective of this invention is achieved through the following technical solution:

[0014] This invention provides a method for implementing a lightweight optical system for a helium optically pumped quantum magnetic measurement system. The helium optically pumped quantum magnetic measurement system includes a light source, a collimating optical system, a polarization device, an atomic gas cell, a focusing optical system, and a photodetector.

[0015] The light source emits a beam of light covering the D0 line spectrum of helium atoms as needed, and the center of the light-emitting surface of the light source is located at the front focal point of the collimating optical system;

[0016] The parameters of the collimating optical system are designed with the cross-sectional dimensions and length of the atomic gas cell as constraints. The collimating optical system collimates the light input from the light source into parallel light that enters the polarization device.

[0017] The incident surface of the polarizing device is in close contact with the exit surface of the collimating optical system, and the exit surface of the polarizing device is in close contact with the incident surface of the atomic gas cell. The polarized light passing through the polarizing device enters the atomic gas cell.

[0018] The exit surface of the atomic gas cell is in close contact with the incident surface of the focusing optical system;

[0019] The focusing optical system parameters are designed with the photosensitive surface size of the photodetector as a constraint. The focusing optical system focuses the light beam passing through the atomic gas cell onto the photodetector at the back end.

[0020] The center of the photosensitive surface of the photodetector is located on the back focal plane of the focusing optical system. The size of the focused spot is within the range of the photosensitive surface of the photodetector, so as to effectively achieve full reception of the photomagnetic detection signal.

[0021] Optionally, the light source is a helium lamp or a laser.

[0022] Optionally, the collimating optical system adopts a two-piece spherical structure, and the parameters of the collimating optical system include the curvature radii of the four spheres, the thickness of the two optical lenses, the spacing between the two optical lenses, and the spacing between the optical lenses and the light source.

[0023] Optionally, the focusing optical system adopts a two-piece spherical structure, and the parameters of the focusing optical system include the curvature radii of the four spheres, the thickness of the two optical lenses, and the spacing between the two optical lenses.

[0024] Optionally, the collimating optical system is provided with a virtual receiving surface for analyzing the size of the collimated spot within the length range of the atomic gas cell.

[0025] Optionally, the focusing optical system is provided with a detection surface for analyzing the size of the light spot after focusing.

[0026] Compared with the prior art, the positive effects of the present invention are:

[0027] 1. This invention proposes a method for implementing a lightweight optical system for a helium-pumped quantum magnetic resonance system. The system mainly includes a collimating optical system and a focusing optical system. The collimating optical system uses light emitted from a helium lamp or laser as input. The parameters of the collimating optical system are designed with the cross-sectional dimensions and length of the atomic gas cell as constraints, ensuring that the collimated light spot fills the atomic gas cell as much as possible and that no light loss occurs due to light incident on the cell wall during transmission, thus guaranteeing the signal amplitude of the magnetic resonance signal. The focusing optical system uses the light after it has passed through the atomic gas cell as input. The parameters of the focusing optical system are designed with the photosensitive surface size of the photodetector as constraints, ensuring that the size of the focused light spot is within the range of the photosensitive surface of the photodetector, effectively achieving full reception of the photomagnetic resonance detection signal.

[0028] 2. This invention makes full use of the space between the collimating optical system and the focusing optical system. While ensuring sufficient space for optical assembly, the incident surface of the polarizing device is tightly attached to the exit surface of the collimating optical system, the exit surface of the polarizing device is tightly attached to the incident surface of the atomic gas cell, and the exit surface of the atomic gas cell should be tightly attached to the incident surface of the focusing optical system. The entire system has the advantages of being lightweight, miniaturized, precise, and efficient, providing strong technical support for the application of lightweight, miniaturized, and low-power helium optically pumped quantum magnetic measurement systems.

[0029] It should be understood that the description in the foregoing summary section is not intended to limit the key or essential features of the embodiments of the present invention, nor is it intended to restrict the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the helium optical pump quantum magnetic measurement system of the present invention;

[0032] Figure 2 This is a structural design diagram of the collimating optical system of the present invention;

[0033] Figure 3 This is a collimated spot diagram of the incident surface of the atomic gas cell;

[0034] Figure 4 This is a collimated spot diagram of the emission surface from the atomic gas cell;

[0035] Figure 5 This is a structural design diagram of the focusing optical system of the present invention;

[0036] Figure 6 This is a focused light spot pattern of the focusing optical system on the photodetector.

[0037] The accompanying drawings have illustrated specific embodiments of this disclosure, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concepts of this disclosure to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] The technical solution of the present invention will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0040] like Figure 1 As shown, the helium optically pumped quantum magnetic measurement system includes a light source 1, a collimating optical system 2, a polarization device 3, an atomic gas cell 4, a focusing optical system 5, and a photodetector 6. This embodiment of the invention provides a method for implementing a lightweight and compact optical system for the helium optically pumped quantum magnetic measurement system, including:

[0041] Light source 1 emits a light beam covering the spectrum of helium atom D0 line (1083.206nm) as required. The center of the light-emitting surface of light source 1 is located at the front focal point of collimating optical system 2. Light source 1 is a helium lamp or a laser.

[0042] Constrained by the cross-sectional dimensions and length of atomic gas cell 4 (which is cylindrical with a length of 25 mm and a base diameter of 16.2 mm), design the parameters of the collimating optical system. The main function of the collimating optical system is to achieve high-performance collimation of the emitted light from the light source, such as... Figure 2 As shown, the collimating optical system 2 is designed as a two-piece spherical structure. The parameters of the collimating optical system are shown in Table 1. In this table, surface number 0 represents the light source, surface numbers 1-4 represent the four optical surfaces of the collimating optical system, and surface number 5 is the virtual receiving surface, which is used to analyze the size of the collimated spot within the length range of the atomic gas cell.

[0043] Table 1. Specific parameters of the collimating optical system

[0044] Face order face shape Radius of curvature (unit: mm) Thickness / Gap (unit: mm) 0 — — 22.90 1 spherical -22.83 3.39 2 spherical -18.81 1.05 3 spherical -158.14 3.37 4 spherical -61.48 1 5 — — 0

[0045] The collimating optical system 2 collimates the light input from the light source 1 into parallel light, so that the collimated light spot fills the atomic gas cell 4. The collimated polarized light is used to irradiate the helium atoms in the gas cell, causing the metastable helium atoms to absorb energy and undergo directional transitions, thereby changing the distribution of helium atoms between Zeeman energy levels, causing the atoms to become polarized, and no light loss occurs due to light incident on the gas cell wall during the transmission process.

[0046] Evaluate the size of the collimated light spot. Figure 3 and Figure 4 The images show the collimated spot size at the incident and exit surfaces of the atomic gas cell, with RMS spot diameters of 16.13 mm and 16.10 mm, respectively. From these two images, it can be seen that within the length of the atomic gas cell, the collimated spot size is within the cell's range and close to its cross-sectional dimensions.

[0047] To ensure the system is lightweight and compact, the space between the collimating optical system 2 and the focusing optical system 5 is fully utilized. While ensuring the space for optical assembly and adjustment, the incident surface of the polarizing device 3 is close to the exit surface of the collimating optical system 2, the exit surface of the polarizing device 3 is close to the incident surface of the atomic gas cell 4, and the exit surface of the atomic gas cell 4 is close to the incident surface of the focusing optical system 5.

[0048] Using the photosensitive surface size of photodetector 6 as a constraint, and employing a small F-number and short focal length design, the parameters of the focusing optical system are designed. The main function of the focusing optical system is to focus the light beam passing through atomic gas cell 4 onto the photodetector 6 at the rear, ensuring that the size of the focused light spot is within the range of the photosensitive surface of photodetector 6, thereby effectively achieving the reception of photomagnetic detection signals. Figure 5 As shown, the focusing optical system 5 is designed as a two-piece spherical structure. The parameters of the focusing optical system are shown in Table 2. Among them, surface number 1-4 represents the four optical surfaces of the focusing optical system, and surface number 5 represents the detection surface, which is used to analyze the size of the light spot after focusing.

[0049] Table 2 Specific parameters of the focusing optical system

[0050]

[0051] To ensure optimal light reception, the center of the photosensitive surface of the photodetector 6 is located on the back focal plane of the focusing optical system 5, and the size of the focused light spot is within the range of the photosensitive surface of the photodetector 6, so as to effectively achieve full reception of the optical-magnetic detection signal.

[0052] Figure 6 To focus the optical system on the photodetector, its RMS spot size is 0.005672 mm, which is much smaller than the photosensitive surface size of current mature photodetectors, thus effectively achieving full reception of optical and magnetic detection signals.

[0053] 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 or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for implementing a lightweight optical system for a helium optically pumped quantum magnetic measurement system, wherein the helium optically pumped quantum magnetic measurement system includes a light source, a collimating optical system, a polarization device, an atomic gas cell, a focusing optical system, and a photodetector, characterized in that... include: The light source emits a beam of light covering the D0 line spectrum of helium atoms as needed, and the center of the light-emitting surface of the light source is located at the front focal point of the collimating optical system; The parameters of the collimating optical system are designed with the cross-sectional dimensions and length of the atomic gas cell as constraints. The collimating optical system collimates the light input from the light source into parallel light that enters the polarization device. The incident surface of the polarizing device is in close contact with the exit surface of the collimating optical system, and the exit surface of the polarizing device is in close contact with the incident surface of the atomic gas cell. The polarized light passing through the polarizing device enters the atomic gas cell. The exit surface of the atomic gas cell is in close contact with the incident surface of the focusing optical system; The focusing optical system parameters are designed with the photosensitive surface size of the photodetector as a constraint. The focusing optical system focuses the light beam passing through the atomic gas cell onto the photodetector at the back end. The center of the photosensitive surface of the photodetector is located on the back focal plane of the focusing optical system. The size of the focused spot is within the range of the photosensitive surface of the photodetector, so as to effectively achieve full reception of the photomagnetic detection signal.

2. The method for implementing a lightweight optical system for a helium optical pump quantum magnetic measurement system according to claim 1, characterized in that, The light source is a helium lamp or a laser.

3. The method for implementing a lightweight optical system for a helium optical pump quantum magnetic measurement system according to claim 1, characterized in that, The collimating optical system adopts a two-piece spherical structure. The parameters of the collimating optical system include the curvature radius of the four spherical surfaces, the thickness of the two optical lenses, the spacing between the two optical lenses, and the spacing between the optical lenses and the light source.

4. The method for implementing a lightweight optical system for a helium optical pump quantum magnetic measurement system according to claim 1, characterized in that, The focusing optical system adopts a two-piece spherical structure. The parameters of the focusing optical system include the curvature radius of the four spherical surfaces, the thickness of the two optical lenses, and the spacing between the two optical lenses.

5. The method for implementing a lightweight optical system for a helium optical pump quantum magnetic measurement system according to claim 3, characterized in that, The collimating optical system is equipped with a virtual receiving surface at the rear, which is used to analyze the size of the collimated spot within the length range of the atomic gas cell.

6. The method for implementing a lightweight optical system for a helium optical pump quantum magnetic measurement system according to claim 4, characterized in that, The focusing optical system is equipped with a detection surface for analyzing the size of the light spot after focusing.

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