Bridged parallel cryogenic optical cooler

Abstract

This utility model relates to the field of cryogenic refrigeration technology, and provides a bridged parallel cryogenic optical cooler, including a pump laser; multiple cooling crystals arranged in parallel and all located within a non-resonant optical cavity, so that each cooling crystal can receive the pump laser; a bridging thermal link connecting the multiple cooling crystals; and a cold finger connected to the side of the bridging thermal link opposite to the cooling crystal, the cold finger being used to dissipate cold energy. The bridged parallel cryogenic optical cooler provided by this utility model, by arranging multiple cooling crystals in parallel, all located within a non-resonant optical cavity, so that each cooling crystal can receive the pump laser, and by bridging thermal links connecting the multiple cooling crystals and the cold finger connected to the side of the bridging thermal link opposite to the cooling crystal, increases the number of cooling units, effectively increasing the absorbed pump laser power and providing greater cooling power.

Description

Technical Field

[0001] This utility model relates to the field of cryogenic refrigeration technology, and in particular to a bridged parallel cryogenic optical cooler. Background Technology

[0002] Cryogenic optical coolers are specialized cooling devices designed for precision time and frequency measurement systems, cryogenic electron microscopes, germanium-based gamma-ray spectrometers, optical devices, or infrared detection equipment. They can reduce the operating temperature to the cryogenic range and maintain a stable cryogenic environment.

[0003] Cryogenic optical coolers based on solid-state laser cooling are characterized by being all-solid-state, compact, small in size, lightweight, and free from electromagnetic radiation interference, and have important application prospects in national defense security, space exploration, precision metrology, and life sciences.

[0004] However, most existing cryogenic refrigerators are based on a single refrigeration unit, making it difficult to further increase their refrigeration power, which greatly limits their practical applications.

[0005] Therefore, how to provide a bridging parallel cryogenic optical cooler is a technical problem that urgently needs to be solved by those skilled in the art. Utility Model Content

[0006] This invention provides a bridged parallel cryogenic optical cooler to address the shortcomings of low cooling power in existing technologies, thereby effectively increasing pump laser power and providing greater cooling power.

[0007] This utility model provides a bridged parallel cryogenic optical cooler, comprising: Pumped laser; Multiple cooling crystals are arranged in parallel and are all located in a non-resonant optical cavity so that each cooling crystal can receive the pump laser; A bridging thermal link connects multiple of the aforementioned cooling crystals; A cold finger, connected to the side of the bridging thermal link opposite to the cooling crystal, is used to discharge cold energy.

[0008] According to the bridging parallel cryogenic optical cooler provided by this utility model, it further includes: A vacuum dewar; the vacuum dewar has an infrared window, which corresponds to the cold output end of the cold finger, and the infrared window is used to detect external infrared light signals.

[0009] According to the present invention, a bridged parallel cryogenic optical cooler further includes a black radiation shielding cavity disposed inside the vacuum Dewar, a non-resonant optical cavity located inside the black radiation shielding cavity, and a cold finger penetrating the black radiation shielding cavity and correspondingly disposed with respect to the infrared window.

[0010] According to the present invention, a bridging parallel cryogenic optical cooler includes two cooling crystals, and the black radiation shielding cavity includes: A heat sink is used to be inserted between the two cooling crystals to separate them; A light-absorbing film is disposed on the inner peripheral side of the heat sink facing the cooling crystal.

[0011] According to the bridging parallel cryogenic optical cooler provided by this utility model, it further includes: An optical fiber, sealed at one end, extends through the vacuum Dewar and is close to the cooling crystal; the optical fiber is used to collect the fluorescence emitted by the cooling crystal. A spectrometer is located outside the vacuum Dewar, and the spectrometer is used to monitor the fluorescence spectrum of the cooling crystal in real time.

[0012] According to the present invention, a bridging parallel cryogenic optical cooler is provided, wherein a reflective metal film is provided at the interface between the bridging thermal link and the cold finger.

[0013] According to the bridging parallel cryogenic optical cooler provided by this utility model, it further includes: A polarization beam splitter is used to receive the pump laser and to separate or combine the pump lasers according to their polarization state. The first and second reflecting mirrors both receive the light emitted from the polarizing beam splitter and reflect it to the two cooling crystals respectively.

[0014] According to the present invention, a bridged parallel cryogenic optical cooler is provided, wherein the non-resonant optical cavity includes two third mirrors and two fourth mirrors, wherein the third mirrors and the fourth mirrors are respectively located on both sides of the cooling crystal.

[0015] According to the present invention, a bridging parallel cryogenic optical cooler is provided, wherein the third reflector is a perforated spherical reflector and the fourth reflector is a cylindrical reflector.

[0016] According to the bridging parallel cryogenic optical cooler provided by this utility model, it further includes: A silica aerogel is disposed between the cold finger and the heat sink, and the silica aerogel is used to support the cold finger.

[0017] The bridging parallel cryogenic optical cooler provided by this utility model uses multiple cooling crystals connected in parallel, all of which are located in a non-resonant optical cavity, so that each cooling crystal can receive pump laser. A bridging thermal link connects multiple cooling crystals, and a cold finger is connected to the side of the bridging thermal link facing away from the cooling crystal. The cold finger is used to discharge cold energy, which increases the cooling unit and can effectively increase the absorbed pump laser power, providing greater cooling power. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this utility model 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 some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is one of the structural schematic diagrams of the bridged parallel cryogenic optical cooler provided by this utility model.

[0020] Figure 2 This is the second schematic diagram of the bridging parallel cryogenic optical cooler provided by this utility model.

[0021] Figure label: 1. Pump laser; 2. Cooling crystal; 3. Bridging thermal link; 4. Cold finger; 5. Vacuum Dewar; 6. Infrared window; 7. Heat sink; 8. Light-absorbing film; 9. Optical fiber; 10. Spectrometer; 11. Reflective metal film; 12. Polarizing beam splitter; 13. First mirror; 14. Second mirror; 15. Third mirror; 16. Fourth mirror; 17. Silica aerogel. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0023] The following is combined with Figures 1-2 This invention describes a bridging parallel cryogenic optical cooler.

[0024] like Figure 1 and Figure 2As shown, this utility model embodiment provides a bridged parallel cryogenic optical cooler, including a pump laser 1, multiple cooling crystals 2, a bridging thermal link 3, and a cold finger 4. The multiple cooling crystals 2 are arranged in parallel, significantly increasing the total number of cooling units. Compared to a single cooling crystal 2, this doubles the cooling power, thereby greatly improving the overall cooling capacity and cooling speed. The cooling crystals 2 are all located within a non-resonant optical cavity, allowing each cooling crystal 2 to receive the pump laser 1. This simplifies the optical system and alignment requirements, reduces the limitation on the stability of the pump laser wavelength, and makes the system more stable. The bridging thermal link 3 connects the multiple cooling crystals 2. The cold finger 4 is connected to the side of the bridging thermal link 3 facing away from the cooling crystals 2, and is used to export the cooling energy. The cold finger 4 can be easily coupled to the target device to be cooled, stably and efficiently exporting the collected powerful cooling energy, thus giving the entire cooler excellent practicality and application flexibility.

[0025] The bridging parallel low-temperature optical cooler provided in this embodiment of the invention increases the cooling unit by bridging the cooling crystal, thereby improving the cooling efficiency.

[0026] Specifically, the thermal expansion coefficient of the bridging thermal link 3 should match that of the cooling crystal 2, the thermal conductivity should be as high as possible, the visible and infrared bands should be as transparent as possible, the purity should be as high as possible, and the structure should be conducive to fluorescence escape. MgF, high-purity LuLiF4 crystals, or sapphire crystals can be used.

[0027] In some feasible embodiments of this invention, a vacuum Dewar 5 is also included. The vacuum Dewar 5 encapsulates the cooling crystal 2, the bridging thermal link 3, and the cold finger 4 within a high-vacuum environment, providing excellent thermal insulation. By isolating the air from heat conduction and convection, it significantly reduces the interference of parasitic heat loads from the external environment on the cryogenic system, thereby ensuring that the cooling capacity generated by the cooler can be effectively utilized for target cooling rather than being offset by ambient heat. An infrared window 6 is provided on the vacuum Dewar 5, creating a clear, low-loss optical channel for external infrared light signals to enter the vacuum cavity without compromising the high vacuum level inside the Dewar 5. The infrared window 6 corresponds to the cold energy output end of the cold finger 4 and is used to detect external infrared light signals. This ensures that the signal light entering through the infrared window 6 can be accurately focused or projected onto the sensitive area of ​​the detector, which has been cooled to its optimal operating temperature, thus achieving a perfect integration of cooling and detection functions and maximizing signal reception efficiency.

[0028] In some feasible embodiments of this invention, a black radiation shielding cavity is also included, disposed inside the vacuum Dewar 5. The black radiation shielding cavity establishes an effective radiative heat barrier between the cooling core and the external environment, actively intercepting and absorbing thermal radiation from the walls of the vacuum Dewar 5, thereby greatly reducing the radiative heat transferred to the core cooling area. This plays a decisive role in reducing the extreme temperature of the cooler and increasing the net cooling power at a specific temperature. The non-resonant optical cavity is located inside the black radiation shielding cavity, and the cold finger 4 penetrates the black radiation shielding cavity and is correspondingly positioned with the infrared window 6. This allows the powerful cooling energy gathered inside the shielding cavity to be directed to the device to be cooled (such as a detector), while ensuring that the device being cooled is also protected within the radiation shielding cavity and is not disturbed by ambient thermal radiation.

[0029] In some feasible embodiments of this invention, the black radiation shielding cavity includes a heat sink 7, and two cooling crystals 2 are included. The heat sink 7 is inserted between the two cooling crystals 2 to separate them. The heat sink 7 can effectively block incompletely absorbed pump laser light emitted from one cooling crystal 2 or its own generated fluorescence, preventing these stray lights from irradiating the other cooling crystal 2 and causing parasitic heat load. This ensures that each cooling unit can operate independently and efficiently without interference from the other, maximizing the overall net cooling power of the parallel system. A light-absorbing film 8 is adhered to the inner circumference of the heat sink 7 facing the cooling crystal 2. The light-absorbing film 8 has a high absorption rate for pump laser and fluorescence wavelengths. Its direct effect is that it can efficiently absorb all stray photons irradiating the isolation surface of the heat sink 7 and convert them into heat energy, rather than reflecting them back into the optical system. The absorbed heat is uniformly received and managed by the large heat capacity component, heat sink 7, which avoids the disordered scattering of stray light in the cavity and heating of the cooling crystal or other low-temperature components. This greatly improves the energy utilization and thermal stability of the system, providing a solid guarantee for achieving deeper cooling temperatures and higher cooling efficiency.

[0030] In some feasible embodiments of this invention, a non-contact differential fluorescence thermometry system is also included. This system comprises an optical fiber 9 and a spectrometer 10. One end of the optical fiber 9 is sealed and extends through the vacuum dewar 5 and is close to the cryogenic crystal 2. This not only enables in-situ signal extraction without compromising the high vacuum level of the cavity or affecting the overall thermal insulation performance of the system, but also significantly improves the efficiency of target signal collection by being close to the cryogenic crystal 2, obtaining high signal-to-noise ratio raw spectral data, thus laying the foundation for subsequent precise analysis. The optical fiber 9 is used to collect the fluorescence emitted by the cryogenic crystal 2. The spectrometer 10 is positioned outside the vacuum dewar 5 and is used to monitor the fluorescence spectrum of the cryogenic crystal 2 in real time, realizing a high-precision non-contact real-time temperature measurement method. By analyzing the spectral line shape or peak ratio of the fluorescence spectrum, the absolute temperature of the cryogenic crystal 2 can be accurately determined, avoiding the additional heat load and measurement inaccuracies in extremely low temperature regions associated with traditional physical probes.

[0031] In some feasible embodiments of this utility model, a reflective metal film 11 is provided at the interface between the bridging hot link 3 and the cold finger 4. The reflective metal film 11 can reflect stray photons that reach the cold finger 4 back along the original path, so that they are far away from the coldest core area of ​​the cooler.

[0032] In some feasible embodiments of this invention, a polarization beam splitter 12, a first reflector 13, and a second reflector 14 are also included. The polarization beam splitter 12 is used to receive the pump laser 1 and to separate or combine the two beams according to the polarization state of the pump laser 1. Using a single laser source significantly reduces the cost, size, and complexity of the system, while also fundamentally ensuring that the two pump beams subsequently split have exactly the same wavelength and coherence. The polarization beam splitter 12 not only has extremely high beam splitting efficiency and low energy loss, but also provides a simple and precise method for adjusting the power ratio of the two output beams. The operator can easily balance the power distributed to each cooling crystal 2 by controlling the polarization of the input laser.

[0033] The first reflector 13 and the second reflector 14 both receive the light emitted from the polarization beam splitter 12 and reflect it to the two cooling crystals 2 respectively. On the one hand, this makes the optical path design more flexible, enabling a more compact layout within the limited vacuum Dewar space by folding the optical path. On the other hand, it ensures that each pump beam can be precisely aligned and focused onto the central region of the corresponding cooling crystal. This is a necessary guarantee to maximize the interaction volume between the light and the crystal, avoid parasitic heating caused by beam offset, and thus obtain the highest cooling efficiency. In some feasible embodiments of this utility model, the non-resonant optical cavity includes two third mirrors 15 and two fourth mirrors 16. The third mirrors 15 and the fourth mirrors 16 are located on both sides of the cooling crystal 2. The pump laser passes back and forth through the cooling crystal 2 and is reflected back and forth between the cavity mirrors until it is almost completely absorbed by the cooling crystal 2. This ensures that most of the pump energy is used to excite the fluorescence cooling process, thereby directly and significantly enhancing the cooling power of each cooling crystal 2, making the cooling speed faster and the achievable limit temperature lower, maximizing energy utilization, and avoiding the scattering of unabsorbed laser light within the cavity.

[0034] In some feasible embodiments of this invention, the third reflecting mirror 15 is a perforated spherical reflecting mirror, and the fourth reflecting mirror 16 is a cylindrical reflecting mirror. In other embodiments, other types of reflecting mirrors can also be used, as long as they can achieve light path reflection.

[0035] In some feasible embodiments of this invention, silica aerogel 17 is further included, disposed between the cold finger 4 and the heat sink 7. The silica aerogel 17 supports the cold finger 4, providing rigid mechanical support and ensuring that the cold finger 4 and the devices mounted on it can be stably maintained in a preset position. Furthermore, silica aerogel 17 is a solid material with low thermal conductivity; utilizing its low thermal conductivity, it provides reliable mechanical support while offering a path with extremely high thermal resistance.

[0036] In the description of the embodiments of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this utility model according to the specific circumstances.

[0037] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "method," "specific method," or "some methods," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or method is included in at least one embodiment or method of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or method. Furthermore, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or methods. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or methods described in this specification, as well as the features of different embodiments or methods.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model 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. Such 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 this utility model.

Claims

1. A bridged parallel cryogenic optical cooler, characterized in that, include: Pumped laser (1); Multiple cooling crystals (2) are arranged in parallel and are all located in a non-resonant optical cavity so that each of the cooling crystals (2) can receive the pump laser (1). A bridging thermal link (3) is used to connect multiple cooling crystals (2); The cold finger (4) is connected to the side of the bridging thermal link (3) facing away from the cooling crystal (2), and the cold finger (4) is used to export cold energy.

2. The bridging parallel cryogenic optical cooler according to claim 1, characterized in that, Also includes: A vacuum dewar (5) is provided with an infrared window (6), which corresponds to the cold output end of the cold finger (4). The infrared window (6) is used to detect external infrared light signals.

3. The bridging parallel cryogenic optical cooler according to claim 2, characterized in that, It also includes a black radiation shielding cavity, which is located inside the vacuum dewar (5). The non-resonant optical cavity is located inside the black radiation shielding cavity, and the cold finger (4) penetrates the black radiation shielding cavity and is correspondingly arranged with the infrared window (6).

4. The bridging parallel cryogenic optical cooler according to claim 3, characterized in that, The cooling crystal (2) comprises two, and the black radiation shielding cavity comprises: A heat sink (7) is used to be inserted between the two cooling crystals (2) to separate the two cooling crystals (2). A light-absorbing film (8) is disposed on the inner peripheral side of the heat sink (7) facing the cooling crystal (2).

5. The bridging parallel cryogenic optical cooler according to claim 2, characterized in that, Also includes: An optical fiber (9) is sealed at one end and extends through the vacuum Dewar (5) and is close to the cooling crystal (2); the optical fiber (9) is used to collect the fluorescence emitted by the cooling crystal (2); A spectrometer (10) is located outside the vacuum dewar (5) and is used to monitor the fluorescence spectrum of the cooling crystal (2) in real time.

6. The bridging parallel cryogenic optical cooler according to claim 1, characterized in that, A reflective metal film (11) is provided at the interface between the bridging thermal link (3) and the cold finger (4).

7. The bridging parallel cryogenic optical cooler according to claim 3, characterized in that, Also includes: A polarization beam splitter (12) is used to receive the pump laser (1) and to separate or combine the pump laser (1) according to its polarization state. The first reflector (13) and the second reflector (14) both receive the light emitted from the polarization beam splitter (12) and reflect it to the two cooling crystals (2) respectively.

8. The bridging parallel cryogenic optical cooler according to claim 7, characterized in that, The non-resonant optical cavity includes two third mirrors (15) and two fourth mirrors (16), which are located on both sides of the cooling crystal (2).

9. The bridging parallel cryogenic optical cooler according to claim 8, characterized in that, The third reflector (15) is a perforated spherical reflector, and the fourth reflector (16) is a cylindrical reflector.

10. The bridging parallel cryogenic optical cooler according to claim 4, characterized in that, Also includes: Silica aerogel (17) is disposed between the cold finger (4) and the heat sink (7), and the silica aerogel (17) is used to support the cold finger (4).

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