A large-temperature-range precision temperature control device and method for low-temperature refractive index testing

Abstract

A large-temperature-range precision temperature control device and method for low-temperature refractive index testing, through a precision temperature control device including a test sample block, a cold plate, a heat conduction lock, a refrigeration machine secondary cold head, a refrigeration machine primary cold head, a heat insulation support, a rotary table, a cold screen, a vacuum pump, a vacuum tank body, a heat insulation support, and a precision temperature control instrument, precise temperature control of an infrared optical lens sample in a range of 40K-300K is performed, the temperature control precision of the sample can reach ±0.2K, the temperature measurement precision can reach ±0.02K, the temperature stability can reach 0.1K / h, the temperature uniformity can reach 0.03K, the cooling time is not more than 4h from 293K to 40K, the heating time is not more than 30min from any temperature point in the range of 40K-300K to 40K and stable, and the heating and cooling rate is not more than 4K / min.

Description

TECHNICAL FIELD

[0001] The present application relates to a large temperature range precision temperature control device and method for low temperature refractive index testing, and belongs to the field of large temperature range precision temperature control testing. BACKGROUND

[0002] At present, the existing large temperature range precision temperature control mainly has high-precision refrigeration control and high-precision heating control. Taking the low temperature refractive index testing project as an example, the high-precision refrigeration control adjusts the output refrigeration power by adjusting the input current and voltage of the refrigerator, so that the sample block reaches the target temperature. This scheme has a complex temperature control strategy, a long control link, and the control precision cannot meet the requirement of ±0.2K. Therefore, the high-precision heating control scheme is adopted. The sample block is first cooled below the target temperature by using the refrigerator, and then the high-precision closed-loop heating temperature control is realized to achieve high temperature stability and temperature uniformity of the sample block. Moreover, the temperature rise and fall rate can be accurately controlled through the control software to meet the testing requirements of the refractive index of the low temperature lens. SUMMARY

[0003] The technical problem solved by the present application is that, in view of the problems of complex temperature control strategy, long control chain and insufficient control precision in the prior art, a large temperature range precision temperature control device and method for low temperature refractive index testing are provided.

[0004] The present application solves the above technical problems by the following technical scheme:

[0005] A large temperature range precision temperature control device for low temperature refractive index testing, comprising a test sample block, a cold plate, a heat conduction lock, a refrigerator secondary cold head, a refrigerator primary cold head, a heat insulation support, a rotary table, a cold screen, a vacuum pump, a vacuum tank body, a heat insulation support, and a precision temperature control instrument, wherein:

[0006] The cold plate is arranged in the cold screen, the test sample block is fixedly installed on one end of the cold plate through the heat conduction lock, the other end of the cold plate is provided with the refrigerator secondary cold head, the refrigerator primary cold head passes through the cold screen and is connected and installed with the refrigerator secondary cold head, the refrigerator primary cold head and the refrigerator secondary cold head are used for manufacturing a low temperature environment in the cold screen, one end of the heat insulation support is arranged on the rotary table for adjusting the angle change of the test sample block, the other end is installed below the cold plate and supports the cold plate and the test sample block, the cold screen is installed in the vacuum tank body through the heat insulation support, the vacuum pump for ensuring the vacuum degree in the cold screen is installed outside the vacuum tank body, and the precision temperature control instrument for heating and closed-loop temperature control of the test sample block is connected with the test sample block through a through-tank cable.

[0007] The cold plate and the heat conduction lock are both made of red copper material to reduce the heat transfer temperature difference between the refrigerator secondary cold head and the test sample block.

[0008] The heat insulation support is made of polyimide material, is a thin-walled cylindrical structure, and is designed with lightening holes to control the equivalent cross-sectional area to be less than a specified value.

[0009] The cold shield is made of red copper material, and is wrapped with multiple layers of heat insulation components on the outer side and the inner side to control the equivalent emissivity within a specified range.

[0010] The precision temperature control instrument is used for precision temperature control of a temperature control loop composed of a test sample, a cold plate, a secondary cold head of a refrigerator, a primary cold head of the refrigerator, and a rotary table. The precision temperature control instrument is provided with an electric heater, and high-precision power resistors are used for power heating. The power resistors are RIG222C type power resistors, and mounting through holes are designed on the two sides of the power resistors. The power resistors are mounted on the mounting surface of the precision temperature control instrument by screws and are coated with thermal conductive silicone grease, and are packaged with a copper structure.

[0011] The heat conduction lock is a copper wire woven structure, and two sections are provided with mounting flanges. The copper wire and the mounting flanges are made of oxygen-free copper and are formed by welding. The heat conduction lock is used for controlling the heat transfer temperature difference between the secondary cold head of the refrigerator and the test sample to be within a specified range, and is matched with the test sample to adapt to the rotation of the rotary table at any angle.

[0012] The temperature sensor is mounted on the cold plate by mechanical connection, preferably a four-wire PT1000 type platinum resistor. The conversion between temperature and resistance value is fitted by a segmented formula. The temperature sensor is packaged with a copper structure, is a cylindrical structure, is mounted on the mounting surface of the precision temperature control instrument by screws, and is coated with thermal conductive silicone grease.

[0013] A large-temperature-zone precision temperature control method for low-temperature refractive index testing, comprising:

[0014] The test sample is placed at a specified position on the cold plate.

[0015] The vacuum tank is vacuumized by a vacuum pump.

[0016] A low-temperature environment is created in the cold shield by the secondary cold head of the refrigerator and the primary cold head of the refrigerator.

[0017] When the temperature of the test sample is reduced to a preset value, the test sample is heated by the precision temperature control instrument according to the temperature requirement preset by the test task. The test sample is rotated during the heating process, and the refractive index of the test sample is monitored in real time to realize temperature control testing of the test sample.

[0018] The test sample is heated by the electric heater of the precision temperature control instrument. The electric heater is a RIG222C type power resistor. The temperature control loop composed of the test sample, the cold plate, the secondary cold head of the refrigerator, the primary cold head of the refrigerator, and the rotary table is precision temperature controlled by the electric heater. The RIG222C type power resistor is designed with mounting through holes on the two sides, is mounted on the mounting surface of the precision temperature control instrument by screws, is coated with thermal conductive silicone grease, and is packaged with a copper structure.

[0019] In the cooling process of manufacturing low-temperature environment in the cold screen by the secondary cold head of the refrigerator and the primary cold head of the refrigerator, the time from 293K to 40K is not more than 4h;

[0020] In the heating process of heating by the precision temperature controller, in the range of 40K-300K, from any temperature point, the time of heating 40K and stabilizing is not more than 30min;

[0021] The heating and cooling rate is not more than 4K / min.

[0022] Compared with the prior art, the present application has the following advantages:

[0023] (1) The present application provides a large-temperature-zone precision temperature control device and method for low-temperature refractive index testing, which adopts a high-precision heating and temperature control method, avoids the shortcomings of complex control system, redundancy, poor temperature stability and the like caused by the refrigeration temperature control mode, provides an almost constant cold environment for the test sample block through the secondary refrigeration mode, fully shields external interference, ensures the temperature control precision of the sample block, and designs a heat conduction lock with a copper wire weaving structure, which can realize efficient heat transfer and adapt to the rotation of ±180° of the rotary table.

[0024] (2) The present application adopts a heat insulation support as the main support structure of the test sample block, which can realize an ultra-high thermal resistance of 955K / W while meeting the mechanical conditions, and realizes high-precision and high-stability temperature control of the sample block based on the four-wire platinum resistance and power resistor through the precision temperature controller, the temperature control precision reaches ±0.2℃, the temperature measurement precision reaches ±0.02℃, the temperature stability reaches 0.1K / h, the temperature uniformity reaches 0.03K, and the platinum resistance and power resistor are both connected in a mechanical connection mode, so that the installation reliability and test precision of the temperature measurement and control elements under high-low temperature alternating conditions are ensured. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The structure of the precision temperature control device provided by the present application is shown in the front view.

[0026] Figure 2 The heat insulation support structure of the precision temperature control device provided by the present application is shown in the front view.

[0027] Figure 3 The sample stage temperature control diagram of the precision temperature control device provided by the present application is shown in the front view.

[0028] Figure 4 The cold plate temperature control diagram of the precision temperature control device provided by the present application is shown in the front view.

[0029] Figure 5 The cold screen temperature control diagram of the precision temperature control device provided by the present application is shown in the front view.

[0030] Figure 6 Temperature control element diagram of the precision temperature control device provided for the invention;

[0031] Figure 7 Heat conduction lock structure diagram of the precision temperature control device provided for the invention; DETAILED DESCRIPTION

[0032] A large-temperature-range precision temperature control device and method for low-temperature refractive index testing, through a precision temperature control device including a test sample block, a cold plate, a heat conduction lock, a refrigerator secondary cold head, a refrigerator primary cold head, a heat insulation support, a rotary table, a cold shield, a vacuum pump, a vacuum tank body, a heat insulation support, and a precision temperature control instrument, precise temperature control of an infrared optical lens sample 40K-300K range is performed, the temperature control precision of the sample can reach ±0.2K, the temperature measurement precision can reach ±0.02K, the temperature stability can reach 0.1K / h, the temperature uniformity can reach 0.03K, the cooling time is not more than 4h from 293K to 40K, the heating time is not more than 30min from any temperature point to 40K-300K range, and the heating and cooling rate is not more than 4K / min.

[0033] The specific structure of the precision temperature control device is as follows:

[0034] The cold plate is arranged in the cold shield, the test sample block is fixedly installed at one end of the cold plate through the heat conduction lock, the other end of the cold plate is provided with the refrigerator secondary cold head, the refrigerator primary cold head passes through the cold shield and is connected and installed with the refrigerator secondary cold head, the refrigerator primary cold head and the refrigerator secondary cold head are used to create a low-temperature environment in the cold shield, one end of the heat insulation support is arranged on the rotary table for adjusting the angle change of the test sample block, the other end is installed below the cold plate and supports the cold plate and the test sample block, the cold shield is installed in the vacuum tank body through the heat insulation support, the vacuum pump for ensuring the vacuum degree in the cold shield is installed outside the vacuum tank body, and the precision temperature control instrument for heating and closed-loop temperature control of the test sample block is connected with the test sample block through the tank-penetrating cable.

[0035] Preferably, the cold plate and the heat conduction lock are made of red copper material to reduce the heat transfer temperature difference between the refrigerator secondary cold head and the test sample block.

[0036] The heat insulation support is made of polyimide material and has a thin-walled cylindrical structure and a lightening hole designed to control the equivalent cross-sectional area.

[0037] The cold shield is made of red copper material and is wrapped with multiple layers of heat insulation components on the outside and the inside to ensure the equivalent emissivity.

[0038] The precision temperature control instrument is used for precision temperature control of a temperature control loop composed of a test sample, a cold plate, a two-stage cold head of a refrigerator, a one-stage cold head of the refrigerator and a rotary table, and the precision temperature control instrument is provided with an electric heater, and high-precision power resistors are used for power heating, and the RIG222C power resistor is used, and mounting holes are designed on both sides of the RIG222C power resistor, and the RIG222C power resistor is mounted on the mounting surface of the precision temperature control instrument by screws, and the RIG222C power resistor is coated with heat-conducting silicone grease, and the RIG222C power resistor is packaged by copper structure;

[0039] Meanwhile, the temperature sensor adopts a four-wire PT1000 type platinum resistor, and the conversion between temperature and resistance value is fitted by a segmented formula, and the temperature sensor is packaged by copper structure, and the temperature sensor has a cylindrical structure, and the temperature sensor is mounted on the mounting surface of the precision temperature control instrument by screws, and the temperature sensor is coated with heat-conducting silicone grease;

[0040] The heat-conducting lock is a copper wire woven structure, and two sections are provided with mounting flanges, and the copper wire and the mounting flanges are both made of oxygen-free copper and are formed by welding, and the heat-conducting lock is used for controlling the heat transfer temperature difference between the two-stage cold head of the refrigerator and the test sample to be within a specified range, and the heat-conducting lock is used in cooperation with the test sample to adapt to the rotation of the rotary table at any angle.

[0041] The precision temperature control device further comprises a temperature sensor mounted on the cold plate by mechanical connection.

[0042] The precision temperature control device can realize a large-temperature-zone precision temperature control method for low-temperature refractive index testing, and the specific steps are as follows:

[0043] The test sample is placed at a specified position on the cold plate.

[0044] The vacuum tank is vacuumized by a vacuum pump.

[0045] A low-temperature environment is created in the cold shield by the two-stage cold head of the refrigerator and the one-stage cold head of the refrigerator.

[0046] When the temperature of the test sample is reduced to a preset value, the precision temperature control instrument is used for heating according to the temperature requirement preset by the test task, the rotary table is controlled to rotate the test sample during the heating process, the refractive index of the test sample is monitored in real time, and the temperature control test of the test sample is realized.

[0047] The following is further described according to specific embodiments:

[0048] In the current embodiment, as Figure 1As shown, the structure of the large temperature range precision temperature control device for low temperature refractive index test, including test sample block 1, cold plate 2, heat conduction lock 3, refrigerator two-stage cold head 4, refrigerator one-stage cold head 5, heat insulation support 6, rotary table 7, cold shield 8, vacuum pump 9, vacuum tank 10, heat insulation support 11, precision temperature control instrument 12; test sample block 1 is connected to one end of cold plate 2 through heat conduction lock 3, the other end of cold plate 2 is connected to refrigerator two-stage cold head 4, refrigerator one-stage cold head 5 is connected to cold shield 8, the outer surface of cold shield 8 is coated with 20 units of multilayer thermal insulation material, the inner surface is coated with 10 units of multilayer thermal insulation material, and is connected with vacuum tank 10 through heat insulation support 11, heat insulation support 6 is used for main support of test sample block 1, which meets the mechanical condition and high thermal resistance characteristics, rotary table 7 is used for angle change of test sample block, which realizes the rotation range of ±180°, vacuum pump 9 is installed outside vacuum tank 10, which ensures that the vacuum degree of test environment reaches 1×10 -3 , the precision temperature control instrument 12 is placed outside the vacuum tank, connected with the internal temperature control loop through the tank cable, the temperature control element adopts PT1000 type platinum resistance and precision power resistor, which is used for heating and closed-loop temperature control of the sample block.

[0049] The heat insulation support is the core heat insulation support of the test sample block of the precision temperature control device, and its structure is shown in Figure 2 . The test sample block obtains a wide range of temperature control 40K-300K, and the deep cooling environment provided by the refrigerator is the prerequisite for the whole precision temperature control system. However, under the condition of 253K temperature difference between 40K deep low temperature and environment temperature, sufficient reduction of support conduction heat leakage and matching with the two-stage refrigeration capacity of the refrigerator can successfully reduce the temperature of the test sample block to the preset value. According to the design, the total thermal resistance of the heat insulation support needs to realize 955K / W, and considering the influence of mechanical structure support strength and thermal deformation, the heat insulation support is designed as a 4mm thin-walled cylindrical structure, the material is polyimide, the thermal conductivity coefficient is about 0.3, and the equivalent cross-sectional area is less than 3.84cm 2 , and the total length is about 110mm.

[0050] As shown in Figures 3 to 5 , the temperature control loop of the sample stage, the cold plate and the cold shield is designed in detail, as shown in Figure 6The diagram shows the detailed configuration of the heating element. The heating element uses a RIG222C type power resistor, which features small size, large power capacity, stable and reliable performance, and easy installation. It is a dual-lead resistor with a double-hole metal mounting plate (neither end is connected to the metal mounting plate). The resistors form a series circuit, with a maximum single-circuit heating power of 500W, which can meet the heating requirements of the project. Furthermore, this type of resistor has Φ4mm through holes on both sides, mechanically connected to the mounting surface via M3 screws. Thermal grease is applied between the contact surfaces, and the screw preload is 1.2N. Temperature sensing... The instrument uses a four-wire PT1000 platinum resistance thermometer. The conversion between temperature and resistance is achieved through piecewise formula fitting, resulting in a calibration accuracy of ±0.02K. The platinum resistance thermometer is encapsulated in copper, with an outer dimension of Φ10mm and a thickness of 5mm. It is mechanically connected to the mounting surface via M3 screws, with thermal grease applied between the contact surfaces. The screw preload is 1.2N. After the precision temperature controller collects the resistance value of the sensor, it converts it into temperature through a fitting formula. Then, it outputs the duty cycle of the heater through a PID control method to achieve precise temperature control of the test sample.

[0051] like Figure 7 The diagram shown is a structural diagram of the thermally conductive lock. The thermally conductive lock is a copper wire braided structure with a total length of 250mm. Mounting flanges are located at both ends. Both the copper wire and the mounting flanges are made of oxygen-free copper and are welded together. Each copper wire has a diameter of Φ0.15mm, and 30 wires are bundled together, forming 48 strands woven into a mesh. The equivalent cross-sectional area after forming is 44mm². 2 It can ensure that the heat-conducting lock has sufficient flexibility to adapt to the ±180° rotation of the turntable, and can also ensure that the heat transfer temperature difference between the secondary cold head of the refrigerator and the test sample is less than 3K.

[0052] The test sample is made of infrared lens materials such as germanium, silicon, and zinc selenide. The cold plate is made of 9mm thick copper material and is black anodized. The refrigerator is an industrial-grade variable frequency GM refrigerator, which can achieve 80K / 30W for the first-stage cold head and 30K / 10W for the second-stage cold head. The cold screen is made of 3mm thick copper material and is black anodized.

[0053] The precision temperature control device enables precise temperature control of infrared optical lens samples within the range of 40K-300K, achieving a temperature control accuracy of ±0.2K, a temperature measurement accuracy of ±0.02K, a temperature stability of 0.1K / h, and a temperature uniformity of 0.03K. The cooling time from 293K to 40K does not exceed 4 hours; the heating time, starting from any temperature point within the 40K-300K range, does not exceed 30 minutes for a 40K temperature rise and stabilization; and the heating / cooling rate is no greater than 4K / min.

[0054] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0055] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A large-temperature-range precision temperature control device for low-temperature refractive index testing, employing a two-stage refrigeration method, adapting to the high-precision temperature control and refractive index testing requirements within the range of 40K-300K and ±180° rotation, characterized in that... include: Test sample (1), cold plate (2), thermal lock (3), secondary cold head of refrigerator (4), primary cold head of refrigerator (5), thermal insulation bracket (6), turntable (7), cold screen (8), vacuum pump (9), vacuum tank (10), thermal insulation support (11), precision temperature controller (12); The cold plate (2) is set inside the cold screen (8), the test sample (1) is fixedly installed on one end of the cold plate (2) by the thermal lock (3), the other end of the cold plate (2) is provided with the secondary cold head of refrigerator (4), the primary cold head of refrigerator (5) passes through the cold screen (8) and is connected to the secondary cold head of refrigerator (4), the primary cold head of refrigerator (5) and the secondary cold head of refrigerator (4) are connected to each other. The head (4) is used to create a low-temperature environment inside the cold shield (8); one end of the heat insulation bracket (6) is set on the turntable (7) for adjusting the angle of the test sample block, and the other end is installed below the cold plate (2) to support the cold plate (2) and the test sample block (1); the vacuum pump (9) is installed outside the vacuum tank (10), the cold shield (8) is installed inside the vacuum tank (10) through the heat insulation support (11), and the precision temperature controller (12) is connected to the internal temperature control circuit through the can-penetrating cable; the heat insulation bracket (6) is made of polyimide material and has a thin-walled cylindrical structure, designed with lightening holes to control the equivalent cross-sectional area to be less than a specified value; the equivalent cross-sectional size is less than 3.84 cm. 2 Achieving a total thermal resistance of 955 K / W.

2. The large-temperature-range precision temperature control device for low-temperature refractive index testing according to claim 1, characterized in that: The cold plate (2) and the heat-conducting lock (3) are made of copper, so that the heat transfer temperature difference between the secondary cold head and the sample block is less than 3K.

3. The large-temperature-range precision temperature control device for low-temperature refractive index testing according to claim 1, characterized in that: The cold shield (8) is made of copper and is covered with multiple layers of heat insulation components on both the outer and inner sides to control the equivalent emissivity within a specified range.

4. The large-temperature-range precision temperature control device for low-temperature refractive index testing according to claim 1, characterized in that: The precision temperature controller (12) operates outside the vacuum tank and achieves precise temperature control of the internal temperature control circuit. The electric heater uses a high-precision power resistor, and the temperature sensor uses a packaged PT1000 platinum resistance thermometer, which is mechanically connected to the cold plate (2).

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