Optical Fiber Ring Temperature and Temperature Difference Testing Device

Abstract

The present application provides an optical fiber loop temperature and temperature difference testing device, which includes an upper temperature control plate and a lower temperature control plate arranged in parallel at intervals. The optical fiber loop is placed between the upper temperature control plate and the lower temperature control plate. The device further includes a hot pool, a cold pool and at least two mixers. Liquid media are provided in the hot pool and the cold pool. The liquid media in the hot pool and the cold pool are mixed by each mixer and then respectively transported into the upper temperature control plate and the lower temperature control plate. The device also includes a reversing valve island, in which a reversing valve is provided. The upper temperature control plate and the lower temperature control plate are connected to two inlets of the reversing valve, and two outlets of the reversing valve are respectively connected to the hot pool and the cold pool. The connection status of the two inlets and the two outlets can be exchanged, solving the problem of differential temperature testing at both end faces of the polarization-maintaining optical fiber loop.

Description

Technical Field

[0001] The present invention relates to the field of polarization-maintaining fiber loop testing for fiber optic gyroscopes, and particularly to a device for testing the temperature and temperature difference of a fiber loop. Background Art

[0002] The fiber loop is the core component of a fiber optic gyroscope. Its function is to convert the angular velocity of the fiber loop itself moving in inertial space into the time difference or phase difference of the light incident from both ends of the fiber loop when it exits. The functions of other components of the fiber optic gyroscope are to convert this phase difference into an electrical signal for measurement, and finally output a measurement signal of the angular velocity.

[0003] The core working principle of the fiber loop is the Sagnac effect. However, at the same time, there are also interference effects such as the Shupe effect, stress birefringence effect, and Kerr effect in the fiber loop. These effects will also generate a non-reciprocal phase difference for the light transmitted in the fiber loop, disturbing or causing a continuous drift of the target phase difference generated by the Sagnac effect. In severe cases, it will cause an intolerable output offset of the fiber optic gyroscope. And these effects will weaken or strengthen with the influence of environmental factors (such as temperature, stress, magnetic field, etc.). Moreover, the current production of fiber loops is still in a semi-automated state, lacking effective production process control indicators, and unable to quantitatively control various interference effects during the production process. Therefore, the finished product inspection of the fiber loop has become a particularly important step in the production of fiber loops.

[0004] Temperature is one of the most important interference factors for fiber optic gyroscopes. The Shupe effect caused by temperature changes is the most important interference effect on the accuracy of fiber optic gyroscopes. The Shupe effect can be excited not only by the overall temperature change of the fiber loop, but also by an uneven temperature distribution field. The start-up drift phenomenon of fiber optic gyroscopes is simultaneously excited by temperature changes and an uneven temperature field.

[0005] However, at present, most of the temperature performance tests of fiber loops are carried out using a temperature chamber. The temperature chamber does not have the ability to locally control the temperature and can only heat and cool the fiber loop relatively uniformly. And the current evaluation indicators for the temperature performance of fiber loops (such as full-temperature crosstalk, full-temperature loss, full-temperature zero-bias peak-to-peak value, etc.) all regard the fiber loop as a whole, ignoring the possible influence caused by the uneven temperature distribution in the fiber loop. The test of the influence of an uneven temperature field on the fiber loop is currently a blank in the testing of fiber loops. Summary of the Invention

[0006] The present invention provides a device for testing the temperature and temperature difference of a fiber loop, which solves the problem of testing the differential temperature between the two end faces of a polarization-maintaining fiber loop.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is as follows: An optical fiber loop temperature and temperature difference testing device, comprising an upper temperature control plate and a lower temperature control plate arranged in parallel at intervals, an optical fiber loop is placed between the upper temperature control plate and the lower temperature control plate, and further comprising a hot pool, a cold pool and at least two mixers. Liquid media are provided in the hot pool and the cold pool, and the liquid media in the hot pool and the cold pool are mixed by each mixer and then respectively transported into the upper temperature control plate and the lower temperature control plate;

[0008] It further comprises a reversing valve island, a reversing valve is provided in the reversing valve island, two inlets of the reversing valve are connected to the upper temperature control plate and the lower temperature control plate, and two outlets of the reversing valve are respectively connected to the hot pool and the cold pool, and the connection states of the two inlets and the two outlets can be exchanged.

[0009] At present, the gyro performance test of the optical fiber loop generally uses an anti-vibration temperature control box as the temperature control device. The anti-vibration temperature control box uses a split design to separate the compressor and the test box body to reduce the conduction of vibration; and an independent anti-vibration platform is arranged in the test box body, and the support columns of the anti-vibration platform extend directly from the foundation into the temperature control box, so that the platform can effectively isolate the vibration generated by the box body fan; in addition, the gap between the support column and the temperature control box body is filled with soft materials to ensure the airtightness of the test box body.

[0010] The temperature control box adopts the method of circulating air inside the box for uniform temperature control, but the wind blowing the ring body or the tail fiber will generate test noise. Therefore, during the test, the optical fiber loop is generally sealed in a tooling, and then the tooling is fixed on the anti-vibration platform for testing. Since there is no heat convection inside and outside the tooling and it is in direct contact with the large anti-vibration platform, the temperature inside the tooling lags seriously behind the outside of the tooling, and the temperature change rate depends on the temperature difference between the inside and outside of the tooling. The temperature difference is an indirect control quantity, resulting in a lag and roughness in the temperature rate control of the temperature control box. In addition, although the anti-vibration temperature control box adopts the design of separating the anti-vibration platform from the box body to reduce the influence of the vibration of the box body during the test, the vibration of the box body will still be transmitted to the anti-vibration platform through the airtight structure of the anti-vibration platform strut, and the optical fiber out of the temperature control box will also be affected by the vibration of the box body, generating a certain amount of test noise.

[0011] And there is another temperature control device on the market - a semiconductor temperature control box. However, its temperature change rate is relatively low, and since its heating wire and refrigeration sheet need to be powered on, the magnetic field generated by the current will also affect the test of the optical fiber loop to a certain extent.

[0012] Therefore, in the preferred solution, a temperature control box is further provided, the upper temperature control plate and the lower temperature control plate are arranged in the temperature control box, a cross frame is further provided, the cross frame passes through the temperature control box, a plurality of optical fiber loops are placed in the middle of the cross frame, and a base device is further provided. The base device comprises a shock-absorbing plate and a base, a shock-absorbing spacer is provided between the shock-absorbing plate and the base, the base is used to support the temperature control box, and the shock-absorbing plate supports the cross frame.

[0013] In a preferred embodiment, the temperature control box is composed of a upper half box body and a lower half box body spliced together. The upper temperature control plate is arranged inside the upper half box body, and the lower temperature control plate is arranged inside the lower half box body.

[0014] In a preferred embodiment, a connecting shaft is sleeved on the upper end of the base. A height adjusting plate is arranged at the upper end of the connecting shaft. The height adjusting plate is connected to the lower half box body. The height adjusting plate is provided with a positioning boss hole. The positioning boss hole of the height adjusting plate is slidably sleeved on the upper end of the connecting shaft. The height adjusting plate is provided with a locking knob for locking the height of the height adjusting plate.

[0015] In a preferred embodiment, a first spring is arranged between the base and the height adjusting plate. The two ends of the first spring respectively abut against the base and the height adjusting plate.

[0016] In a preferred embodiment, guide posts are arranged inside the upper half box body. A second spring is sleeved on the guide posts. The upper temperature control plate is slidably sleeved on the guide posts. The end face of the upper temperature control plate abuts against the second spring. A tension bolt is also provided. The tension bolt passes through the upper temperature control plate and is threadedly connected to the upper half box body.

[0017] In a preferred embodiment, an opening is provided at the connection part of the tension bolt on the upper half box body.

[0018] In a preferred embodiment, a plurality of hollow holes are provided in the middle of the cross frame. A ring frame is arranged inside the hollow holes. A plurality of blocking pieces are arranged along the circumferential direction at the lower end of the ring frame. The blocking pieces are used for placing the optical fiber ring. A gap is provided between the outer wall of the optical fiber ring and the inner wall of the ring frame.

[0019] In a preferred embodiment, cavities are provided inside the upper temperature control plate and the lower temperature control plate. A plurality of vertical posts are arranged inside the cavities. The vertical posts are used for winding liquid pipelines. One end of the upper temperature control plate and the lower temperature control plate is provided with a heat-conducting cover that can be opened.

[0020] In a preferred embodiment, a spring balance frame is arranged on one side of the temperature control box. The spring balance frame includes a sliding block that can slide up and down. A spring balancer is arranged at the upper end of the sliding block. The sliding block is provided with a transverse connecting arm, and the transverse connecting arm is connected to the upper half box body.

[0021] The beneficial effects of the present invention are as follows: A test device for the temperature change rate sensitivity and axial temperature difference sensitivity of an optical fiber loop is proposed, which can achieve precise temperature control of the upper and lower surfaces of the optical fiber loop, thereby stimulating a stable non-uniform temperature field and realizing the test of the axial temperature difference sensitivity of the optical fiber loop; the temperature control is rapid and the distance between the temperature control device and the optical fiber loop is extremely close, enabling precise control of the surface temperature of the optical fiber loop; while having a good shock absorption structure, it can quickly and precisely test the temperature performance of the optical fiber loop; liquid temperature control is adopted to eliminate the interference of the magnetic field generated by the current on the test; the hollow ring frame and the upper and lower separated temperature box structure are adopted to avoid the problems of narrow fiber outlet and easy breakage or scratching of the test optical fiber in the traditional integrated temperature box; it has good expandability, and multiple temperature boxes with different required temperatures can be driven to test simultaneously through the mixing of the hot pool and the cold pool, without the need for multiple independent heating and cooling modules, saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described below with reference to the drawings and embodiments.

[0023] Figure 1 is a schematic diagram of the present invention.

[0024] Figure 2 is a connection schematic diagram of the present invention.

[0025] Figure 3 is a multi-temperature box test expansion diagram of the present invention.

[0026] Figure 4 is a structural diagram of the present invention.

[0027] Figure 5 is a schematic diagram of the base device of the present invention.

[0028] Figure 6 is a front sectional schematic diagram of the present invention.

[0029] Figure 7 is a side sectional schematic diagram of the present invention.

[0030] Figure 8 is a structural diagram of the ring frame of the present invention.

[0031] Figure 9 is an exploded view of the half box body of the present invention.

[0032] Figure 10 is a structural diagram for adjusting the distance between the temperature control plates of the present invention.

[0033] Figure 11 is an optimized structural diagram of the ring frame of the present invention.

[0034] In the figure: temperature control box 1; upper temperature control plate 101; lower temperature control plate 102; upper half box body 103; lower half box body 104; horizontal frame 105; ring frame 106; baffle 107; stop portion 108; packing ring 109; vertical pile 110; heat conduction cover 111; first shock absorption groove 112; thin ring piece 113; base device 2; shock absorption plate 201; base 202; shock absorption spacer 203; connecting shaft 204; height adjusting plate 205; first spring 206; locking knob 207; guide post 208; second spring 209; tension bolt 210; opening 211; second shock absorption groove 212; mixer 3; heat pool 4; heater 401; cold pool 5; refrigerator 501; controller 6; reversing valve island 7; reversing valve 701; optical fiber ring 8; spring balance frame 9; sliding block 901; horizontal connecting arm 902; workbench 10; raised foundation 11; third shock absorption groove 1101. Detailed implementation mode

[0035] As Figures 1-11 In [reference], a device for testing the temperature and temperature difference of an optical fiber ring includes an upper temperature control plate 101 and a lower temperature control plate 102 arranged in parallel at intervals. The optical fiber ring 8 is placed between the upper temperature control plate 101 and the lower temperature control plate 102. It also includes a heat pool 4, a cold pool 5 and at least two mixers 3. Liquid media are provided in the heat pool 4 and the cold pool 5. The liquid media in the heat pool 4 and the cold pool 5 are mixed by each mixer 3 and then respectively transported into the upper temperature control plate 101 and the lower temperature control plate 102.

[0036] It also includes a controller 6. The controller 6 controls each component. The heat pool 4 is provided with a heater 401, and the cold pool 5 is provided with a refrigerator 501. Therefore, the temperatures of the liquid media in the heat pool 4 and the cold pool 5 can be adjusted. The pumping flow rates of the liquid media in the heat pool 4 and the cold pool 5 to the mixer 3 are also controlled by the controller 6. Therefore, the temperature in the mixer 3 can be adjusted to a set temperature. The two mixers 3 supply liquid to the upper temperature control plate 101 and the lower temperature control plate 102 respectively. The liquid media in the upper temperature control plate 101 and the lower temperature control plate 102 finally circulate back to the heat pool 4 and the cold pool 5.

[0037] The liquid medium is preferably water or oil.

[0038] In a preferred solution, it also includes a reversing valve island 7. A reversing valve 701 is provided in the reversing valve island 7. The upper temperature control plate 101 and the lower temperature control plate 102 are connected to two inlets of the reversing valve 701. The two outlets of the reversing valve 701 are respectively connected to the heat pool 4 and the cold pool 5. The connection status of the two inlets and the two outlets can be exchanged.

[0039] The controller 6 compares the water temperatures in the upper temperature control plate 101 and the lower temperature control plate 102, transports the high-temperature liquid to the heat pool 4, and transports the low-temperature liquid to the cold pool 5 to achieve the purpose of energy conservation.

[0040] In a preferred embodiment, a temperature control box 1 is further provided. The upper temperature control plate 101 and the lower temperature control plate 102 are arranged inside the temperature control box 1. A cross frame 105 is also provided. The cross frame 105 passes through the temperature control box 1. A plurality of optical fiber rings 8 are placed in the middle of the cross frame 105. A base device 2 is further provided. The base device 2 includes a shock-absorbing plate 201 and a base 202. A shock-absorbing spacer 203 is arranged between the shock-absorbing plate 201 and the base 202. The base 202 is used to support the temperature control box 1, and the shock-absorbing plate 201 supports the cross frame 105.

[0041] A through hole is provided in the middle of the temperature control box 1. The cross frame 105 has a thin neck portion here. The neck passes through the through hole and does not contact the cross frame 105. A packing ring 109 is sleeved at the joint to block the remaining gap. The outer wall of the temperature control box 1 is covered with heat-insulating and heat-preserving materials.

[0042] The gap between the upper temperature control plate 101 and the lower temperature control plate 102 and the optical fiber ring 8 is small but they do not contact. A shock-absorbing spacer 203 made of vibration-isolating materials such as rubber or silica gel is arranged between the shock-absorbing plate 201 and the base 202 to reduce the influence of the water flow vibration in the upper temperature control plate 101 and the lower temperature control plate 102 on the optical fiber ring 8.

[0043] The shock-absorbing plate 201 is made of non-metallic shock-absorbing materials. Second shock-absorbing grooves 212 arranged in a staggered manner up and down are provided along the contact portion with the base 202. The second shock-absorbing grooves 212 on the upper side and the second shock-absorbing grooves 212 on the lower side have overlapping portions in the thickness direction, effectively blocking the transmission of vibration waves.

[0044] The cross frame 105 is also provided with first shock-absorbing grooves 112 arranged in a staggered manner along the vibration wave transmission direction.

[0045] In a preferred embodiment, the temperature control box 1 is composed of a upper half box body 103 and a lower half box body 104 spliced together. The upper temperature control plate 101 is arranged inside the upper half box body 103, and the lower temperature control plate 102 is arranged inside the lower half box body 104.

[0046] The upper half box body 103 can be opened to expose the middle of the cross frame 105, which is convenient for placing the optical fiber ring 8.

[0047] The base 202 stands on the workbench 10. The shock-absorbing plate 201 does not contact the workbench 10. The workbench 10 stands on the raised foundation 11. Third shock-absorbing grooves 1101 are provided around the raised foundation 11. Vibration sources such as the heat pool 4, the cold pool 5, the controller 6 and the night pump are placed outside the third shock-absorbing grooves 1101.

[0048] A spring balance frame 9 is provided on one side of the temperature control box 1. The spring balance frame 9 includes a sliding block 901 that can slide up and down. The upper end of the sliding block 901 is suspended by a spring balancer. The sliding block 901 is provided with a horizontal connecting arm 902, and the horizontal connecting arm 902 is connected to the upper half box body 103.

[0049] Fiber ports and outlet pipes are opened on the sides of the upper half box body 103 and the lower half box body 104.

[0050] In addition, since the cross frame 105 passes through the temperature control box 1, but needs to be non-contact with the temperature control box 1 to prevent conduction vibration, in order to reduce the installation difficulty, the height of the temperature control box 1 needs to be adjusted as a whole.

[0051] Therefore, in a preferred solution, a connecting shaft 204 is sleeved on the upper end of the base 202, a height adjustment plate 205 is provided at the upper end of the connecting shaft 204, the height adjustment plate 205 is connected to the lower half box body 104, the height adjustment plate 205 is provided with a positioning boss hole, the positioning boss hole of the height adjustment plate 205 is slidably sleeved on the upper end of the connecting shaft 204, and the height adjustment plate 205 is provided with a locking knob 207, and the locking knob 207 locks the height of the height adjustment plate 205.

[0052] Both the base 202 and the height adjustment plate 205 are provided with boss holes. One end of the connecting shaft 204 is threadedly connected to the boss hole of the base 202, the other end of the connecting shaft 204 is slidably sleeved on the positioning boss hole of the height adjustment plate 205, and a plurality of annular grooves for increasing the friction coefficient are provided on the outer wall of the upper end of the connecting shaft 204. The locking knob 207 passes through the positioning boss hole of the height adjustment plate 205 and abuts against the annular groove area on the outer wall of the connecting shaft 204.

[0053] In a preferred solution, a first spring 206 is provided between the base 202 and the height adjustment plate 205, and both ends of the first spring 206 abut against the base 202 and the height adjustment plate 205 respectively.

[0054] Since the temperature control box 1 has a certain weight, in order to facilitate reducing the difficulty during height adjustment, the first spring 206 is used to balance the self-weight of the temperature control box 1 and the internal temperature control plate.

[0055] In a preferred solution, a guide post 208 is provided in the upper half box body 103, a second spring 209 is sleeved on the guide post 208, the upper temperature control plate 101 is slidably sleeved on the guide post 208, the end face of the upper temperature control plate 101 abuts against the second spring 209, and a tension bolt 210 is further provided, and the tension bolt 210 passes through the upper temperature control plate 101 to be threadedly connected to the upper half box body 103.

[0056] The spacing adjustment structure between the lower half box body 104 and the lower temperature control plate 102 is the same. Transparent observation windows are provided on the sides of the upper half box body 103 and the lower half box body 104. After the general height position of the temperature control box 1 is adjusted, lock the locking knob 207, rotate the tensioning bolt 210 in the lower half box body 104, and finely adjust the gap between the lower temperature control plate 102 and the lower end face of the optical fiber ring 8, getting as close as possible but not touching. Then cover and roughly adjust the tensioning bolt 210 in the upper half box body 103, close the upper half box body 103, observe the spacing between the upper temperature control plate 101 and the upper end face of the optical fiber ring 8. If the distance is too large or too small, open the upper half box body 103, finely adjust the tensioning bolt 210 again and then close the upper half box body 103.

[0057] Since the operation of opening and closing the upper half box body 103 multiple times is troublesome, in the preferred solution, an opening 211 is provided at the connection of the tensioning bolt 210 on the upper half box body 103.

[0058] The end of the tensioning bolt 210 is provided with an internal hexagonal groove, which is convenient for directly rotating the tensioning bolt 210 from the outside without opening the upper half box body 103, so as to achieve the effect of adjusting the spacing between the upper temperature control plate 101 and the end face of the optical fiber ring 8.

[0059] In the preferred solution, a plurality of hollow holes are provided in the middle of the cross frame 105, a ring frame 106 is provided in the hollow holes, a plurality of retaining pieces 107 are provided along the circumferential direction at the lower end of the ring frame 106, the retaining pieces 107 are used to place the optical fiber ring 8, and there is a gap between the outer wall of the optical fiber ring 8 and the inner wall of the ring frame 106.

[0060] In the preferred solution, the retaining pieces 107 are connected by a thin ring piece 113, and the optical fiber ring 8 is placed on the thin ring piece 113 to ensure that the lower end face of the optical fiber ring 8 will not be suspended and deformed by heat.

[0061] Since the material used for the ring frame 106 is different from that of the optical fiber ring 8 and the thermal expansion coefficients are different, a gap needs to be left between the outer wall of the optical fiber ring 8 and the inner wall of the ring frame 106.

[0062] The ring frame 106 is provided with a stop portion 108, the stop portion 108 is hung on the cross frame 105, the hollow structure of the ring frame 106 is convenient for the optical fiber ring 8 to lead out fibers from the outer wall, and at the same time the overall height of the ring frame 106 is slightly greater than the thickness of the optical fiber ring 8 to prevent the upper temperature control plate 101 and the lower temperature control plate 102 from damaging the optical fiber ring 8 when adjusting the spacing.

[0063] In the preferred solution, cavities are provided inside the upper temperature control plate 101 and the lower temperature control plate 102, a plurality of vertical posts 110 are provided in the cavities, the vertical posts 110 are used for winding liquid pipes, and one end of the upper temperature control plate 101 and the lower temperature control plate 102 is provided with an openable heat conduction cover 111.

[0064] The heat-conducting cover 111 is arranged at one end close to the optical fiber ring 8. The heat-conducting performance of the heat-conducting cover 111 is better than that of other parts of the upper temperature control plate 101 and the lower temperature control plate 102. Even other parts can use heat-insulating materials, and only the heat-conducting cover 111 conducts heat. After the transported liquid enters, the heat is concentrated in the cavity and is transferred only through this surface of the heat-conducting cover 111, directing the heat to the optical fiber ring 8 and reducing the heat dissipation at other positions. In addition, a vertically gradient and uniform temperature difference field is formed between the upper temperature control plate 101 and the lower temperature control plate 102, with higher controllability of the experimental environment and more ideal experimental results.

[0065] A temperature sensor is arranged in the cavity to monitor the temperature.

[0066] The controller needs to collect the real-time temperatures of the upper and lower temperature control plates and the cold and hot water pools, and use the PID control algorithm to regulate the mixer to achieve precise control of the temperature control plates.

[0067] If the upper and lower temperature control plates are set to be isothermal, the traditional incubator can be replaced.

[0068] The above embodiments are only the preferred technical solutions of the present invention and should not be regarded as limitations on the present invention. The protection scope of the present invention should be the technical solutions recorded in the claims, including the equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, the equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. An optical fiber loop temperature and temperature difference testing device, characterized in that: It includes an upper temperature control plate (101) and a lower temperature control plate (102) arranged in parallel at intervals. The optical fiber loop (8) is placed between the upper temperature control plate (101) and the lower temperature control plate (102). It also includes a hot pool (4), a cold pool (5) and at least two mixers (3). Liquid media are provided in the hot pool (4) and the cold pool (5). The liquid media in the hot pool (4) and the cold pool (5) are mixed by each mixer (3) and then respectively delivered into the upper temperature control plate (101) and the lower temperature control plate (102). It also includes a reversing valve island (7). A reversing valve (701) is provided in the reversing valve island (7). The upper temperature control plate (101) and the lower temperature control plate (102) communicate with two inlets of the reversing valve (701). Two outlets of the reversing valve (701) communicate with the hot pool (4) and the cold pool (5) respectively, and the connection status of the two inlets and the two outlets can be exchanged. Internal cavities are provided in the upper temperature control plate (101) and the lower temperature control plate (102). A plurality of vertical piles (110) are provided in the cavities for winding liquid pipelines. One end of the upper temperature control plate (101) and the lower temperature control plate (102) is provided with a heat-conducting cover (111) that can be opened. A temperature control box (1) is also provided. The upper temperature control plate (101) and the lower temperature control plate (102) are arranged in the temperature control box (1). A cross frame (105) is also provided. The cross frame (105) passes through the temperature control box (1). A plurality of optical fiber loops (8) are placed in the middle of the cross frame (105). A base device (2) is also provided. The base device (2) includes a shock-absorbing plate (201) and a base (202). A shock-absorbing spacer (203) is provided between the shock-absorbing plate (201) and the base (202). The base (202) is used to support the temperature control box (1), and the shock-absorbing plate (201) supports the cross frame (105).

2. The optical fiber loop temperature and temperature difference testing device according to claim 1, wherein: The temperature control box (1) is composed of a spliced upper half box body (103) and a lower half box body (104). The upper temperature control plate (101) is arranged in the upper half box body (103), and the lower temperature control plate (102) is arranged in the lower half box body (104).

3. The optical fiber loop temperature and temperature difference testing device according to claim 2, characterized in that: A connecting shaft (204) is sleeved on the upper end of the base (202). A height adjusting plate (205) is provided at the upper end of the connecting shaft (204). The height adjusting plate (205) is connected to the lower half box body (104). The height adjusting plate (205) is provided with a positioning boss hole, and the positioning boss hole of the height adjusting plate (205) is slidably sleeved on the upper end of the connecting shaft (204). The height adjusting plate (205) is provided with a locking knob (207), and the locking knob (207) locks the height of the height adjusting plate (205).

4. The optical fiber loop temperature and temperature difference test device according to claim 3, characterized in that: A first spring (206) is provided between the base (202) and the height adjusting plate (205). Two ends of the first spring (206) respectively abut against the base (202) and the height adjusting plate (205).

5. The optical fiber loop temperature and temperature difference testing device according to claim 4, characterized in that: A guide post (208) is provided in the upper half box body (103). A second spring (209) is sleeved on the guide post (208). The upper temperature control plate (101) is slidably sleeved on the guide post (208). The end face of the upper temperature control plate (101) abuts against the second spring (209). A tension bolt (210) is also provided. The tension bolt (210) passes through the upper temperature control plate (101) to be threadedly connected to the upper half box body (103).

6. The optical fiber loop temperature and temperature difference testing device according to claim 5, characterized in that: There is an opening (211) at the connection of the tension bolt (210) on the upper half box body (103).

7. The optical fiber loop temperature and temperature difference testing device according to claim 1, characterized in that: There are multiple hollow holes in the middle of the cross frame (105). There is an annular frame (106) inside the hollow holes. There are multiple retaining pieces (107) arranged along the circumference at the lower end of the annular frame (106). There is also a thin annular piece (113). The thin annular piece (113) connects the upper end faces of the retaining pieces (107). The thin annular piece (113) is used to place the optical fiber ring (8). There is a gap between the outer wall of the optical fiber ring (8) and the inner wall of the annular frame (106).

8. The fiber optic loop temperature and temperature difference testing device according to claim 2, characterized in that: There is a spring balance frame (9) on one side of the temperature control box (1). The spring balance frame (9) includes a sliding block (901). The sliding block (901) can slide up and down. There is a spring balancer at the upper end of the sliding block (901). The sliding block (901) is provided with a transverse connecting arm (902). The transverse connecting arm (902) is connected to the upper half box body (103).

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