Laser doppler rotational speed calibration device

Abstract

The application is a laser Doppler rotational speed calibration device, belonging to the technical field of Doppler velocity measurement, comprising a shell, a regulating cavity is formed in the inner side of the shell, an installation cavity two is formed in one end of the regulating cavity, an installation cavity three is formed in the end of the installation cavity two away from the regulating cavity, and a helium-neon laser is arranged in the inner side of the installation cavity three. The application solves the problem that only the inner cavity of the rotating drum can be detected, which requires the laser to be obliquely shot into the inner cavity of the rotating drum, and since the diameter and depth of the rotating drum of each centrifuge are different, the laser directly irradiating the rotating drum is hindered. In the application, the laser focusing points of the first and zero levels can be adjusted through the use of the sliding block, so as to facilitate the automatic adjustment of the detection distance of the device, make the laser focusing points hit the detection column, so that the outer side of the detection column is hit, and the rotation of the detection column can be detected, and the laser can directly hit the detection column horizontally.

Description

Technical Field

[0001] This invention belongs to the field of Doppler velocimetry technology, specifically relating to a laser Doppler speed calibration device. Background Technology

[0002] Doppler velocimetry measures the Doppler signal of tracer particles passing through a laser probe, and then obtains the velocity based on the relationship between velocity and Doppler frequency. Since it is a laser measurement, it does not interfere with the flow field, has a wide velocity measurement range, and since the Doppler frequency and velocity have a linear relationship, it is independent of the temperature and pressure at that point, making it the most accurate velocity measurement method in the world to date.

[0003] Existing Doppler velocimetry devices are mostly designed to measure the speed of linear motion. Directly measuring the rotational speed of an object brings many problems. For example, when inspecting and calibrating the rotor of a centrifuge, since the rotor of a medical centrifuge is located in the inner cavity of the centrifuge, only the inner cavity of the rotor can be measured. This requires the laser to be angled and injected into the inner cavity of the rotor. Moreover, since the diameter and depth of the rotor of each centrifuge are different, this creates a certain obstacle to the direct irradiation of the rotor by the laser. Therefore, a laser Doppler rotational speed calibration device is proposed. Summary of the Invention

[0004] This invention provides a laser Doppler speed calibration device, which aims to solve the problems caused by the fact that most existing Doppler velocimetry devices are designed to measure the speed of linear motion. Directly measuring the rotational speed of an object brings many problems. For example, when inspecting and calibrating the rotor of a centrifuge, since the rotor of a medical centrifuge is located in the inner cavity of the centrifuge, only the inner cavity of the rotor can be detected. This requires the laser to be angled to enter the inner cavity of the rotor. Moreover, since the diameter and depth of the rotor of each centrifuge are different, this creates a certain obstacle to the direct irradiation of the rotor by the laser.

[0005] This invention provides a laser Doppler speed calibration device, comprising a housing, an adjustment cavity formed on the inner side of the housing, a second mounting cavity formed at one end of the adjustment cavity, a third mounting cavity formed at the end of the second mounting cavity away from the adjustment cavity, a helium-neon laser disposed on the inner side of the third mounting cavity, an emitter electrically connected to one end of the helium-neon laser, the emitter extending into the second mounting cavity, a half-wave plate and an acousto-optic modulator sequentially disposed on the inner side of the second mounting cavity, a funnel-shaped cavity at one end of the second mounting cavity, the funnel-shaped cavity being directly connected to the third mounting cavity, and a cooling mechanism inserted into the bottom end of the third mounting cavity;

[0006] Inside the control cavity, a first reflector, a second reflector, a second half-wave plate, and a first lens are sequentially installed. The first reflector and the second half-wave plate are located at the top of the control cavity and are rotatably connected to the inner wall of the control cavity. The second half-wave plate is installed between the first lens and the first reflector. The second reflector is located in the middle of the control cavity. An air outlet groove is opened at the bottom of the inner wall of the control cavity. The second lens and a photoelectric receiver are installed inside the air outlet groove. The photoelectric receiver is installed on a bracket, which is fixed inside the air outlet groove. A first filter is inserted into the bottom of the air outlet groove.

[0007] The control cavity has a connecting groove at the end away from the second mounting cavity. A detection column is placed near the connecting groove on the housing, and the detection column is placed at the position of the housing away from the connecting groove.

[0008] By adopting the above scheme, the detection column and the linkage sleeve are used to link the detection column with the rotating drum inside the centrifuge. This allows the rotation of the detection column to be detected outside the centrifuge. Furthermore, since the radius of the detection column is known, the rotational speed of the rotating drum can be detected without knowing its inner diameter. This greatly simplifies the calculation of the detection structure. By measuring the rotational speed of the detection column, the rotational speed of the rotating drum inside the centrifuge can be measured non-contactly. Then, the measured rotational speed is used as a basis to calibrate the rotational speed of the rotating drum inside the centrifuge.

[0009] Furthermore, the bottom end of the second mounting cavity has a pre-reserved mounting port for communicating with the outside, and a sealing plate is snapped into the mounting port of the second mounting cavity.

[0010] By adopting the above scheme, the mounting port facilitates the installation and maintenance of the half-wave plate and the acousto-optic modulator.

[0011] Furthermore, the air-cooling mechanism includes an air-cooling base, a drive motor, an airflow generating slot, a filter screen, and fan blades. An airflow generating slot is provided on the inner side of the air-cooling base, and a filter screen is provided at the bottom end of the airflow generating slot. A drive motor is installed on the inner side of the air-cooling base, and a fan blade is connected to the rotating rod of the drive motor. An inclined air guide plate is provided on the inner side of the mounting cavity near the sound and light modulator.

[0012] By adopting the above scheme, the air-cooling mechanism generates airflow that passes sequentially through mounting cavity three, mounting cavity two, and control cavity, and is discharged from the air outlet slot, thereby cooling the structures inside mounting cavity three, mounting cavity two, air outlet slot, and control cavity.

[0013] Furthermore, several drying balls are installed on the inner side of the airflow generating trough, and carbon powder particles and calcium chloride particles are installed on the inner side of the drying balls. The drying balls are spherical and have several small holes with a diameter of 0.03-0.05 mm.

[0014] By adopting the above method, carbon powder particles and calcium chloride particles can clean and dry the air entering the control chamber.

[0015] Furthermore, a hinge seat is provided at one end of the housing, and a horizontal cover is hinged to the hinge seat. A stop rod is fixedly connected to one end of the hinge seat. The stop rod is horizontally installed. A snap-fit ​​groove is provided at the end of the horizontal cover near the hinge seat. The snap-fit ​​groove and the stop rod are movably connected. A limit rod is provided at the end of the horizontal cover away from the housing. A horizontal support plate is installed on one side of the horizontal cover. A limit groove is provided at one end of the horizontal support plate. The limit groove and the limit rod are slidably connected. The limit rod is in the shape of a trapezoidal column. A detection column is installed on the horizontal support plate.

[0016] By adopting the above solution, the horizontal support plate provides a stable horizontal platform for the centrifuge and the test column, enabling the centrifuge and the test column to be placed simply, quickly and stably.

[0017] Furthermore, the detection column is installed on the top of the centrifuge, which is placed on a horizontal support plate. A rotating drum is rotatably connected to the inside of the centrifuge, and the detection column is installed on the inside of the rotating drum. A connecting column is provided at the bottom of the detection column, and a linkage sleeve is sleeved on the outside of the connecting column. The linkage sleeve is inserted into the inside of the rotating drum. The linkage sleeve is made of phenolic resin and is shaped like a bottle stopper. The linkage sleeve enables the rotating drum and the detection column to move together.

[0018] By adopting the above scheme, the detection column can be linked with the rotating drum inside the centrifuge, so that the rotation of the detection column can be detected outside the centrifuge. Moreover, the radius of the detection column is known, and the rotation speed of the rotating drum can be detected without knowing the inner diameter of the rotating drum.

[0019] Furthermore, the photodetector is connected to a hardware circuit, which is then connected to a computer device for processing using the LabVIEW program. The hardware circuit includes a two-stage preamplifier circuit.

[0020] By adopting the above scheme, since the photodetector collects scattered light, the output signal is very weak, only about tens of microwatts, and the signal frequency is relatively high. In order to facilitate signal processing, a two-stage preamplifier circuit is used to amplify the signal.

[0021] Furthermore, the lens is installed on the inner side of the mounting base, a rubber sealing ring is provided on the outer side of the mounting base, a slider is provided at the top of the mounting base, a sliding track is provided at the top of the control cavity, the inner side of the sliding track is movably connected to the slider, a servo motor is provided on the inner side of the housing, a lead screw is fixedly connected to the rotor of the servo motor, and the outer side of the lead screw is threadedly connected to the slider.

[0022] By adopting the above scheme, the relative position of lens one and the control cavity can be adjusted by the cooperation of the lead screw and the slider.

[0023] Compared with the prior art, the above-mentioned technical solution of the present invention has the following beneficial technical effects:

[0024] 1. In this invention, the use of a slider allows for positional movement, thereby enabling adjustment of the laser focus points for levels 1 and 0. This facilitates the automatic adjustment of the detection distance of the device, ensuring the laser focus point hits the detection column on its outer side, thus allowing the rotation of the detection column to be detected. The laser can be directly and horizontally struck on the detection column. By using the detection column and the linkage sleeve, the detection column is linked to the rotating drum inside the centrifuge, allowing the rotation of the detection column to be detected outside the centrifuge. Furthermore, the radius of the detection column is known, eliminating the need to know the inner diameter of the rotating drum to detect its rotational speed, which greatly simplifies the calculation of the detection structure. The slider also seals the deep interior of the control cavity, preventing dust from entering through the connecting groove.

[0025] 2. In this invention, a two-stage preamplifier circuit is used to amplify the signal. The photodetector collects scattered light, and the output signal is very weak, only about tens of microwatts, and the signal frequency is relatively high. In order to facilitate signal processing, an amplifier circuit is needed to amplify the signal.

[0026] 3. In this invention, a dry airflow is generated by a wind-cooling mechanism to cool the electronic equipment structure in mounting cavity three, mounting cavity two, air outlet groove and control cavity;

[0027] 4. In this invention, a horizontal support plate provides a stable horizontal platform for the centrifuge and the test column, enabling the centrifuge and the test column to be placed simply, quickly and stably.

[0028] 5. In this invention, the rotational speed of the drum inside the centrifuge is measured non-contactly using this device, and then the rotational speed of the drum inside the centrifuge is calibrated based on the measured rotational speed.

[0029] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description and the drawings. Attached Figure Description

[0030] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0031] Figure 1 This is a front view of the present invention.

[0032] Figure 2 For the present invention Figure 1 A partially enlarged structural diagram of part A in the middle;

[0033] Figure 3 For the present invention Figure 1 A partially enlarged structural diagram of part B;

[0034] Figure 4 For the present invention Figure 1 A partially enlarged structural diagram of section C;

[0035] Figure 5 This is a three-dimensional structural diagram of the limiting rod (11) of the present invention;

[0036] Figure 6 This is a schematic diagram showing the positional relationship between the detection column (13) and the centrifuge (40) of the present invention;

[0037] Figure 7 This is a schematic diagram of the photoelectric receiving circuit of the present invention;

[0038] Figure 8 This is a schematic diagram of the two-stage preamplifier circuit of the present invention;

[0039] Figure 9 This is a flowchart of the data processing procedure of the present invention;

[0040] Figure 10 This is the differential Doppler laser optical path diagram of the present invention;

[0041] Figure 11 This is a schematic diagram of the phase-sensitive detector circuit of the present invention.

[0042] Reference numerals: Housing—1; Control cavity—2; Reflector one—3; Reflector two—4; Half-wave plate two—5; Servo motor—6; Lead screw—7; Slider—8; Sliding track—9; Horizontal cover—10; Limiting rod—11; Limiting groove—12; Detection column—13; Horizontal receiving plate—14; Connecting groove—15; Lens one—17; Mounting base—18; Filter one—19; Air outlet groove—22; Photoelectric receiver—21; Air outlet groove—22; Lens two— 23; Acousto-optic modulator—24; Mounting cavity two—25; Half-wave plate one—26; Transmitter—27; Air-cooled base—28; Helium-neon laser—29; Mounting cavity three—30; Air guide plate—31; Hinge base—32; Stop rod—33; Snap-fit ​​groove—34; Drive motor—35; Airflow generating groove—36; Drying ball—37; Filter screen one—38; Fan blade—39; Centrifuge—40; Rotary drum—41; Connecting column—42; Linkage sleeve—43. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The same reference numerals in the drawings represent the same components. It should be noted that the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0044] like Figure 1-11 As shown, the present invention proposes a laser Doppler speed calibration device, including a housing 1. An adjustment cavity 2 is provided on the inner side of the housing 1. A second mounting cavity 25 is provided at one end of the adjustment cavity 2. A third mounting cavity 30 is provided at the end of the second mounting cavity 25 away from the adjustment cavity 2. A helium-neon laser 29 is provided on the inner side of the third mounting cavity 30. A transmitter 27 is electrically connected to one end of the helium-neon laser 29. The transmitter 27 extends into the second mounting cavity 25. A half-wave plate 26 and an acousto-optic modulator 24 are sequentially installed on the inner side of the second mounting cavity 25. The cavity at one end of the second mounting cavity 25 is funnel-shaped. The funnel-shaped cavity is directly connected to the third mounting cavity 30. A wind-cooling mechanism is inserted into the bottom end of the third mounting cavity 30.

[0045] The inner side of the control cavity 2 is sequentially equipped with a reflector 3, a reflector 4, a half-wave plate 5, and a lens 17. The reflector 3 and the half-wave plate 5 are located at the top of the control cavity 2 and are rotatably connected to the inner wall of the control cavity 2. The half-wave plate 5 is installed between the lens 17 and the reflector 3. The reflector 4 is located in the middle of the control cavity 2. An air outlet groove 22 is opened at the bottom of the inner wall of the control cavity 2. A lens 23 and a photoelectric receiver 21 are arranged on the inner side of the air outlet groove 22. The photoelectric receiver 21 is installed on a bracket, which is fixed to the inner side of the air outlet groove 22. A filter 19 is inserted into the bottom end of the air outlet groove 22.

[0046] The control cavity 2 has a connecting groove 15 at the end away from the mounting cavity 25. The housing 1 has a detection column 13 placed near the connecting groove 15, and the housing 1 has a corresponding position for the detection column 13 away from the connecting groove 15.

[0047] By using the detection column 13 and the linkage sleeve 43, the detection column 13 is linked to the rotating drum 41 inside the centrifuge 40, allowing the rotation of the detection column 13 to be detected outside the centrifuge 40. Since the radius of the detection column 13 is known, the rotational speed of the rotating drum 41 can be detected without knowing its inner diameter, which greatly simplifies the calculation of the detection structure. By measuring the rotational speed of the detection column 13, the rotational speed of the rotating drum 41 inside the centrifuge 40 can be measured non-contactly, and then the rotational speed of the rotating drum 41 inside the centrifuge 40 can be calibrated based on the measured rotational speed.

[0048] The bottom end of the second mounting cavity 25 is provided with an installation port for communicating with the outside world, and a sealing plate is snapped into the installation port of the second mounting cavity 25;

[0049] The mounting port facilitates the installation and maintenance of the half-wave plate 26 and the acousto-optic modulator 24.

[0050] The air-cooling mechanism includes an air-cooling base 28, a drive motor 35, an airflow generating slot 36, a filter screen 38, and fan blades 39. The air-cooling base 28 has an airflow generating slot 36 on its inner side, and a filter screen 38 is provided at the bottom of the airflow generating slot 36. The drive motor 35 is installed on the inner side of the air-cooling base 28, and the fan blades 39 are connected to the rotating rod of the drive motor 35. An inclined air guide plate 31 is provided on the inner side of the mounting cavity 25 near the sound and light modulator 24.

[0051] The air-cooling mechanism generates airflow that passes sequentially through mounting cavity 30, mounting cavity 25, and regulating cavity 2, and is discharged from the air outlet 22, thereby cooling the structures inside mounting cavity 30, mounting cavity 25, air outlet 22, and regulating cavity 2.

[0052] Several drying balls 37 are installed on the inner side of the airflow generating groove 36. Carbon powder particles and calcium chloride particles are installed on the inner side of the drying balls 37. The drying balls 37 are spherical and have several small holes with a diameter of 0.03-0.05 mm.

[0053] Carbon powder particles and calcium chloride particles can clean and dry the air entering the control chamber 2.

[0054] A hinge seat 32 is provided at one end of the housing 1. A horizontal cover 10 is hinged to the hinge seat 32. A stop rod 33 is fixedly connected to one end of the hinge seat 32. The stop rod 33 is horizontally installed. A snap-fit ​​groove 34 is provided at the end of the horizontal cover 10 near the hinge seat 32. The snap-fit ​​groove 34 and the stop rod 33 are movably connected. A limit rod 11 is provided at the end of the horizontal cover 10 away from the housing 1. A horizontal support plate 14 is installed on one side of the horizontal cover 10. A limit groove 12 is provided at one end of the horizontal support plate 14. The limit groove 12 and the limit rod 11 are slidably connected. The limit rod 11 is trapezoidal column in shape. A detection column 13 is installed on the horizontal support plate 14.

[0055] The horizontal support plate 14 provides a stable horizontal platform for the centrifuge 40 and the test column 13, enabling the centrifuge 40 and the test column 13 to be placed simply, quickly and stably.

[0056] The detection column 13 is installed on the top of the centrifuge 40, which is placed on a horizontal support plate 14. A rotating drum 41 is rotatably connected to the inside of the centrifuge 41, and the detection column 13 is installed on the inside of the rotating drum 41. A connecting column 42 is provided at the bottom of the detection column 13, and a connecting sleeve 43 is sleeved on the outside of the connecting column 42. The connecting sleeve 43 is inserted into the inside of the rotating drum 41. The material of the connecting sleeve 43 is phenolic resin, and the shape of the connecting sleeve 43 is bottle stopper-shaped. The connecting sleeve 43 enables the rotating drum 41 and the detection column 13 to move together.

[0057] The detection column 13 can be linked with the rotating drum 41 inside the centrifuge 40, so that the rotation of the detection column 13 can be detected outside the centrifuge 40. Moreover, the radius of the detection column 13 is known, and the rotation speed of the rotating drum 41 can be detected without knowing the inner diameter of the rotating drum 41.

[0058] The photoelectric receiver 21 is connected to a hardware circuit, which is then connected to a computer device for processing using a LabVIEW program. The hardware circuit includes a two-stage preamplifier circuit.

[0059] Because the photodetector 21 collects scattered light, the output signal is very weak, only about tens of microwatts, and the signal frequency is relatively high. In order to facilitate signal processing, a two-stage preamplifier circuit is used to amplify the signal.

[0060] The lens 17 is installed on the inner side of the mounting base 18. A rubber sealing ring is provided on the outer side of the mounting base 18. A slider 8 is provided at the top of the mounting base 18. A sliding track 9 is opened at the top of the control cavity 2. The inner side of the sliding track 9 is movably connected to the slider 8. A servo motor 6 is provided on the inner side of the housing 1. A lead screw 7 is fixedly connected to the rotating rod of the servo motor 6. The outer side of the lead screw 7 is threadedly connected to the slider 8.

[0061] The lead screw 7 and the slider 8 work together to adjust the relative position of the lens 17 and the control cavity 2.

[0062] The linkage sleeve 43 presses against the inner side of the rotating drum 41, causing the linkage sleeve 43 and the rotating drum 41 to move together. The linkage sleeve 43 also causes the connecting column 42 and the detection column 13 to move together with the rotating drum 41.

[0063] The half-wave plate 25 is a λ / 2 half-wave plate.

[0064] The laser Doppler speed calibration device adopts the differential laser Doppler principle, and its formula is: Let the velocity in the tangential direction of the detection column 13 be V;

[0065] The frequencies of the level 1 and level 0 lines are F1 and F1+F2, respectively. F2 is the modulation frequency of the acousto-optic modulator 24. The angle between them after passing through lens 17 is A. The angles between them and the tangent direction are a1 and a2, respectively. The angle between the observation direction and the tangent direction is a3.

[0066] The Doppler frequency shift of the scattered light from beam 1 in the observation direction is:

[0067] ΔF1=F1×V / c(cosa1+cosa3);

[0068] The Doppler frequency shift of the scattered light from beam 2 in the observation direction is:

[0069] ΔF2=(F1+F2)×V / c(cosa2+cosa3);

[0070] The scattered light from two beams in the observation direction forms an optical beat, and the beat frequency is the frequency difference of the Doppler frequency shift of the two beams:

[0071] f=ΔF1-ΔF2=F2+F1×V / c(cosa1-cosa2);

[0072] In the above formula, F1, F2, and c are all known quantities whose values ​​do not change with velocity, while a1 and a2 are a pair of supplementary angles. From the sum-to-product formula, we can obtain:

[0073] f = F2 + 2F1 × V / c(sin(A / 2));

[0074] From this equation, it can be seen that once the parameters of the optical path system are determined, the beat frequency of the two beams is determined only by the velocity of the object. Therefore, by measuring the beat frequency of the scattered light, the relative velocity of the object can be obtained. Here, F2 is the acousto-optic modulation frequency, introduced to reduce fundamental frequency interference and improve the signal-to-noise ratio. F1 is a fixed 40MHz. The Doppler frequency shift caused by the object's motion is on the order of kHz. Therefore, in subsequent signal processing, filtering techniques can be used to remove F2, thus obtaining the Doppler frequency shift signal f containing only the object's velocity information.

[0075] f = 2 × F1 × V / c(sin(A / 2))

[0076] Then the tangential velocity is V = f × c(sin(A / 2)) / 2 × F1;

[0077] Since the rotating drum 41 and the detection column 13 have the same rotation speed n, and since V=2×π×r×n, we can get n=V / (2×π×r)=(f×c(sin(A / 2)) / 2×F1) / (2×π×r), where r is the diameter of the detection column 13.

[0078] The measurement optical path adopts the differential laser Doppler principle. After the laser output from the transmitter 27 enters the 40MHz acousto-optic modulator 24, due to anomalous Bragg diffraction, the output frequencies of the 0th and 1st order diffracted beams differ by 40MHz, have approximately the same intensity, and are perpendicular to each other. A half-wave plate 25 is added to the 1st order diffracted beam path, and its orientation is adjusted so that its fast axis is at 45° to the vibration direction of the 1st order diffracted beam, changing its polarization direction by 90°, so that the polarization directions of the two beams are parallel to each other. The reflector 3 is adjusted to make the two beams parallel. When the 1st and 0th order beams pass through the lens 17, they are deflected and converged onto the surface of the rotating detection cylinder 13. The lens 17 and the reflector 24 are used to collect part of the beat signal scattered from this surface, and the lens 23 is used to converge this beat signal onto the photosensitive surface of the photodetector 21. The voltage signal generated by the photodetector 21 is first preprocessed by the hardware circuit: the signal is amplified by a two-stage amplifier circuit, then filtered by a bandpass filter, and then compared with the light from the acousto-optic modulator 24.

[0079] The signals enter the phase-sensitive detector circuit together, separating the Doppler frequency shift signal containing the object's motion from the 40MHz acousto-optic modulator frequency 24, and finally filtering through a low-pass filter. The signal from the hardware circuit enters the data acquisition card, where data is acquired and processed by a program written in LabVIEW software, and the measurement results are finally obtained.

[0080] The specific implementation method is as follows: The helium-neon laser 29 emits laser light through the transmitter 27, which passes through the half-wave plate 26 and reaches the acousto-optic modulator 24. The acousto-optic modulator 24 modulates the laser light into two parts, level 1 and level 0. The level 1 laser light reaches the surface of the reflector 3 and is reflected. The two beams of light after reflection are parallel. When the two beams of light pass through the lens 17, they are deflected and converged onto the surface of the rotating detection cylinder 13. The lens 17 and the reflector 4 are used to collect part of the beat light signal scattered from this surface, and the lens 23 is used to converge this beat signal onto the photosensitive surface of the photodetector 21. The voltage signal generated by the photodetector 21 is first preprocessed by the hardware circuit: the signal is amplified by a two-stage amplifier circuit, then filtered by a bandpass filter, and then compared with the light from the acousto-optic modulator 24.

[0081] The signals enter the phase-sensitive detection circuit together, separating the Doppler frequency shift signal containing the object's motion from the 40MHz acousto-optic modulator frequency 24, and finally filtering through a low-pass filter. The signal from the hardware circuit enters the data acquisition card, where data is acquired and processed by a program written in LabVIEW software. The data is then input into the calculation formula to obtain the measurement result.

[0082] The air-cooling mechanism generates airflow that passes sequentially through mounting cavity 30, mounting cavity 25, and control cavity 2, and is discharged from the air outlet 22, thereby cooling the structures and instruments within mounting cavity 30, mounting cavity 25, air outlet 22, and control cavity 2.

[0083] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A laser Doppler rotation speed calibration device, comprising a housing (1), characterized in that, The inner side of the housing (1) is provided with a control cavity (2), one end of the control cavity (2) is provided with a second mounting cavity (25), the end of the second mounting cavity (25) away from the control cavity (2) is provided with a third mounting cavity (30), a helium-neon laser (29) is provided on the inner side of the third mounting cavity (30), one end of the helium-neon laser (29) is electrically connected to a transmitter (27), the transmitter (27) extends into the second mounting cavity (25), a half-wave plate (26) and an acousto-optic modulator (24) are sequentially installed on the inner side of the second mounting cavity (25), the cavity at one end of the second mounting cavity (25) is funnel-shaped, the funnel-shaped cavity is directly connected to the third mounting cavity (30), and a wind-cooling mechanism is inserted into the bottom end of the third mounting cavity (30). The inner side of the control cavity (2) is sequentially equipped with a reflector 1 (3), a reflector 2 (4), a half-wave plate 2 (5), and a lens 1 (17). The reflector 1 (3) and the half-wave plate 2 (5) are located at the top of the control cavity (2) and are rotatably connected to the inner wall of the control cavity (2). The half-wave plate 2 (5) is installed between the lens 1 (17) and the reflector 1 (3). The reflector 2 (4) is located in the middle of the control cavity (2). An air outlet groove (22) is opened at the bottom of the inner wall of the control cavity (2). A lens 2 (23) and a photoelectric receiver (21) are arranged on the inner side of the air outlet groove (22). The photoelectric receiver (21) is installed on a bracket. The bracket is fixed to the inner side of the air outlet groove (22). A filter screen 1 (19) is inserted into the bottom end of the air outlet groove (22). A connecting groove (15) is opened at the end of the control cavity (2) away from the installation cavity 2 (25). The air-cooling mechanism includes an air-cooling base (28), a drive motor (35), an airflow generating slot (36), a filter screen (38), and fan blades (39). The air-cooling base (28) has an airflow generating slot (36) on its inner side, and a filter screen (38) is provided at the bottom of the airflow generating slot (36). The drive motor (35) is installed on the inner side of the air-cooling base (28), and the fan blades (39) are connected to the rotating rod of the drive motor (35). An obliquely placed air guide is provided on the inner side of the mounting cavity (25) near the acoustic-optical modulator (24). The inner side of the airflow generating groove (36) is provided with several drying balls (37), and carbon powder particles and calcium chloride particles are provided on the inner side of the drying balls (37). The drying balls (37) are spherical and have several small holes with a diameter of 0.03-0.05 mm. One end of the shell (1) is provided with a hinge seat (32), and a horizontal cover (10) is hinged on the hinge seat (32). One end of the hinge seat (32) is fixedly connected to a stop rod (33). 3) Horizontal installation: The horizontal cover (10) has a snap-fit ​​groove (34) at one end near the hinge seat (32), which engages with the stop rod (33). A limit rod (11) is provided at the end of the horizontal cover (10) away from the housing (1). A horizontal support plate (14) is installed on one side of the horizontal cover (10). A limit groove (12) is provided at one end of the horizontal support plate (14), and the limit groove (12) and the limit rod (11) are slidably connected. The limit rod (11) is a trapezoidal column. The horizontal support plate (14) is installed on the other side of the housing (11). 4) A detection column (13) is installed on the top; the lens (17) is installed on the inner side of the mounting base (18), a rubber sealing ring is provided on the outer side of the mounting base (18), a slider (8) is provided at the top of the mounting base (18), a sliding track (9) is opened at the top of the control cavity (2), the inner side of the sliding track (9) is movably connected to the slider (8), a servo motor (6) is provided on the inner side of the housing (1), a lead screw (7) is fixedly connected to the rotor of the servo motor (6), and the outer side of the lead screw (7) is threadedly connected to the slider (8).

2. The laser Doppler rotation speed calibration device according to claim 1, characterized in that: The housing (1) has a detection column (13) placed near the connecting groove (15). The bottom of the second mounting cavity (25) has a reserved mounting port for communicating with the outside world. The mounting port of the second mounting cavity (25) is fitted with a sealing plate.

3. The laser Doppler rotation speed calibration device according to claim 2, characterized in that: The detection column (13) is installed on the top of the centrifuge (40), the centrifuge (40) is placed on the horizontal support plate (14), the inner side is rotatably connected to the rotating drum (41), the detection column (13) is installed on the inner side of the rotating drum (41), the bottom of the detection column (13) is provided with a connecting column (42), the outer side of the connecting column (42) is sleeved with a linkage sleeve (43), the outer side of the linkage sleeve (43) and the inner side of the rotating drum (41) are inserted, the material of the linkage sleeve (43) is phenolic resin, and the shape of the linkage sleeve (43) is bottle stopper shaped.

4. The laser Doppler rotation speed calibration device according to claim 1, characterized in that: The photoelectric receiver (21) is connected to a hardware circuit, which is then connected to a computer device for processing using a LabVIEW program. The hardware circuit includes a two-stage preamplifier circuit.

Images