Pressure sensor in-situ dynamic calibration light path adjusting system based on laser cavitation

Abstract

The invention discloses an optical path adjusting system for in-situ dynamic calibration of a pressure sensor based on laser cavitation. In a ship working underwater, a pulse laser is used for emitting a beam of pulse laser, the pulse laser passes through a designed light path adjusting system and then is focused near a calibrated pressure sensor through a light through hole in a cabin wall in the ship, and a laser-induced cavitation phenomenon is generated. A microsecond pressure shock wave generated by cavitation bubbles in a collapse stage is used as an excitation signal to calibrate the pressure sensor in an actual in-situ environment. Meanwhile, a set of algorithm is designed on the basis of a light path adjusting system, and pressure sensors at different positions can be calibrated. According to the light path adjusting system, the required device is simple in structure, the cost is lower, and the system is suitable for popularization.

Description

Technical Field

[0001] The invention belongs to the technical field of pressure sensor calibration, and in particular relates to an optical path adjustment system for in-situ dynamic calibration of a pressure sensor based on laser cavitation. Background Art

[0002] Pressure sensors are widely used in many fields such as industrial automation, transportation, water conservancy, aviation, etc. They are also important in deep-sea exploration, national defense technology, etc. When measuring rapidly changing pressures such as explosion shock waves, the dynamic characteristics of the sensor are a very important indicator. Therefore, in-situ dynamic calibration of pressure sensors is the key to ensuring measurement accuracy.

[0003] The current calibration procedures ignore the influence of factors such as medium density, static pressure and temperature in the in-situ environment on the dynamic performance of the sensor. The existing underwater pressure sensor dynamic calibration often uses the standard material method. The standard material method uses the shock wave generated by the underwater explosion of explosives as the excitation source for dynamic calibration. Using explosives as the excitation source has poor repeatability and safety. Shock and vibration will form noise signals that interfere with the normal data acquisition of the sensor and reduce the accuracy of the underwater pressure dynamic calibration system.

[0004] To address the above issues, researchers designed a high-pressure liquid environment simulation chamber, which uses laser-induced cavitation to achieve dynamic calibration of pressure sensors. This scheme uses the shock wave pressure generated during cavitation collapse as the excitation source for dynamic calibration, and uses a high-pressure liquid environment simulation chamber to simulate the in-situ environment.

[0005] However, the actual in-situ environment may include factors such as static pressure changes, electromagnetic interference, and mechanical vibrations, and these conditions are difficult to fully reproduce in a high-pressure liquid environment simulation box, which will ultimately make the dynamic response of the sensor more ideal than in the in-situ environment. In addition, due to the small space of the high-pressure liquid environment simulation box and the fixed position of the calibrated pressure sensor, the optical path system design of this scheme is single and fixed. In order to achieve true in-situ calibration and better use the laser-induced cavitation method to dynamically calibrate the sensor in the in-situ environment, the present invention proposes an optical path adjustment system for dynamic calibration of pressure sensors in an actual in-situ environment. Summary of the invention

[0006] In view of the fact that the existing dynamic calibration methods of underwater pressure sensors are all carried out in a simulated in-situ environment, ignoring the impact of the actual in-situ environment on the pressure sensor and the measurement system, and the fact that the optical path currently designed using the laser method is single and fixed, the present invention proposes an optical path adjustment system for in-situ dynamic calibration of pressure sensors based on laser cavitation.

[0007] The optical path adjustment system for in-situ dynamic calibration of pressure sensors based on laser cavitation includes:

[0008] A laser, for emitting pulsed laser;

[0009] The optical path refraction device is used to change the laser optical path and focus it on a specified position, and the optical path refraction device includes:

[0010] Beam expander, used to expand the laser beam diameter;

[0011] A focusing lens, used to focus the laser;

[0012] An electrically controlled translation stage is used to control the movement of the focusing mirror, thereby changing the focusing position of the laser;

[0013] Water prism, used to refract laser light to change its propagation direction;

[0014] A pulse trigger, used to trigger the laser to generate pulse laser;

[0015] A computer, used for controlling the movement of the electric-controlled translation stage and processing the calibration results of the sensor;

[0016] A signal acquisition device, used to acquire a response signal of the calibrated pressure sensor to pressure excitation;

[0017] The calibrated pressure sensor is located in the actual in-situ environment and is used to receive the pressure shock wave generated by the laser-induced cavitation as an excitation signal;

[0018] The optical path adjustment system calculates the displacement of the focusing mirror through an algorithm, and controls the movement of the focusing mirror through an electrically controlled displacement stage, so that the laser is focused on a specified position of the pressure-sensitive surface of the calibrated pressure sensor in an actual in-situ environment, thereby generating cavitation. The pressure shock wave generated after the collapse of the cavitation serves as an excitation signal for the calibrated sensor, thereby realizing dynamic calibration of the pressure sensor.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The present invention makes up for the shortcomings of the simulated in-situ environment by using the pressure change caused by the optical breakdown of the laser directly in the actual in-situ environment to dynamically calibrate the pressure sensor.

[0021] (2) The present invention proposes an optical path adjustment system in an actual in-situ environment, which can dynamically calibrate pressure sensors at different positions according to the designed algorithm module.

[0022] (3) The optical path adjustment system of the present invention requires a simple device structure, has lower cost, and is suitable for promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the optical path adjustment system;

[0024] Figure 2 for Figure 1 Schematic diagram of the optical path adjustment system for different viewing angles;

[0025] Figure 3 This is the optical path schematic. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings and examples.

[0027] The basic concept of this application is as follows: This application uses a pulsed laser to emit a pulsed laser inside a ship operating underwater, and then focuses the pulsed laser through the light hole on the internal bulkhead of the ship to the vicinity of the pressure sensor to be calibrated through the designed optical path adjustment system, and generates laser-induced cavitation. The microsecond pressure shock wave generated by the cavitation bubble during the collapse stage is used as an excitation signal to calibrate the pressure sensor in the actual in-situ environment. At the same time, a set of algorithms is designed based on the optical path adjustment system to calibrate pressure sensors at different locations.

[0028] like Figure 1 and Figure 2 As shown, this embodiment proposes an optical path adjustment system for in-situ dynamic calibration of a pressure sensor based on laser cavitation. This embodiment includes a laser 1, an optical path refraction device 4, a pulse trigger 2, a computer 3, a signal acquisition device 5, and a calibrated pressure sensor 6; the optical path refraction device includes a water prism 7, a beam expander 10, a focusing lens 8, and an electrically controlled displacement stage 9.

[0029] The pulse laser is triggered by a digital delay trigger to generate a pulse laser. The laser is directed to the optical path refraction device. First, the laser passes through the beam expander. After passing through the beam expander, the diameter of the laser beam becomes larger. Then the laser is directed to the focusing lens and then reaches the water prism. Under the refraction of the water prism, the propagation direction of the laser changes and is emitted from the light hole. The electric control displacement stage is adjusted according to the actual position of the calibrated pressure sensor, and finally focused on the specified position of the pressure-sensitive surface of the calibrated sensor in the actual in-situ environment, thereby generating cavitation. The pressure shock wave generated after the cavitation collapses is used as the excitation signal of the calibrated sensor. The signal acquisition device displays the response signal of the calibrated sensor to the pressure excitation on the computer, and finally the sensor is dynamically calibrated by the sound pressure formula of the laser-induced acoustic theory.

[0030] Furthermore, the position of the beam expander is fixed, and the focusing mirror is placed on an electrically controlled displacement stage, and the movement of the focusing mirror is controlled by the electrically controlled displacement stage, thereby changing the focusing position of the laser.

[0031] Furthermore, the water prism is arranged closely to the light-through hole, and is used to refract the laser light so that its propagation direction is changed and focused on the pressure-sensitive surface of the pressure sensor to be calibrated.

[0032] Furthermore, the signal acquisition device includes an acquisition card, a signal amplifier and a filter circuit, which are used to acquire and process the response signal of the calibrated pressure sensor to pressure excitation, and transmit the acquired signal to a computer for analysis and calibration.

[0033] Furthermore, the optical path adjustment system also includes an algorithm module for calculating the displacement of the focusing mirror according to the actual position of the calibrated pressure sensor, and controlling the movement of the focusing mirror through an electric-controlled displacement stage, thereby changing the final focusing position of the laser to achieve dynamic calibration of pressure sensors at different positions.

[0034] Furthermore, the laser is a pulsed laser that can generate pulsed laser light for inducing cavitation in an actual in-situ environment and generating microsecond pressure shock waves as excitation signals for dynamic calibration.

[0035] Furthermore, the optical path adjustment system calculates the actual focusing position coordinates of the laser by establishing a plane rectangular coordinate system and combining the parameters of the beam expander, focusing lens and water prism, and adjusts the position of the focusing lens through an electrically controlled displacement stage so that the laser is focused on the specified position of the calibrated pressure sensor.

[0036] Furthermore, the refractive index of the water prism is the same as that of water, which is used to ensure precise control of the propagation direction and focusing position of the laser in water.

[0037] Furthermore, the optical path adjustment system also includes a monitoring module for real-time monitoring of pressure changes during the laser-induced cavitation process and feeding back the monitoring data to a computer so as to adjust and optimize the calibration process in real time.

[0038] Furthermore, the optical path adjustment system is suitable for underwater working environments and can realize in-situ dynamic calibration of pressure sensors inside underwater ships or other underwater equipment.

[0039] Figure 3 The figure shows a complete optical path principle diagram, and the algorithm module of the present application is derived based on the optical path shown in the figure.

[0040] A plane rectangular coordinate system is established with the center of the beam expander as the origin. The right-angle side of the water prism is ; The diameter of the incident beam is The wavelength is ; The focal length of the beam expander is ; The focal length of the focusing lens is ; The distance between the beam expander and the focusing lens is ; The distance between the beam expander and the hypotenuse of the water prism is ;The refractive index of light in air ; Water prism and the refractive index of light in water ; All of the above are known quantities.

[0041] After passing through the beam expander and reaching the focusing lens, the beam diameter becomes ; Angle of incidence , ; Refraction angle , ; is the beam diameter at the intersection of the laser and the water prism, is the distance between the two intersection points of the laser and the water prism, is the distance from the intersection of the laser and the water prism to the hypotenuse of the water prism; the beam diameter at the focus of the focusing lens is ; The divergence angle of the laser after focusing (without passing through the water prism) is ; The distance between the actual focusing position and the hypotenuse of the water prism is ; Plane coordinates of the actual focus position All are calculated quantities.

[0042] When a beam of parallel light passes through the beam expander and reaches the focusing lens, the beam diameter is becomes . From the beam expansion optical path diameter formula:

[0043]

[0044] The calculation formula of the spot diameter at the intersection of the focusing mirror is:

[0045]

[0046] According to the divergence formula of light after focusing:

[0047]

[0048] From formula (1)(2)(3), we can get:

[0049]

[0050] Therefore , , is a known quantity.

[0051] The laser passes through the focusing mirror and is directed to the midpoint of the right-angle side of the water prism and refracted. The incident angle and the refraction angle satisfy the refraction formula of light:

[0052]

[0053]

[0054] From geometric knowledge we can conclude that:

[0055]

[0056]

[0057] From formula (5)(6)(7)(8), we can get:

[0058]

[0059]

[0060] Therefore:

[0061]

[0062]

[0063] Therefore: , , , is a known quantity.

[0064] From the properties of similar triangles we can conclude that:

[0065]

[0066]

[0067] Combining (13) and (14), we get:

[0068]

[0069]

[0070] From the law of sine we get:

[0071]

[0072] Right now:

[0073]

[0074] Therefore , , is a known quantity.

[0075] From the sine theorem and the tangent theorem we can deduce that:

[0076]

[0077]

[0078] Right now:

[0079]

[0080]

[0081] From geometry knowledge we know:

[0082]

[0083] Therefore, the coordinates of the actual focus position are It is calculated that by changing the displacement of the focusing mirror through the electric control stage, the actual focusing position will change, and the coordinates of the actual focusing position can be calculated by the above formula. At the same time, when the coordinates of the calibrated sensor are known, the displacement amount that the focusing mirror should move can be deduced according to the above formula.

[0084] The present invention is not limited to the above-mentioned embodiments, and all equivalent changes and modifications made within the scope of application of the present invention should fall within the scope of the present invention.

Claims

1. An optical path adjustment system for in-situ dynamic calibration of pressure sensors based on laser cavitation, characterized in that: The system comprises: A laser (1) for emitting pulsed laser light; The optical path refraction device is used to change the laser optical path and focus it on a specified position, and the optical path refraction device includes: A beam expander (10) is used to expand the diameter of the laser beam; A focusing lens (8) for focusing the laser light; An electrically controlled displacement stage (9) for controlling the movement of the focusing mirror, thereby changing the focusing position of the laser; A water prism (7) is used to refract the laser light so as to change its propagation direction; A pulse trigger (2), used for triggering the laser to generate pulsed laser; A computer (3) is used to control the movement of the electric-controlled displacement stage and process the calibration results of the sensor; A signal acquisition device (5) for acquiring a response signal of the calibrated pressure sensor (6) to pressure excitation; The calibrated pressure sensor (6) is located in the actual in-situ environment and is used to receive the pressure shock wave generated by the laser-induced cavitation as an excitation signal; The optical path adjustment system calculates the displacement of the focusing mirror through an algorithm, and controls the movement of the focusing mirror through an electrically controlled displacement stage, so that the laser is focused on a specified position of the pressure-sensitive surface of the calibrated pressure sensor in an actual in-situ environment, thereby generating cavitation. The pressure shock wave generated after the collapse of the cavitation serves as an excitation signal for the calibrated sensor, thereby realizing dynamic calibration of the pressure sensor.

2. The optical path adjustment system for in-situ dynamic calibration of a pressure sensor based on laser cavitation according to claim 1 is characterized in that: The position of the beam expander (10) is fixed, and the focusing mirror (8) is placed on an electrically controlled displacement stage (9). The movement of the focusing mirror is controlled by the electrically controlled displacement stage, thereby changing the focusing position of the laser.

3. The optical path adjustment system for in-situ dynamic calibration of a pressure sensor based on laser cavitation according to claim 1 or 2, characterized in that: The water prism (7) is arranged closely to the light-through hole and is used to refract the laser light so as to change its propagation direction and focus it on the pressure-sensitive surface of the pressure sensor (6) to be calibrated.

4. The optical path adjustment system for in-situ dynamic calibration of a pressure sensor based on laser cavitation according to claim 1, characterized in that: The signal acquisition device (5) comprises an acquisition card, a signal amplifier and a filter circuit, and is used to acquire and process the response signal of the calibrated pressure sensor (6) to pressure excitation, and transmit the acquired signal to the computer (3) for analysis and calibration.

5. The optical path adjustment system for in-situ dynamic calibration of a pressure sensor based on laser cavitation according to claim 1 or 4, characterized in that: The optical path adjustment system also includes an algorithm module for calculating the displacement of the focusing mirror (8) according to the actual position of the calibrated pressure sensor (6), and controlling the movement of the focusing mirror through the electric control displacement stage (9) to achieve dynamic calibration of pressure sensors at different positions.

6. The optical path adjustment system for in-situ dynamic calibration of a pressure sensor based on laser cavitation according to claim 1, characterized in that: The laser (1) is a pulsed laser capable of generating pulsed laser light for inducing cavitation in an actual in-situ environment, generating microsecond-level pressure shock waves as an excitation signal for dynamic calibration.

7. The optical path adjustment system for in-situ dynamic calibration of a pressure sensor based on laser cavitation according to claim 1, characterized in that: The optical path adjustment system establishes a plane rectangular coordinate system, combines the parameters of the beam expander, focusing lens and water prism, calculates the actual focusing position coordinates of the laser, and adjusts the position of the focusing lens through the electric control displacement stage to focus the laser on the specified position of the calibrated pressure sensor.

8. The optical path adjustment system for in-situ dynamic calibration of a pressure sensor based on laser cavitation according to claim 7, characterized in that: The refractive index of the water prism (7) is the same as that of water, and is used to ensure accurate control of the propagation direction and focus position of the laser in water.

9. The optical path adjustment system for in-situ dynamic calibration of a pressure sensor based on laser cavitation according to claim 5, characterized in that: The optical path adjustment system also includes a monitoring module for real-time monitoring of pressure changes during the laser-induced cavitation process and feeding back the monitoring data to a computer (3) so as to adjust and optimize the calibration process in real time.

10. The optical path adjustment system for in-situ dynamic calibration of a pressure sensor based on laser cavitation according to claims 1 and 9, characterized in that: The optical path adjustment system is suitable for underwater working environments and can realize in-situ dynamic calibration of pressure sensors inside underwater ships or other underwater equipment.

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