Optical path adjustment system for in-situ dynamic calibration of pressure sensors based on laser cavitation

Abstract

This invention discloses an optical path adjustment system for in-situ dynamic calibration of pressure sensors based on laser cavitation. Inside a vessel operating underwater, a pulsed laser beam is emitted from a pulsed laser. After passing through a designed optical path adjustment system, the beam is focused onto the vicinity of the pressure sensor being calibrated via a light-transmitting aperture on the vessel's internal bulkhead, generating laser-induced cavitation. The microsecond-level pressure shock wave generated during the collapse phase of the cavitation bubbles is used as the excitation signal to calibrate the pressure sensor in the actual in-situ environment. Simultaneously, an algorithm is designed based on the optical path adjustment system to calibrate pressure sensors at different locations. This invention's optical path adjustment system requires a simple structure, has lower cost, and is suitable for widespread application.

Description

Technical Field

[0001] This invention belongs to the field of pressure sensor calibration technology, specifically relating to an optical path adjustment system for in-situ dynamic calibration of pressure sensors based on laser cavitation. Background Technology

[0002] Pressure sensors are widely used in various fields such as industrial automation, transportation, water conservancy, and aviation, and also have important applications in deep-sea exploration and defense technology. When measuring rapidly changing pressures, such as those caused by explosive shock waves, the dynamic characteristics of the sensor are a crucial indicator. Therefore, in-situ dynamic calibration of pressure sensors is key to ensuring measurement accuracy.

[0003] Current verification procedures neglect the influence of factors such as medium density, static pressure, and temperature in the in-situ environment on the dynamic performance of sensors. Existing dynamic calibration of underwater pressure sensors often employs the standard substance method. This method uses the shock wave generated by an underwater explosion of explosives as the excitation source for dynamic calibration. Using explosives as the excitation source results in poor repeatability and safety; the impact and vibration can generate noise signals that interfere with the sensor's normal data acquisition, reducing the accuracy of the underwater pressure dynamic calibration system.

[0004] To address the aforementioned issues, researchers designed a high-pressure liquid-phase environment simulation chamber, which achieves dynamic calibration of pressure sensors through laser-induced cavitation. This scheme utilizes the shock wave pressure generated during cavitation collapse as the excitation source for dynamic calibration, and uses the high-pressure liquid-phase 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 vibration, which are difficult to fully reproduce in a high-pressure liquid environment simulation chamber. This ultimately leads to a more idealized dynamic response of the sensor compared to the in-situ environment. Furthermore, due to the limited space of the high-pressure liquid environment simulation chamber and the fixed position of the pressure sensor being calibrated, the optical path system design of this scheme is simple and fixed. To achieve true in-situ calibration and better utilize laser-induced cavitation to dynamically calibrate the sensor in an in-situ environment, this invention proposes a dynamic calibration optical path adjustment system for pressure sensors in a real in-situ environment. Summary of the Invention

[0006] In view of the fact that existing dynamic calibration methods for underwater pressure sensors are all carried out in simulated in-situ environments, ignoring the influence of the actual in-situ environment on the pressure sensor and measurement system, and that the optical path designed using the laser method is single and fixed, this 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 used to emit pulsed laser light;

[0009] An optical path refraction device is used to change the laser beam path and focus it at a specified position. The optical path refraction device includes:

[0010] Beam expanders are used to increase the diameter of a laser beam.

[0011] A focusing lens is used to focus a laser beam.

[0012] An electrically controlled displacement stage is used to control the movement of the focusing lens, thereby changing the focusing position of the laser.

[0013] A water prism is used to refract laser light, causing it to change its propagation direction.

[0014] A pulse trigger, used to trigger a laser to generate pulsed laser light;

[0015] A computer is used to control the movement of the electrically controlled displacement stage and to process the calibration results of the sensors.

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

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

[0018] The optical path adjustment system calculates the displacement of the focusing lens through an algorithm and controls the movement of the focusing lens through an electronically controlled displacement stage, so that the laser is focused on a designated position on the pressure-sensing surface of the pressure sensor to be calibrated in the actual in-situ environment, thereby generating a cavitation bubble. The pressure shock wave generated after the cavitation bubble collapses serves as the excitation signal for the sensor to be calibrated, thus realizing the dynamic calibration of the pressure sensor.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] (1) This invention overcomes the shortcomings of simulating in-situ environments. By directly generating pressure changes through optical breakdown in the actual in-situ environment using laser, the pressure sensor is dynamically calibrated using these pressure changes.

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

[0022] (3) The optical path adjustment system of the present invention has a simple structure and lower cost, and is suitable for promotion. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the optical path adjustment system;

[0024] Figure 2 for Figure 1 Schematic diagram of optical path adjustment system from different perspectives;

[0025] Figure 3 This is a schematic diagram of the optical path. Detailed Implementation

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

[0027] The basic concept of this application is as follows: Inside a vessel operating underwater, a pulsed laser beam is emitted from a pulsed laser. After passing through a designed optical path adjustment system, the beam is focused onto the vicinity of the pressure sensor being calibrated via a light-transmitting aperture on the vessel's internal bulkhead, generating laser-induced cavitation. The microsecond-level pressure shock wave generated during the collapse phase of the cavitation bubbles is used as the excitation signal to calibrate the pressure sensor in a real-world, in-situ environment. Simultaneously, an algorithm 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 pressure sensor to be calibrated 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] A pulsed laser is generated by triggering a pulsed laser using a digital delay trigger. The laser beam is directed towards an optical refraction device, first passing through a beam expander, which increases the beam diameter. The laser then travels to a focusing lens and finally to a water prism. Refraction by the water prism changes the laser's propagation direction, causing it to exit through a light-passing aperture. An electrically controlled displacement stage is adjusted based on the actual position of the pressure sensor being calibrated, ultimately focusing the beam at a designated location on the sensor's pressure-sensing surface in the actual in-situ environment, thus generating a cavitation bubble. The pressure shock wave generated after the cavitation bubble collapses serves as the excitation signal for the sensor. A signal acquisition device displays the sensor's response to the pressure excitation on a computer. Finally, the sensor is dynamically calibrated using the laser-induced acoustic theory's sound pressure formula.

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

[0031] Furthermore, the water prism is positioned close to the light-transmitting hole to refract the laser, causing its propagation direction to change and focus onto the pressure-sensing surface of the pressure sensor being calibrated.

[0032] Furthermore, the signal acquisition device includes an acquisition card, a signal amplifier, and a filtering circuit, used to acquire and process the response signal of the pressure sensor under test 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 lens based on the actual position of the pressure sensor being calibrated, and controlling the movement of the focusing lens through an electronically 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, capable of generating pulsed laser light to induce cavitation in a real in-situ environment, generating microsecond-level pressure shock waves as excitation signals for dynamic calibration.

[0035] Furthermore, the optical path adjustment system establishes a Cartesian coordinate system, combines the parameters of the beam expander, focusing lens, and water prism to calculate the actual focusing position coordinates of the laser, 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 pressure sensor being calibrated.

[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 the water.

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

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

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

[0040] Establish a Cartesian coordinate system with the center of the beam expander as the origin, and the right-angled side of the water prism is... The diameter of the incident beam is 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 The refractive index of light in a water prism and water All of the above are known quantities.

[0041] The diameter of the beam reaching the focusing lens after passing through the beam expander becomes... Angle of incidence , ; Angle of refraction , ; Let be the diameter of the laser beam at the intersection of the laser and the water prism. The distance between the two intersection points of the laser and the water prism. The distance from the intersection of the laser beam and the lower edge of the water prism to the hypotenuse of the water prism; the beam diameter at the focal point of the focusing lens is... The divergence angle of the laser after focusing (without passing through a water prism) is: The actual focusing position is at a distance from the hypotenuse of the water prism. Planar coordinates of the actual focusing position All quantities are calculated.

[0042] When a beam of parallel light passes through a beam expander and reaches a focusing lens, the beam diameter is reduced from... Become From the formula for the diameter of the beam expander, we get:

[0043]

[0044] The formula for calculating the spot diameter at the intersection of the focusing lenses is as follows:

[0045]

[0046] From the formula for the divergence of focused light, we get:

[0047]

[0048] From formulas (1)(2)(3):

[0049]

[0050] Therefore , , The quantity is known.

[0051] A laser beam passes through a focusing lens and strikes the midpoint of the right-angled side of a water prism, where it is refracted. The angle of incidence and the angle of refraction satisfy the formula for the refraction of light:

[0052]

[0053]

[0054] Based on geometric knowledge, we can conclude that:

[0055]

[0056]

[0057] From formulas (5)(6)(7)(8):

[0058]

[0059]

[0060] Therefore:

[0061]

[0062]

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

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

[0065]

[0066]

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

[0068]

[0069]

[0070] By the Law of Sines:

[0071]

[0072] Right now:

[0073]

[0074] Therefore , , The quantity is known.

[0075] From the Law of Sines and the Law of Tangent, we can derive:

[0076]

[0077]

[0078] Right now:

[0079]

[0080]

[0081] From geometric knowledge, we know:

[0082]

[0083] Therefore, the coordinates of the actual focusing position It has been calculated that by changing the displacement of the focusing lens through an electrically controlled displacement stage, the actual focusing position will change, and the coordinates of the actual focusing position can be calculated using the above formula. Furthermore, when the coordinates of the sensor being calibrated are known, the amount of displacement the focusing lens should move can be derived using the above formula.

[0084] This invention is not limited to the embodiments described above. All equivalent changes and modifications made within the scope of this invention should be considered within the scope of this invention.

Claims

1. A light path adjustment system for in-situ dynamic calibration of a laser cavitation based pressure sensor, suitable for underwater operating environment, capable of achieving in-situ dynamic calibration of a pressure sensor in the interior of an underwater vessel or other underwater equipment, characterized in that, The system comprises: a laser (1) for emitting pulsed laser; a light path refracting device for changing the laser light path and focusing on a specified position, the light path refracting device comprising: a beam expander (10) for expanding the beam diameter of the laser; a focusing lens (8) for focusing the laser; an electrically controlled displacement stage (9) for controlling the movement of the focusing lens to change the focusing position of the laser; a water prism (7) for refracting the laser to change its propagation direction; a pulse trigger (2) for triggering the laser to generate pulsed laser; a computer (3) for controlling the movement of the electrically controlled displacement stage and processing the calibration results of the sensor; a signal acquisition device (5) for acquiring the 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 used to receive the pressure shock wave generated by laser-induced cavitation as an excitation signal; the light path adjusting system calculates the displacement amount of the focusing lens through an algorithm and controls the movement of the focusing lens through the electrically controlled displacement stage, so that the laser is focused on the specified position of the pressure sensing surface of the calibrated pressure sensor in the actual in-situ environment, thereby generating a cavitation bubble, and the pressure shock wave generated after the collapse of the cavitation bubble is used as the excitation signal of the calibrated sensor, realizing dynamic calibration of the pressure sensor; the light path adjusting system further comprises an algorithm module for calculating the displacement amount of the focusing lens (8) according to the actual position of the calibrated pressure sensor (6) and controlling the movement of the focusing lens through the electrically controlled displacement stage (9) to realize dynamic calibration of pressure sensors at different positions.

2. The laser cavitation based pressure sensor in-situ dynamic calibration optical path adjustment system of claim 1, wherein, The position of the beam expander (10) is fixed, and the focusing lens (8) is placed on the electrically controlled displacement stage (9), and the movement of the focusing lens is controlled through the electrically controlled displacement stage, thereby changing the focusing position of the laser.

3. Laser cavitation based pressure sensor in-situ dynamic calibration optical path adjustment system according to claim 1 or 2, characterized in that, The water prism (7) is arranged close to the light transmission hole and used to refract the laser to change its propagation direction and focus on the pressure sensing surface of the calibrated pressure sensor (6).

4. The laser cavitation based pressure sensor in-situ dynamic calibration optical path adjustment system of claim 1, wherein, 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 laser cavitation based pressure sensor in-situ dynamic calibration optical path adjustment system of claim 1, wherein, The laser (1) is a pulsed laser capable of generating pulsed laser, which is used to induce cavitation phenomenon in the actual in-situ environment and generate microsecond-level pressure shock wave as the excitation signal for dynamic calibration.

6. The laser cavitation based pressure sensor in-situ dynamic calibration optical path adjustment system of claim 1, wherein, The light path adjusting 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, the focusing lens and the water prism, and adjusts the position of the focusing lens through the electrically controlled displacement stage to focus the laser on the specified position of the calibrated pressure sensor.

7. The laser cavitation based pressure sensor in-situ dynamic calibration optical path adjustment system of claim 6, wherein, The refractive index of the water prism (7) is the same as that of water, which is used to ensure the accurate control of the propagation direction and focusing position of the laser in water.

8. The laser cavitation based pressure sensor in-situ dynamic calibration optical path adjustment system of claim 1, wherein, The light path adjusting system further comprises a monitoring module for monitoring the pressure change in the process of laser-induced cavitation in real time and feeding back the monitoring data to the computer (3) to adjust and optimize the calibration process in real time.

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