Underwater optical turbulence intensity test system and method

Abstract

The invention belongs to the technical field of underwater optical turbulence intensity testing, and discloses an underwater optical turbulence intensity testing system and method.The underwater optical turbulence intensity testing system comprises a power supply unit, a driving control unit and a laser head, and the driving control unit is used for driving the laser head to generate laser beams and regulating and controlling the laser emission intensity; the system further comprises a power supply unit, an underwater binocular telescope, an underwater image sensor and an upper computer, the underwater binocular telescope comprises two optical receiving lenses which are identical but independent from each other, the two optical receiving lenses are used for receiving the same laser beam from the laser emitting module at the same time, and two light spots are formed on the underwater image sensor; the upper computer is used for extracting the change condition of the coordinates of the centroids of the two light spots and calculating the jitter variance of the centroid distance; according to the invention, the laser emission module and the optical receiving and processing module are utilized to realize the measurement of the dithering variances of different underwater distances, the optical turbulence intensity can be visually evaluated through the dithering variances, and the current situation of lack of underwater optical turbulence intensity measurement means at present is made up.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater optical turbulence intensity testing, and in particular to an underwater optical turbulence intensity testing system and method. Background Art

[0002] Approximately 71% of the Earth's surface is covered by seawater, which harbors a diverse array of biological resources and rich mineral resources. Since the 21st century, humanity's understanding of the ocean has deepened through both manned and unmanned exploration, leading to a widespread international consensus on exploring and utilizing the ocean to meet the sustainable development of human society. Consequently, the ocean has become a fierce arena for major power competition. With the rapid development of optical technology, the application of optics underwater is becoming increasingly prominent. A large number of new theories, technologies, and methods in underwater optics are constantly emerging, finding widespread application in underwater video recording, high-speed data transmission, and sensor detection.

[0003] As is well known, light transmission in seawater faces significant light intensity attenuation due to the dual effects of absorption and scattering, influenced by various components in the seawater medium, including water molecules, suspended particulate matter, colored dissolved organic matter, salts, inorganic matter, and phytoplankton. This severely limits the underwater range of optical detection and communication equipment. However, within a fixed body of water and a fixed transmission distance, optical absorption can be considered constant; strong optical backscattering is also often concentrated within 0-5 meters from the light transmitter. Range gating or time gating techniques can effectively avoid the influence of scattering effects on detection results. The impact of long-range optical backscattering on detection is negligible and can be ignored.

[0004] Therefore, the use of miniaturized high-power lasers can greatly increase the transmission distance of light underwater. However, the random fluctuations in light intensity caused by underwater optical turbulence become a significant factor affecting the accuracy of underwater long-distance optical detection. The refractive index fluctuations caused by turbulence can cause optical signals to exhibit intensity flicker (fluctuations), phase distortion, and beam expansion. This not only exacerbates the attenuation and distortion of the optical signal, reducing transmission distance and imaging clarity, but also affects the stable detection of sensors. Currently, there is no effective method for measuring underwater optical turbulence intensity.

[0005] Therefore, it is urgent to develop a method for testing underwater optical turbulence intensity. Summary of the Invention

[0006] The present invention aims to provide an underwater optical turbulence intensity testing system and method. By utilizing a laser emission module and an optical receiving and processing module, the jitter variance at different underwater distances can be measured. The optical turbulence intensity can be intuitively evaluated through the jitter variance, thus making up for the current lack of underwater optical turbulence intensity measurement methods.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] An underwater optical turbulence intensity testing system includes a laser emission module and an optical receiving and processing module;

[0009] The laser emission module includes a power supply unit, a laser drive control unit and a laser head. The laser drive control unit is connected to the laser head. The laser head is used to emit a laser beam. The laser drive control unit is used to drive the laser head to generate a laser beam and regulate the laser emission intensity.

[0010] The optical receiving and processing module includes a power supply unit, an underwater binocular, an underwater image sensor, and a host computer. The underwater binocular is connected to the underwater image sensor, which is in turn connected to the host computer. The underwater binocular includes two identical but independent optical receiving lenses.

[0011] The two optical receiving lenses are used to simultaneously receive the same laser beam from the laser emitting module and form two light spots on the underwater image sensor;

[0012] The host computer is used to extract the changes in the coordinates of the centroids of the two light spots formed by the underwater image sensor in the same coordinate system, and calculate the jitter variance of the centroid distance.

[0013] Furthermore, the laser emission module also includes a collimator lens, which is used to shape the laser beam emitted by the laser head to improve the beam quality.

[0014] Furthermore, the laser beam emitted by the laser head is a continuous laser in the 532nm band.

[0015] Furthermore, the underwater image sensor adopts a CMOS chip.

[0016] The method for detecting underwater optical turbulence intensity using the underwater optical turbulence intensity testing system described above comprises the following steps:

[0017] S1, the laser drive control unit drives the laser head to generate a laser beam and regulates the laser emission intensity;

[0018] S2, two optical receiving lenses simultaneously receive the same laser beam from the laser transmitting module and form two light spots on the underwater image sensor;

[0019] S3. The host computer extracts the changes in the coordinates of the center of mass of the two light spots formed by the underwater image sensor in the same coordinate system and calculates the jitter variance of the center of mass distance. The jitter variance is used as the basis for judging the optical turbulence intensity on the currently measured underwater optical propagation path. If the jitter variance is large, the turbulence intensity is large, and if the jitter variance is small, the turbulence intensity is weak.

[0020] The beneficial effects of the technical solution are:

[0021] The present invention provides an underwater optical turbulence intensity testing system and method, which utilizes a laser emission module and an optical receiving and processing module to measure the jitter variance at different underwater distances. The jitter variance can be used to intuitively evaluate the optical turbulence intensity, which is a manifestation of turbulence intensity and is also a relatively easy-to-implement method. This method can make up for the current lack of underwater optical turbulence intensity measurement methods. At the same time, it can provide an optical path status evaluation method for underwater testing of underwater optical equipment, and it is low-cost and easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of an underwater optical turbulence intensity testing system in Example 1 of the present invention. DETAILED DESCRIPTION

[0023] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0024] Example 1

[0025] An underwater optical turbulence intensity testing system includes a laser emission module and an optical receiving and processing module;

[0026] The laser emission module includes a power supply unit, a laser drive control unit, a laser head and a collimating mirror. The laser drive control unit is connected to the laser head. The laser head is used to emit a laser beam. The laser beam emitted by the laser head is a 532nm band continuous laser with good underwater penetration, good directionality and coherence, and can propagate relatively stably underwater.

[0027] The laser drive control unit drives the laser head to generate a laser beam and regulates the laser emission intensity. The collimator is used to shape the laser beam emitted by the laser head and improve the beam quality. Specifically, the collimator converts the divergent laser beam emitted by the laser head into a parallel beam. By placing the collimator in the laser head's light output path, the laser beam is refracted or reflected by the collimator, becoming a parallel light output, thereby improving the laser beam's directionality and transmission efficiency.

[0028] The power supply unit is connected to the laser head and laser drive control unit, providing power to them. The power supply unit utilizes waterproof, well-sealed, and corrosion-resistant underwater batteries, such as lithium-ion batteries and nickel-metal hydride batteries. The batteries must be waterproof to prevent water from entering the battery and causing short circuits or other damage. Special sealing techniques and materials, such as rubber seals and waterproof casings, are typically employed to ensure the battery's ability to function properly underwater. In this embodiment, the underwater battery can be designed based on the duration of underwater testing, using mature lithium batteries in an oil-filled, water-tight package.

[0029] The optical receiving and processing module includes a power supply unit, an underwater binocular, an underwater image sensor and a host computer. The power supply unit is respectively connected to the underwater image sensor and the host computer to supply power to them; the underwater binocular is connected to the underwater image sensor, and the underwater image sensor is connected to the host computer.

[0030] The underwater binoculars include two identical but independent optical receiving lenses. The center distance between the two lenses can be adjusted or completely fixed according to the situation. The two optical receiving lenses are used to simultaneously receive the same laser beam from the laser transmitting module and form two light spots on the underwater image sensor. Specifically, light will be refracted and focused when passing through the lens. The optical properties of the lens (such as focal length, curvature, etc.) make the laser beam focus on its focal plane. The laser beam focused by the lens forms two light spots when it continues to propagate to the underwater image sensor. The underwater image sensor can use a high-sensitivity CMOS chip or a conventional CMOS chip according to needs. The sensor is independently watertightly packaged and powered by an underwater battery.

[0031] Under the influence of underwater optical turbulence, the two light spots on the underwater image sensor flicker constantly, indicating that the center of mass of each light spot constantly changes. Simultaneously, the relative positions of the two center of mass of the light spots also change. Through image processing, the host computer extracts the changes in the coordinates of the two center of mass of the light spots in the same coordinate system and calculates the jitter variance of the center of mass distance. This can be used as a basis for judging the intensity of optical turbulence on the currently measured underwater optical propagation path. A large variance indicates high turbulence intensity, while a small variance indicates low turbulence intensity, indicating a stable propagation path. The host computer can be an industrial computer.

[0032] Example 2

[0033] A method for detecting underwater optical turbulence intensity using an underwater optical turbulence intensity testing system according to Example 1 comprises the following steps:

[0034] S1, the laser drive control unit drives the laser head to generate a laser beam and regulates the laser emission intensity; wherein, a collimator is placed in the light output path of the laser head, and the laser emitted from the laser head is shaped by the collimator to improve the beam quality;

[0035] S2, two optical receiving lenses simultaneously receive the same laser beam shaped by the collimator, and form two light spots on the underwater image sensor;

[0036] S3. The host computer extracts the changes in the coordinates of the centroids of the two light spots formed by the underwater image sensor in the same coordinate system and calculates the jitter variance of the centroid distance. The jitter variance is used as a basis for judging the optical turbulence intensity on the currently measured underwater optical propagation path. If the jitter variance is large, the turbulence intensity is high, and if the jitter variance is small, the turbulence intensity is weak.

[0037] Assume that the coordinates of the two light spots are A(X1, Y1) and B(X2, Y2), and the jitter amounts are △X=X1-X2 and △Y=Y1-Y2, respectively. Their variances are: and

[0038] The distance between the two light spots is The jitter variance is: Var(D)=E[D 2 ]-(E[D]) 2 .

[0039] In summary, the present invention provides an underwater optical turbulence intensity testing system and method, which can measure the jitter variance at different underwater distances by utilizing a laser transmitting module and an optical receiving and processing module. The optical turbulence intensity can be intuitively evaluated through the jitter variance, which is a manifestation of turbulence intensity and is also a relatively easy-to-implement method. This method can make up for the current lack of underwater optical turbulence intensity measurement means, and at the same time can provide an optical path state evaluation means for underwater testing of underwater optical equipment, and it is low-cost and easy to operate.

[0040] The above is only an embodiment of the present invention, and common knowledge such as the specific technical solutions or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the description can be used to interpret the content of the claims.

Claims

1. An underwater optical turbulence intensity testing system, characterized in that: Includes a laser emission module and an optical receiving and processing module; The laser emission module includes a power supply unit, a laser drive control unit and a laser head. The laser drive control unit is connected to the laser head. The laser head is used to emit a laser beam. The laser drive control unit is used to drive the laser head to generate a laser beam and regulate the laser emission intensity. The optical receiving and processing module includes a power supply unit, an underwater binocular, an underwater image sensor, and a host computer. The underwater binocular is connected to the underwater image sensor, which is in turn connected to the host computer. The underwater binocular includes two identical but independent optical receiving lenses. The two optical receiving lenses are used to simultaneously receive the same laser beam from the laser emitting module and form two light spots on the underwater image sensor; The host computer is used to extract the changes in the coordinates of the centroids of the two light spots formed by the underwater image sensor in the same coordinate system, and calculate the jitter variance of the centroid distance.

2. The underwater optical turbulence intensity measurement system according to claim 1, characterized in that: The laser emission module further includes a collimator lens, which is used to shape the laser beam emitted by the laser head to improve the beam quality.

3. The underwater optical turbulence intensity measurement system according to claim 1, characterized in that: The laser beam emitted by the laser head is a continuous laser in the 532nm band.

4. The underwater optical turbulence intensity measurement system according to claim 1, characterized in that: The underwater image sensor adopts a CMOS chip.

5. A method for detecting underwater optical turbulence intensity using the underwater optical turbulence intensity testing system according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, the laser drive control unit drives the laser head to generate a laser beam and regulates the laser emission intensity; S2, two optical receiving lenses simultaneously receive the same laser beam from the laser transmitting module and form two light spots on the underwater image sensor; S3. The host computer extracts the changes in the coordinates of the center of mass of the two light spots formed by the underwater image sensor in the same coordinate system and calculates the jitter variance of the center of mass distance. The jitter variance is used as the basis for judging the optical turbulence intensity on the currently measured underwater optical propagation path. If the jitter variance is large, the turbulence intensity is large, and if the jitter variance is small, the turbulence intensity is weak.

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