阅读说明：本技术 一种基于涡旋光的水下激光雷达系统 (Vortex rotation-based underwater laser radar system ) 是由 杨苏辉 廖英琦 林学彤 李坤 李卓 王欣 张金英 于 2021-02-19 设计创作，主要内容包括：本发明公开了一种所述系统包括：发射端、接收端和计算机,其中发射端包括：激光器、信号发生器和电光调制器；接收端包括：缩束透镜组、螺旋相位板、不透明元件、滤光片、探测器和示波器；激光器、电光调制器、缩束透镜组、螺旋相位板、不透明元件、滤光片、探测器、示波器、计算机依次连接；信号发生器分别与电光调制器、示波器连接。本发明通过缩束透镜组提高了探测的信号强度,增加探测的信噪比,通过螺旋相位板将目标反射光转换为涡旋光,再结合不透明元件减少了探测器对于涡旋中心的散射光的接收,通过滤光片进一步减少了散射光的接收,提升了探测的精度。(The invention discloses a system comprising: transmitting terminal, receiving terminal and computer, wherein the transmitting terminal includes: a laser, a signal generator and an electro-optical modulator; the receiving end includes: the device comprises a beam-shrinking lens group, a spiral phase plate, an opaque element, a light filter, a detector and an oscilloscope; the laser, the electro-optical modulator, the beam-shrinking lens group, the spiral phase plate, the opaque element, the optical filter, the detector, the oscilloscope and the computer are sequentially connected; the signal generator is respectively connected with the electro-optical modulator and the oscilloscope. According to the invention, the detection signal intensity is improved through the beam-shrinking lens group, the signal to noise ratio of detection is increased, the target reflected light is converted into vortex rotation through the spiral phase plate, the receiving of scattered light at the center of the vortex by the detector is reduced by combining the opaque element, the receiving of the scattered light is further reduced through the optical filter, and the detection precision is improved.)

1. An underwater laser radar system based on vortex rotation is characterized in that: the system comprises: a transmitting end, a receiving end and a computer, wherein,

the transmitting end includes: a laser, a signal generator and an electro-optical modulator;

the receiving end includes: the device comprises a beam-shrinking lens group, a spiral phase plate, an opaque element, a light filter, a detector and an oscilloscope;

the laser is a blue-green laser with the wavelength of 532nm, is used for generating Gaussian light and transmitting the Gaussian light to the electro-optic modulator, and the Gaussian light is direct current light;

the signal generator is used for generating signal waves and sending the signal waves to the electro-optical modulator;

the electro-optical modulator is used for modulating signals and then transmitting the signals, modulating the direct current light generated by the laser through signal waves by the electro-optical modulator to obtain modulated light, and transmitting the modulated light to underwater, wherein the modulated light is reflected back after touching a measured target to obtain target reflected light, and the modulated light is a light echo signal of which the light intensity is in a high-frequency sine wave form;

the beam-shrinking lens group is used for receiving the target reflected light and shrinking the beam;

the spiral phase plate is used for converting the condensed target reflected light into an eddy rotation;

the opaque element is used for eliminating scattered light of a target reflected light center;

the filter is a 532nm narrow-band filter and is used for filtering light out of a 532nm wave band;

the detector is a photomultiplier tube detector PMT and is used for receiving light and converting the light into an electric signal, amplifying the electric signal and sending the electric signal to an oscilloscope, wherein the electric signal is an echo signal;

the oscilloscope is used for receiving a reference signal sent by the signal generator and an echo signal of the detector, and then sending the waveforms of the reference signal and the echo signal to a computer for calculation;

the computer is used for calculating the distance;

the laser, the electro-optical modulator, the beam reduction lens group, the spiral phase plate, the opaque element, the optical filter, the detector, the oscilloscope and the computer are sequentially connected;

and the signal generator is respectively connected with the electro-optical modulator and the oscilloscope.

2. The vortex rotation based underwater lidar system of claim 1, wherein: the frequency of the high-frequency sine wave modulation signal is more than 100 MHz.

3. The vortex rotation based underwater lidar system of claim 1, wherein: the signal generator is also used for sending the high-frequency sine wave modulation signal to an oscilloscope as a reference signal.

4. The vortex rotation based underwater lidar system of claim 1, wherein: the beam-shrinking lens group consists of two lenses which are coaxial and confocal and are in a parallel shape, the lens close to one end of reflected light is a first lens, the lens far away from one end of the reflected light is a second lens, the diameter of the first lens is larger than that of the second lens, the focal length of the second lens is smaller than that of the first lens, and the lenses are all 532nm high-transmittance plano-convex lenses.

5. The vortex rotation based underwater lidar system of claim 1, wherein: the formation of the vortex rotation enables the reflected light to be in a circular ring shape, and all the light at the center of the circle is scattered light.

6. The vortex rotation based underwater lidar system of claim 5, wherein: the spiral phase plate is a glass element.

7. The vortex rotation based underwater laser + lidar system of claim 1, wherein: the opaque element is a 532nm high-transmittance glass sheet with the center plated with black paint, the diameter of the black paint is the same as that of a hollow core of vortex rotation, and the hollow core is a vortex center.

8. The vortex rotation based underwater lidar system of claim 1, wherein: the oscilloscope is a high-speed high-bandwidth oscilloscope.

9. The vortex rotation based underwater lidar system of claim 1, wherein: the distance measuring method of the computer comprises the following steps: the phase difference between the reference signal and the echo signal is calculated by cross-correlation, and the time difference is calculated from the phase difference, thereby obtaining the distance information relative to the reference signal.

Technical Field

The invention relates to the field of underwater radars, in particular to an underwater laser radar system based on vortex rotation.

Background

In the process of detecting and developing the ocean, the underwater ranging radar has important application in the aspects of construction and maintenance of ocean engineering, ocean ecological observation, salvaging of submarine airplanes and sunken ship remains, underwater mine exploration and potential exploration and the like. Sonar is large in size and cannot be spread on water, so that a blue-green laser radar is often used in shallow water.

The accuracy of the existing laser radar is seriously limited by seawater scattering. Backscattered light can be suppressed by a combination of a pulsed light source and a range gate detector, and continuous light with modulation frequencies exceeding 100MHz also has a significant effect on backscattering. Forward scattered light remains a major limiting factor for detection radar.

The laser detection radar emits laser in the sea to irradiate an object and receives an echo, so that the distance information of the object is obtained. The scattered light carries wrong distance information, so that an underwater continuous light radar system based on vortex rotation is improved, forward scattered light is restrained, and the detection accuracy of the radar is improved.

Disclosure of Invention

The invention aims to provide an underwater laser radar system based on vortex rotation to solve the problems in the prior art.

In order to achieve the purpose, the invention provides the following scheme:

the invention provides an underwater laser radar system based on vortex rotation, which is characterized by comprising the following components: a transmitting end, a receiving end and a computer, wherein,

the transmitting end includes: a laser, a signal generator and an electro-optical modulator;

the receiving end includes: the device comprises a beam-shrinking lens group, a spiral phase plate, an opaque element, a light filter, a detector and an oscilloscope;

the laser is a blue-green laser with the wavelength of 532nm, is used for generating Gaussian light and transmitting the Gaussian light to the electro-optic modulator, and the Gaussian light is direct current light;

the signal generator is used for generating signal waves and sending the signal waves to the electro-optical modulator;

the electro-optical modulator is used for modulating signals and then transmitting the signals, modulating the direct current light generated by the laser through signal waves by the electro-optical modulator to obtain modulated light, and transmitting the modulated light to underwater, wherein the modulated light is reflected back after touching a measured target to obtain target reflected light, and the modulated light is a light echo signal of which the light intensity is in a high-frequency sine wave form;

the beam-shrinking lens group is used for receiving the target reflected light and shrinking the beam;

the spiral phase plate is used for converting the condensed target reflected light into an eddy rotation;

the opaque element is used for eliminating scattered light of a target reflected light center;

the filter is a 532nm narrow-band filter and is used for filtering light out of a 532nm wave band;

the detector is a photomultiplier tube detector PMT and is used for receiving light and converting the light into an electric signal, amplifying the electric signal and sending the electric signal to an oscilloscope, wherein the electric signal is an echo signal;

the oscilloscope is used for receiving a reference signal sent by the signal generator and an echo signal of the detector, and then sending the waveforms of the reference signal and the echo signal to a computer for calculation;

the computer is used for calculating the distance; the laser, the electro-optical modulator, the beam reduction lens group, the spiral phase plate, the opaque element, the optical filter, the detector, the oscilloscope and the computer are sequentially connected;

and the signal generator is respectively connected with the electro-optical modulator and the oscilloscope.

Further, the frequency of the high-frequency sine wave modulation signal is more than 100 MHz.

Further, the signal generator is also used for sending the high-frequency sine wave modulation signal to an oscilloscope as a reference signal.

Further, the beam reduction lens group comprises two lenses, the two lenses are coaxial and have a common focus and are in a parallel shape, the lens close to one end of the reflected light is a first lens, the lens far away from one end of the reflected light is a second lens, the diameter of the first lens is larger than that of the second lens, the focal length of the second lens is smaller than that of the first lens, and the lenses are all 532nm high-transmittance planoconvex lenses.

Further, the formation of the vortex rotation makes the reflected light in a circular ring shape, and all the light at the center of the circle is scattered light.

Further, the spiral phase plate is a glass element.

Further, the opaque element is a 532nm high-transmittance glass sheet with the center plated with black paint, the diameter of the black paint is the same as that of a hollow core of vortex rotation, and the hollow core is a vortex center.

Further, the oscilloscope is a high-speed high-bandwidth oscilloscope.

Further, the distance measuring method of the computer comprises the following steps:

the phase difference between the reference signal and the echo signal is calculated by cross-correlation, and the time difference is calculated from the phase difference, thereby obtaining the distance information relative to the reference signal.

The invention discloses the following technical effects:

the invention receives and contracts the target reflected light scattered due to scattering through the beam-contracting lens group, improves the detected signal intensity, increases the detected signal-to-noise ratio, converts the contracted target reflected light into vortex rotation through the spiral phase plate, reduces the receiving of the detector to the scattered light by matching with the opaque element, improves the detection precision, and filters the target reflected light by using the optical filter before entering the detector, further reduces the receiving of the detector to the scattered light, and improves the detection precision.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is a system framework diagram of the present invention;

FIG. 2 is a schematic illustration of suppressing scattering using vortex light;

FIG. 3 is a schematic diagram of distance determination by continuous light phase difference.

Detailed Description

Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The specification and examples are exemplary only.

As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.

The "parts" in the present invention are all parts by mass unless otherwise specified.

Example 1

Referring to fig. 1-3, the invention provides an underwater laser ranging radar system based on vortex rotation, which comprises a transmitting end, a receiving end and a computer, wherein the transmitting end is connected with the receiving end through a cable;

the transmitting end comprises a laser, a modulator and a signal generator;

the receiving end comprises a beam-shrinking lens group, a spiral phase plate, an opaque shading element, an optical filter, a detector and an oscilloscope;

the laser is connected with the modulator;

the signal generator is respectively connected with the modulator and the oscilloscope;

the laser, the beam-shrinking lens group, the spiral phase plate, the opaque shading element, the optical filter, the detector, the oscilloscope and the computer are sequentially connected.

The laser is a 532nm blue-green laser for generating continuous light, the modulator is controlled by the signal generator to convert the continuous light into a radio frequency modulation signal larger than 100MHz, and the signal generator is used for generating signal waves.

The modulator is an electro-optical modulator, intensity modulation is carried out on the light intensity changed by the direct current signal through signal waves to obtain a high-frequency sine wave intensity modulation signal, the high-frequency sine wave modulation signal inhibits scattering in seawater, the signal is transmitted to the underwater through the high-frequency sine wave intensity modulation signal, when the high-frequency sine wave intensity modulation signal touches a measured target, an echo signal is reflected, and the echo signal is received by the beam-shrinking lens group.

The signal generator takes the radio frequency sine wave intensity modulation signal as a reference signal and sends the reference signal to the oscilloscope.

The beam shrinking lens group consists of two lenses and shrinks the scattered echo. The two lenses are coaxial confocal points and are in parallel, the lens close to one end of reflected light is a first lens, the lens far away from one end of the reflected light is a second lens, the diameter of the first lens is larger than that of the second lens, the focal length of the second lens is smaller than that of the first lens, the two lenses are both 532nm high-transmittance plano-convex lenses, focusing is firstly carried out, then divergence is carried out, and the two lenses have a coincident focal point. The echo scattered due to scattering is received by the beam shrinking lens group, the detected signal intensity is improved, and the signal to noise ratio of detection is increased, wherein 532nm is a coating film on the lens, so that the 532nm light transmittance of the lens is high, and the loss is reduced.

The spiral phase plate is a glass element, and Gaussian light passing through the spiral phase plate can be converted into vortex rotation, the vortex light has spiral wave front, the center of the circle is a phase singularity, and the light intensity is zero, and the vortex rotation is also called dark hollow light beam. The formation of vortex light beams has requirements on spatial coherence, only target reflected light with the spatial coherence reserved can be converted into vortex rotation, and scattered light loses the spatial coherence after being collided for many times in water, so that the original state is maintained unchanged.

The opaque element is formed by plating black paint at the center of a 532nm high-transmittance glass sheet, the diameter of the black paint is the same as the hollow diameter of vortex rotation, and scattered light distributed at the center of the vortex can be completely shielded, so that the receiving of the scattered light by a detector is reduced, but the receiving of target reflected light distributed on the vortex is not influenced.

The filter is a 532nm narrow-band filter, only the 532nm waveband is reserved, and ambient stray light with other wavelengths is filtered and cannot enter the detector.

The detector is PMT, receives and amplifies the echo, performs analog-to-digital conversion on the optical signal of the echo, converts the optical signal into an electric signal, obtains a volume curve of the light intensity changing along with time, and sends the volume curve to the oscilloscope.

The oscilloscope is a high-speed high-bandwidth oscilloscope, receives a reference signal sent by a signal generator and an echo signal received by a detector, and sends two signal waveforms to a computer for calculation through a USB flash disk.

The distance is calculated in the computer by a phase ranging method, namely the phase difference between a reference signal and an echo signal is calculated through cross correlation, and then the time difference is calculated through the phase difference, so that the distance information relative to the reference signal is obtained.

Example 2

The signal generator generates a radio frequency sine wave signal and sends the radio frequency sine wave signal to the electro-optical modulator, and the electro-optical modulator modulates the 532nm direct current optical signal into a radio frequency intensity modulation signal. The Gaussian light modulated by the radio frequency intensity emitted by the laser irradiates objects in the water, and is absorbed and scattered in the water. Under the action of scattering, the echo is diffused, received by the beam-shrinking optical lens group and compressed. The condensed light passes through a spiral phase plate, wherein the target reflected light with spatial coherence preserved therein can be converted into vortex rotation of dark hollow, and the scattered light with spatial coherence lost due to multiple collisions in water is kept in the original state. Thus, only scattered light is distributed in the center of the hollow vortex light. This portion of the light is blocked by the opaque element and can be prevented from being received without affecting the target reflected light on the vortex. The light passes through a 532nm narrow band filter before entering the detector, which filters out ambient light. The detector receives the echo and sends the echo to the oscilloscope.

The oscilloscope receives the reference wave sent by the signal generator and the echo received by the detector, the phase difference between the reference wave and the echo is related to the distance of light propagation, and the oscilloscope carries the position information of the target. The waveform information received by the oscilloscope is transferred to a computer for calculation.

In the computer, the two-mode phase difference information is obtained by cross-correlation, and the distance can be obtained by the phase difference.

In addition, when detecting, the target is firstly placed near the window of the water jar, and the phase difference and the distance are calculated at the moment to be used as the reference. Then, the target is placed in a water tank, and the distance information of the reference is subtracted from the obtained distance information to obtain the actual position of the target.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.