Multi-spectral water body attenuation and forward small-angle scattering measurement device

Abstract

The utility model discloses a multispectral water body attenuation and forward small-angle scattering measurement device, which is characterized by comprising a light source, a scatterer and a water body attenuation and forward scattering luminous flux detection module, wherein the light source comprises N collimation lasers and a laser output gating module; each collimating laser is transmitted or reflected by the laser output gating module after being subjected to electric control time-sharing gating, and then outputs a single-wavelength collimating working light source in a time-sharing manner; the single-wavelength collimation working light source is scattered by the scatterer to form scattered light in different directions; the water body attenuation and forward scattering luminous flux detection module comprises a scattered light receiving and converging hyperbolic convex lens, an optical filter and an area array CCD (Charge Coupled Device); scattered light is collimated and converged to a radial optical filter through a scattered light receiving and converging hyperbolic convex lens, and scattered light signals are attenuated by the optical filter according to the attenuation amount of the radial optical filter in proportion and then are incident to a photosensitive element of the area array CCD. According to the utility model, measurement of multi-wavelength multi-angle forward small-angle volume scattering functions is realized.

Description

Technical Field

[0001] This utility model relates to a measuring device, specifically a multispectral water body attenuation and forward small-angle scattering measuring device. Background Technology

[0002] In marine optics, the volume scattering function (VSF, β(λ,φ)) is an important intrinsic optical parameter describing the angular distribution of light scattered on a scatterer in a water body. It is a function of wavelength (λ) and scattering angle (φ). Using the volume scattering function and absorption coefficient, all characteristic intrinsic optical parameters (c = a + b) of the water body and its components, as well as the remote sensing reflectance R, can be calculated. The volume scattering function is directly related to the water body's components. Different water components (such as algae and other plankton, air bubbles, suspended sediment, etc.) have characteristic contributions to the volume scattering function at different wavelengths and in different directions. With the deepening of marine research, the volume scattering function, especially multi-angle (0°-180° range) volume scattering functions covering both forward and backward directions, is increasingly demonstrating its importance in oceanographic fields such as water color remote sensing, underwater military target tracking, ecosystem modeling, and early warning and forecasting of nearshore disasters. Currently, online / profile measurement techniques for multi-angle volume scattering functions are basically based on a single wavelength. Due to technological limitations, spectral distribution data on multi-angle water volume scattering functions are extremely scarce.

[0003] Volume scattering measurement of seawater is one of the most challenging problems in measuring the optical properties of water bodies, especially the estimation of scattering coefficients based on the volume scattering function. This is mainly due to the large dynamic range of the forward and backward distribution of scattered light. Approximately 15% of the scattered light in water is concentrated within the forward 0.1° range, while 18%–28% is concentrated within the 1° range, and 58%–75% is concentrated within the forward 10° range. High angular resolution measurement of forward small-angle volume scattering function and flux is crucial for obtaining the scattering coefficient based on the volume scattering function, and is also closely related to effective underwater optical imaging and reliable optical communication. Currently, there are very few instruments available for measuring forward small-angle volume scattering function; the only commercially available instrument is the LISST series, which mainly utilizes the forward small-angle scattering principle to obtain the particle size distribution of seawater particles. However, LISST's measurement wavelength is single, making it unable to achieve multispectral water attenuation and forward small-angle scattering measurements. Furthermore, LISST's photodetector uses a 32-array fixed ring detector, limiting the angular resolution of the scattering measurement. Utility Model Content

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a multispectral water body attenuation and forward small-angle scattering measurement device to realize the measurement of multi-wavelength, multi-angle forward small-angle volume scattering functions.

[0005] To achieve the above objectives, the technical solution of this utility model is as follows:

[0006] A multispectral water body attenuation and forward small-angle scattering measurement device, characterized in that it includes a light source, a scattering body, and a water body attenuation and forward scattered light flux detection module; wherein,

[0007] The light source includes N collimated lasers and a laser output gating module; each collimated laser, after being electronically controlled and time-division selected, is transmitted or reflected by the laser output gating module and then outputs a single-wavelength collimated working light source in a time-division manner; N is an integer greater than 1;

[0008] The single-wavelength collimated light source forms scattered light in different directions after being scattered by the scatterer;

[0009] The water body attenuation and forward scattered light flux detection module includes a hyperbolic convex lens for receiving and converging scattered light, a filter, and a transmission and forward scattered light detection module; the transmission and forward scattered light detection module includes a CCD array.

[0010] The scattered light is collimated and focused onto the radial filter by the scattered light receiving and converging hyperboloid lens. The filter attenuates the scattered light signal proportionally to the attenuation of the radial filter before it is incident on the photosensitive surface of the area CCD.

[0011] Optionally, the laser output gating module consists of N-1 binary beam splitters.

[0012] Optionally, the center of the area CCD is collinear with the central axis of the collimated laser's output parallel light.

[0013] Optionally, the light source further includes a reference light detection module for monitoring and supplementing changes in the light source. The reference light detection module includes a semi-transparent mirror and a photodetector. The semi-transparent mirror is installed at the output front end of the collimating laser, and the photodetector is installed in the reflected light path of the semi-transparent mirror.

[0014] Compared with the prior art, the advantages of this utility model are as follows:

[0015] The multispectral water body attenuation and forward small-angle scattering measurement device provided in this application uses a multi-band time-division output light source, which can quickly measure the forward small-angle volume scattering function of multiple wavelengths and angles without changing the light source. At the same time, the detector uses a planar CCD instead of a ring detector, making full use of the rich lattice information of the planar CCD. Without changing the detector, the angular resolution of the scattering detection can be adjusted as needed to achieve the measurement of the forward small-angle volume scattering function of different angle ranges and different angular resolutions. Attached Figure Description

[0016] Figure 1 A schematic diagram of the measurement principle of the multispectral water body attenuation and forward small-angle scattering measurement device provided in the embodiments of this application;

[0017] Figure 2 A schematic diagram of a CCD array and methods for measuring volume scattering functions at different angles and resolutions;

[0018] In the diagram: 1. Light source; 11. Collimated laser; 12. Laser output gating module; 13. Photodetector; 14. Electronically controlled time-division gating; 2. Scatterer; 3. Water attenuation and forward scattered light flux detection module; 31. Scattered light receiving and converging hyperboloid lens; 32. Filter; 33. Transmission and forward scattered light detection module. Detailed Implementation

[0019] Example:

[0020] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0021] See Figure 1 As shown, the multispectral water body attenuation and forward small-angle scattering measurement device provided in this embodiment mainly includes a light source 1, a scatterer 2, and a water body attenuation and forward scattering light flux detection module 3.

[0022] The light source 1 includes N (N is an integer greater than 1) collimated lasers 11 and a laser output gating module 12. Each collimated laser 11 is transmitted or reflected by the laser output gating module 12 after being electronically controlled for time division gating 14, and then outputs a single wavelength collimated working light source in a time division manner. With this setting, the light source can output multiple wavelengths in a time division manner, and the measurement of forward small-angle volume scattering function of multiple wavelengths and multiple angles can be quickly realized without changing the light source, thereby solving the problem that the existing forward small-angle volume scattering function measuring instrument is a single wavelength.

[0023] The single-wavelength collimated working light source forms scattered light in different directions after being scattered by the scatterer 2; the water body attenuation and forward scattered light flux detection module 3 includes a scattered light receiving and converging hyperbolic convex lens 31, a filter 32, and a transmission and forward scattered light detection module 33; the transmission and forward scattered light detection module 33 includes one M*M (M>1) area array CCD.

[0024] The scattered light is collimated and focused by the hyperbolic convex lens 31 onto the radially graded neutral density filter 32. The radially graded neutral density filter 32 can attenuate the scattered light signals of different angles and flux levels according to the attenuation of the radial filter before they are incident on the photosensitive surface of the area CCD. In this way, the detector uses an area CCD instead of a ring detector, making full use of the rich lattice information of the area CCD. There is no need to replace the detector. The angular resolution of the scattering detection can be adjusted as needed to realize the measurement of the forward small-angle volume scattering function at different angle ranges and different angular resolutions.

[0025] Therefore, it can be seen that the multispectral water body attenuation and forward small-angle scattering measurement device provided in this embodiment adopts multi-band time-division output of light source, which can quickly realize the measurement of forward small-angle volume scattering function of multiple wavelengths and multiple angles without changing the light source. At the same time, the detector adopts area array CCD instead of ring detector, making full use of the rich lattice information of area array CCD. Without changing the detector, the angular resolution of scattering detection can be adjusted as needed to realize the measurement of forward small-angle volume scattering function of different angle ranges and different angular resolutions.

[0026] In one specific embodiment, such as Figure 2 As shown, with the exact center point (M / 2, M / 2) of the CCD photosensitive surface as the center, and denoted as the relative position (0,0), a 1*2 circle is formed. y 2*2 y 3*2 y ...K*2 y For radius (y≥1, K*2) y ≤M / 2), forming 1*2 radius arrays on a CCD array. y 2*2 y 3*2 y ...K*2 y Given K circles, the area of ​​each circle corresponds to a pixel with a value of π*(2πkJ / ... y ) 2 π*(2*2) y ) 2 π*(3*2) y ) 2 ...π*(K*2) y ) 2； K circles are used to detect the scattered light flux at one transmission angle and K-1 scattering angles. The angles formed by the optical axis of the point source emitted by the light source and the arcs of the K circles successively form the transmission angle and K-1 scattering angle, with the maximum scattering angle being β (0 < β < 10). The scattering angle increment compensation (angular resolution) is α, (2 yβ / (M / 2))≤α≤β, the scattering angles formed sequentially are α, 2α, 3α...Kα; when measuring the volume scattering function of β / α scattering angles within the range of 0 to β angles with α angle resolution, the transmitted light flux is calculated as follows: with the center point (M / 2, M / 2) of the area array CCD as the center, and with a radius of 1*2... y The sum of photoelectric signals from all pixels within a circle of radius K*2. The scattered light flux received at the Kth scattering angle is the sum of the photoelectric signals from all pixels within a circle of radius K*2. y The Kth circle and the circle with radius (K-1)*2 y The sum of photoelectric signals from all pixels within the ring formed by the (K-1)th circle is processed into a digital signal by the photoelectric processing circuit. After calibration, the transmission (attenuation) and the volume scattering function at the corresponding angle can be obtained. Thus, the angular resolution of the scattering detection can be adjusted as needed to measure the forward small-angle volume scattering function at different angular ranges and resolutions.

[0027] In one specific embodiment, the laser output gating module 12 is composed of N-1 phase beam splitters to enable each collimated laser 11 to output a single wavelength collimated working light source after being transmitted or reflected by the laser output gating module after being electronically controlled and time-division selected; the center position of the area array CCD is collinear with the central axis of the collimated laser output parallel light.

[0028] In a preferred embodiment, the light source further includes a reference light detection module for monitoring and compensating for changes in the light source. The reference light detection module includes a semi-transparent mirror for beam splitting and a photodetector 13 for detection. The semi-transparent mirror is installed at the output front end of the collimating laser 11, and the photodetector 13 is installed on the reflected light path of the semi-transparent mirror.

[0029] The above embodiments are merely illustrative of the technical concept and features of this utility model, and are intended to enable those skilled in the art to understand the content of this utility model and implement it accordingly. They should not be construed as limiting the scope of protection of this utility model. All equivalent changes or modifications made based on the substance of the content of this utility model should be covered within the scope of protection of this utility model.

Claims

1. A multispectral water body attenuation and forward small-angle scattering measurement device, characterized in that, This includes modules for detecting light source, scatterer, water attenuation, and forward scattered light flux; among which, The light source includes N collimated lasers and a laser output gating module; each collimated laser, after being electronically controlled and time-division selected, is transmitted or reflected by the laser output gating module and then outputs a single-wavelength collimated working light source in a time-division manner; N is an integer greater than 1; The single-wavelength collimated light source forms scattered light in different directions after being scattered by the scatterer; The water attenuation and forward scattered light flux detection module includes a hyperboloidal convex lens for receiving and converging scattered light, a filter, and a transmission and forward scattered light detection module; the transmission and forward scattered light detection module includes a CCD array. The scattered light is collimated and focused onto the filter by the scattered light receiving and converging hyperboloid lens. The filter attenuates the scattered light signal proportionally to the attenuation of the radial filter before it is incident on the photosensitive surface of the area CCD.

2. The multispectral water body attenuation and forward small-angle scattering measurement device as described in claim 1, characterized in that, The laser output gating module consists of N-1 binary beam splitters.

3. The multispectral water body attenuation and forward small-angle scattering measurement device as described in claim 1, characterized in that, The center of the area CCD is collinear with the central axis of the collimated laser output parallel light.

4. The multispectral water body attenuation and forward small-angle scattering measurement device as described in claim 1, characterized in that, The light source also includes a reference light detection module for monitoring and supplementing changes in the light source. The reference light detection module includes a semi-transparent mirror and a photodetector. The semi-transparent mirror is installed at the output front end of the collimating laser, and the photodetector is installed in the reflected light path of the semi-transparent mirror.

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