An immersion factor measuring device for underwater photosynthetically active radiation sensor equipment

Abstract

The present invention relates to an immersion factor measuring device for underwater photosynthetically active radiation sensor equipment, comprising: a point light source, an aperture, a collimating lens, a wavelength filter wheel, an intensity filter wheel, a focusing lens, a homogenizing rod and a beam expander collimator arranged in sequence along an optical path; a monitoring probe and a control terminal; a water tank, a probe to be tested and an electric-controlled lifting platform, the electric-controlled lifting platform is placed in the water tank and drives the probe to be tested to rise and fall in the water tank, and the probe to be tested and the electric-controlled lifting platform are both connected to a sub-control terminal; a beam splitter is arranged after the beam expander collimator, and the incident light beam is divided into a first light beam and a second light beam, which are respectively irradiated to the monitoring probe and the probe to be tested. Compared with the prior art, the present invention has the advantages of improving the accuracy of immersion factor measurement, etc.

Description

Technical Field

[0001] The invention relates to the field of marine technology, and in particular to an immersion factor measuring device for underwater photosynthetically active radiation sensor equipment. Background Art

[0002] Underwater photosynthetically active radiation sensors are used to measure the spectral irradiance available for phytoplankton to photosynthesize. They are important tools for measuring underwater ambient light and assessing the depth of the ocean's true photosphere. During use, underwater photosynthetically active radiation sensors may experience baseline drift and calibration coefficient failure due to detector aging, component contamination, or reduced sensitivity, which may cause measurement errors to exceed the allowable range. Therefore, sensors need to be calibrated regularly to ensure the accuracy and reliability of measurement data.

[0003] The factory calibration of underwater photosynthetically active radiation sensors is performed in air. However, when the sensor is immersed in an underwater environment, due to the different optical refractive indices of air and water, the original instrument calibration coefficient must be corrected before it can be applied to the underwater environment. This correction coefficient is called the immersion factor.

[0004] The theoretical idea of ​​immersion factor measurement is to shine a beam of light on the sensor surface and obtain it based on the ratio of the measurement results of the sensor device in the air and just under the water surface. Patent CN1121610C discloses a measuring device, in which a cosine corrector is installed on an integrating sphere, and the sealing part is waterproofed. Then the integrating sphere is fixed on a rotating frame at the bottom of the water tank, and a parallel light tube is placed above the water tank. The distance from the sensor surface to the water surface is changed by gradually reducing the amount of water. This device can only calibrate the cosine corrector material and cannot be used directly to calibrate the sensor. In addition, the intensity and spectrum of the light beam used are difficult to adjust, resulting in a narrow range of application of the device, insufficient flexibility, and poor reproducibility of the measurement results. In addition, the distance from the liquid surface to the light source will constantly change during the working process, resulting in unstable measurement conditions, affecting the measurement accuracy. Summary of the invention

[0005] The purpose of the present invention is to provide an immersion factor measuring device for underwater photosynthetically active radiation sensor equipment.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] An immersion factor measuring device for underwater photosynthetically active radiation sensor equipment, comprising:

[0008] A point light source, an aperture, a collimating lens, a wavelength filter wheel, an intensity filter wheel, a focusing lens, a homogenizing rod and a beam expanding collimating lens are sequentially arranged along the optical path;

[0009] Monitoring probes and control terminals;

[0010] A water tank, a probe to be tested and an electric-controlled lifting platform, wherein the electric-controlled lifting platform is placed in the water tank and drives the probe to be tested to rise and fall in the water tank, and the probe to be tested and the electric-controlled lifting platform are both connected to the control terminal;

[0011] The beam splitter is arranged after the beam expansion collimator, and splits the incident light beam into a first light beam and a second light beam, which are respectively irradiated to the monitoring probe and the probe to be tested.

[0012] The electric-controlled lifting platform includes a mounting frame, a support rod and a stepper motor. The support rod is arranged on the mounting frame and moves up and down along the mounting frame. The output end of the stepper motor is connected to the support rod and drives the support rod to move. The probe to be tested is installed on the support rod, and the stepper motor is connected to the control terminal.

[0013] The beam splitter is a semi-transparent and semi-reflective mirror.

[0014] The included angle between the beam splitter and the horizontal plane is 45 degrees.

[0015] The top of the mounting frame is located near the liquid surface.

[0016] The top of the mounting frame is located above the liquid level.

[0017] The mounting frame is located at the side wall inside the water tank.

[0018] The point light source is a light bulb.

[0019] The control terminal is configured to perform the following steps:

[0020] In total darkness, record the background reading Rd of the monitoring probe and the background reading RAWd of the probe to be tested;

[0021] When the point light source is lit and lasts for a set period of time, the basic reading R0 of the monitoring probe is recorded;

[0022] The electric lifting platform is controlled to drive the probe to be tested to move up and down below the liquid level in the water tank, and the experimental reading R1 of the monitoring probe and the experimental reading RAW1 of the probe to be tested are collected at each height;

[0023] Convert the experimental reading RAW1 of the probe to be tested corresponding to each height into a corrected reading;

[0024] The immersion factor is calculated based on the corrected readings of the probe under test corresponding to each height and the optical path distance between the probe under test and the point light source.

[0025] The corrected reading of the probe to be tested is:

[0026]

[0027] Where: S1 is the corrected reading of the probe to be tested.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The wavelength and intensity can be adjusted by rotating the wavelength filter wheel and the intensity filter wheel, so as to cover the detection needs of the devices to be tested (i.e. the probes to be tested) with different dynamic ranges and sensitivities; the light intensity distribution in the end face of the outgoing light beam is adjusted by a hexagonal or circular light homogenizing rod to achieve a high uniformity of light intensity distribution, so that the central axis of the probe to be tested does not need to be strictly coincident with the central axis of the light beam, nor does it need to maintain a fixed distance, which can greatly reduce the difficulty of installation and adjustment, especially in repeated measurements or batch measurements; the lifting and lowering of the probe to be tested is achieved by an electrically controlled lifting platform, so that the distance between the water surface and the light source does not change, the measurement conditions are kept constant, the measurement error is reduced, and the output signal when infinitely close to the water surface can be calculated by extrapolation, thereby improving the accuracy of the immersion factor.

[0030] 2. The angle between the beam splitter and the horizontal plane is 45 degrees, so the light can be directed vertically downward toward the probe to be tested, reducing the impact of light refraction in the water.

[0031] 3. The mounting bracket is located on the side wall of the water tank, which provides higher stability.

[0032] 4. The monitoring probe and the probe to be tested start working at the same time. The monitoring probe will monitor the change of the bulb intensity over time in real time and use it to correct the reading of the probe to be tested, thereby improving the accuracy of the measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of the present invention;

[0034] Among them: 1. point light source, 2. aperture, 3. collimating lens, 4. wavelength filter wheel, 5. intensity filter wheel, 6. focusing lens, 7. homogenizing rod, 8. beam expanding collimating lens, 9. beam splitter, 10. monitoring probe, 11. water tank, 12. mounting frame, 13. support rod, 14. stepping motor, 15. probe to be inspected. DETAILED DESCRIPTION

[0035] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0036] An immersion factor measuring device for underwater photosynthetically active radiation sensor equipment, such as Figure 1 As shown, including:

[0037] Point light source 1, aperture 2, collimating lens 3, wavelength filter wheel 4, intensity filter wheel 5, focusing lens 6, homogenizing rod 7 and beam expander collimator 8 are arranged in sequence along the optical path. The optical path of this part is generally horizontal.

[0038] Monitoring probe 10 and control terminal 16;

[0039] A water tank 11, a probe to be tested 15 and an electric-controlled lifting platform, the electric-controlled lifting platform is placed in the water tank 11 and drives the probe to be tested 15 to rise and fall in the water tank 11, the probe to be tested 15 and the electric-controlled lifting platform are both connected to a sub-control terminal 16, wherein the monitoring probe 10 and the probe to be tested 15 have the same working wavelength;

[0040] The beam splitter 9 is disposed after the beam expander collimator 8 , and splits the incident light beam into a first light beam and a second light beam, which are respectively irradiated to the monitoring probe 10 and the probe to be tested 15 .

[0041] The electric-controlled lifting platform includes a mounting frame 12, a support rod 13 and a stepper motor 14. The support rod 13 is arranged on the mounting frame 12 and moves up and down along the mounting frame 12. The output end of the stepper motor 14 is connected to the support rod 13 and drives the support rod to move. The probe 15 to be tested is installed on the support rod 13. The stepper motor 14 is connected to the control terminal 16, and all the components of the electric-controlled lifting platform are painted black.

[0042] In this embodiment, filters with different passbands are loaded on the wavelength filter wheel 4. Neutral attenuation filters with different optical densities are loaded on the intensity filter wheel 5.

[0043] In this embodiment, the light homogenizing rod 7 is made of quartz, and the aperture may be cylindrical, hexagonal or conical.

[0044] In this embodiment, the water tank 11 is a cube or a cylinder, the top of the water tank 11 is open, the side walls and the bottom of the water tank 11 are coated with optical matte paint, and the water tank 11 contains ultrapure water or standard seawater.

[0045] In this embodiment, the beam splitter 9 is a semi-transparent and semi-reflective mirror, and the angle between the beam splitter 9 and the horizontal plane is 45 degrees, so that the light can be directed vertically downward toward the probe to be tested to avoid angle changes caused by refraction.

[0046] In some embodiments, the top of the mounting frame 12 is located at a height close to the liquid surface, but in other embodiments, the top of the mounting frame 12 is located above the liquid surface, so that test data closer to the water surface can be obtained. In addition, the mounting frame 12 is fixed to the bottom of the water tank, and a metal wire rod is erected on the mounting frame 12, and a ball nut is provided on the wire rod. The length of the support rod is adjustable, and one end of the support rod is provided with a nut seat connector, which can be fixedly connected with the ball nut, and the other end is provided with a fixture for fixing the device to be tested, and the fixture is provided with a rotating ring and a locking screw, which can fix the device to be tested containing the probe 15 to be tested in a vertical upward position. The stepper motor 14 of the electric control lifting platform is a closed-loop control type, and the stepper motor 14 can control the rotation of the wire rod, thereby controlling the lifting and lowering of the support rod 13 and the device to be tested. There is a communication cable between the stepper motor 14 and the control terminal 16, and the control terminal 16 instructs the stepper motor 14 to work and receives the lifting displacement data sent back by the stepper motor 14.

[0047] In this embodiment, the mounting frame 12 is located at the side wall of the water tank 11, and the point light source 1 is a light bulb, which can be a halogen lamp, an LED lamp or a xenon lamp.

[0048] In the present application, the outgoing light of the light bulb forms a circular light spot after passing through the aperture hole. After the light spot is collimated by the lens, the output wavelength and light intensity are adjusted by the wavelength filter and the light intensity attenuation plate respectively. The adjusted light is then focused by another lens and shot into the homogenizing rod 7. After the incident light is totally internally reflected multiple times in the homogenizing rod 7, the light intensity of each wavelength is evenly distributed on the other end face of the homogenizing rod 7, and then collimated by a large-diameter lens and shot to the beam splitter 9. The beam splitter 9 divides the incident light into two parts, one of which is received by the monitoring probe 10 after passing through the beam splitter 9, and the other is reflected and shot vertically to the probe 15 to be tested in the water tank 11.

[0049] In the present application, the device to be inspected is fixed on an electrically controlled lifting platform, with the photosensitive surface facing vertically upward. The horizontal position of the device to be inspected is adjusted by adjusting the extension of the support rod 13, and the angle of the photosensitive surface is fine-tuned by the clamp swivel so that the photosensitive surface faces vertically to the incident light beam. The device to be inspected changes its distance from the water surface and the light source through the electrically controlled lifting platform, and the electrical signal output by the device to be inspected is transmitted to the control terminal 16 through a cable.

[0050] In the prior art, the intensity and wavelength of the light source used are inconvenient to adjust, and the uniformity of the output light beam is not enough, which cannot meet the needs of detecting the wavelength or intensity response difference of the equipment to be inspected, and the placement of the probe to be inspected is strictly required, which brings a lot of installation and adjustment workload for repeated measurements or batch measurements. In the present application, the wavelength and intensity of the output light can be adjusted by rotating the wavelength filter wheel 4 and the intensity filter wheel 5, so as to cover the detection needs of the equipment to be inspected with different dynamic ranges and sensitivities. The homogenizing rod can homogenize the light intensity distribution of the cross section of the outgoing light beam, so that the central axis of the probe to be inspected does not have to strictly coincide with the central axis of the light beam, nor does it have to maintain a fixed distance, which can greatly reduce the difficulty of installation and adjustment, especially in repeated measurements or batch measurements.

[0051] During implementation, firstly, an adjustable light source is arranged in the horizontal direction, the center of the light outlet of the aperture 2 is fixed at the object focal position of the collimating lens 3, and the light bulb is installed on the left side of the aperture 2; then the wavelength filter wheel 4 and the intensity filter wheel 5 are installed in sequence, so that the collimated light path passes through the filters on the two wheels; the focusing lens 6 is placed on the right side of the filter wheel 5; the position of the homogenizing rod 7 is adjusted so that its incident end face coincides with the image focal plane of the focusing lens 6, and the exit end face coincides with the object focal plane of the beam expander collimator 8, and the beam splitter 9 is placed in the image space of the beam expander collimator 8 at an angle of 45 degrees.

[0052] After the light source 1 is turned on, the light passes through the aperture 2 and becomes parallel light through the collimating lens 3. The wavelength and intensity of the parallel light can be adjusted by the filter wheel 4 and the intensity filter wheel 5 according to needs; after the parallel light passes through the wavelength filter wheel 4 and the intensity filter wheel 5, it is converged by the focusing lens 6 to the incident section of the homogenizing rod 7, and then undergoes multiple total internal reflections in the homogenizing rod 7. The intensity of the light on the exit section of the homogenizing rod 7 is evenly distributed. The beam expander collimator 8 further expands and collimates the light and then projects it to the beam splitter 9; the beam splitter 9 divides the uniform collimated light into two parts, one part passes through the beam splitter in parallel and is received by the monitoring probe 10, and the other part is vertically projected onto the photosensitive surface of the probe 15 to be tested in the water tank 11.

[0053] The probe 15 to be tested is fixed in the fixture of the support rod 13, and the up and down movement of the support rod 13 on the mounting frame 12 is controlled by the stepper motor 14. The mounting frame 12 is fixedly installed near the side wall of the water tank 11. The water tank 11 contains ultrapure water or standard seawater, and the probe 15 to be tested, the support rod 13, the mounting frame 12 and the stepper motor 14 are all submerged under the water surface. The distance between the probe 15 to be tested and the water surface is controlled by the stepper motor 14. The stepper motor 14, the device to be tested 15 and the monitoring probe 10 are all controlled by the control terminal 16. The data of the device to be tested, the monitoring probe data and the distance data at each distance are finally read and processed by the control terminal 16. After one cycle of measurement, the wavelength filter wheel 4 and the intensity filter wheel 5 can be adjusted to switch to other light wavelengths or intensity conditions to carry out the next round of testing.

[0054] Furthermore, the control terminal 16 is configured to perform the following steps:

[0055] In the case of total darkness, record the background reading Rd of the monitoring probe 10 and the background reading RAWd of the probe to be tested 15;

[0056] When the point light source 1 is lit and lasts for a set period of time, the basic reading R0 of the monitoring probe 10 is recorded;

[0057] Control the electric lifting platform to drive the probe 15 to be tested to move up and down below the liquid level in the water tank 11, and collect the experimental reading R1 of the monitoring probe 10 and the experimental reading RAW1 of the probe 15 to be tested at each height;

[0058] The experimental reading RAW1 of the probe 15 to be tested corresponding to each height is converted into a corrected reading;

[0059] The immersion factor is calculated based on the corrected readings of the probe 15 to be tested corresponding to each height and the optical path distance between the probe 15 to be tested and the point light source 1 .

[0060] The corrected reading of the probe 15 to be tested is:

[0061]

[0062] Wherein: S1 is the corrected reading of the probe 15 to be tested.

[0063] The calculation process of the immersion factor is as follows: the probe 15 to be tested faces the uniform parallel light emitted by the light source. Under water-free conditions, the correction reading of the detector at different distances from the light source is constant, and the signal at this time is recorded as J0. After the water tank is filled with water, the distance between the detector and the light source is changed, and the measurement signal changes with the distance; the measurement signals at different water depths are recorded, and the relationship between the two is established through the least squares fitting method, and then the signal value when the water depth is exactly 0 is calculated, which is recorded as J1. Immersion factor = J0 / J1.

[0064] If the functions implemented by the above-mentioned control terminal are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0065] In addition, the accuracy of this application is higher: mainly reflected in two points:

[0066] 1. The measurement of the immersion factor requires obtaining data when the device to be tested is just below the water surface. This can be achieved by adjusting the distance between the device to be tested and the water surface, recording the output signals at different positions, and then using the extrapolation method to deduce the output signal when it is infinitely close to the water surface. Other conditions must remain unchanged during the entire measurement process. In the prior art, distance adjustment relies on gradually reducing the amount of water in the water tank and then measuring the water level with a ruler. However, this approach changes the positional relationship between the water surface and the light source, resulting in unstable measurement conditions and increased measurement errors. In the present application, the distance between the device to be tested and the water surface is adjusted by an electrically controlled lifting frame submerged in the water body. During the adjustment process, the amount of water does not decrease, and the distance between the water surface and the light source remains unchanged, thereby reducing the error caused by changes in measurement conditions.

[0067] 2. During the measurement process, the intensity of the light bulb will change, especially for xenon light sources. The existing technology does not correct the influence of light intensity fluctuation of the light source. In the present invention, the monitoring probe is set to work at the same time as the device to be tested. The monitoring probe will monitor the change of the bulb intensity over time in real time and use it to correct the reading of the device to be tested, which will improve the accuracy of the measurement. The correction steps are as follows:

[0068] In a completely dark environment, record the background readings of the device to be inspected and the monitoring probe, which are recorded as RAWd and Rd respectively.

[0069] Turn on the light bulb, adjust the intensity filter, preheat for 15 minutes, and record the monitoring probe reading (recorded as R0).

[0070] Start the test and record the readings of the probe to be tested and the monitoring probe, which are recorded as RAW1 and R1 respectively;

[0071] Correct the RAW1 reading of the probe to be inspected according to the following formula, and record the corrected reading as S1.

[0072] In addition, the operation is easier: mainly reflected in two points:

[0073] 1. In the prior art, the energy distribution of the light beam directed to the water tank is uneven, with strong energy in the center area and weak energy in the edge area. This results in the need to carefully adjust the device to be tested each time a measurement is made to ensure that the central axis of the photosensitive surface of the device to be tested is aligned with the same position of the light beam. In the present invention, since the light homogenizer can homogenize the intensity of the multi-wavelength light source, the light energy of the light beam directed to the water tank is evenly distributed after collimation, and the energy at each point on the cross section of the light beam is the same, the readings of the device to be tested at different lateral distances in the light beam are the same, so the device to be tested only needs to be within the range of the light beam, which greatly improves the simplicity of installation and adjustment, especially in the case of batch testing or repetitive testing.

[0074] 2. In the prior art, the distance data between the equipment to be inspected and the water surface is manually read by a ruler, which is inconvenient to operate and has large errors. In the present invention, the distance information is measured and recorded by a stepper motor and directly output to the control terminal 16, which improves convenience and measurement accuracy.

Claims

1. An immersion factor measuring device for underwater photosynthetically active radiation sensor equipment, characterized in that: include: A point light source (1), an aperture (2), a collimating lens (3), a wavelength filter wheel (4), an intensity filter wheel (5), a focusing lens (6), a light homogenizing rod (7), and a beam expanding collimating lens (8) are sequentially arranged along the optical path; Monitoring probe (10) and control terminal (16); A water tank (11), a probe to be tested (15) and an electrically controlled lifting platform, wherein the electrically controlled lifting platform is placed in the water tank (11) and drives the probe to be tested (15) to rise and fall in the water tank (11), and the probe to be tested (15) and the electrically controlled lifting platform are both connected to the control terminal (16); A beam splitter (9) is arranged behind the beam expanding collimator (8) and splits the incident light beam into a first light beam and a second light beam, which are respectively irradiated to the monitoring probe (10) and the probe to be tested (15); The control terminal (16) is configured to perform the following steps: In a completely dark environment, record the background reading Rd of the monitoring probe (10) and the background reading RAWd of the probe to be tested (15); When the point light source (1) is lit and remains lit for a set period of time, a basic reading R0 of the monitoring probe (10) is recorded; Controlling the electrically controlled lifting platform to drive the probe to be tested (15) to move up and down below the liquid level in the water tank (11), and collecting the experimental reading R1 of the monitoring probe (10) and the experimental reading RAW1 of the probe to be tested (15) at each height; Convert the experimental reading RAW1 of the probe (15) to be tested corresponding to each height into a corrected reading; The immersion factor is calculated based on the corrected readings of the probe to be tested (15) corresponding to each height and the optical path distance between the probe to be tested (15) and the point light source (1); The corrected reading of the probe (15) to be tested is: , Where: S1 is the corrected reading of the probe (15) to be tested; The calculation process of the immersion factor is as follows: the probe to be tested (15) faces the uniform parallel light emitted by the light source. Under water-free conditions, the corrected readings of the probe to be tested (15) at different distances from the light source remain unchanged, and the signal at this time is recorded as J0. After the water tank (11) is filled with water, the distance between the probe to be tested (15) and the light source is changed, and the measurement signal changes with the distance; the measurement signals at different water depths are recorded, and the relationship between the two is established by the least squares fitting method, and then the signal value when the water depth is 0 is calculated, which is recorded as J1, and the immersion factor = J0 / J1.

2. The immersion factor measuring device of an underwater photosynthetically active radiation sensor device according to claim 1, characterized in that: The electric-controlled lifting platform comprises a mounting frame (12), a support rod (13) and a stepping motor (14); the support rod (13) is arranged on the mounting frame (12) and moves up and down along the mounting frame (12); the output end of the stepping motor (14) is connected to the support rod (13) and drives the support rod to move; the probe (15) to be tested is installed on the support rod (13); and the stepping motor (14) is connected to the control terminal (16).

3. The immersion factor measuring device of an underwater photosynthetically active radiation sensor device according to claim 1, characterized in that: The beam splitter (9) is a semi-transparent and semi-reflective mirror.

4. The immersion factor measuring device of an underwater photosynthetically active radiation sensor device according to claim 1 or 3, characterized in that: The angle between the beam splitter (9) and the horizontal plane is 45 degrees.

5. The immersion factor measuring device of an underwater photosynthetically active radiation sensor device according to claim 2, characterized in that: The top of the mounting frame (12) is located near the liquid surface.

6. The immersion factor measuring device of an underwater photosynthetically active radiation sensor device according to claim 2, characterized in that: The top of the mounting frame (12) is located above the liquid surface.

7. The immersion factor measuring device of an underwater photosynthetically active radiation sensor device according to claim 2, characterized in that: The mounting frame (12) is located on a side wall inside the water tank (11).

8. The device for measuring the immersion factor of an underwater photosynthetically active radiation sensor device according to claim 1, characterized in that: The point light source (1) is a light bulb.

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