Ultraviolet imaging method based on digital micromirror device and application

Abstract

The invention discloses an ultraviolet imaging method based on a digital micromirror device. The method specifically comprises the following steps: step 1, constructing an optical system and a signal processing system; 2, adjusting the positions of the lens, the spectroscope and the DMD; 3, the ZYNQ microprocessor sends addressing information to the DMD controller, so that the n * n micro-mirror surfaces corresponding to one pixel point deflect by + 12 degrees at the same time, and the photomultiplier is arranged on a reflection light path where the micro-mirror surfaces are located after the micro-mirror surfaces deflect by + 12 degrees; step 4, completing data acquisition of one pixel point; step 5, judging whether the acquisition of the data of the pixel points of one image is completed, and if not, repeating the steps 3-5 until the acquisition of the data of all the pixel points of the same image is completed; 6, the ZYNQ processor obtains visible light camera data, and the visible light image and the ultraviolet light image at the same moment are fused and superposed; and step 7, realizing video continuous output of the ultraviolet light and visible light fusion image. The cost of the ultraviolet imaging system is reduced, the imaging speed is high, and the precision is high.

Description

Technical Field

[0001] The invention belongs to the technical field of photoelectric detection methods, and in particular relates to an ultraviolet imaging method based on a digital micromirror device, and also relates to the application of the ultraviolet imaging method based on a digital micromirror device. Background Art

[0002] When the voltage value of high-voltage equipment and high-voltage lines rises to a certain level, the air on the surface of the wire is in a highly free state, destroying its good insulation performance and turning it into a conductor. At this time, corona discharge will occur, increasing the safety risks of power transmission. Traditional detection technology has the disadvantages of being easily affected by external interference, difficult to locate the discharge position, and delayed fault warning. Imported ultraviolet imaging equipment is expensive.

[0003] A digital micromirror device (DMD) is an array of multiple high-speed digital optical reflective switches. It is composed of many small aluminum reflective mirrors. The number of mirrors is determined by the display resolution, and one micromirror corresponds to one pixel. DMD has the characteristics of high reflectivity and high contrast. By imaging the object on the DMD device, through the pixel-level controllable characteristics of the DMD device and its high-speed flip frequency, each image point is scanned onto the detector in turn, and high-speed passive point scanning imaging can be achieved. Active scanning imaging can also be achieved by adding an appropriate light source. Summary of the invention

[0004] The purpose of the present invention is to propose an ultraviolet imaging method based on a digital micromirror device to solve the problem of delayed early warning of fault points of high-voltage electrical equipment.

[0005] The technical solution adopted by the present invention is an ultraviolet imaging method based on a digital micromirror device, which is specifically implemented according to the following steps:

[0006] Step 1: Build the optical system and signal processing system.

[0007] Step 2: Adjust the position of the lens, beam splitter and DMD.

[0008] Step 3, the ZYNQ microprocessor sends addressing information to the DMD controller, so that the n×n micromirrors corresponding to one pixel are deflected by +12° at the same time, and the photomultiplier tube is placed on the reflected light path after the micromirror is deflected by +12°;

[0009] Step 4: Complete the data collection of one pixel point;

[0010] Step 5: determine whether the data collection of the pixel points of an image is completed. If not, repeat steps 3-5 until the data collection of all the pixel points of the same image is completed.

[0011] Step 6: The ZYNQ processor obtains the visible light camera data, merges and superimposes the visible light image and the ultraviolet light image at the same time, and outputs them to the HDMI screen;

[0012] Step 7: Repeat steps 1 to 6 to achieve continuous video output of the ultraviolet light and visible light fusion image.

[0013] The present invention is also characterized in that:

[0014] In step 1, the optical system consists of an ultraviolet light collecting lens, an ultraviolet light spectroscope, a DMD, a filter, and a photomultiplier tube. The signal processing system consists of an I / V processing circuit, a high-speed AD, and a ZYNQ microprocessor. The ultraviolet light imaging lens can transmit ultraviolet light with a wavelength of 250nm to 450nm.

[0015] In step 2, the positions of the lens, the beam splitter and the DMD are adjusted so that the DMD reflective surface is located at the focus of the lens, and the ultraviolet light can be clearly imaged on the DMD reflective surface after passing through the lens and the beam splitter. The reflection wavelength coverage range of the digital micromirror device is 355 to 420 nm, the wavelength range of the photomultiplier tube is 185 nm to 650 nm in the day-blind band, and the image output by the ZYNQ microprocessor is a fusion image of ultraviolet light and visible light in the day-blind band of 355 nm to 420 nm. The photomultiplier tube is used to convert the ultraviolet light signal in the day-blind band of 185 nm to 650 nm into an electrical signal, and the output voltage of the photomultiplier tube is limited to 0 V to 5 V.

[0016] The specific process of setting parameters of the ZYNQ microprocessor in step 1 is: setting the bit width of high-speed ADC sampling to 16 bits and the single sampling length to L in the ZYNQ microprocessor, starting the sampling of the high-speed ADC when the photomultiplier tube receives each ultraviolet signal and outputs analog data, obtaining ultraviolet image data, and adjusting the resolution parameters of the ultraviolet image according to actual conditions.

[0017] In step 3, according to the imaging resolution, n×n micromirrors are set as the reflection surface of a pixel point, and the ZYNQ microprocessor sends addressing information to the DMD controller, so that the n×n micromirrors corresponding to a pixel point are deflected by +12° at the same time, and the photomultiplier tube is placed on the reflection light path after the micromirror is deflected by +12°. The reflected ultraviolet light can be irradiated vertically to the photosensitive surface of the photomultiplier tube, and the photomultiplier tube will measure the light intensity of a pixel point of the ultraviolet light image imaged on the DMD reflection surface.

[0018] The specific process of step 3 is: when the DMD is working, when an ultraviolet light signal is detected on a certain micromirror surface through addressing, V+ is added to one of the addressing electrodes and the other addressing electrode is grounded, so that an electrostatic field is formed between the addressing electrodes of the micromirrors and the addressing electrodes of the torsion arm beam and the torsion arm beam, thereby generating an electrostatic torque, causing the micromirror unit to rotate +12° around the torsion arm beam. Under the action of the torque, the micromirror unit remains at this position for time t until the reset signal appears.

[0019] In step 4, the signal output by the photomultiplier tube is sequentially subjected to I / V conversion, filtering processing, and high-speed A / D conversion to obtain a digital signal, which is stored in the DDR3 of the ZYNQ microprocessor to complete the data acquisition of one pixel.

[0020] In step 5, all the micromirrors are flipped in turn through steps 3 and 4, and the photomultiplier tubes output the digital value of each pixel in turn to determine whether the data collection of the pixel points of an image is completed. If not, repeat steps 3 to 5 to continue collecting the data of the next pixel point of the same image until the data collection of all the pixel points of the same image is completed.

[0021] In step 6, the visible light reaches the visible light camera through the light collecting lens and the ultraviolet light spectroscope. The ZYNQ processor obtains the visible light camera data, fuses and superimposes the visible light image and the ultraviolet light image at the same time, and outputs it to the HDMI screen. At the same time, the remote transmission of a fused image is realized through the 4G module.

[0022] Another technical solution adopted by the present invention is characterized by the application of ultraviolet imaging method based on digital micromirror device in live detection of insulation faults in power systems.

[0023] The beneficial effects of the present invention are:

[0024] The present invention realizes ultraviolet imaging based on a digital micromirror device, and the scanning time and scanning accuracy of the image are adjustable, which enriches the detection means of insulation faults of high-voltage electrical facilities, reduces the purchase cost of the ultraviolet imaging system, and has fast imaging speed and high accuracy. The present invention solves the problems that infrared imaging in the existing insulation fault detection technology of the power system is greatly interfered by the external environment, weak discharges cannot be detected, and ultraviolet imaging equipment is expensive. When an insulation fault occurs in the high-voltage equipment, the system will detect the ultraviolet light signal and display the corresponding spot area according to the strength of the signal. The larger the spot area, the stronger the discharge and the more serious the insulation fault here. The insulation discharge part can be discovered in time in the early stage of the fault and the discharge strength can be intuitively displayed, which provides a new means for maintaining the safe operation of the power grid. The system can realize all-weather detection and long-distance image acquisition and transmission, saving manpower, material resources and financial resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is the overall block diagram of the ultraviolet imaging optical system model of the present invention;

[0026] Figure 2 It is a schematic diagram of adjusting the ultraviolet image resolution by setting the number of micro-mirrors for single deflection in the present invention;

[0027] Figure 3 It is a flow chart of the algorithm for controlling the digital micromirror device to scan an image in the present invention;

[0028] Figure 4 It is a main program flow chart of the ultraviolet light scanning imaging method based on photomultiplier tube of the present invention. DETAILED DESCRIPTION

[0029] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] Example 1

[0031] Taking into account that when high-voltage electrical facilities have local discharges, corona discharge, flashover or arc phenomena will occur depending on the electric field strength. Even if the discharge is very weak, detectable ultraviolet photons will still be generated. The ultraviolet imaging system images the detected ultraviolet photons, and the fault condition of the high-voltage electrical facilities is evaluated by the detected ultraviolet photon intensity and imaging shape. If it is fused with visible light imaging, the location of the fault point can be further determined.

[0032] The ultraviolet imaging method based on a digital micromirror device of the present invention is specifically implemented according to the following steps:

[0033] Step 1: Build an optical system consisting of an ultraviolet light collection lens, an ultraviolet light spectroscope, a DMD, a filter, a photomultiplier tube, etc.; build a signal processing system consisting of an I / V processing circuit, a high-speed AD, a ZYNQ microprocessor, etc.;

[0034] Step 2: By adjusting the positions of the lens, the beam splitter and the DMD, the DMD reflection surface is located at the focus of the lens, and the ultraviolet light can be clearly imaged on the DMD reflection surface through the lens and the beam splitter;

[0035] Step 3: According to the imaging resolution, n×n micromirrors are set as the reflection surface of a pixel. The larger the n, the lower the resolution and the faster the imaging speed. The ZYNQ microprocessor sends addressing information to the DMD controller, so that the n×n micromirrors corresponding to a pixel are deflected by +12° at the same time. The photomultiplier tube is placed on the reflection light path after the micromirror is deflected by +12°. The reflected ultraviolet light can be vertically irradiated to the photosensitive surface of the photomultiplier tube. At this time, the photomultiplier tube will measure the light intensity of a pixel of the ultraviolet light image imaged on the DMD reflection surface.

[0036] The specific process of step 3 is: when the DMD is working, V+ is added to one addressing electrode through addressing, and the other addressing electrode is grounded, so that an electrostatic field is formed between the addressing electrodes of the micromirrors and the addressing electrodes of the torsion beams, thereby generating an electrostatic torque, so that the micromirror unit rotates +12° around the torsion beam. Under the action of the torque, the micromirror unit remains at this position for t time until the reset signal appears. Within t time, the ADC sampling of ZYNQ is started to capture the ultraviolet image data;

[0037] Step 4: Perform I / V conversion, filtering, and high-speed A / D conversion on the signal output by the photomultiplier tube in sequence to obtain a digital signal, which is stored in the DDR3 of the ZYNQ microprocessor to complete the data acquisition of one pixel point;

[0038] Step 5: All micromirrors are flipped in sequence through step 3 and step 4, and the photomultiplier tube outputs the digital value of each pixel in sequence to determine whether the data collection of the pixel points of an image is completed. If not, repeat step 3 to step 5 to continue collecting the data of the next pixel point of the same image until the data collection of all the pixel points of the same image is completed;

[0039] Step 6: Visible light reaches the visible light camera through the light collecting lens and the ultraviolet light spectroscope. The ZYNQ processor obtains the visible light camera data, fuses and superimposes the visible light image and the ultraviolet light image at the same time, and outputs them to the HDMI screen. At the same time, the remote transmission of a fused image is realized through the 4G module.

[0040] The specific process of step 6 is: the ZYNQ microprocessor is connected to the HDMI display and the 4G module, and the image stream data is converted into bit data through the customized IP core and then output to the display for display after serial-to-parallel conversion. At the same time, the image data is connected to the network through the 4G module to transmit the image data to the remote PC through the network, thus realizing the remote acquisition and transmission of image data;

[0041] Step 7: Repeat steps 1 to 6 to achieve continuous video output of the ultraviolet light and visible light fusion image.

[0042] Example 2

[0043] like Figure 1 As shown, an optical system consisting of an ultraviolet light collecting lens, an ultraviolet light spectroscope, a DMD, a filter, a photomultiplier tube, etc. is built in sequence; a signal processing system consisting of an I / V processing circuit, a high-speed AD, a ZYNQ microprocessor, etc. is built; the pulse parameters of the digital micromirror device controller are set to flip the micromirror surface and reflect the ultraviolet photons into the photomultiplier tube, and the parameters of the ZYNQ microprocessor are set to process the ultraviolet light signal, thereby establishing a model of an ultraviolet optical imaging system.

[0044] The ultraviolet imaging lens can transmit ultraviolet light with a wavelength of 250nm to 450nm, and the reflectivity of the beam splitter at 245nm to 500nm is 70%.

[0045] The reflection wavelength range of the digital micromirror device is 355nm~420nm, the wavelength range of the photomultiplier tube is 185nm~650nm solar-blind band, the filter wavelength range is: 240nm~420nm, and the image output by the ZYNQ microprocessor is a fusion image of ultraviolet light imaging in the solar-blind band of 355nm~420nm and visible light.

[0046] After receiving the ultraviolet light signal, the photomultiplier tube outputs a negative voltage signal, and the amplitude changes with the change of the irradiation light intensity. The pulse signal output by the photomultiplier tube is tested for spectrum, and the negative voltage signal is reversed through the IV conversion circuit. A low-pass filter circuit is designed to filter out the high-frequency components in the signal. According to the measured pulse width and pulse interval of the photomultiplier tube output signal, the single ADC sampling time and the number of sampling times for taking the ADC average value of a pixel are set, and the maximum value of all sampling values ​​within the sampling time of a pixel is stored in the ZYNQ microprocessor.

[0047] The specific process of setting the parameters of the ZYNQ microprocessor is: in the ZYNQ microprocessor, the bit width of the high-speed ADC sampling is set to 16 bits, and the single sampling length is L, which is generally set to 5-10. The longer the sampling length, the more accurate the result. When the photomultiplier tube receives each ultraviolet signal and outputs analog data, the high-speed ADC sampling is started to obtain ultraviolet image data. At the same time, the resolution parameters of the ultraviolet image can be adjusted according to actual conditions.

[0048] Example 3

[0049] The present invention is based on the ultraviolet light scanning imaging method of the digital micromirror device, wherein in step 3, n×n micromirrors are set as the reflection surface of a pixel point, and the larger n is, the lower the resolution is, and the faster the imaging speed is. Figure 2 As shown in the figure, the resolution of the ultraviolet image is controlled by setting 4 micromirrors in a 2x2 area to represent a pixel. The ZYNQ microprocessor sends addressing information to the DMD controller, so that the n×n micromirrors corresponding to a pixel are deflected by +12° at the same time. The photomultiplier tube is placed on the reflection light path after the micromirror is deflected by +12°, and the reflected ultraviolet light can be vertically irradiated onto the photosensitive surface of the photomultiplier tube. At this time, the photomultiplier tube will measure the light intensity of a pixel of the ultraviolet image imaged on the DMD reflection surface. The control process of the micromirror is as follows: Figure 3 shown.

[0050] Step 4: Main control process Figure 4As shown, when the micromirror is deflected and transmits the ultraviolet light signal to the next-level photomultiplier tube; when the photomultiplier tube receives each ultraviolet signal and outputs analog data, the signal output by the photomultiplier tube is sequentially subjected to I / V conversion and filtering, and the high-speed ADC sampling is started. The light signal that is reflected by the micromirror of the digital micromirror device and irradiates the photomultiplier tube is the light data of a pixel point collected.

[0051] The application of ultraviolet light scanning imaging method based on photomultiplier tube in live detection of insulation fault in power system. When the power system fails, ultraviolet light signal will be detected, and the corresponding spot area will be displayed according to the strength of the signal; the larger the spot area, the stronger the discharge, and the more serious the insulation fault here.

[0052] The invention is based on the ultraviolet light scanning imaging method of digital micromirror devices, and realizes two-dimensional row and column scanning imaging by using photomultiplier tubes as ultraviolet detection devices, thereby reducing the cost of ultraviolet light imaging systems and solving the problems of the inability to detect insulation faults in the existing power system in an early stage, the inability to locate discharge points, and the high price of imported ultraviolet light imaging equipment. The present invention realizes ultraviolet two-dimensional scanning imaging through an ultraviolet optical system and a signal processing system. The scanning time and scanning accuracy of an image are adjustable, which enriches the detection means of insulation faults of high-voltage electrical facilities, reduces the purchase cost of the ultraviolet imaging system, and solves the problems of infrared imaging being greatly interfered by the external environment, being unable to detect weak discharges, and the high price of ultraviolet imaging equipment in the existing insulation fault detection technology of the power system. When an insulation fault occurs in the high-voltage equipment, the system will detect the ultraviolet light signal and display the corresponding spot area according to the strength of the signal. The larger the spot area, the stronger the discharge and the more serious the insulation fault here. The insulation discharge part can be discovered in time in the early stage of the fault and the discharge strength can be intuitively displayed, which provides a new means for maintaining the safe operation of the power grid. The system can realize all-weather detection and long-distance image acquisition and transmission, saving manpower, material resources and financial resources.

Claims

1. A UV imaging method based on a digital micromirror device, characterized in that: Follow the steps below to implement it: Step 1: Build the optical system and signal processing system; Step 2: Adjust the position of the lens, beam splitter and DMD; Step 3, the ZYNQ microprocessor sends addressing information to the DMD controller, so that the n×n micromirrors corresponding to one pixel are deflected by +12° at the same time, and the photomultiplier tube is placed on the reflected light path after the micromirror is deflected by +12°; Step 4: Complete the data collection of one pixel point; Step 5: determine whether the data collection of the pixel points of an image is completed. If not, repeat steps 3-5 until the data collection of all the pixel points of the same image is completed. Step 6: The ZYNQ processor obtains the visible light camera data, merges and superimposes the visible light image and the ultraviolet light image at the same time, and outputs them to the HDMI screen; Step 7: Repeat steps 1 to 6 to achieve continuous video output of the ultraviolet light and visible light fusion image.

2. The ultraviolet imaging method based on a digital micromirror device according to claim 1, characterized in that: The optical system in step 1 is composed of an ultraviolet light collecting lens, an ultraviolet light spectroscope, a DMD, a filter, and a photomultiplier tube. The signal processing system is composed of an I / V processing circuit, a high-speed AD, and a ZYNQ microprocessor. The ultraviolet light imaging lens can transmit ultraviolet light with a wavelength of 250nm to 450nm.

3. The ultraviolet imaging method based on a digital micromirror device according to claim 1, characterized in that: In step 2, the positions of the lens, the beam splitter and the DMD are adjusted so that the DMD reflection surface is located at the focus of the lens, and the ultraviolet light can be clearly imaged on the DMD reflection surface after passing through the lens and the beam splitter. The reflection wavelength coverage range of the digital micromirror device is 355 to 420 nm, the wavelength range of the photomultiplier tube is 185 nm to 650 nm in the day-blind band, and the image output by the ZYNQ microprocessor is a fusion image of ultraviolet light and visible light in the day-blind band of 355 nm to 420 nm. The photomultiplier tube is used to convert the ultraviolet light signal in the day-blind band of 185 nm to 650 nm into an electrical signal, and the output voltage of the photomultiplier tube is limited to 0 V to 5 V.

4. The ultraviolet imaging method based on a digital micromirror device according to claim 1, characterized in that: The specific process of setting the parameters of the ZYNQ microprocessor in step 1 is: setting the bit width of the high-speed ADC sampling to 16 bits and the single sampling length to L in the ZYNQ microprocessor, starting the high-speed ADC sampling when the photomultiplier tube receives each ultraviolet signal and outputs analog data, obtaining ultraviolet image data, and adjusting the resolution parameters of the ultraviolet image according to actual conditions.

5. The ultraviolet imaging method based on a digital micromirror device according to claim 1, characterized in that: In step 3, according to the imaging resolution, n×n micromirrors are set as the reflection surface of one pixel, and the ZYNQ microprocessor sends addressing information to the DMD controller, so that the n×n micromirrors corresponding to one pixel are deflected by +12° at the same time, and the photomultiplier tube is placed on the reflection light path after the micromirror is deflected by +12°. The reflected ultraviolet light can be irradiated vertically to the photosensitive surface of the photomultiplier tube, and the photomultiplier tube will measure the light intensity of one pixel of the ultraviolet light image imaged on the DMD reflection surface.

6. The ultraviolet imaging method based on a digital micromirror device according to claim 5, characterized in that: The specific process of step 3 is: when the DMD is working, when an ultraviolet light signal is detected on a certain micromirror surface through addressing, V+ is added to one of the addressing electrodes, and the other addressing electrode is grounded, so that an electrostatic field is formed between the addressing electrodes of the micromirrors and the addressing electrodes of the torsion arm beam and the torsion arm beam, thereby generating an electrostatic torque, so that the micromirror unit rotates +12° around the torsion arm beam. Under the action of the torque, the micromirror unit remains at the position at time t until the reset signal appears.

7. The ultraviolet imaging method based on a digital micromirror device according to claim 1, characterized in that: In step 4, the signal output by the photomultiplier tube is sequentially subjected to I / V conversion, filtering processing, and high-speed A / D conversion to obtain a digital signal, which is stored in the DDR3 of the ZYNQ microprocessor to complete the data collection of one pixel.

8. The ultraviolet imaging method based on a digital micromirror device according to claim 1, characterized in that: In step 5, all the micromirrors are flipped in sequence through steps 3 and 4, and the photomultiplier tubes output the digital value of each pixel in sequence to determine whether the data collection of the pixel points of an image is completed. If not, steps 3 to 5 are repeated to continue collecting the data of the next pixel point of the same image until the data collection of all the pixel points of the same image is completed.

9. The ultraviolet imaging method based on a digital micromirror device according to claim 1, characterized in that: In step 6, the visible light reaches the visible light camera through the light collecting lens and the ultraviolet light spectroscope, and the ZYNQ processor obtains the visible light camera data, fuses and superimposes the visible light image and the ultraviolet light image at the same time, and outputs it to the HDMI screen. At the same time, the remote transmission of a fused image is realized through the 4G module.

10. Application of the ultraviolet imaging method based on a digital micromirror device according to any one of claims 1 to 9 in live detection of insulation faults in power systems.

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