A single point detector imaging performance characterization system

Abstract

The application relates to the technical field of optical application, in particular to a single-point detector imaging performance characterization system; the characterization system comprises a data acquisition platform, a laser, an objective lens, a bright-field imaging image sensor, a single-point detector, a source table and an optical path assembly; the data acquisition platform is connected with the laser to receive an electric signal after photoelectric conversion of the single-point detector; the source table is further connected with a current amplifier and an oscilloscope; and the optical path assembly guides a light path; on the basis of the prior art, the structure of the characterization system is improved, the simulation physical imaging mode is adopted, the device is simplified, the position of the single-point detector in the optical path is easy to determine, the photosensitive surface size of the detector can be as small as microns, the characterization system is especially suitable for scientific research, the imaging characterization of the full-waveband single-point detector can be realized by replacing the laser, the optical path stability can be maintained, and rich information amount such as current size, responsivity and response speed can be contained in single characterization.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical application, and particularly relates to a single-point detector imaging performance characterization system. BACKGROUND

[0002] In recent years, single-pixel imaging technology has developed rapidly due to its high detection sensitivity, wide wavelength coverage, and low-cost access to special band images. The cornerstone of this imaging technology, the single-point detector, has attracted widespread attention and research due to its lower manufacturing cost and wider detection wavelength range than the surface array detector.

[0003] The commonly used method in the prior art is to use a scanning galvanometer, an objective lens, a pinhole diaphragm, a single-point detector, and a signal acquisition card or a lock-in amplifier to compose a scanning imaging system. The scanning galvanometer is used to change the angle of the incident light, the pinhole diaphragm is used to detect only the light passing through the optical axis of the system to achieve optical filtering, the light passing through the optical axis of the system is used to irradiate the photosensitive surface of the single-point detector to achieve photoelectric conversion, and the signal acquisition card or the lock-in amplifier is used to collect photoelectric signals at different galvanometer angles, so as to realize the collection of two-dimensional optical images.

[0004] However, the existing device involves a scanning galvanometer, which has a relatively high cost. In addition, due to the limitation of the wavelength used by the mirror coating material of the scanning galvanometer, it is only suitable for use in a certain waveband, and cannot realize imaging characterization of a full-waveband single-point detector by using a group of galvanometers. The replacement of the galvanometer will change the optical path of the system, greatly increasing the difficulty of use. In addition, the working mode is single, the collected data is only the photocurrent value, the amount of information contained is single, and the required response and speed of the single-point detector for imaging cannot be analyzed. SUMMARY

[0005] The present application aims to provide a single-point detector imaging performance characterization system to solve the problems of single working mode, insufficient information in single characterization, and high difficulty of use in the prior art.

[0006] To achieve the above-mentioned purpose, the present application provides a single-point detector imaging performance characterization system, which comprises a data acquisition platform, a laser, an objective lens, a bright-field imaging image sensor, a single-point detector, a source table, and an optical path assembly. The data acquisition platform is connected to the laser to compile different voltage values and output them to the laser. The laser is a modulatable light source, and the wavelength is selected according to the response range of the single-point detector to be detected. The objective lens cooperates with the single-point detector to focus the laser on the photosensitive surface of the single-point detector. The source table is electrically connected to the single-point detector to receive the electrical signal after photoelectric conversion of the single-point detector. The source table is also connected in series with a current amplifier and an oscilloscope. The optical path assembly guides the light path.

[0007] The data acquisition platform is used to compile different voltage values and output to the laser, the laser as a characterization light source, is a modulatable light source, the wavelength can be selected according to the response range of the single-point detector to be detected, and the device can be compatible with the use of full-waveband lasers, and the objective lens is used to focus the laser on the photosensitive surface of the single-point detector.

[0008] The working principle of the device is as follows:

[0009] First, an arbitrary reference picture is selected and imported into the data acquisition platform, the R, G and B values of each pixel point of the reference picture are read and converted into gray values, the gray values are calculated according to the formula Gray = 0.299 * R + 0.587 * G + 0.114 * B, the maximum value of the gray value of the reference picture is Gmax, and the minimum value is Gmin, different gray values are correspondingly compiled into different voltage values Vout = (Vmax / Gmax) * Gray + Vth, wherein Vmax is the maximum voltage of the laser used, Vth is the threshold voltage of the laser used, the voltage output by the data acquisition platform is output to the laser, different voltage values correspond to different light intensity values I of the laser, generally for semiconductor lasers, the voltage value and the light intensity value are linearly related (I = (Imax / (Vmax-Vth)*(Vout-Vth), wherein Imax is the maximum light intensity of the laser used), the specific corresponding relationship is related to the laser used, the photosensitive surface of the single-point detector is observed in the bright field imaging image sensor, and the laser is focused on the photosensitive surface of the single-point detector through the objective lens, the single-point detector receives the optical signal and converts the optical signal into an electrical signal, the reference picture is scanned pixel by pixel through the data acquisition platform, the source table synchronously displays the current value of the single-point detector and forms a pixel-current two-dimensional image with the same pixel information as the reference picture, and the imaging performance of the single-point detector can be analyzed by analyzing the difference between the two-dimensional image obtained by scanning and the reference image.

[0010] The light path assembly includes a mirror, an off-axis parabolic mirror, a first beam splitter, a second beam splitter and a bright field illumination light source, the off-axis parabolic mirror is used to collimate the laser and send the laser to the mirror, the bright field illumination light source emits a light beam, which is irradiated to the second beam splitter after passing through the first beam splitter, and the second beam splitter is used to reflect the bright field illumination light source and then irradiate it to the single-point detector through the objective lens.

[0011] The electrical signal is directly read out through the source table or read out through the source table + current amplifier + oscilloscope, which is used to receive the electrical signal after the photoelectric conversion of the single-point detector.

[0012] The control output mode of the data acquisition platform comprises digital output, analog output and analog modulation output.

[0013] The digital output is a reference picture gray threshold value, and the data acquisition platform control output voltage is 0 when the threshold value is lower than the threshold value, the laser does not emit light, and the single-point detector output is a dark current value; the data acquisition platform control output voltage is a constant value when the threshold value is greater than or equal to the threshold value, the laser outputs the same light intensity, and the single-point detector outputs a photocurrent value.

[0014] The analog output is that the data acquisition platform compiles corresponding voltage values according to the gray value of each pixel of the reference picture and outputs the voltage values to the laser, so as to control the laser to output corresponding light intensity at different gray value pixel points, and the single-point detector outputs corresponding photocurrent at different gray value pixel points.

[0015] The analog modulation output compiles corresponding voltage values according to the gray value of each pixel of the reference picture and is switch modulated at a certain set frequency, finally uses the combination of the source table, the current amplifier and the oscilloscope to read the waveform at each test pixel point of the reference picture, records the current value in the laser switch state, and obtains the photocurrent by difference.

[0016] In the present application, the control output mode of the data acquisition platform has three modes: digital output, analog output and analog modulation output. The digital output is a reference picture gray threshold value, and the data acquisition platform control output voltage is 0 when the threshold value is lower than the threshold value, the laser does not emit light, and the single-point detector output is a dark current value; the data acquisition platform control output voltage is a constant value when the threshold value is greater than or equal to the threshold value, the laser outputs the same light intensity, and the single-point detector outputs a photocurrent value, the analog output is that the data acquisition platform compiles corresponding voltage values according to the gray value of each pixel of the reference picture and outputs the voltage values to the laser, so as to control the laser to output corresponding light intensity at different gray value pixel points, and the single-point detector outputs corresponding photocurrent at different gray value pixel points, the current receiving device in the digital output and analog output modes is the source table, and the difference between the analog modulation output and the analog output is that the analog modulation output not only compiles corresponding voltage values according to the gray value of each pixel of the reference picture and is switch modulated at a certain set frequency, finally uses the combination of the source table, the current amplifier and the oscilloscope to read the waveform at each test pixel point of the reference picture, records the current value in the laser switch state, and obtains the photocurrent by difference. This mode is suitable for single-point detectors with large or unstable dark current.

[0017] The single-point detector imaging performance characterization system provided by the application improves the structure of the characterization system on the basis of the prior art, adopts a simulation physical imaging mode, can achieve the purpose of characterizing the imaging performance of the single-point detector, simplifies the device, makes the position of the single-point detector in the optical path easy to determine, and makes the size of the photosensitive surface of the detector as small as microns, is especially suitable for scientific research, can realize imaging characterization of full-waveband single-point detectors by replacing the laser, can maintain the stability of the optical path, and can contain rich information such as current size, responsivity, and response speed in single characterization. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0019] Figure 1 Fig. 1 is a structural schematic diagram of a single-point detector imaging performance characterization system provided by the application.

[0020] Figure 2 Fig. 2 is an imaging performance characterization result schematic diagram and a two-point corresponding output waveform diagram of the single-point detector imaging performance characterization system provided by the application. DETAILED DESCRIPTION

[0021] Please refer to Figure 1 and Figure 2 The application provides a single-point detector imaging performance characterization system, which comprises a data acquisition platform, a laser, an objective lens, a bright-field imaging image sensor, a single-point detector, a source table, and an optical path assembly. The data acquisition platform is connected with the laser, is used to compile different voltage values and output to the laser, the laser is a modulatable light source, wavelength selection is performed according to the response range of the single-point detector to be detected, the objective lens is matched with the single-point detector, so as to focus the laser on the photosensitive surface of the single-point detector, the source table is electrically connected with the single-point detector, so as to receive the electrical signal after photoelectric conversion of the single-point detector, the source table is also connected in series with a current amplifier and an oscilloscope, and the optical path assembly guides the light path.

[0022] The data acquisition platform is used to compile different voltage values and output to the laser, the laser is used as a characterization light source, is a modulatable light source, wavelength selection is performed according to the response range of the single-point detector to be detected, the objective lens is used to focus the laser on the photosensitive surface of the single-point detector;

[0023] The working principle of the device of the present application is as follows:

[0024] Referring to Figure 1 , an arbitrary reference image is first selected and imported into the data acquisition platform. In the drawing, the R, G, and B values of each pixel point of the reference image are read by (cDAQ) and converted into a gray value. The gray value is calculated according to the formula Gray = 0.299 * R + 0.587 * G + 0.114 * B. The maximum value of the gray value of the reference image is Gmax, and the minimum value is Gmin. Different gray values are correspondingly compiled into different voltage values Vout = (Vmax / Gmax) * Gray + Vth, wherein Vmax is the maximum voltage of the laser used, and Vth is the threshold voltage of the laser used. The voltage output by the data acquisition platform is output to the laser. Different voltage values correspond to different laser light intensity values I. Generally, for a semiconductor laser, the voltage value and the light intensity value are linearly related (I = (Imax / (Vmax - Vth) * (Vout - Vth), wherein Imax is the maximum light intensity of the laser used). The specific correspondence is related to the laser used. The photosensitive surface of the single-point detector is observed in the bright-field imaging image sensor, and the laser is focused on the photosensitive surface of the single-point detector through the objective lens. The single-point detector receives the optical signal and converts it into an electrical signal. The reference image is scanned pixel by pixel through the data acquisition platform. The source table synchronously displays the current value of the single-point detector and forms a pixel-current two-dimensional image with the same pixel information as the reference image. The imaging performance of the single-point detector can be analyzed by analyzing the difference between the two-dimensional image obtained by scanning and the reference image.

[0025] Further, the optical path assembly includes a mirror, an off-axis parabolic mirror, a first beam splitter, a second beam splitter, and a bright-field illumination light source. The off-axis parabolic mirror is used to collimate the laser and send the laser to the mirror. After being irradiated to the rear end of the objective lens through the mirror, the bright-field illumination light source emits a light beam, which is irradiated to the second beam splitter after passing through the first beam splitter. The second beam splitter is used to reflect the bright-field illumination light source and then irradiate it to the single-point detector through the objective lens.

[0026] The electrical signal is directly read out by the source table or read out by the source table + current amplifier + oscilloscope, which is used to receive the electrical signal after the photoelectric conversion of the single-point detector.

[0027] Further, the control output mode of the data acquisition platform includes digital output, analog output, and analog modulation output.

[0028] Further, the digital output is a reference picture gray scale threshold value, below the threshold value the data acquisition platform control output voltage is 0, the laser does not emit light, the single point detector output is dark current value; greater than or equal to the threshold value the data acquisition platform control output voltage is a constant value, the laser output same size light intensity, the single point detector output is photocurrent value.

[0029] Further, the analog output is that the data acquisition platform compiles corresponding voltage values according to the gray scale value of each pixel of the reference picture and outputs to the laser to control the laser to output corresponding light intensity at different gray scale value pixel points, then the single point detector outputs corresponding photocurrent at different gray scale value pixel points.

[0030] Further, the analog modulation output compiles corresponding voltage values according to the gray scale value of each pixel of the reference picture and is switch modulated with a set frequency, finally uses the combination of the source table, the current amplifier and the oscilloscope to read waveforms at each test pixel point of the reference picture and records current values under the laser switch state, and the photocurrent is obtained by difference.

[0031] In the application, the control output mode of the data acquisition platform has three kinds: digital output, analog output and analog modulation output, the digital output is a reference picture gray scale threshold value, below the threshold value the data acquisition platform control output voltage is 0, the laser does not emit light, the single point detector output is dark current value; greater than or equal to the threshold value the data acquisition platform control output voltage is a constant value, the laser output same size light intensity, the single point detector output is photocurrent value, the analog output is that the data acquisition platform compiles corresponding voltage values according to the gray scale value of each pixel of the reference picture and outputs to the laser to control the laser to output corresponding light intensity at different gray scale value pixel points, then the single point detector outputs corresponding photocurrent at different gray scale value pixel points, the current receiving device in the digital output and analog output mode is the source table, the difference between the analog modulation output and the analog output is that the analog modulation output not only compiles corresponding voltage values according to the gray scale value of each pixel of the reference picture and is switch modulated with a set frequency, finally uses the combination of the source table+the current amplifier+the oscilloscope to read waveforms at each test pixel point of the reference picture and records current values under the laser switch state, and the photocurrent is obtained by difference. This mode is suitable for the single point detector with large or unstable dark current.

[0032] Further, the gray scale value of each pixel of the reference picture is obtained by the following formula:

[0033] Gray=0.299*R+0.587*G+0.114*B,

[0034] wherein,

[0035] R, G, B are the read R, G, B values of each pixel point of the reference picture, and Gray is a gray value.

[0036] Further, different gray values are correspondingly compiled into different voltage values:

[0037] V = (Vmax / Gmax)*Gray + Vth, wherein V is an output voltage, Vmax is a maximum voltage of the laser, Vth is a threshold voltage of the laser, and Gmax is a maximum gray value. Specific embodiments:

[0039] Taking the Lena picture as a reference picture, imaging performance characterization is performed by the following steps:

[0040] The Lena picture is imported into the data acquisition platform by a computer, color gray value calculation is performed on each pixel point of the reference picture, different gray values are correspondingly compiled into different voltage values, the voltage compiled by the data acquisition platform is output to the laser, and is modulated by a switch at a certain set frequency. The wavelength of the laser in this embodiment is 520 nm, and the modulation frequency is 1 KHz. Different voltage values correspond to different laser light intensity values;

[0041] The laser is coupled into an optical fiber, and then enters the optical path assembly of the application. If other wavelengths are used as excitation light sources, only the laser needs to be replaced and coupled into the optical fiber, without changing the optical path assembly of the device;

[0042] The laser is collimated by the off-axis parabolic mirror, then irradiated to the rear end of the objective lens through the mirror, and then focused into a point-shaped light spot by the objective lens. The objective lens used in this embodiment is a reflective objective lens suitable for all wavelengths;

[0043] The light beam of the bright field illumination light source is irradiated to the second beam splitter through the first beam splitter, the second beam splitter reflects the illumination light source, and then irradiates to the single-point detector through the objective lens. The topography of the single-point detector can be observed in the bright field imaging image sensor, and the laser spot is also observed in the bright field imaging image sensor. The photosensitive surface of the single-point detector is translated to the position of the laser spot by the translation stage. In this device, the bright field imaging function generally works first to focus and observe the topography of the single-point detector. The excitation laser is turned on in the imaging focusing state, and the laser is also in the focusing state;

[0044] The second beam splitter is switched out of the optical path, that is, the illumination light source is switched out of the optical path, only the laser light source is retained, the single-point detector receives the excitation laser signal and converts the optical signal into an electric current signal. The single-point detector in this embodiment is a commercial detector;

[0045] The current signal is collected by the source meter, and then output by the source meter to the current amplifier. After being amplified by the current amplifier and converted into a voltage signal, it is output to the oscilloscope for reading.

[0046] The data acquisition platform scans the reference image pixel by pixel, and the oscilloscope synchronously records the waveform data of each pixel, as shown in the attached figure. Figure 2 As shown in the right figure, the current value under laser switching state is obtained through waveform data, the difference is used to obtain the photocurrent, and a pixel-current two-dimensional image with the same pixel information as the reference image is formed, as shown in the figure. Figure 2 As shown in the left figure.

[0047] according to Figure 2 The content shows that it is almost identical to the Lena diagram, indicating that the single-point detector described herein has excellent imaging performance. Figure 2 The image on the right is Figure 2 The waveforms corresponding to two points in the left figure contain information such as the dark current, photocurrent, and response speed of the single-point detector.

[0048] This invention discloses a single-point detector imaging performance characterization system. Based on existing technologies, the system improves upon the existing structure by employing a simulated real-object imaging method. This achieves the goal of characterizing the imaging performance of a single-point detector while simplifying the device. It makes it easy to determine the position of the single-point detector in the optical path and allows the size of the detector's photosensitive surface to be as small as the micrometer level, making it particularly suitable for scientific research. Furthermore, imaging characterization of a single-point detector across the entire wavelength range can be achieved by replacing the laser. The system maintains optical path stability, and a single characterization can contain a wealth of information, such as current magnitude, responsivity, and response speed.

[0049] The above description discloses only one preferred embodiment of the present invention, and should not be construed as limiting the scope of the present invention. Those skilled in the art will understand that all or part of the processes of the above embodiments can be implemented, and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A single-point detector imaging performance characterization system, characterized in that, The characterization system includes a data acquisition platform, a laser, an objective lens, a bright-field imaging sensor, a single-point detector, a source meter, and an optical path assembly. The data acquisition platform is connected to the laser to compile different voltage values ​​and output them to the laser. The laser is a modulated light source, and the wavelength is selected according to the response range of the single-point detector to be detected. The objective lens works with the single-point detector to focus the laser onto the photosensitive surface of the single-point detector. The source meter is electrically connected to the single-point detector to receive the electrical signal after photoelectric conversion by the single-point detector. The source meter is also connected in series with a current amplifier and an oscilloscope. The optical path assembly guides the light path. The single-point detector receives optical signals and converts them into electrical signals. It scans a reference image pixel by pixel through a data acquisition platform. The source table synchronously displays the current value of the single-point detector and forms a pixel-current two-dimensional image with the same pixel information as the reference image. The imaging performance of the single-point detector can be analyzed by analyzing the difference between the scanned two-dimensional image and the reference image. The control output methods of the data acquisition platform include: digital output, analog output, and analog modulation output; The digital output is a grayscale threshold set for a reference image. When the grayscale value is below the threshold, the control output voltage of the data acquisition platform is 0, the laser does not emit light, and the single-point detector outputs a dark current value. When the grayscale value is greater than or equal to the threshold, the control output voltage of the data acquisition platform is a constant value, the laser outputs the same light intensity, and the single-point detector outputs a photocurrent value. The analog output is that the data acquisition platform compiles the corresponding voltage value based on the gray value of each pixel in the reference image and outputs it to the laser to control the laser to output the corresponding light intensity at pixels with different gray values. Then, the single-point detector will output the corresponding photocurrent at pixels with different gray values. The analog modulation output is compiled to generate the corresponding voltage value based on the grayscale value of each pixel in the reference image and then modulated with a set frequency. Finally, the waveform is read at each test pixel of the reference image using the combination of the source meter, the current amplifier and the oscilloscope, and the current value under the laser switching state is recorded. The difference is then used to obtain the photocurrent.

2. The single-point detector imaging performance characterization system as described in claim 1, characterized in that, The optical path assembly includes a reflector, an off-axis parabolic mirror, a first beam splitter, a second beam splitter, and a bright-field illumination source. The off-axis parabolic mirror is used to collimate the laser and send the laser to the reflector, which then illuminates the rear end of the objective lens. The bright-field illumination source emits a beam of light, which passes through the first beam splitter and then illuminates the second beam splitter. The second beam splitter reflects the bright-field illumination source and then illuminates the single-point detector through the objective lens.

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