Optical signal measurement device, method

Abstract

This invention discloses a photoelectric signal measurement device and method, relating to the field of photoelectric signal measurement technology. The device includes: a chopper, which modulates a target light beam using chopper blades to output transmitted and reflected light; first and second photomultiplier tubes, respectively positioned in the optical paths of the transmitted and reflected light, performing photoelectric conversion on the transmitted and reflected light respectively, wherein the first photomultiplier tube is located at the end of the sample stage where the test sample is placed, away from the chopper; a motor, which drives the chopper blades to rotate and outputs encoded values ​​through a motor encoder; and a signal processing board, which acquires the electrical signals corresponding to the transmitted and reflected light, obtains first and second reference signals based on the encoded values ​​and the number of chopper blades, and mixes the two electrical signals using the first and second reference signals respectively, calculating the transmittance or reflectance of the test sample based on the first and second complex signals obtained before and after placing the test sample. This improves the accuracy of photoelectric signal measurement.

Description

Technical Field

[0001] This invention relates to the field of photoelectric signal measurement technology, and in particular to a photoelectric signal measurement device and method. Background Technology

[0002] In related technologies, photoelectric switches are used to measure the frequency of a chopper in order to achieve photoelectric signal measurement. However, the light from the photoelectric switch itself can interfere with the measurement, resulting in low accuracy of photoelectric signal measurement. Summary of the Invention

[0003] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, one object of this invention is to provide a photoelectric signal measuring device to achieve high-precision measurement.

[0004] The second objective of this invention is to provide a method for measuring photoelectric signals.

[0005] To achieve the above objectives, a first aspect of the present invention provides a photoelectric signal measurement device, comprising: a chopper configured to modulate a target light beam by means of a chopper blade, outputting transmitted light and reflected light; a first photomultiplier tube disposed in the optical path of the transmitted light and located at one end of a sample stage away from the chopper, configured to perform photoelectric conversion on the transmitted light, wherein the sample stage is used to place a test sample; a second photomultiplier tube disposed in the optical path of the reflected light, configured to perform photoelectric conversion on the reflected light; a motor configured to drive the chopper blade to rotate and output encoded values ​​through a motor encoder; and a signal... The processing board is configured to acquire electrical signals corresponding to the transmitted light and the reflected light, obtain a first reference signal and a second reference signal based on the encoded value and the number of choppers, mix the two electrical signals using the first reference signal and the second reference signal respectively, perform low-pass filtering on the mixed signal to obtain a first complex signal and a second complex signal, and calculate the transmittance or reflectance of the test sample based on the two sets of complex signals. The two sets of complex signals include the first complex signal and the second complex signal obtained when the test sample is not placed, and the first complex signal and the second complex signal obtained when the test sample is placed.

[0006] In addition, the photoelectric signal measuring device according to embodiments of the present invention may also have the following additional technical features: In one embodiment of the present invention, the signal processing board includes: a first acquisition module configured to acquire a first electrical signal corresponding to the transmitted light; a second acquisition module configured to acquire a second electrical signal corresponding to the reflected light; and a processing chip configured to obtain a first reference signal and a second reference signal based on the encoded value and the number of choppers, and to mix the first electrical signal and the second electrical signal using the first reference signal and the second reference signal respectively, to perform low-pass filtering on the mixed signal to obtain a first complex signal and a second complex signal, and to calculate the transmittance or reflectance of the test sample based on the two sets of complex signals.

[0007] In one embodiment of the present invention, the first acquisition module and the second acquisition module have the same structure. The first acquisition module includes: a cross-group amplifier configured to convert the electrical signal corresponding to the transmitted light from a current signal to a voltage signal; and an ADC acquisition circuit configured to acquire the voltage signal to obtain the first electrical signal.

[0008] In one embodiment of the present invention, the processing chip includes: a reference signal generation module configured to generate a first reference signal and a second reference signal according to the encoded value and the number of choppers; a transmitted light processing module configured to mix the first electrical signal using the first reference signal and the second reference signal to obtain a first complex signal, and to perform amplitude calculation on the first complex signal to obtain an amplitude value of the first complex signal; a reflected light processing module configured to mix the second electrical signal using the first reference signal and the second reference signal to obtain a second complex signal, and to perform amplitude calculation on the second complex signal to obtain an amplitude value of the second complex signal; and a calculation module configured to calculate the transmittance or reflectance of the test sample based on the amplitude values ​​of the first complex signal obtained when the test sample is not placed and the amplitude values ​​of the second complex signal obtained when the test sample is placed.

[0009] In one embodiment of the present invention, the reference signal generation module includes: a square wave signal generation unit configured to generate a square wave signal according to the encoded value; a frequency measurement unit configured to measure the frequency of the square wave signal; and a numerically controlled oscillator configured to generate the first reference signal and the second reference signal according to the frequency of the square wave signal.

[0010] In one embodiment of the present invention, the transmitted light processing module and the reflected light processing module have the same structure. The transmitted light processing module includes: a bandpass filter configured to filter out interference signals and noise other than the fundamental frequency in the first electrical signal; a mixer configured to mix the signal output by the bandpass filter using the first reference signal and the second reference signal; a low-pass filter configured to filter out high-frequency components in the signal output by the mixer to obtain the first complex signal; and an amplitude calculation unit configured to perform amplitude calculation on the first complex signal to obtain the amplitude value of the first complex signal.

[0011] To achieve the above objectives, a second aspect of the present invention provides a photoelectric signal measurement method for the aforementioned photoelectric signal measurement device. The method includes: acquiring electrical signals corresponding to transmitted light and reflected light output by the chopper when no test sample is placed on the sample stage; obtaining a first reference signal and a second reference signal based on the encoding value output by the motor encoder and the number of choppers; mixing the two electrical signals using the first reference signal and the second reference signal to obtain a first complex signal and a second complex signal; and calculating the transmittance or reflectance of the test sample based on the two sets of complex signals, wherein the two sets of complex signals include the first complex signal and the second complex signal obtained when no test sample is placed, and the first complex signal and the second complex signal obtained when the test sample is placed.

[0012] In addition, the photoelectric signal measurement method according to embodiments of the present invention may also have the following additional technical features: In one embodiment of the present invention, the first reference signal and the second reference signal are represented by the following formula: X = cos(2 × π × F² × t) Y = sin(2 × π × F² × t) Where X is the first reference signal, Y is the second reference signal, t is the sampling period, F2 is the frequency of the first reference signal, F2=m×F1, m is the number of choppers, and F1 is the frequency of the square wave signal generated according to the encoded value.

[0013] In one embodiment of the present invention, the transmittance or the reflectance is obtained by the following formula: , Wherein, η is the transmittance or the reflectance, R_test1 and R_test2 are the amplitude values ​​of the first complex signal when the test sample is not placed and when the test sample is placed, respectively, and R_ref1 and R_ref2 are the amplitude values ​​of the second complex signal when the test sample is not placed and when the test sample is placed, respectively.

[0014] In one embodiment of the present invention, the method further includes: calculating the amplitude values ​​of a plurality of first complex signals, and calculating the average value of the amplitude values ​​of the plurality of first complex signals as the final amplitude value of the transmitted light path signal; calculating the amplitude values ​​of a plurality of second complex signals, and calculating the average value of the amplitude values ​​of the plurality of second complex signals as the final amplitude value of the reflected light path; and calculating the transmittance or reflectance of the test sample based on the final amplitude values ​​of the transmitted light path signal and the final amplitude values ​​of the reflected light path obtained when the test sample is not placed and when the test sample is placed.

[0015] According to an embodiment of the present invention, a photoelectric signal measurement device and method include: a chopper configured to modulate a target light beam through a chopper blade to output transmitted light and reflected light; a first photomultiplier tube disposed in the optical path of the transmitted light and located at the end of the sample stage away from the chopper, configured to perform photoelectric conversion on the transmitted light, wherein the sample stage is used to place a test sample; a second photomultiplier tube disposed in the optical path of the reflected light, configured to perform photoelectric conversion on the reflected light; a motor configured to drive the chopper blade to rotate and output an encoded value through a motor encoder; and a signal processing board configured to acquire electrical signals corresponding to the transmitted light and reflected light, and obtain a first reference signal and a second reference signal according to the encoded value and the number of chopper blades, and to mix the two electrical signals using the first reference signal and the second reference signal respectively, perform low-pass filtering on the mixed signal to obtain a first complex signal and a second complex signal, and calculate the transmittance or reflectance of the test sample based on the two sets of complex signals, wherein the two sets of complex signals include a first complex signal and a second complex signal obtained when no test sample is placed, and a first complex signal and a second complex signal obtained when the test sample is placed. Therefore, photoelectric signal measurement can be performed without the need for photoelectric switches, thus achieving high-precision photoelectric signal measurement.

[0016] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0017] Figure 1 This is a structural block diagram of the photoelectric signal measuring device according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the operation of a photoelectric signal measuring device according to a specific embodiment of the present invention; Figure 3 This is a flowchart of the photoelectric signal measurement method according to an embodiment of the present invention. Detailed Implementation

[0018] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0019] The photoelectric signal measurement device and method of the present invention are described below with reference to the accompanying drawings.

[0020] Figure 1 This is a structural block diagram of the photoelectric signal measuring device according to an embodiment of the present invention.

[0021] like Figure 1 As shown, the photoelectric signal measurement device 100 includes: a chopper 101 configured to modulate a target beam through a chopper blade, outputting transmitted light and reflected light; a first photomultiplier tube 105 disposed in the optical path of the transmitted light and located at the end of the sample stage away from the chopper 101, configured to perform photoelectric conversion on the transmitted light, wherein the sample stage is used to place a test sample; a second photomultiplier tube 106 disposed in the optical path of the reflected light, configured to perform photoelectric conversion on the reflected light; and a motor 102 configured to drive the chopper blade to rotate and output encoded values ​​through a motor encoder. The signal processing board 127 is configured to acquire electrical signals corresponding to transmitted and reflected light, obtain a first reference signal and a second reference signal based on the encoding value and the number of choppers, and mix the two electrical signals using the first and second reference signals respectively, perform low-pass filtering on the mixed signals to obtain a first complex signal and a second complex signal, and calculate the transmittance or reflectance of the test sample based on the two sets of complex signals. The two sets of complex signals include the first complex signal and the second complex signal obtained when no test sample is placed, and the first complex signal and the second complex signal obtained when the test sample is placed.

[0022] Specifically, in order to achieve accurate photoelectric signal measurement, a photoelectric signal measurement device 100 is proposed, which includes a chopper 101, a sample stage, a first photomultiplier tube 105, a second photomultiplier tube 106, a clicker, and a signal processing board 127.

[0023] When photoelectric signal measurement is required, a target beam is first emitted to the chopper 101. This target beam is the beam used to measure the test sample.

[0024] The target beam will be directed toward the chopper 101, which includes a chopper blade. The chopper blade and the motor 102 are integrated. For example, the motor 102 and the chopper blade can be configured to rotate coaxially, that is, the rotation axis of the chopper blade is fixedly connected to the rotation axis of the motor 102, so that the rotation speed of the chopper blade is the same as the rotation speed of the motor 102.

[0025] When the chopper rotates, the blades on the chopper pass through the optical path of the target beam at intervals. When the blades on the chopper are in the optical path of the target beam, the target beam is reflected by the blades, and the chopper collects the reflected beam to obtain the reflected light; when the blades on the chopper are not in the optical path of the target beam, the target beam passes directly through the chopper to obtain the transmitted light.

[0026] After receiving the reflected and transmitted light, the chopper 101 emits transmitted light to the first photomultiplier tube 105 and reflected light to the second photomultiplier tube 106. Since the sample stage is located in the optical path of the transmitted light, when a test sample is placed on the sample stage, the transmitted light contains information about the test sample; when no test sample is placed on the sample stage, the transmitted light does not contain information about the test sample.

[0027] The first photomultiplier tube 105 can perform photoelectric conversion on the received transmitted light to obtain the electrical signal corresponding to the transmitted light, and the second photomultiplier tube 106 can perform photoelectric conversion on the received reflected light to obtain the electrical signal corresponding to the reflected light.

[0028] Furthermore, the motor 102 includes a motor encoder, which can obtain the rotational speed of the motor 102, obtain an encoded value based on the rotational speed of the motor 102, and send the encoded value to the signal processing board 127.

[0029] After obtaining the electrical signals corresponding to the transmitted light, the reflected light, and the encoded values, the signal processing board 127 can calculate the transmittance or reflectance of the test sample based on the two sets of complex signals. Whether transmittance or reflectance is calculated depends on the specific placement of the detectors, including the photomultiplier tube, and is independent of the operation of the aforementioned photoelectric signal measuring device 100.

[0030] The two sets of complex signals mentioned above are, in one set, the first and second complex signals obtained when no test sample is placed, and in the other set, the first and second complex signals obtained when a test sample is placed.

[0031] Therefore, photoelectric signal measurement can be achieved without the need for photoelectric switches, thus enabling high-precision photoelectric signal measurement.

[0032] In some embodiments of the present invention, the signal processing board 127 includes: a first acquisition module configured to acquire a first electrical signal corresponding to transmitted light; a second acquisition module configured to acquire a second electrical signal corresponding to reflected light; and a processing chip configured to obtain a first reference signal and a second reference signal based on the encoded value and the number of choppers, and to mix the first electrical signal and the second electrical signal using the first reference signal and the second reference signal respectively, to perform low-pass filtering on the mixed signal to obtain a first complex signal and a second complex signal, and to calculate the transmittance or reflectance of the test sample based on the two sets of complex signals.

[0033] In some embodiments of the present invention, the first acquisition module and the second acquisition module have the same structure. The first acquisition module includes: a cross-group amplifier configured to convert the electrical signal corresponding to the transmitted light from a current signal to a voltage signal; and an ADC acquisition circuit configured to acquire the voltage signal to obtain a first electrical signal.

[0034] Therefore, by setting up a cross-group amplifier and converting the current and voltage through a transimpedance amplifier, various bandpass and low-pass filtering algorithms, signal demodulation amplitude calculation, and mean filtering can be flexibly implemented within a single processing chip, resulting in strong anti-interference capabilities, higher integration, and more flexible design.

[0035] In some embodiments of the present invention, the processing chip includes: a reference signal generation module configured to generate a first reference signal and a second reference signal based on an encoded value and the number of choppers; a transmitted light processing module configured to mix a first electrical signal using the first reference signal and the second reference signal to obtain a first complex signal, and to perform amplitude calculation on the first complex signal to obtain an amplitude value of the first complex signal; a reflected light processing module configured to mix a second electrical signal using the first reference signal and the second reference signal to obtain a second complex signal, and to perform amplitude calculation on the second complex signal to obtain an amplitude value of the second complex signal; and a calculation module configured to calculate the transmittance or reflectance of the test sample based on the amplitude values ​​of the first complex signal obtained when no test sample is placed and the amplitude values ​​of the second complex signal obtained when a test sample is placed.

[0036] In some embodiments of the present invention, the reference signal generation module includes: a square wave signal generation unit configured to generate a square wave signal according to an encoded value; a frequency measurement unit configured to measure the frequency of the square wave signal; and a numerically controlled oscillator configured to generate a first reference signal and a second reference signal according to the frequency of the square wave signal.

[0037] In some embodiments of the present invention, the transmitted light processing module and the reflected light processing module have the same structure. The transmitted light processing module includes: a bandpass filter configured to filter out interference signals and noise other than the fundamental frequency in the first electrical signal; a mixer configured to mix the signal output from the bandpass filter using a first reference signal and a second reference signal; a low-pass filter configured to filter out high-frequency components in the signal output from the mixer to obtain a first complex signal; and an amplitude calculation unit configured to perform amplitude calculation on the first complex signal to obtain the amplitude value of the first complex signal. The signal output from the mixer is the mixed signal described above.

[0038] The following is combined Figure 2 The specific embodiments shown will be described in detail.

[0039] exist Figure 2 In the specific embodiment shown, 101 is a chopper, 104 is a sample stage, 105 is a first photomultiplier tube, 106 is a second photomultiplier tube, 107 is a cross-group amplifier, 109 is an ADC acquisition circuit, 111 is a bandpass filter, 113 is a mixer, 115 is a low-pass filter, 117 is an amplitude calculation unit, 119 is an accumulation averaging processing unit, 120 is a ratio calculation unit, 121 is a network port, 122 is a motor encoder, 123 is a square wave signal generation unit, 124 is a frequency measurement unit, 125 is a digitally controlled oscillator, 126 is a processing chip, and 127 is a signal processing board.

[0040] Specifically, a motor 102 with encoder output is used. The motor 102 and the chopper rotate coaxially, and the motor 102 and the chopper rotate at a set frequency F0, that is, the motor 102 rotates F0 revolutions per second.

[0041] It should be noted that, in this specific embodiment, since the output signal of the motor encoder 122 is incremental, it can be known that for every N increment in the encoded value, the motor 102 and the chopper rotate one revolution. It can be set that for every 360 / N degrees rotated by the motor 102, the encoded value output by the motor encoder 122 increments by one, and after the motor 102 has rotated 360 degrees, the motor encoder 122 clears the output encoded value to zero and restarts counting.

[0042] The motor encoder 122 outputs an encoded value, which is then input to the signal processing board 127.

[0043] In this specific embodiment, the signal processing board 127 is configured to include a ZYNQ chip, which is the processing chip 126.

[0044] After the encoded value enters the ZYNQ chip, it first enters the square wave signal generation unit 123 within the ZYNQ chip. If the specific value of the encoded value is less than or equal to N / 2, the square wave signal is at a high level; otherwise, the square wave signal is at a low level. The square wave signal generation unit 123 inputs the square wave signal to the frequency measurement unit 124, and the frequency measurement unit 124 measures the frequency of the square wave as F1.

[0045] In this specific embodiment, the number of blades m in the chopper 101 is 4, and the frequency F2 = m × F1 = 4F1 is taken as the reference frequency. Based on the above reference frequency F2, the IP core of the numerically controlled oscillator 125 in the ZYNQ chip generates a first reference signal X and a second reference signal Y with a frequency of F2. The details are as follows: X = cos(2 × π × F² × t), Y = sin(2 × π × F² × t), Where t is the sampling period, which is the sampling period of the ADC acquisition circuit 109.

[0046] When the target beam is emitted toward the chopper 101, the target beam passes through the chopper 101 and becomes two beams of light, namely reflected light and transmitted light. In this specific embodiment, the target beam is ultraviolet light.

[0047] The following explanation uses the transmitted light when a test sample is on the sample stage 104 as an example.

[0048] First, the transmitted light passes through the sample stage 104 and enters the first photomultiplier tube 105, where it is converted from an optical signal into an electrical signal to obtain the first electrical signal. The first electrical signal is then converted into a voltage signal by the cross-group amplifier 107 on the signal processing board 127. This voltage signal is acquired by the ADC acquisition circuit 109 to obtain the first electrical signal, which is then transmitted to the ZYNQ chip.

[0049] The ZYNQ chip uses a bandpass filter 111, whose passband center frequency is F2 as described above. This filters out interference signals and noise other than the fundamental frequency in the first electrical signal, improving the signal-to-noise ratio. Let signal_t ​​be the signal obtained after the bandpass filter 111 filters the voltage signal corresponding to the first electrical signal.

[0050] The signal signal_t ​​mentioned above can be expressed as follows: , Where A is the electrical signal amplitude of signal_t. This is the phase deviation.

[0051] Mixer 113 mixes the first reference signal X and the second reference signal Y with signal_t, and then passes them through low-pass filter 115 to filter out high-frequency components, resulting in signals X1 and Y1. The filtered high-frequency components include high-frequency signals of 2 times F2 and above.

[0052] The signals X1 and Y1 obtained by low-pass filtering the mixed signals can be expressed as follows:

[0053] After obtaining signals X1 and Y1, the first complex signal Z = X1 + iY1 when the test sample is placed can be obtained based on signals X1 and Y1. The amplitude value of the complex signal is calculated as follows:

[0054] Where R is the amplitude value of the complex signal. When the test sample is placed on the sample stage 104, if the complex signal is the first complex signal Z, then R is the amplitude value R_test1 of the first complex signal Z. If the complex signal is the second complex signal, then R is the amplitude value R_ref1 of the second complex signal.

[0055] After obtaining the first complex signal Z when the test sample is placed, the amplitude calculation unit 117 can be used to calculate the amplitude value R_test1 of the first complex signal Z when the test sample is placed, which is the amplitude value R_test1 of the first complex signal when the test sample is placed.

[0056] Since the first acquisition module and the second acquisition module have the same structure, and the transmitted light processing module and the reflected light processing module have the same structure, the processing of reflected light when the test sample is placed on the sample stage 104 can refer to the above-described processing of transmitted light. The only difference is that the processed light is reflected light, not transmitted light, and a second photomultiplier tube 106 is used. At this time, the amplitude value R_ref1 of the second complex signal when the test sample is placed can be obtained.

[0057] Furthermore, the transmitted light when no test sample is placed on the sample stage 104 is obtained. The processing of the transmitted light when no test sample is placed on the sample stage 104 is the same as the processing flow of the transmitted light when a test sample is placed on the sample stage 104. At this time, the amplitude value R_test2 of the first complex signal when no test sample is placed can be obtained.

[0058] The processing of reflected light when no test sample is placed on the sample stage 104 is the same as the processing of reflected light when a test sample is placed on the sample stage 104. At this time, the amplitude value R_ref2 of the second complex signal when no test sample is placed can be obtained.

[0059] After obtaining R_test1, R_ref1, R_test2, and R_ref2, the ratio calculation unit 120 can calculate the transmittance or reflectance of the test sample according to the following formula. : .

[0060] Transmittance or reflectance is calculated in ratio calculation unit 120. Then, the calculated transmittance or reflectance can be transmitted via network port 121. Upload to the host computer.

[0061] Optionally, after obtaining R_test1, R_ref1, R_test2, and R_ref2, the cumulative averaging processing unit 119 can be activated to perform cumulative averaging processing on R_test1, R_ref1, R_test2, and R_ref2, further reducing measurement errors. The cumulative averaging result is then: , , , , in, This is the cumulative average of the amplitude values ​​of the first complex signal when the test sample is placed. This is the cumulative average of the amplitude values ​​of the second complex signal when the test sample is placed. This is the cumulative average of the amplitude values ​​of the first complex signal when no test sample is placed. This is the cumulative average of the amplitude values ​​of the second complex signal when no test sample is placed. M is the number of accumulation points, i.e., M measurements are performed to obtain M amplitude values, which are then accumulated and averaged. Let be the amplitude value of the first complex signal obtained during the i-th measurement when the test sample is placed. Let be the amplitude value of the second complex signal obtained during the i-th measurement when the test sample is placed. Let be the amplitude value of the first complex signal obtained in the i-th measurement when no test sample is placed. The amplitude value of the second complex signal obtained in the i-th measurement when no test sample is placed is denoted as .

[0062] In other words, after obtaining M R_test1 values, the above formula can be used to perform a cumulative average on these M R_test1 values ​​to obtain... After obtaining M R_ref1 values, the M R_ref1 values ​​are summed and averaged according to the above method to obtain... After obtaining M R_test1 samples, the M R_test2 samples are summed and averaged according to the above formula to obtain... After obtaining M R_ref2 values, the M R_ref2 values ​​are summed and averaged according to the above method to obtain... .

[0063] The above This is the final amplitude value of the transmitted light path signal when the test sample is placed. This is the final amplitude value of the reflected light path when the test sample is placed. This is the final amplitude value of the transmitted light path signal when no test sample is placed. This is the final amplitude value of the reflected light path when no test sample is placed.

[0064] At this point, the ratio calculation unit 120 calculates the transmittance or reflectance of the test sample. for: .

[0065] In summary, the photoelectric signal measurement device of this invention includes: a chopper configured to modulate a target beam through a chopper blade to output transmitted light and reflected light; a first photomultiplier tube disposed in the optical path of the transmitted light and located at the end of the sample stage away from the chopper, configured to perform photoelectric conversion on the transmitted light, wherein the sample stage is used to place a test sample; a second photomultiplier tube disposed in the optical path of the reflected light, configured to perform photoelectric conversion on the reflected light; a motor configured to drive the chopper blade to rotate and output an encoded value through a motor encoder; and a signal processing board configured to acquire electrical signals corresponding to the transmitted light and reflected light, and obtain a first reference signal and a second reference signal according to the encoded value and the number of chopper blades, and to mix the two electrical signals using the first reference signal and the second reference signal respectively, perform low-pass filtering on the mixed signal to obtain a first complex signal and a second complex signal, and calculate the transmittance or reflectance of the test sample based on the two sets of complex signals, wherein the two sets of complex signals include the first complex signal and the second complex signal obtained when no test sample is placed, and the first complex signal and the second complex signal obtained when the test sample is placed. Therefore, photoelectric signal measurement can be performed without the need for photoelectric switches, thus achieving high-precision photoelectric signal measurement.

[0066] Furthermore, this invention proposes a photoelectric signal measurement method.

[0067] Figure 3 This is a flowchart of the photoelectric signal measurement method according to an embodiment of the present invention.

[0068] In this embodiment of the invention, the photoelectric signal measurement method is used in the photoelectric signal measurement device described in the above embodiment.

[0069] like Figure 3 As shown, the photoelectric signal measurement method includes: S11. When no test sample is placed on the sample stage, the electrical signals corresponding to the transmitted light and reflected light output by the chopper are collected respectively. The first reference signal and the second reference signal are obtained according to the encoding value output by the motor encoder and the number of choppers. The two electrical signals are mixed using the first reference signal and the second reference signal respectively to obtain the first complex signal and the second complex signal.

[0070] S12, calculate the transmittance or reflectance of the test sample based on the two sets of complex signals, wherein the two sets of complex signals include the first complex signal and the second complex signal obtained when the test sample is not placed, and the first complex signal and the second complex signal obtained when the test sample is placed.

[0071] In some embodiments of the present invention, the first reference signal and the second reference signal are represented by the following formula: X = cos(2 × π × F² × t), Y = sin(2 × π × F² × t), Where X is the first reference signal, Y is the second reference signal, t is the sampling period, F2 is the frequency of the first reference signal, F2=m×F1, m is the number of choppers, and F1 is the frequency of the square wave signal generated according to the encoded value.

[0072] In some embodiments of the present invention, the transmittance or reflectance is obtained by the following formula: , Where η is the transmittance or reflectance, R_test1 and R_test2 are the amplitude values ​​of the first complex signal when no test sample is placed and when a test sample is placed, respectively, and R_ref1 and R_ref2 are the amplitude values ​​of the second complex signal when no test sample is placed and when a test sample is placed, respectively.

[0073] In some embodiments of the present invention, the photoelectric signal measurement method further includes: calculating the amplitude values ​​of a plurality of first complex signals, and calculating the average value of the amplitude values ​​of the plurality of first complex signals as the final amplitude value of the transmitted light path signal; calculating the amplitude values ​​of a plurality of second complex signals, and calculating the average value of the amplitude values ​​of the plurality of second complex signals as the final amplitude value of the reflected light path; and calculating the transmittance or reflectance of the test sample based on the final amplitude values ​​of the transmitted light path signal obtained when the test sample is not placed and when the test sample is placed.

[0074] It should be noted that other specific embodiments of the photoelectric signal measurement method of the present invention can be found in the photoelectric signal measurement device of the above embodiments.

[0075] The photoelectric signal measurement method of this invention can achieve photoelectric signal measurement without the need for a photoelectric switch, thereby achieving high-precision photoelectric signal measurement.

[0076] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0077] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0078] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0079] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0080] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0081] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0082] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0083] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An optoelectrical signal measuring device, characterized in that, include: A chopper is configured to modulate a target beam through a chopper plate, outputting transmitted and reflected light; A first photomultiplier tube is disposed in the optical path of the transmitted light and located at the end of the sample stage away from the chopper. It is configured to perform photoelectric conversion on the transmitted light, wherein the sample stage is used to place the test sample. A second photomultiplier tube is disposed in the optical path of the reflected light and is configured to perform photoelectric conversion on the reflected light; The motor is configured to drive the chopper to rotate and output encoded values ​​through a motor encoder; The signal processing board is configured to acquire electrical signals corresponding to the transmitted light and the reflected light, obtain a first reference signal and a second reference signal according to the encoded value and the number of choppers, mix the two electrical signals using the first reference signal and the second reference signal respectively, perform low-pass filtering on the mixed signal to obtain a first complex signal and a second complex signal, and calculate the transmittance or reflectance of the test sample based on the two sets of complex signals, wherein the two sets of complex signals include the first complex signal and the second complex signal obtained when the test sample is not placed, and the first complex signal and the second complex signal obtained when the test sample is placed; The signal processing board includes: The first acquisition module is configured to acquire the first electrical signal corresponding to the transmitted light; The second acquisition module is configured to acquire the second electrical signal corresponding to the reflected light; The processing chip is configured to obtain the first reference signal and the second reference signal according to the encoded value and the number of choppers, and to mix the first electrical signal and the second electrical signal with the first reference signal and the second reference signal respectively, to perform low-pass filtering on the mixed signal to obtain the first complex signal and the second complex signal, and to calculate the transmittance or reflectance of the test sample based on the two sets of complex signals. The processing chip includes: A reference signal generation module is configured to generate a first reference signal and a second reference signal based on the encoded value and the number of choppers; The transmitted light processing module is configured to mix the first electrical signal using the first reference signal and the second reference signal to obtain the first complex signal, and to perform amplitude calculation on the first complex signal to obtain the amplitude value of the first complex signal; The reflected light processing module is configured to mix the second electrical signal using the first reference signal and the second reference signal to obtain the second complex signal, and to perform amplitude calculation on the second complex signal to obtain the amplitude value of the second complex signal; The calculation module is used to calculate the transmittance or reflectance of the test sample based on the amplitude values ​​of the first complex signal and the second complex signal obtained when the test sample is not placed and when the test sample is placed. The reference signal generation module includes: A square wave signal generation unit is configured to generate a square wave signal according to the encoded value; A frequency measurement unit is configured to measure the frequency of the square wave signal; A numerically controlled oscillator is configured to generate the first reference signal and the second reference signal according to the frequency of the square wave signal; The motor rotates coaxially with the chopper. For every 360 / N degrees the motor rotates, the encoded value output by the motor encoder is incremented by one. After the motor rotates 360 degrees, the motor encoder resets the encoded value to zero. When the encoded value is less than or equal to N / 2, the square wave signal is at a high level. When the encoded value is greater than N / 2, the square wave signal is at a low level. N is a positive integer greater than 1. The transmitted light processing module has the same structure as the reflected light processing module, and the transmitted light processing module includes: A bandpass filter is configured to filter out interference signals and noise other than the fundamental frequency in the first electrical signal; A mixer is configured to mix the signal output from the bandpass filter using the first reference signal and the second reference signal; A low-pass filter is configured to filter out high-frequency components in the signal output by the mixer to obtain the first complex signal; An amplitude calculation unit is configured to perform amplitude calculation on the first complex signal to obtain the amplitude value of the first complex signal; The passband center frequency of the bandpass filter is the product of the number of blades of the chopper and the frequency of the square wave signal. The first reference signal and the second reference signal are represented by the following formula: X = cos(2 × π × F² × t) Y = sin(2 × π × F² × t) Where X is the first reference signal, Y is the second reference signal, t is the sampling period, F2 is the frequency of the first reference signal, F2=m×F1, m is the number of choppers, and F1 is the frequency of the square wave signal generated according to the encoded value.

2. The optoelectronic signal measuring device of claim 1, wherein, The first acquisition module has the same structure as the second acquisition module, and the first acquisition module includes: A cross-group amplifier is configured to convert the electrical signal corresponding to the transmitted light from a current signal to a voltage signal; An ADC acquisition circuit is configured to acquire the voltage signal to obtain the first electrical signal.

3. A method of measuring an optoelectronic signal, characterized by, The method for a photoelectric signal measuring device as described in any one of claims 1-2 comprises: When no test sample is placed on the sample stage, the electrical signals corresponding to the transmitted light and reflected light output by the chopper are collected respectively. The first reference signal and the second reference signal are obtained according to the encoding value output by the motor encoder and the number of choppers. The two electrical signals are mixed using the first reference signal and the second reference signal respectively to obtain the first complex signal and the second complex signal. The transmittance or reflectance of the test sample is calculated based on two sets of complex signals, wherein the two sets of complex signals include a first complex signal and a second complex signal obtained when the test sample is not placed, and a first complex signal and a second complex signal obtained when the test sample is placed.

4. The photoelectric signal measurement method according to claim 3, characterized in that, The transmittance or the reflectance is obtained by the following formula: ， Wherein, η is the transmittance or the reflectance, R_test1 and R_test2 are the amplitude values ​​of the first complex signal when the test sample is not placed and when the test sample is placed, respectively, and R_ref1 and R_ref2 are the amplitude values ​​of the second complex signal when the test sample is not placed and when the test sample is placed, respectively.

5. The method of measuring an optical signal according to claim 3, wherein The method further includes: The amplitude values ​​of multiple first complex signals are calculated, and the average value of the amplitude values ​​of the multiple first complex signals is calculated as the final amplitude value of the transmitted optical path signal; The amplitude values ​​of multiple second complex signals are calculated, and the average value of the amplitude values ​​of the multiple second complex signals is calculated as the final amplitude value of the reflected optical path; The transmittance or reflectance of the test sample is calculated based on the final amplitude values ​​of the transmitted light path signal and the reflected light path signal obtained with and without the test sample.

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