CN116793227A - Device and method for compensating loss error of single-frequency laser interference signal - Google Patents
Device and method for compensating loss error of single-frequency laser interference signal Download PDFInfo
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- CN116793227A CN116793227A CN202310783220.5A CN202310783220A CN116793227A CN 116793227 A CN116793227 A CN 116793227A CN 202310783220 A CN202310783220 A CN 202310783220A CN 116793227 A CN116793227 A CN 116793227A
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- 238000012545 processing Methods 0.000 claims abstract description 30
- 230000003750 conditioning effect Effects 0.000 claims abstract description 19
- 230000003287 optical effect Effects 0.000 claims abstract description 19
- 238000001514 detection method Methods 0.000 claims abstract description 16
- 230000007423 decrease Effects 0.000 claims description 6
- 238000012986 modification Methods 0.000 claims description 5
- 230000004048 modification Effects 0.000 claims description 5
- 238000005070 sampling Methods 0.000 claims description 5
- 238000001228 spectrum Methods 0.000 claims description 5
- 238000006243 chemical reaction Methods 0.000 claims description 2
- 230000001105 regulatory effect Effects 0.000 claims description 2
- 230000001276 controlling effect Effects 0.000 claims 1
- 238000005259 measurement Methods 0.000 abstract description 6
- 238000004364 calculation method Methods 0.000 abstract description 4
- 238000004556 laser interferometry Methods 0.000 description 7
- 238000010586 diagram Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 2
- 230000035559 beat frequency Effects 0.000 description 1
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/4802—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/495—Counter-measures or counter-counter-measures using electronic or electro-optical means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/497—Means for monitoring or calibrating
Abstract
The invention provides a device and a method for compensating loss errors of single-frequency laser interference signals. The device comprises an avalanche diode 1, a negative high-voltage module 2, a transimpedance amplifier 3, a signal conditioning unit 4, a voltage detection unit 5, a voltage control unit 6 and a signal processing unit 7, wherein the method is to compensate the amplitude and direct current bias of the optical power and the AC/DC difference of a four-channel single-frequency laser interference signal by utilizing the phase characteristic of the single-frequency laser interference measurement signal. The method can be used for error compensation of hardware in single-frequency laser signal phase calculation, and effectively reduces the calculation difficulty of a single-frequency laser interference system on error processing, thereby improving the accuracy of phase calculation.
Description
Field of the art
The invention relates to a device and a method for compensating loss errors of single-frequency laser interference signals, belonging to the technical field of optical and electronic engineering.
(II) background art
The single-frequency laser phase resolving technology is widely applied to the fields of industrial manufacture, robot navigation, three-dimensional imaging, terrain measurement and the like and is used for precise measurement. For example, in robot navigation, the robot measures the shape and distance of the surrounding environment using a single frequency laser to determine its own position and movement path.
The main purpose of single frequency laser phase resolution is to measure the distance or shape of an object. After being reflected on the surface of the object, the single-frequency laser returns to the laser emission source, interference fringes are formed through interference, and the phase change of the interference fringes is related to the shape and the distance of the surface of the object. By resolving the phase change of the interference fringes, the shape and distance of the object surface can be calculated.
The power stability of the laser source, the light energy loss in the light path, the device assembly error and other reasons are all easy to cause the difference between the optical power and the AC/DC value of the laser signal output to the phase resolving board by the single-frequency laser interferometer.
In order to solve the problems, the invention designs a device and a method for compensating the loss error of a single-frequency laser interference signal, which are used for compensating the error caused in the single-frequency laser optical path transmission and signal access processes.
(III) summary of the invention
Aiming at the defects of fixed gain, poor environment adaptability, sensitivity to interference generated by the environment, high requirement on the stability of an optical path, large inter-channel difference and the like of the traditional control mode of single-frequency laser interferometry, the invention aims to provide a device and a method for compensating the loss error of a single-frequency laser interference signal, which have the advantages of simple structure, easy operation and adjustment, strong anti-interference performance and small inter-channel error.
The purpose of the invention is realized in the following way:
a single-frequency laser interference signal loss error compensation device is characterized in that: the device consists of an avalanche diode 1, a negative high voltage module 2, a transimpedance amplifier 3, a signal conditioning unit 4, a voltage detection unit 5, a voltage control unit 6 and a signal processing unit 7.
The signal processing unit 7 is connected with the voltage control unit 6 to regulate the negative high-voltage module 2 to output reverse bias voltage;
the signal processing unit 7 is connected with the voltage control unit 6 to output direct current bias and gain control voltage;
the negative high voltage module 2 in the device provides reverse bias to drive the avalanche diode 1;
in the device, a avalanche diode 1 is connected with a transimpedance amplifier 3 to convert an optical signal into a weak electrical signal;
in the device, a transimpedance amplifier 3 is connected with a signal conditioning unit 4 to adjust the weak electric signal gain to an electric signal meeting the optimal sampling range of a voltage detection unit 5.
In the device, a conditioning unit 4 is connected with a voltage detection unit 5 to record the amplitude and average value of a current sampling signal;
the voltage detection unit 5 in the device collects electric signals and sends the electric signals to the signal processing unit 7;
the signal processing unit 7 in the device is used for system control and phase resolution.
The hardware structure of the device will be further described below.
The negative high-voltage module 2 adopted in the device for compensating the loss error of the single-frequency laser interference signal is characterized in that: the module provides avalanche voltage for the avalanche diode 1, and the output voltage is regulated by a negative high voltage control signal output by the signal processing unit 7 to compensate the optical power difference of the single-frequency laser interference signal among channels.
The signal conditioning unit in the single-frequency laser interference signal loss error compensation device comprises the steps of compensating the amplitude and peak-to-peak value of the photoelectric detection signal, filtering thermal noise, shot noise, dark current and other noises generated by photoelectric conversion and a large amount of electronic interference generated by various electronic equipment in the working environment, and compensating the AC/DC difference of the single-frequency laser interference signal among channels.
The signal processing unit 7 adopted in the single-frequency laser interference signal loss error compensation device is characterized in that: the method is used for calculating the copy characteristics and frequency spectrum of the acquired signals, the signal to noise ratio under various working conditions, the reverse bias voltage, the direct current bias voltage and the gain adjustment and increment voltage of the negative high-voltage module.
A single-frequency laser interference loss error compensation method comprises the following steps:
(1) Four laser signals with stable frequency, 90 degrees phase difference and close AC/DC ratio are generated by a single-frequency laser interferometer;
(2) The device FPGA sets a direct-current bias voltage and a gain voltage initial value according to an initial preset optical power value;
(3) The device voltage detection unit 5 samples the output voltage value of the signal conditioning unit in real time;
(4) The device obtains amplitude-frequency characteristic data of the acquired signals through FPGA operation, and calculates the signal-to-noise ratio of the signals under the gain point;
(5) If the signal-to-noise ratio of the signal at the gain point is significantly lower, the voltage control unit 6 adjusts the negative high voltage module to increase/decrease the voltage with the preset reverse bias initial value as the center;
(6) If the signal-to-noise ratio of the signal at the gain point is slightly lower, the voltage control unit 6 adjusts the signal conditioning unit to increase/decrease the voltage by taking the preset gain initial value as the center;
(7) Repeating the steps (4), (5) and (6) until the device finishes measuring the gain point to be measured, and comparing the signal to noise ratio to select the gain with proper signal to noise ratio;
(8) The device discovers a gain point with optimal signal-to-noise ratio, and records the optimal gain point for the next gain selection;
(IV) description of the drawings
FIG. 1 is one embodiment of a single frequency laser interference loss error compensation apparatus: a hardware structure schematic diagram of four-channel single-frequency laser interferometry.
Fig. 2 is a schematic structural diagram of a single-frequency laser interference loss error compensation device.
FIG. 3 is a partial measurement flow diagram containing one embodiment of a single frequency laser interference loss error compensation method.
(fifth) detailed description of the invention
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It will be apparent that the described embodiments are some of the application embodiments of the present invention and are not intended to limit the scope of the invention which can be practiced. Variations or modifications of the embodiments without materially altering the technology content are also considered to be within the scope of the invention as it may be practiced.
Referring to fig. 2, fig. 2 shows an embodiment of an apparatus and method for compensating for interference loss error of a single frequency laser.
The apparatus of fig. 2 is an embodiment of a four-channel single frequency laser interferometry measurement apparatus employing apparatus and method for single frequency laser interferometry signal loss error compensation, where the optical signal input to the apparatus is a laser signal having an optical power, frequency, AC/DC ratio approaching, and having fixed phase differences of 0 °, 90 °, 180 ° and 270 °.
The four channels of the device embodiment have the same hardware structure and consist of an avalanche diode 1, a negative high-voltage module 2, a transimpedance amplifier 3, a signal conditioning unit 4, a voltage detection unit 5, a voltage control unit 6 and a signal processing unit 7, and can commonly use one FPGA.
In the embodiment of the device, a signal processing unit 7 is connected with a four-channel voltage control unit 6 to respectively adjust the negative high-voltage module output reverse bias voltage and the direct current bias and gain control voltage of a signal conditioning unit 4;
in the embodiment of the device, a signal processing unit 7 is connected with a voltage detection unit 5 to record output voltages of four-channel signal conditioning units respectively;
the negative high-voltage module 2 in the device respectively drives the avalanche diode 1 by reverse bias;
in the device, a four-channel avalanche diode 1 is connected with a transimpedance amplifier 3 to convert optical signals respectively input into four channels into electrical signals suitable for sampling;
the four-channel voltage detection unit 5 in the device respectively collects four-channel electric signals and sends the four-channel electric signals to the signal processing unit 7;
the signal processing unit 7 in the device is used for system control and phase calculation, calculates the frequency spectrum of the acquisition signal and calculates the signal to noise ratio according to the frequency spectrum.
In the embodiment, according to the basic principle of single-frequency laser interferometry, due to the Doppler frequency shift effect, the device receives a sinusoidal light intensity signal, the beat frequency of the light intensity generated by the single-frequency laser interferometer changes along with the change of the moving speed of the measured object, and when the object is stationary, the light intensity generated by the single-frequency laser interferometer is a direct current light intensity signal which does not contain an AC state.
In the embodiment, the error compensation mode of the device is as follows: the signal processing unit 7 calculates the reverse bias voltage, the direct current bias voltage and the gain control voltage output by the signal-to-noise ratio adjusting voltage control unit 6 according to the frequency spectrum, controls the negative high voltage module 2 to output avalanche voltage suitable for each path of optical power, and controls the signal conditioning unit 4 to adjust each path of AC/DC value to be the same. The voltage control unit 6 can select a multichannel low-speed high-precision DAC, and the resolution of the DAC affects the voltage control step size.
Referring to fig. 3, fig. 3 shows an embodiment of error compensation in a single frequency laser interferometry specific measurement process, namely:
(1) The measuring optical signals of the device are laser signals with the optical power and the approximate AC/DC ratio, the frequency is stable, the fixed phase differences of 0 DEG, 90 DEG, 180 DEG and 270 DEG exist, and the four-way signals are all light intensity signals without AC characteristics because the measured object is static;
(2) Entering an error compensation flow;
(3) The four-channel voltage detection unit 5 of the device of the embodiment acquires the amplitude and average value of the signal conditioning unit 4 and sends the data to the signal processing unit 7;
(4) The signal processing unit 7 of the device of the embodiment sets the initial values of the direct current bias voltage and the gain voltage according to the preset optical power value;
(5) The device of the embodiment obtains amplitude-frequency characteristic data of the signals collected under the current working condition through the operation of the signal processing unit 7, and calculates the signal-to-noise ratio of the gain point;
(6) The embodiment device adjusts the reverse bias voltage value according to the preset optical power value, and increases or decreases the gain voltage value according to the set step length;
(7) The device of the embodiment uses the signal processing unit 7 to calculate the amplitude-frequency characteristic of the input signal, and calculates the signal-to-noise ratio of the signal according to the preset frequency of the signal;
(8) The embodiment device adjusts the direct current bias and the gain control voltage value by a preset AC/DC value, and increases or decreases the gain voltage value according to the set step length;
(9) The device of the embodiment uses the signal processing unit 7 to calculate the amplitude-frequency characteristic of the input signal, and calculates the signal-to-noise ratio of the signal according to the preset frequency of the signal;
(10) Repeating the step (6), the step (7), the step (8) and the step (9) until the gain of the optimal signal to noise ratio is measured, and calculating and storing the current gain;
(11) Ending the single-frequency laser interferometry error compensation flow;
the examples are merely illustrative of the principles of the present invention and its efficacy, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.
Claims (7)
1. A single-frequency laser interference signal loss error compensation device is characterized in that: the device consists of an avalanche diode 1, a negative high voltage module 2, a transimpedance amplifier 3, a signal conditioning unit 4, a voltage detection unit 5, a voltage control unit 6 and a signal processing unit 7.
The single-frequency laser interference signal in the device is a laser signal with optical power and an AC/DC ratio close to each other, the frequency is stable, and a fixed phase difference of 0 degree, 90 degrees, 180 degrees and 270 degrees exists;
the signal processing unit 7 is connected with the voltage control unit 6 to regulate the negative high-voltage module 2 to output reverse bias voltage;
the signal processing unit 7 is connected with the voltage control unit 6 to output direct current bias and gain control voltage;
the negative high voltage module 2 in the device provides reverse bias to drive the avalanche diode 1;
in the device, a avalanche diode 1 is connected with a transimpedance amplifier 3 to convert an optical signal into a weak electrical signal;
in the device, a transimpedance amplifier 3 is connected with a signal conditioning unit 4 to adjust the weak electric signal gain into an electric signal meeting the sampling range of a voltage detection unit 5;
the conditioning module 4 in the device is connected with the voltage detection unit 5 to record the amplitude and average value of the current sampling signal;
the voltage detection unit 5 in the device collects electric signals and sends the electric signals to the signal processing unit 7;
the signal processing unit 7 in the device is used for system control and phase resolution.
2. The negative high voltage module 2 used in the device for compensating loss error of single frequency laser interference signal according to claim 1, characterized in that: the avalanche voltage provided by the module to the avalanche diode 1 is regulated by a negative high voltage control signal output by the signal processing unit 7.
3. The signal conditioning unit in the device for compensating loss error of single-frequency laser interference signal according to claim 1, wherein the signal conditioning unit compensates amplitude and peak-to-peak value of the photodetection signal, and filters thermal noise, shot noise, dark current and other noise generated by photoelectric conversion and a large amount of electronic interference generated by various electronic devices in the working environment.
4. The signal processing unit 7 used in the apparatus for compensating loss error of single frequency laser interference signal according to claim 1, characterized in that: the method is used for calculating the amplitude characteristics and the frequency spectrum of the acquired signals and the signal to noise ratio under various working conditions, and controlling the reverse bias voltage, the direct current bias voltage and the gain adjustment and increment voltage of the negative high-voltage module.
5. A method for compensating loss error of single-frequency laser interference signals comprises the following steps:
(1) Four laser signals with stable frequency, 90 degrees phase difference and close AC/DC ratio are generated by a single-frequency laser interferometer;
(2) The device signal processing unit 7 sets a DC bias voltage and a gain voltage initial value according to an initial preset optical power value;
(3) The device voltage detection unit 5 samples the output voltage value of the signal conditioning unit in real time;
(4) The device obtains amplitude-frequency characteristic data of the acquired signals through the operation of the signal processing unit 7, and calculates the signal-to-noise ratio of the signals under the gain point;
(5) If the signal-to-noise ratio of the signal at the gain point is significantly lower, the voltage control unit 6 adjusts the negative high voltage module to increase/decrease the voltage with the preset reverse bias initial value as the center;
(6) If the signal-to-noise ratio of the signal at the gain point is slightly lower, the voltage control unit 6 adjusts the signal conditioning unit to increase/decrease the voltage by taking the preset gain initial value as the center;
(7) Repeating the steps (4), (5) and (6) until the device finishes measuring the gain point to be measured, and comparing the signal to noise ratio to select the gain with proper signal to noise ratio;
(8) The device finds the gain point with the optimal signal-to-noise ratio and records the optimal gain point for the next gain selection.
6. The preset gain according to claim 5, wherein: the theoretical signal-to-noise ratio of the avalanche diode 1 currently used is the optimum gain or the signal-to-noise ratio measured last time is the optimum gain.
7. The voltage modification according to claim 5, wherein the voltage output from the voltage control unit 6 is controlled by the signal processing unit 7, and the step size of the modification is determined.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202310783220.5A CN116793227A (en) | 2023-06-29 | 2023-06-29 | Device and method for compensating loss error of single-frequency laser interference signal |
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| CN202310783220.5A CN116793227A (en) | 2023-06-29 | 2023-06-29 | Device and method for compensating loss error of single-frequency laser interference signal |
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| CN116793227A true CN116793227A (en) | 2023-09-22 |
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| CN202310783220.5A Pending CN116793227A (en) | 2023-06-29 | 2023-06-29 | Device and method for compensating loss error of single-frequency laser interference signal |
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