CN113607046A - Laser interferometry signal processing device and signal subdivision method - Google Patents
Laser interferometry signal processing device and signal subdivision method Download PDFInfo
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Abstract
The invention relates to a laser interferometry signal processing device which comprises a quadruple path polarized light unit, wherein the output end of the quadruple path polarized light unit is connected with the input end of a photoelectric signal conversion unit, the output end of the photoelectric signal conversion unit is connected with the input end of a signal pre-amplification conditioning unit, the output end of the signal pre-amplification conditioning unit is connected with the input end of a signal differential operation unit, the output end of the signal differential operation unit is connected with the input end of an orthogonal signal compensation unit, and the output end of the orthogonal signal compensation unit is connected with the input end of an orthogonal signal difference value subdivision counting unit. The invention also discloses a signal subdivision method of the laser interferometry signal processing device. The invention improves the resolution of the measuring system by 800 times, thereby meeting the high precision requirement of the laser interference measuring system, improving the dynamic capability of the laser interference displacement measuring system, and improving the dynamic frequency measuring response of the system from 0.1 second to 0.04 second.
Description
Technical Field
The invention relates to the technical field of high-precision measurement, in particular to a laser interference measurement signal processing device and a signal subdivision method.
Background
To make interferometers achieve high precision measurements with nanometer-scale accuracy, high resolution is first obtained. At present, there are two main methods for improving the resolution of an interferometer: firstly, interference signals are subdivided through a circuit; the second is to multiply the optical path difference. The laser interference measuring system has limited frequency multiplication of optical path difference due to factors such as structure, and the measurement accuracy provided by the laser interference measuring system depends on a signal processing and subdivision method to a great extent.
The method comprises the following steps of subdividing two periodic orthogonal signals output by an interferometer, wherein if hardware subdivision is adopted, the higher the subdivision number is, the more complex an electronic system is, and the nonlinear error can be added to the system due to noise brought by a processing circuit; if software subdivision is adopted, subdivision is usually realized by using a method of distinguishing trigrams and table lookup, but a program and a tangent table need to be modified to realize high-power subdivision, the software query is slow in subdivision speed, and the method is mainly used for a measuring system with low input signal frequency, and restricts the application of a laser interference measuring system in real-time, high-speed and other scenes to a certain extent.
Disclosure of Invention
The invention aims to provide a laser interference measurement signal processing device which can improve the resolution of a laser interference displacement measurement system so as to meet the requirements of high precision, high speed and real-time dynamic response of the laser interference measurement system.
In order to achieve the purpose, the invention adopts the following technical scheme: a laser interferometry signal processing apparatus comprising:
the quadruple path polarized light unit adopts a polarized beam splitter and a lambda/4 wave plate, and performs 4-time subdivision on the signals by using an optical path difference amplification technology, and the interference fringes perform spatial phase shifting to obtain four paths of interference output light intensity signals E1, E2, E3 and E4 with phases different by 90 degrees in sequence;
the photoelectric signal conversion unit adopts a four-path photoelectric detector to convert four-path light intensity signals E1, E2, E3 and E4 into four-path orthogonal current signals I1, I2, I3 and I4 respectively;
the signal pre-amplification conditioning unit converts current signals I1, I2, I3 and I4 into voltage signals V1, V2, V3 and V4 by adopting I/F conversion setting, and performs post-stage operational amplification and conditioning on the voltage signals V1, V2, V3 and V4 by adopting an amplification circuit, a direct current regulation circuit and a low-pass filter circuit;
the signal difference operation unit eliminates direct current components in signals of two interference light signals with opposite phases of V1, V2, V3 and V4 through an addition circuit to obtain two orthogonal signals with better common mode rejection, sends the two paths of differential interference signals into an analog circuit for further amplification and conditioning, subtracts every two of four paths of voltage signals of V1, V2, V3 and V4 with opposite phases through a subtraction circuit, and outputs orthogonal voltage signals of V5 and V6;
the orthogonal signal compensation unit is used for carrying out high-speed real-time automatic correction and compensation according to an orthogonal vector circle correction model after carrying out A/D high-speed conversion on the orthogonal voltage signals V5 and V6, and synthesizing the voltage signals V5 and V6 into a vector circle signal V7;
the orthogonal signal interpolation subdivision counting unit is used for continuously interpolating vector circle signals V7 in each signal period, counting the signal periods by matching with a 20-bit reversible counter and carrying out 16-bit interpolation subdivision on the signals in two paths of orthogonal signal periods at 8M/S high-speed A/D sampling frequency;
the output end of the quadruple-path polarized light unit is connected with the input end of the photoelectric signal conversion unit, the output end of the photoelectric signal conversion unit is connected with the input end of the signal pre-amplification conditioning unit, the output end of the signal pre-amplification conditioning unit is connected with the input end of the signal differential operation unit, the output end of the signal differential operation unit is connected with the input end of the orthogonal signal compensation unit, and the output end of the orthogonal signal compensation unit is connected with the input end of the orthogonal signal differential value subdivision counting unit.
The orthogonal signal interpolation subdivision unit comprises:
the reversible calculation module adopts a bidirectional counter for forward/reverse parallel counting and 20-bit binary complement codes to count the whole period signals for forward and reverse displacement measurement;
the interpolation module is used for carrying out 16-bit continuous interpolation on the monocycle signals and outputting interpolation numbers in real time;
and the resetting module starts an alarm function and resets the module in time when the relative errors of the direct current level and the amplitude drift of the orthogonal signal are more than 5% and the vector circle signal V7 is abnormal.
Another object of the present invention is to provide a signal subdivision method of a laser interferometry signal processing apparatus, the method comprising the following sequential steps:
(1) initializing, carrying out 4-time signal subdivision on interference fringes through a polarization beam splitter of a quadruple-time polarization light unit and a lambda/4 wave plate, and obtaining four paths of interference output light intensity signals E1, E2, E3 and E4 with phases different by 90 degrees in sequence through spatial phase shifting;
(2) the four-channel detection circuit with differential zero-offset design is adopted to carry out photoelectric conversion through the photoelectric signal conversion unit, and four paths of interference output light intensity signals E1, E2, E3 and E4 of the quadruple-path polarized light unit are converted into current signals I1, I2, I3 and I4 respectively;
(3) then, the current signals I1, I2, I3 and I4 are converted into voltage signals V1, V2, V3 and V4 by a signal pre-amplification conditioning unit and a current conversion voltage circuit, and the voltage signals are subjected to operational amplification and conditioning by an amplifying circuit, a direct current regulating circuit and a low-pass filter circuit;
(4) then two interference light signals with opposite phases of V1, V2, V3 and V4 are eliminated by a signal difference operation unit through a summing circuit to obtain two orthogonal signals with better common mode rejection, the two differential interference signals are sent to an analog circuit for further amplification and conditioning, after passing through each stage of processing circuits in the unit device, four voltage signals with opposite phases are subtracted by a subtraction circuit in pairs, namely V1-V2 and V3-V4, and finally two orthogonal voltage signals V5 and V6 with 90-degree phase difference are obtained;
(5) then, the orthogonal signal compensation unit is used for carrying out A/D high-speed conversion on the two processed orthogonal voltage signals V5 and V6, loading an orthogonal vector circle correction model, carrying out high-speed real-time automatic correction and compensation, and synthesizing the voltage signals V5 and V6 into a vector signal V7;
(6) then, through an orthogonal signal interpolation subdivision counting unit, when the periodic signal is counted, the signal with less than one period is interpolated; and judging whether the orthogonal vector composite signal has interpolation, if not, automatically correcting and then carrying out interpolation subdivision.
The orthogonal vector circle correction model in the step (5) specifically includes:
when two paths of orthogonal signals have non-orthogonality and non-equal amplitude, the component of the vector composite signal V7 in the X, Y axis direction is expressed as:
wherein, I'xIs the component, I ', of the vector signal V7 in the X-axis direction'yAs a component of the vector signal V7 in the Y-axis direction, α represents a non-orthogonal error; g is the ratio of the amplitudes of the two paths of measurement signals; p and q are the direct current drift sizes of the two paths of measurement signals respectively; when α ≠ 0, G ≠ 1, or p ≠ q, the resultant vector circle signal is an ellipse instead of a standard circle, where the relationship of the ellipse equation to G, p, q is described as:
the formula (1-2) is simplified as follows:
wherein, R is the variable radius of the elliptic equation, A, B, C, D, E are respectively different coefficients of the elliptic equation, and the coefficient A is R2cos2α-p2-G2q2-2 Gpqsin α; coefficient B ═ G2(ii) a The coefficient C ═ 2Gsin α; the coefficient D is 2p +2Gqsin α; coefficient E ═ 2G2q+2Gpsinα；
The coefficients A, B, C, D, E are respectively calculated and solved by a multiple linear regression method to obtain alpha, G, R, p and q, which are expressed as the formula (1-4):
with compensation correction, the vector signal synthesis is a standard circular vector signal V7:
the step (6) of determining whether the orthogonal vector composite signal has interpolation, and if not, the step of automatically correcting and then subdividing the interpolation specifically includes:
(6a) firstly, starting judgment, judging whether the relative errors of phase angle orthogonality, direct current level and amplitude drift of an original signal are less than 5%, and automatically correcting and compensating to enable a synthetic vector circle signal V7 to be a standard circle;
(6b) recording the count N of the measured forward and reverse whole-period signals through a 20-bit binary complement reversible calculation circuit;
(6c) then 16-bit interpolation sampling is carried out on the non-full-period signal at the rate of 8M/S, the waveform, the amplitude and the phase of the synthetic vector circular signal V7 are respectively subjected to interpolation sampling, and the signal is subdivided by 200 times by adopting a mapping transformation mode and a subdivision algorithm;
(6d) finally, by synthesizing the signal 4 times subdivision of the quadruple path polarized light unit and the orthogonal signal interpolation counting 200 times subdivision, the 800 times signal subdivision of the laser wavelength lambda of the laser interference displacement measurement system is finally realized, so that the resolution of the laser interference displacement measurement system reaches lambda/800;
(6e) when the relative error of the phase orthogonality, the direct current level and the amplitude drift of the orthogonal signal is larger than 5%, the vector circle signal V7 is distorted, the subdivision counting of the interpolation signal is stopped, and the laser interferometry signal processing device is reset again.
According to the technical scheme, the beneficial effects of the invention are as follows: firstly, the invention eliminates the direct current component of the signal, can improve the quality of the interference signal and realize the measurement signal of the laser interferometer, adopts the high-speed interpolation subdivision technology, and has higher speed and higher dynamic response compared with the traditional subdivision technology. Secondly, the invention adopts a signal subdivision method, firstly subdivides signals by adopting a 4-time double-pass technology, and then realizes 200-time signal subdivision of 16-bit continuous interpolation at high speed through the signal processing device, so that the resolution of a final measurement system is improved by 800 times, and the dynamic response of the system is shortened to 0.01 second.
Drawings
FIG. 1 is a schematic block diagram of the apparatus of the present invention;
fig. 2 is a flow chart of the method of the present invention.
Detailed Description
As shown in fig. 1, a laser interferometry signal processing apparatus includes:
the quadruple path polarized light unit adopts a polarized beam splitter and a lambda/4 wave plate, and performs 4-time subdivision on the signals by using an optical path difference amplification technology, and the interference fringes perform spatial phase shifting to obtain four paths of interference output light intensity signals E1, E2, E3 and E4 with phases different by 90 degrees in sequence;
the photoelectric signal conversion unit adopts a four-path photoelectric detector to convert four-path light intensity signals E1, E2, E3 and E4 into four-path orthogonal current signals I1, I2, I3 and I4 respectively;
the signal pre-amplification conditioning unit converts current signals I1, I2, I3 and I4 into voltage signals V1, V2, V3 and V4 by adopting I/F conversion setting, and performs post-stage operational amplification and conditioning on the voltage signals V1, V2, V3 and V4 by adopting an amplification circuit, a direct current regulation circuit and a low-pass filter circuit;
the signal difference operation unit eliminates direct current components in signals of two interference light signals with opposite phases of V1, V2, V3 and V4 through an addition circuit to obtain two orthogonal signals with better common mode rejection, sends the two paths of differential interference signals into an analog circuit for further amplification and conditioning, subtracts every two of four paths of voltage signals of V1, V2, V3 and V4 with opposite phases through a subtraction circuit, and outputs orthogonal voltage signals of V5 and V6;
the orthogonal signal compensation unit is used for carrying out high-speed real-time automatic correction and compensation according to an orthogonal vector circle correction model after carrying out A/D high-speed conversion on the orthogonal voltage signals V5 and V6, and synthesizing the voltage signals V5 and V6 into a vector circle signal V7;
the orthogonal signal interpolation subdivision counting unit is used for continuously interpolating vector circle signals V7 in each signal period, counting the signal periods by matching with a 20-bit reversible counter and carrying out 16-bit interpolation subdivision on the signals in two paths of orthogonal signal periods at 8M/S high-speed A/D sampling frequency;
the output end of the quadruple-path polarized light unit is connected with the input end of the photoelectric signal conversion unit, the output end of the photoelectric signal conversion unit is connected with the input end of the signal pre-amplification conditioning unit, the output end of the signal pre-amplification conditioning unit is connected with the input end of the signal differential operation unit, the output end of the signal differential operation unit is connected with the input end of the orthogonal signal compensation unit, and the output end of the orthogonal signal compensation unit is connected with the input end of the orthogonal signal differential value subdivision counting unit.
The orthogonal signal interpolation subdivision unit comprises:
the reversible calculation module adopts a bidirectional counter for forward/reverse parallel counting and 20-bit binary complement codes to count the whole period signals for forward and reverse displacement measurement;
the interpolation module is used for carrying out 16-bit continuous interpolation on the monocycle signals and outputting interpolation numbers in real time;
and the resetting module starts an alarm function and resets the module in time when the relative errors of the direct current level and the amplitude drift of the orthogonal signal are more than 5% and the vector circle signal V7 is abnormal.
As shown in fig. 2, the method comprises the following sequence of steps:
(1) initializing, carrying out 4-time signal subdivision on interference fringes through a polarization beam splitter of a quadruple-time polarization light unit and a lambda/4 wave plate, and obtaining four paths of interference output light intensity signals E1, E2, E3 and E4 with phases different by 90 degrees in sequence through spatial phase shifting;
(2) the four-channel detection circuit with differential zero-offset design is adopted to carry out photoelectric conversion through the photoelectric signal conversion unit, and four paths of interference output light intensity signals E1, E2, E3 and E4 of the quadruple-path polarized light unit are converted into current signals I1, I2, I3 and I4 respectively;
(3) then, the current signals I1, I2, I3 and I4 are converted into voltage signals V1, V2, V3 and V4 by a signal pre-amplification conditioning unit and a current conversion voltage circuit, and the voltage signals are subjected to operational amplification and conditioning by an amplifying circuit, a direct current regulating circuit and a low-pass filter circuit;
(4) then two interference light signals with opposite phases of V1, V2, V3 and V4 are eliminated by a signal difference operation unit through a summing circuit to obtain two orthogonal signals with better common mode rejection, the two differential interference signals are sent to an analog circuit for further amplification and conditioning, after passing through each stage of processing circuits in the unit device, four voltage signals with opposite phases are subtracted by a subtraction circuit in pairs, namely V1-V2 and V3-V4, and finally two orthogonal voltage signals V5 and V6 with 90-degree phase difference are obtained;
(5) then, the orthogonal signal compensation unit is used for carrying out A/D high-speed conversion on the two processed orthogonal voltage signals V5 and V6, loading an orthogonal vector circle correction model, carrying out high-speed real-time automatic correction and compensation, and synthesizing the voltage signals V5 and V6 into a vector signal V7;
(6) then, through an orthogonal signal interpolation subdivision counting unit, when the periodic signal is counted, the signal with less than one period is interpolated; and judging whether the orthogonal vector composite signal has interpolation, if not, automatically correcting and then carrying out interpolation subdivision.
The orthogonal vector circle correction model in the step (5) specifically includes:
when two paths of orthogonal signals have non-orthogonality and non-equal amplitude, the component of the vector composite signal V7 in the X, Y axis direction is expressed as:
wherein, I'xIs the component, I ', of the vector signal V7 in the X-axis direction'yAs a component of the vector signal V7 in the Y-axis direction, α represents a non-orthogonal error; g is the ratio of the amplitudes of the two paths of measurement signals; p and q are the direct current drift sizes of the two paths of measurement signals respectively; when α ≠ 0, G ≠ 1, or p ≠ q, the resultant vector circle signal is an ellipse instead of a standard circle, where the relationship of the ellipse equation to G, p, q is described as:
the formula (1-2) is simplified as follows:
wherein, R is the variable radius of the elliptic equation, A, B, C, D, E are respectively different coefficients of the elliptic equation, and the coefficient A is R2cos2α-p2-G2q2-2 Gpqsin α; coefficient B ═ G2(ii) a The coefficient C ═ 2Gsin α; the coefficient D is 2p +2Gqsin α; coefficient E ═ 2G2q+2Gpsinα；
The coefficients A, B, C, D, E are respectively calculated and solved by a multiple linear regression method to obtain alpha, G, R, p and q, which are expressed as the formula (1-4):
with compensation correction, the vector signal synthesis is a standard circular vector signal V7:
the step (6) of determining whether the orthogonal vector composite signal has interpolation, and if not, the step of automatically correcting and then subdividing the interpolation specifically includes:
(6a) firstly, starting judgment, judging whether the relative errors of phase angle orthogonality, direct current level and amplitude drift of an original signal are less than 5%, and automatically correcting and compensating to enable a synthetic vector circle signal V7 to be a standard circle;
(6b) recording the count N of the measured forward and reverse whole-period signals through a 20-bit binary complement reversible calculation circuit;
(6c) then 16-bit interpolation sampling is carried out on the non-full-period signal at the rate of 8M/S, the waveform, the amplitude and the phase of the synthetic vector circular signal V7 are respectively subjected to interpolation sampling, and the signal is subdivided by 200 times by adopting a mapping transformation mode and a subdivision algorithm;
(6d) finally, by synthesizing the signal 4 times subdivision of the quadruple path polarized light unit and the orthogonal signal interpolation counting 200 times subdivision, the 800 times signal subdivision of the laser wavelength lambda of the laser interference displacement measurement system is finally realized, so that the resolution of the laser interference displacement measurement system reaches lambda/800;
(6e) when the relative error of the phase orthogonality, the direct current level and the amplitude drift of the orthogonal signal is larger than 5%, the vector circle signal V7 is distorted, the subdivision counting of the interpolation signal is stopped, and the laser interferometry signal processing device is reset again.
In conclusion, the invention can realize the improvement of the resolution of the laser interference measurement system, the resolution of the measurement system is improved by 800 times by adopting the 4-time subdivision of the optical octave and the high-speed 16-bit continuous interpolation 200 subdivision method of the device, thereby meeting the high-precision requirement of the laser interference measurement system, the dynamic capacity of the laser interference displacement measurement system is improved by adopting the high-speed signal processing and continuous interpolation technology, and the dynamic frequency measurement response of the system is improved from 0.1 second to 0.04 second.
Claims (5)
1. A laser interferometry signal processing apparatus, comprising: the method comprises the following steps:
the quadruple path polarized light unit adopts a polarized beam splitter and a lambda/4 wave plate, and performs 4-time subdivision on the signals by using an optical path difference amplification technology, and the interference fringes perform spatial phase shifting to obtain four paths of interference output light intensity signals E1, E2, E3 and E4 with phases different by 90 degrees in sequence;
the photoelectric signal conversion unit adopts a four-path photoelectric detector to convert four-path light intensity signals E1, E2, E3 and E4 into four-path orthogonal current signals I1, I2, I3 and I4 respectively;
the signal pre-amplification conditioning unit converts current signals I1, I2, I3 and I4 into voltage signals V1, V2, V3 and V4 by adopting I/F conversion setting, and performs post-stage operational amplification and conditioning on the voltage signals V1, V2, V3 and V4 by adopting an amplification circuit, a direct current regulation circuit and a low-pass filter circuit;
the signal difference operation unit eliminates direct current components in signals of two interference light signals with opposite phases of V1, V2, V3 and V4 through an addition circuit to obtain two orthogonal signals with better common mode rejection, sends the two paths of differential interference signals into an analog circuit for further amplification and conditioning, subtracts every two of four paths of voltage signals of V1, V2, V3 and V4 with opposite phases through a subtraction circuit, and outputs orthogonal voltage signals of V5 and V6;
the orthogonal signal compensation unit is used for carrying out high-speed real-time automatic correction and compensation according to an orthogonal vector circle correction model after carrying out A/D high-speed conversion on the orthogonal voltage signals V5 and V6, and synthesizing the voltage signals V5 and V6 into a vector circle signal V7;
the orthogonal signal interpolation subdivision counting unit is used for continuously interpolating vector circle signals V7 in each signal period, counting the signal periods by matching with a 20-bit reversible counter and carrying out 16-bit interpolation subdivision on the signals in two paths of orthogonal signal periods at 8M/S high-speed A/D sampling frequency;
the output end of the quadruple-path polarized light unit is connected with the input end of the photoelectric signal conversion unit, the output end of the photoelectric signal conversion unit is connected with the input end of the signal pre-amplification conditioning unit, the output end of the signal pre-amplification conditioning unit is connected with the input end of the signal differential operation unit, the output end of the signal differential operation unit is connected with the input end of the orthogonal signal compensation unit, and the output end of the orthogonal signal compensation unit is connected with the input end of the orthogonal signal differential value subdivision counting unit.
2. The laser interferometry signal processing apparatus of claim 1, wherein: the orthogonal signal interpolation subdivision unit comprises:
the reversible calculation module adopts a bidirectional counter for forward/reverse parallel counting and 20-bit binary complement codes to count the whole period signals for forward and reverse displacement measurement;
the interpolation module is used for carrying out 16-bit continuous interpolation on the monocycle signals and outputting interpolation numbers in real time;
and the resetting module starts an alarm function and resets the module in time when the relative errors of the direct current level and the amplitude drift of the orthogonal signal are more than 5% and the vector circle signal V7 is abnormal.
3. The signal subdivision method of a laser interferometry signal processing apparatus according to any one of claims 1 to 2, wherein: the method comprises the following steps in sequence:
(1) initializing, carrying out 4-time signal subdivision on interference fringes through a polarization beam splitter of a quadruple-time polarization light unit and a lambda/4 wave plate, and obtaining four paths of interference output light intensity signals E1, E2, E3 and E4 with phases different by 90 degrees in sequence through spatial phase shifting;
(2) the four-channel detection circuit with differential zero-offset design is adopted to carry out photoelectric conversion through the photoelectric signal conversion unit, and four paths of interference output light intensity signals E1, E2, E3 and E4 of the quadruple-path polarized light unit are converted into current signals I1, I2, I3 and I4 respectively;
(3) then, the current signals I1, I2, I3 and I4 are converted into voltage signals V1, V2, V3 and V4 by a signal pre-amplification conditioning unit and a current conversion voltage circuit, and the voltage signals are subjected to operational amplification and conditioning by an amplifying circuit, a direct current regulating circuit and a low-pass filter circuit;
(4) then two interference light signals with opposite phases of V1, V2, V3 and V4 are eliminated by a signal difference operation unit through a summing circuit to obtain two orthogonal signals with better common mode rejection, the two differential interference signals are sent to an analog circuit for further amplification and conditioning, after passing through each stage of processing circuits in the unit device, four voltage signals with opposite phases are subtracted by a subtraction circuit in pairs, namely V1-V2 and V3-V4, and finally two orthogonal voltage signals V5 and V6 with 90-degree phase difference are obtained;
(5) then, the orthogonal signal compensation unit is used for carrying out A/D high-speed conversion on the two processed orthogonal voltage signals V5 and V6, loading an orthogonal vector circle correction model, carrying out high-speed real-time automatic correction and compensation, and synthesizing the voltage signals V5 and V6 into a vector signal V7;
(6) then, through an orthogonal signal interpolation subdivision counting unit, when the periodic signal is counted, the signal with less than one period is interpolated; and judging whether the orthogonal vector composite signal has interpolation, if not, automatically correcting and then carrying out interpolation subdivision.
4. The signal subdivision method of a laser interferometry signal processing apparatus according to claim 3, wherein: the orthogonal vector circle correction model in the step (5) specifically includes:
when two paths of orthogonal signals have non-orthogonality and non-equal amplitude, the component of the vector composite signal V7 in the X, Y axis direction is expressed as:
wherein, I'xIs the component, I ', of the vector signal V7 in the X-axis direction'yAs a component of the vector signal V7 in the Y-axis direction, α represents a non-orthogonal error; g is the ratio of the amplitudes of the two paths of measurement signals; p and q are the direct current drift sizes of the two paths of measurement signals respectively; when α ≠ 0, G ≠ 1, or p ≠ q, the resultant vector circle signal is an ellipse instead of a standard circle, where the relationship of the ellipse equation to G, p, q is described as:
the formula (1-2) is simplified as follows:
wherein, R is the variable radius of the elliptic equation, A, B, C, D, E are respectively different coefficients of the elliptic equation, and the coefficient A is R2cos2α-p2-G2q2-2 Gpqsin α; coefficient B ═ G2(ii) a The coefficient C ═ 2Gsin α; the coefficient D is 2p +2Gqsin α; coefficient E ═ 2G2q+2Gpsinα；
The coefficients A, B, C, D, E are respectively calculated and solved by a multiple linear regression method to obtain alpha, G, R, p and q, which are expressed as the formula (1-4):
with compensation correction, the vector signal synthesis is a standard circular vector signal V7:
5. the signal subdivision method of a laser interferometry signal processing apparatus according to claim 3, wherein: the step (6) of determining whether the orthogonal vector composite signal has interpolation, and if not, the step of automatically correcting and then subdividing the interpolation specifically includes:
(6a) firstly, starting judgment, judging whether the relative errors of phase angle orthogonality, direct current level and amplitude drift of an original signal are less than 5%, and automatically correcting and compensating to enable a synthetic vector circle signal V7 to be a standard circle;
(6b) recording the count N of the measured forward and reverse whole-period signals through a 20-bit binary complement reversible calculation circuit;
(6c) then 16-bit interpolation sampling is carried out on the non-full-period signal at the rate of 8M/S, the waveform, the amplitude and the phase of the synthetic vector circular signal V7 are respectively subjected to interpolation sampling, and the signal is subdivided by 200 times by adopting a mapping transformation mode and a subdivision algorithm;
(6d) finally, by synthesizing the signal 4 times subdivision of the quadruple path polarized light unit and the orthogonal signal interpolation counting 200 times subdivision, the 800 times signal subdivision of the laser wavelength lambda of the laser interference displacement measurement system is finally realized, so that the resolution of the laser interference displacement measurement system reaches lambda/800;
(6e) when the relative error of the phase orthogonality, the direct current level and the amplitude drift of the orthogonal signal is larger than 5%, the vector circle signal V7 is distorted, the subdivision counting of the interpolation signal is stopped, and the laser interferometry signal processing device is reset again.
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| CN114485473A (en) * | 2022-02-21 | 2022-05-13 | 上海电机学院 | Laser interference phase demodulation method based on component synthesis and gradient projection |
| CN117516596A (en) * | 2024-01-05 | 2024-02-06 | 华中科技大学 | High-precision online compensation method of magnetoelectric encoder |
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| CN114485473A (en) * | 2022-02-21 | 2022-05-13 | 上海电机学院 | Laser interference phase demodulation method based on component synthesis and gradient projection |
| CN114485473B (en) * | 2022-02-21 | 2024-01-30 | 上海电机学院 | Laser interference phase demodulation method based on component synthesis and gradient projection |
| CN117516596A (en) * | 2024-01-05 | 2024-02-06 | 华中科技大学 | High-precision online compensation method of magnetoelectric encoder |
| CN117516596B (en) * | 2024-01-05 | 2024-04-26 | 华中科技大学 | High-precision online compensation method of magnetoelectric encoder |
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