High-frequency digital signal edge locking-based laser heterodyne interference signal processing method
A laser heterodyne interference and signal processing technology, which is applied to devices using optical methods, measuring optics, and optical devices, etc., can solve the problem of false triggering of interference fringe counting pulses, affecting the accuracy of reference signal detection, and inconsistent pulse counting triggering time. Accuracy and other issues, to achieve the effect of eliminating false pulse jumps, improving accuracy and measurement accuracy, and improving steepness
Active Publication Date: 2013-05-01
ZHEJIANG SCI-TECH UNIV
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Problems solved by technology
In the frequency demodulation method of heterodyne interference signal, in the direct pulse counting of the Doppler frequency shift signal to realize displacement measurement, the quality of the signal directly affects the accuracy and stability of the counting. When the heterodyne interference signal is amplified and observed, it is found that the rising edge of the signal is not ideal: on the one hand, the rising edge of the signal is not steep enough, which will lead to inaccurate trigger timing of pulse counting, thus affecting the phase difference detection of the reference signal and the measurement signal On the other hand, the phenomenon of multiple rising edges caused by noise and high-frequency harmonic interference will lead to false triggering of the entire cycle of interference fringe counting pulses, thus affecting the correctness of the measurement results
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[0018] The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.
[0019] In the embodiment of the present invention, the light source of the laser heterodyne interferometer is a dual-frequency He-Ne frequency-stabilized laser, the output laser wavelength is 632.8nm, the frequency difference is 2.26MHz, and the maximum operating frequency of the photodetector is 10MHz. The programmable logic chip (FPGA) of EP2C20Q240C8N realizes the laser heterodyne interference signal processing method based on the edge locking of high-frequency digital signal. The maximum internal operating frequency of the EP2C20Q240C8N chip is as high as 400MHz, the operating frequency of the IO port is 50MHz, and the built-in phase-locked loop.
[0020] The specific implementation is as follows:
[0021] like figure 1 As shown, the implementation steps of the laser heterodyne interference signal processing method based on high-frequency digita...
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The invention discloses a high-frequency digital signal edge locking-based laser heterodyne interference signal processing method. A reference signal and a measurement signal of a laser heterodyne interferometer are transmitted into a pulse counting synchronous latch processing module to obtain full-period interference fringe numbers and filling pulse numbers within an interference fringe period of the reference signal and the measurement signal after being processed by own photodetectors, signal amplifiers, filtering circuits, voltage comparators and high-frequency digital edge locking modules, and the full-period interference fringe numbers and the filling pulse numbers within an interference fringe period of the reference signal and the measurement signal are transmitted to a computer through a serial port communication module to obtain the displacement and the speed of a detected object. A high-frequency digital pulse signal is used for locking the rising edge of a laser heterodyne interference signal, so that the steepness of the rising edge of the interference signal can be improved, error pulses caused by noise interference can be eliminated, a signal period cannot be changed, the phase delay of the rising edge of the signal is eliminated, and the accuracy and the stability of subsequent signal processing are improved. The method is applied to various interference measurement technologies, and the measurement accuracy can be remarkably improved.
Description
technical field [0001] The invention relates to a laser heterodyne interference signal processing method, in particular to a laser heterodyne interference signal processing method based on high-frequency digital signal edge locking. Background technique [0002] Laser heterodyne interferometer has the advantages of fast response speed, high measurement accuracy, strong anti-interference ability, insensitivity to laser light intensity changes and direct traceability to meter definition, etc., so it is widely used in high-precision displacement measurement, ultra-precision Processing and manufacturing and instrument testing and calibration. The signal processing methods of laser heterodyne interferometric displacement measurement can be roughly divided into two categories: one is phase demodulation method, which realizes phase measurement by detecting the phase difference between reference signal and measurement signal, and has the characteristics of high measurement resolutio...
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IPC IPC(8): G01B11/02G01P3/36
CPCG01B9/02002G01J9/02G01B9/02067G01B9/02G01B9/02007G01B9/0207G01B9/02083G01B11/14G01P3/36
Inventor 陈本永张恩政严利平
Owner ZHEJIANG SCI-TECH UNIV