Laser Heterodyne Interferometer Signal Processing with Digital Edge Locking
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Solution Overview
Problem
The quality of laser heterodyne interferometric signals, particularly the gradient of the rising edge, is compromised by noise interference and high-frequency harmonics, leading to inaccurate pulse counting and measurement errors in displacement and speed measurements.
Innovation Solution
A high frequency digital pulse signal is used to lock and process the rising edge of the interferometric signal, enhancing its gradient and eliminating noise-induced errors through a synchronized latching processing module, phase locking, and frequency multiplication, allowing for precise displacement and speed calculations without altering the signal cycle or phase delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional pulse counting method is used for heterodyne interferometric signal processing, then measurement speed is high, but measurement precision deteriorates due to inaccurate trigger time and multiple rising edges caused by noise and high-frequency harmonics
Solution Approach 1:
The patent applies preliminary action by performing rising edge locking and signal shaping before the pulse counting process. The high-frequency digital signal locks the rising edge in advance, and the signal processing module pre-processes the interferometric signal to eliminate noise and harmonics before counting, ensuring accurate trigger timing without affecting measurement speed
Solution Approach 2:
The patent introduces an intermediary signal processing module between the interferometric signal source and the pulse counter. This module includes rising edge locking circuitry and signal shaping components that act as a mediator to clean up the signal and provide clean trigger pulses to the counter, resolving the contradiction by adding functional complexity only where needed
2Measurement precision
If signal filtering is applied to reduce noise and high-frequency harmonics, then signal quality improves, but measurement speed decreases due to additional processing time
Solution Approach 1:
The patent replaces traditional analog filtering mechanisms with digital signal processing methods. The high-frequency digital signal and digital logic circuits perform noise rejection and signal shaping without the bandwidth limitations and phase delays associated with analog filters, maintaining measurement speed while improving signal quality
Solution Approach 2:
The patent changes the parameter of signal processing by operating in the digital domain rather than analog domain. This allows for precise control of signal characteristics through software-defined parameters, enabling noise filtering without sacrificing measurement speed through clever parameter selection and digital processing techniques
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method improves the accuracy and precision of laser heterodyne interferometric measurements by stabilizing the rising edge and eliminating noise-induced errors, ensuring high-speed and high-accuracy displacement and speed measurements.
Implementation Method 1
after being processed by photodetector, signal amplifier, filtering circuit, voltage comparator and high frequency digital edge locking module
Implementation Method 2
outputting, by an external clock signal output by an active crystal oscillator, after being processed by a phase locking and frequency multiplying module, a high frequency digital pulse signal with outputting frequency of f
Implementation Method 3
phase locking and frequency multiplying module
Implementation Method 4
Performing, by the high frequency digital edge locking module, an rising edge locking process to the laser heterodyne interferometric signal using a high frequency digital pulse signal
Implementation Method 5
frequency demodulation, achieving displacement measurement via counting the Doppler frequency directly
Implementation Method 6
laser heterodyne interferometer has advanced features of high measurement speed and accuracy
Data Source
AI summary
The present invention discloses a processing method for laser heterodyne interferometric signal based on locking edge with high frequency digital signal. A reference signal and a measurement signal of heterodyne interferometer, after being processed by photodetector, signal amplifier, filtering circuit, voltage comparator and high frequency digital edge locking module, are transferred to pulse counting synchronized latching processing module, to obtain entire cycle interference fringe numbers and filling pulse numbers in one interference fringe cycle, of the reference signal and the measurement signal; the numbers are transferred to a computer to obtain displacement and speed of a measured object; usage of a high frequency digital pulse signal to lock the rising edge of laser heterodyne interferometric signal can improve the gradient of the rising edge of interference signal and eliminate wrong pulse caused by noises, and improve the accuracy and stability of the processing for the following signals.