Laser Measurement Apparatus Beat Signal Sampling
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Solution Overview
Problem
Optical distance meters using frequency-shifted feedback lasers face reduced measurement accuracy due to electric noise, which is typically mitigated by averaging multiple measurements, increasing measurement time and reducing throughput.
Innovation Solution
A measurement apparatus and method that utilizes a frequency-modulated laser beam with a laser resonator, branching the beam into reference and measurement lights, generating beat signals, converting them into digital signals at a frequency greater than or equal to four times the resonator frequency, and calculating distance based on these signals to improve accuracy and reduce measurement time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If results of multiple measurements are averaged to prevent reduction of measurement accuracy, then measurement accuracy is improved, but measurement time increases and throughput reduces
Solution Approach 1:
The patent segments the measurement process by dividing the laser beam into multiple modes and processing their beat signals separately. By sampling at a frequency ≥4 times the resonator frequency, multiple beat signals are generated simultaneously, allowing parallel processing of multiple measurement channels within a single measurement cycle, thus achieving noise reduction without increasing measurement time
Solution Approach 2:
The patent transitions from temporal averaging (multiple sequential measurements) to frequency-domain processing (simultaneous multi-mode signal processing). By utilizing the frequency dimension and processing multiple beat signals from different laser modes concurrently, the system achieves measurement accuracy improvement without the time penalty of sequential averaging
2Measurement precision
If sampling frequency is increased to expand observation band for beat signals, then measurement accuracy is improved, but data processing complexity increases
Solution Approach 1:
The patent changes the sampling frequency parameter to be ≥4 times the resonator frequency, which expands the observation band for beat signals. This parameter change allows simultaneous capture of multiple beat signal frequencies, improving measurement accuracy while the subsequent signal processing methods manage the complexity of handling the expanded frequency range
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
The solution effectively suppresses the reduction in measurement accuracy while shortening measurement time by expanding the observation band for beat signals and averaging signal components, thereby improving throughput and reducing noise influence.
Implementation Method 1
a laser apparatus that has a laser resonator and outputs a frequency-modulated laser beam with a plurality of modes
Implementation Method 2
a beat signal generation part that generates a plurality of beat signals by mixing the reference light and a reflected light
Data Source
AI summary
A measurement apparatus, including: a laser apparatus that outputs a frequency-modulated laser beam with a plurality of modes; a branching part that branches the frequency-modulated laser beam into a reference light and a measurement light; a beat signal generation part that generates a plurality of beat signals by mixing the reference light and a reflected light that is reflected by radiating the measurement light onto an object to be measured; a conversion part that converts the plurality of beat signals into digital signals by sampling the beat signals at a frequency greater than or equal to four times a resonator frequency of the laser resonator; and a calculation part that calculates a distance from the measurement apparatus to the object to be measured on the basis of the digital signals is provided.