Optical Interference Range Sensing with Dual Sweep Averaging
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Solution Overview
Problem
Conventional optical interference range sensors struggle to accurately measure the distance to vibrating objects due to fluctuations caused by the Doppler effect, especially when the distance changes with acceleration.
Innovation Solution
An optical interference range sensor that calculates an average distance value based on multiple measurements using different sweep frequency patterns, reducing fluctuations by alternating between first and second sweep frequency patterns, and converting electrical signals to frequency spectra for precise distance measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical interference range sensors measure distance to vibrating objects, then distance measurement is performed, but measurement precision deteriorates due to fluctuations caused by the Doppler effect when distance changes with acceleration
Solution Approach 1:
The patent applies periodic action by alternating between first and second sweep frequency patterns in a periodic manner. The light source projects light beams using these alternating patterns, and the processing unit calculates average distance values based on measurements from both patterns. This periodic alternation causes the Doppler shift fluctuations to cancel each other out when averaged, thereby improving measurement precision and stability for vibrating objects.
2Measurement precision
If the light source uses a single sweep frequency pattern continuously, then the measurement process is simple, but measurement precision deteriorates due to accumulated Doppler shift errors
Solution Approach 1:
The patent applies parameter changes by varying the sweep frequency pattern parameter between two distinct patterns (first and second patterns). The processing unit calculates average distance values by combining measurements from both patterns, which compensates for Doppler shift errors. This parameter alternation improves measurement precision without requiring complex real-time adjustments, maintaining reasonable system complexity.
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
Enables highly accurate distance measurement to vibrating objects by minimizing shifts caused by acceleration, ensuring high precision even when the target's distance changes.
Implementation Method 1
generate an interference beam by interference between a reference beam and a measurement beam from a light beam projected from a wavelength-swept light source
Implementation Method 2
a light-receiving unit that receives the interference beam and converts it to an electrical signal
Implementation Method 3
the processing unit converts the electrical signal to a frequency spectrum and measures the distance to the measurement target based on the frequency spectrum
Data Source
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AI summary
The distance to a measurement target is measured with high accuracy even if the distance changes with acceleration. An optical interference range sensor 100 includes: a light source 110 configured to project a light beam while continuously varying a wavelength thereof using a predetermined sweep frequency pattern; a processing unit 150 configured to measure the distance to a measurement target based on an electrical signal converted by a light-receiving unit 130; and a storage unit 140 configured to store distance information indicating the measured distance. The predetermined sweep frequency pattern includes a first sweep frequency pattern and a second sweep frequency pattern. The processing unit includes an average distance value calculation unit 153 configured to calculate an average distance value based on the measured distance, first distance information indicating a distance based on a light beam projected using the first sweep frequency pattern, and second distance information indicating a distance based on a light beam projected using the second sweep frequency pattern, of past distance information regarding multiple measurements stored in the storage unit.