Optical Interferometric Range Sensor With Balanced Coupler Split Ratios
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Solution Overview
Problem
Optical interferometric range sensors face challenges in achieving high measurement accuracy due to non-uniform signal strengths of returning light received by the light receiver from multiple interferometers, which can lower measurement precision.
Innovation Solution
The split ratios of optical couplers in the multiple stages are adjusted based on the first and second split ratios of subsequent stages, with a reducer to control light transmission, ensuring appropriate signal strengths and uniformity, thereby improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple optical couplers are connected in series to transmit light sequentially through multiple interferometers, then the measurement accuracy is improved by using multiple interferometers, but the signal strength of returning light becomes non-uniform across different interferometers
Solution Approach 1:
The patent applies local quality by setting different split ratios for different optical couplers in the series connection. Specifically, the first optical coupler has a first split ratio and the second optical coupler has a second split ratio that is different from the first. This allows each stage of the multi-stage interferometric system to receive appropriate light intensity, ensuring uniform signal strength across all interferometers while maintaining the benefits of multiple interferometers for improved measurement accuracy.
2Measurement precision
If the split ratios of optical couplers are adjusted to equalize signal strengths, then measurement accuracy improves, but the device complexity increases due to precise ratio control requirements
Solution Approach 1:
The patent implements parameter changes by optimizing the split ratios of the optical couplers to specific numerical ranges. The first split ratio is set between 1:4 and 4:1, and the second split ratio is set between 1:2 and 2:1. These specific parameter ranges achieve uniform signal strength distribution across multiple interferometers without requiring complex active control mechanisms, thereby improving measurement accuracy while limiting device complexity to passive optical component selection.
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 optical interferometric range sensor achieves high-accuracy distance measurements by adjusting signal strengths of returning light, reducing variations and enhancing measurement precision.
Implementation Method 1
a wavelength swept light source, multiple optical couplers, multiple interferometers corresponding to the respective optical couplers
Implementation Method 2
generates, from light emitted from a wavelength swept light source, interference light based on reference light and measurement light
Implementation Method 3
a light receiver
Data Source
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AI summary
An optical interferometric range sensor can measure a distance with high accuracy with a light receiver receiving, from each of interferometers, returning light having an appropriate signal strength. An optical interferometric range sensor (100) includes a light source (110) that emits light with a changing wavelength, a plurality of interferometers (130a to 130c) that each generate interference light based on measurement light and reference light, optical couplers (120a to 120c) in a plurality of stages, a light receiver (140a to 140c) that receives the interference light to convert the interference light to an electric signal, and a processor (150) that calculates a distance to a measurement target based on the electric signal resulting from conversion performed by the light receiver. The light received by each of the optical couplers (120a to 120c) in the plurality of stages is split based on a first split ratio for a corresponding interferometer and a second split ratio for an optical coupler in a subsequent stage subsequent to a stage including the optical coupler receiving the light. The first split ratio and the second split ratio are set at least based on the first split ratio of the optical coupler receiving the light and a product of a first split ratio and a second split ratio of the optical coupler in the subsequent stage.