Interferometric Detection With Differential-Sensitivity Optical Sensors
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Solution Overview
Problem
Existing interferometric detection systems face challenges in robustness when detecting quantities of interest with rapid temporal variations or low measurement frequencies, leading to erroneous phase unwrapping due to modulo 2π indeterminacy and ambiguity in phase difference direction.
Innovation Solution
Incorporating optical reference sensors with lower sensitivity than measurement sensors, the system uses both to determine and correct erroneous phase values by comparing instantaneous variations and ratios, ensuring accurate phase unwrapping and improved detection robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high sensitivity measurement sensors are used to detect rapid phase variations, then measurement precision is improved, but phase unwrapping errors increase due to modulo 2π indeterminacy
Solution Approach 1:
The patent introduces reference sensors with lower sensitivity as an intermediary element. These reference sensors produce phase signals that do not suffer from modulo 2π ambiguities, serving as a reliable mediator to correct the phase unwrapping of measurement sensors. The reference phase signal acts as a guide to resolve the indeterminacy in measurement phase unwrapping.
Solution Approach 2:
The patent changes the sensitivity parameter of sensors by using multiple sensors with different sensitivity levels. Measurement sensors have high sensitivity to detect rapid phase variations, while reference sensors have lower sensitivity to provide unambiguous phase references. This parameter differentiation allows simultaneous achievement of high measurement precision and reliable phase unwrapping.
2Use of energy by moving object
If measurement frequency is reduced to lower power consumption, then energy efficiency is improved, but detection robustness deteriorates due to missed phase transitions
Solution Approach 1:
Reference sensors serve as intermediaries that continuously monitor phase variations even when measurement frequency is low. They provide a continuous reference phase signal that captures phase transitions missed by infrequent measurements, enabling reliable correction of measurement phase unwrapping without increasing power consumption.
Solution Approach 2:
The patent applies partial action by having reference sensors operate continuously at low power while measurement sensors operate intermittently. The reference sensors perform the essential function of tracking phase variations, while measurement sensors perform detailed measurements only when needed, achieving energy efficiency without sacrificing detection robustness.
3Device complexity
If single sensor system is used to simplify device structure, then device complexity is reduced, but detection accuracy deteriorates due to phase ambiguity
Solution Approach 1:
The patent segments the sensor system into measurement sensors and reference sensors with distinct functions. Measurement sensors focus on detecting phase variations with high sensitivity, while reference sensors provide unambiguous phase references. This functional segmentation improves measurement accuracy without requiring a completely complex new system architecture.
Solution Approach 2:
Both measurement and reference sensors use the same basic interferometric sensor structure, providing multi-functionality. The same sensor type serves dual purposes: high-sensitivity measurement and unambiguous reference tracking, reducing device complexity while improving accuracy through coordinated operation of multiple sensors.
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
Enhances the robustness of phase difference determination by correcting errors in phase unwrapping, particularly in scenarios with significant phase variations between measurement instants, thereby improving the accuracy of quantity detection.
Implementation Method 1
The optical signals circulating in the two waveguides have a first effective phase difference resulting in a change in the intensity of the output optical signal detected by the photodetector, due to constructive or destructive interference between the optical signals circulating in the two arms
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3C
AI summary
The invention relates to an interferometric detection system (1) comprising at least one measurement optical sensor (10m) comprising a sensitive arm (11m) of sensitivity Sm and a reference arm (12r), and at least one reference optical sensor (10r) comprising a sensitive arm (11r) of sensitivity Sr less than Sm and a reference arm (12r), and a processing unit (4) suitable for correcting an erroneous value of an unfolded phase parameter (Φm,d) determined from the optical signal originating from the measurement optical sensor (10m) on the basis of an unfolded phase parameter (Φr,d) determined from the optical signal originating from the reference optical sensor (10r).