Optical Reflectometry Device Using Autocorrelation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional optical low coherence reflectometers require accurate adjustment of the optical path length and are limited by the movable range of the reflective element, making it difficult to measure reflections at various positions in the light propagation direction of a measurement target.
Innovation Solution
A light reflection measurement device that uses a first continuous light source, a second continuous light source as local light, and a signal processing unit to calculate the autocorrelation function between reflected light and shifted light reception signals, allowing reflection measurement without adjusting the optical path length, thereby expanding the measurable distance range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a movable reflective element is used to adjust optical path length for accurate reflection measurement, then measurement precision is improved, but device complexity and ease of operation deteriorate due to required accurate adjustment and stable installation environment
Solution Approach 1:
The patent replaces the mechanical movable reflective element system with a digital signal processing system. Instead of physically moving components to adjust optical path length, the invention uses a delay unit to introduce time delays in the reference light path and an autocorrelation processing unit to process the interference signals. This substitution eliminates mechanical adjustment requirements while maintaining measurement precision.
Solution Approach 2:
The patent changes the parameter of optical path length adjustment from a mechanical physical quantity to a controllable time delay parameter. By using a delay unit with adjustable delay time, the system can precisely control the reference light's arrival time without mechanical movement. The autocorrelation function then processes these time-delayed signals to extract reflection information at different depths.
2Measurement precision
If a movable reflective element is used to measure reflection at different positions, then measurement precision is improved, but ease of operation worsens due to difficulty in performing measurement
Solution Approach 1:
The patent replaces the mechanical movable reflective element system with a digital signal processing system. Instead of physically moving components to adjust optical path length, the invention uses a delay unit to introduce time delays in the reference light path and an autocorrelation processing unit to process the interference signals. This substitution eliminates mechanical adjustment requirements while maintaining measurement precision.
Solution Approach 2:
The autocorrelation processing unit automatically processes the interference signals to extract reflection information without requiring manual adjustment of optical path length. The system performs self-measurement by calculating the autocorrelation function of the received signal, which inherently provides depth-resolved reflection data without operator intervention for positioning.
3Measurement precision
If a movable reflective element is used for reflection measurement, then measurement precision is improved, but the measurable distance range is limited by the movable range of the element
Solution Approach 1:
The patent changes the parameter of optical path length adjustment from a mechanical physical quantity to a controllable time delay parameter. By using a delay unit with adjustable delay time, the system can precisely control the reference light's arrival time without mechanical movement. The autocorrelation function then processes these time-delayed signals to extract reflection information at different depths.
4Measurement precision
If accurate optical system design and stable installation environment are required for OLCR, then measurement precision is improved, but ease of operation worsens
Solution Approach 1:
The patent replaces the mechanical movable reflective element system with a digital signal processing system. Instead of physically moving components to adjust optical path length, the invention uses a delay unit to introduce time delays in the reference light path and an autocorrelation processing unit to process the interference signals. This substitution eliminates mechanical adjustment requirements while maintaining measurement precision.
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 accurate reflection measurement at any position in the light propagation direction without the need for precise optical system adjustments, simplifying the measurement process and increasing the measurable distance range.
Implementation Method 1
an interference signal between reflected light from the measurement target and reflected light from the movable reflective element is used
Implementation Method 2
multiplexing reflected light that is obtained by irradiating a measurement target with one branched light of the first continuous light, reference light that is the other branched light of the first continuous light, and the local light
Data Source
AI summary
The present disclosure is a light reflection measurement device including: a first light source for outputting first continuous light; a second light source for outputting second continuous light as local light; and a signal processing unit for performing digital signal processing on a light reception signal I (t) obtained by multiplexing reflected light that is obtained by irradiating a measurement target with one branched light of the first continuous light, reference light that is the other branched light of the first continuous light, and the local light, in which the signal processing unit calculates an autocorrelation function between the light reception signal I (t) and a light reception signal I (t+τ) obtained by shifting the light reception signal by time τ, and measures reflection on the measurement target by using a position of a peak of the autocorrelation function.