Master-Slave Interferometry for Real-Time Depth Measurement
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Solution Overview
Problem
Current spectral domain interferometry and optical coherence tomography (SDI and SD-OCT) systems require calibration and linearization of data, which is time-consuming and costly, and cannot produce en-face images in real time, limiting their speed and efficiency in imaging and sensing applications.
Innovation Solution
The implementation of Master/Slave Interferometry (MSI) method, where a slave interferometer compares channelled spectra with a master interferometer's reference signal to determine the depth of interest, eliminating the need for calibration and linearization, and allowing for parallel processing of en-face images from multiple depths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional spectral domain interferometry methods are used with calibration and linearization, then measurement precision is improved, but processing time and system complexity increase
Solution Approach 1:
The patent pre-calculates and stores reference channelled spectra for various known path differences in a lookup table during system initialization. During actual measurement, the system simply compares the measured spectrum against these pre-stored references to directly determine depth, eliminating the need for real-time calibration and linearization computations.
Solution Approach 2:
The patent creates a digital copy of reference channelled spectra patterns and stores them in memory. Instead of performing complex mathematical transformations on measured data, the system copies the measured spectrum and compares it directly against stored reference patterns to identify matching path differences, significantly reducing processing time.
2Measurement precision
If traditional spectral domain interferometry methods are used with calibration, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent pre-calculates and stores reference channelled spectra for various known path differences in a lookup table during system initialization. During actual measurement, the system simply compares the measured spectrum against these pre-stored references to directly determine depth, eliminating the need for real-time calibration and linearization computations.
Solution Approach 2:
The patent replaces complex mathematical processing systems (Fourier transforms, calibration algorithms, linearization computations) with a simpler pattern-matching system that compares measured spectra against pre-stored reference patterns. This substitution of computational mechanics with pattern recognition mechanics reduces both device complexity and processing time.
3Measurement precision
If sequential processing of depth information is used, then measurement precision is maintained, but productivity decreases
Solution Approach 1:
The patent segments the spectral data into multiple wavelength ranges, with each range processed by a dedicated processing channel that extracts depth information independently. This parallel segmentation allows simultaneous extraction of depth data from different spectral regions, multiplying the productivity without sacrificing the precision achieved by individual channel analysis.
Solution Approach 2:
The patent transitions from sequential single-depth processing to parallel multi-depth processing by implementing multiple processing channels that simultaneously extract depth information from different spectral segments. This dimensional expansion from one processing stream to multiple concurrent streams enables real-time generation of en-face images at multiple depths.
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
This approach enables real-time, cost-effective generation of en-face images and reflectivity profiles without calibration, significantly speeding up the imaging process and improving the efficiency of SDI and SD-OCT systems.
Implementation Method 1
SD-interferometry and SD-OCT are technologies based on analyzing the spectrum of the interference signal produced between optical signal from an object under investigation and a local optical reference signal
Data Source
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AI summary
The present invention discloses methods and apparatuses for real time depth measurements in sensing in spectral domain interferometry and for en-face and cross section image production in optical coherence tomography. The methods and embodiments presented operate without any need to linearize the data to maximize the output signal and achieve the theoretical depth resolution.A new concept of master –slave interferometry is disclosed, where parameters of a master interferometer dictates the results in a slave interferometer and embodiments are disclosed where the master interferometer can be the same measuring interferometer used in two stages. The parameters of the master interferometer are at least optical path difference (OPD) or the speed of variation of the OPD in the master interferometer. The method and embodiments produce coherence gated data from selected axial positions which can be from positive as well as negative optical path differences,in parallel, that allows generation of en-face(C-scan) OCT images simultaneously from several depths, free from mirror terms,as well as production of A-scans and B-scan OCT images using a plurality of reflectivity values measured in parallel from different depths within A-scans.