Interferometer Clock Generator for High-Speed OCT Sampling
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Solution Overview
Problem
Current OCT apparatuses face challenges in obtaining comprehensive tomographic images of the fundus with a wider angle of view and desired depth range using swept-source OCT, requiring expensive equipment and lengthy image processing due to the need for high-speed sampling and maintaining equal wavenumber properties.
Innovation Solution
The proposed imaging apparatus employs a clock generator with an interferometer having an optical path length difference, utilizing multiple A/D converters to generate a clock with a frequency n times the original, enabling high-speed and cost-effective sampling of interference signals across a wide area with a single scan operation, and maintains equal wavenumber intervals through a k-clock generator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multiple A/D converters are used with interleaving operation to achieve high-speed sampling, then the sampling frequency increases, but the device complexity and cost increase
Solution Approach 1:
The patent divides the high-speed sampling task into multiple parallel A/D converters operating at lower frequencies. Each converter handles a portion of the signal through interleaving, achieving the required sampling rate without needing a single expensive high-speed converter. The clock signal is also segmented into multiple phase-shifted clocks to coordinate the parallel conversion operations.
2Area of stationary object
If the scan angle is increased to achieve wider angle of view, then the observable area increases, but the depth range coverage becomes insufficient
Solution Approach 1:
The patent changes the optical path length difference parameter in the interferometer to correspond to the desired depth range. By carefully selecting and adjusting this parameter, the system achieves both wide angle of view and adequate depth range coverage simultaneously, resolving the trade-off between these two parameters.
3Measurement precision
If the optical path length difference is increased to maintain equal wavenumber property, then the sampling accuracy improves, but the coherence length requirement becomes more stringent
Solution Approach 1:
The patent optimizes the optical path length difference parameter to achieve the required sampling accuracy while maintaining feasibility. By carefully selecting this parameter within practical limits, the system maintains equal wavenumber property without requiring excessively long coherence lengths, thus balancing precision with device feasibility.
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 configuration allows for the comprehensive acquisition of tomographic images over a wide angle of view and desired depth range with improved diagnostic efficiency and accuracy, reducing the need for expensive equipment and processing time.
Implementation Method 1
the interference unit is configured to generate interference light obtained by interference of reflection light reflected from the fundus irradiated with the irradiation light with the reference light
Implementation Method 2
The clock generator is configured as an interferometer including an optical path through which part of the light emitted from the light source passes, the optical path being split into a first optical path and a second optical path having an optical path length difference relative to the first optical path, to generate a clock used by the converter sampling the analog signal at a frequency corresponding to the optical path length difference
Data Source
AI summary
An imaging apparatus includes a converter configured to convert an analog signal obtained from detected interference light into a digital signal and a clock generator configured as an interferometer including an optical path through which part of light emitted from a light source passes, the optical path being split into a first optical path and a second optical path having an optical path length difference therebetween, to generate a clock used by the converter sampling the analog signal at a frequency corresponding to the optical path length difference. The converter includes n A/D converters, n being an integer of at least 2, and is configured to change phases of n clocks obtained from the clock to produce a phase difference therebetween, and to generate a clock having an n-times frequency from the n clocks and n analog signals obtained from the analog signal using the n A/D converters.