Adjustable Optical Path Length for OCT Depth Imaging
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Solution Overview
Problem
Conventional optical tomographic image photographing apparatuses, such as Fourier domain OCT, suffer from reduced visibility and resolution when imaging portions of the eye far from the depth position where the optical path lengths of measurement and reference lights are equal, making it difficult to observe desired areas with high clarity.
Innovation Solution
An optical tomographic image photographing apparatus with an interference optical system that includes an optical scanner and a movable optical member to adjust the optical path length, allowing for the generation of symmetrical tomographic images by Fourier analysis, and combining normal and inverted images to enhance visibility and resolution across the entire eye area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the optical path length is fixed at a single depth position, then high visibility and high resolution are obtained in the vicinity of that depth position, but visibility and resolution are low in portions far from that depth position
Solution Approach 1:
The patent makes the optical path length adjustable by moving the optical member (e.g., lens or mirror) along the optical axis. This dynamic adjustment allows the system to adapt to different depth positions within the eye, enabling high-resolution imaging at multiple depths rather than being fixed at a single depth position.
Solution Approach 2:
The patent changes the optical path length parameter by physically moving the optical member to different positions. This parameter change allows the system to optimize imaging for different depth regions, transforming a static system into one that can adapt its optical path length to match the desired observation depth.
2Measurement precision
If the optical member is moved to adjust optical path length, then visibility and resolution are improved at different depth positions, but the device complexity increases
Solution Approach 1:
The movable optical member serves multiple functions: it acts as a focusing element and simultaneously adjusts the optical path length. This multi-functionality reduces the need for separate adjustment mechanisms, thereby limiting the increase in device complexity while achieving improved imaging at different depths.
Solution Approach 2:
The patent combines the optical focusing function and optical path length adjustment function into a single movable optical member. By merging these functions, the system avoids adding separate complex adjustment mechanisms, thus improving imaging capability without proportionally increasing device complexity.
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 observation of desired areas with high visibility and resolution, improving image quality by adjusting optical path lengths and combining image modes to compensate for visibility and resolution differences across the eye.
Implementation Method 1
an interference optical system arranged to detect spectral information on interference light of measurement light projected onto an examinee's eye and reference light
Implementation Method 2
obtain two symmetrical tomographic images of a subject portion of the eye symmetric to a depth position, at which an optical path length of measurement light and an optical path length of reference light become equal, by performing Fourier analysis on the detected spectral information
Data Source
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AI summary
An apparatus has an optical system (200) detecting spectral information and having an optical scanner (23) and a driving unit (50) changing the optical path length by moving an optical member (31), a monitor (75), and a unit (70) controlling the driving unit, obtaining a tomographic image by performing Fourier analysis on the information and displaying the obtained image, in which a front surface of an examined object is positioned on the back side of a depth position where optical path lengths of measurement light and reference light become equal to obtain a normal image of the tomographic image, the front surface of the examined object is positioned on the front side of the depth position to obtain an inverted image of the tomographic image, and at least one of dispersion correction processing corresponding to the information and image combining processing is performed on both normal and inverted images, and the images are displayed.