Interferometer Path Length Switching for Depth Resolution
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Solution Overview
Problem
Conventional interferometric systems face limitations in measuring depth due to resolution constraints, depth of field, and axial resolution, making it difficult to generate deep section images with an acceptable signal-to-noise ratio, especially when quickly switching between different depths for moving samples.
Innovation Solution
A method and device that utilize a path length switching unit, preferably in the sample arm of an interferometer, to rapidly switch optical paths between positions, allowing for adjustments in focus position, imaging geometry, and dispersion, enabling extended measuring depth with minimal dead time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the path length difference is changed to adjust the measurement depth, then the measurement depth can be extended, but the switching time becomes too long for fast-moving samples
Solution Approach 1:
The patent applies dynamics by making the reference arm length adjustable through a movable mirror positioned on a translation stage. This allows the system to dynamically adapt the reference arm length to match different sample depths, enabling fast switching between depth positions without requiring physical movement of the entire interferometer or sample stage.
Solution Approach 2:
The patent changes the parameter of reference arm length to extend measurement depth. By varying the reference arm length through the movable mirror mechanism, the system can quickly adjust to different depth positions, solving the contradiction between extending measurement depth and maintaining fast switching capability.
2Length of stationary object
If the focus position is adjusted to extend measurement depth, then deeper areas can be imaged, but the lateral resolution deteriorates
Solution Approach 1:
The system dynamically adjusts the reference arm length independently of the focus position. By separating the depth adjustment mechanism (reference arm length change) from the focus adjustment mechanism, the system can extend measurement depth without compromising lateral resolution, as the optical elements remain optimally focused while only the reference path length changes.
3Measurement precision
If the dispersion is adjusted to match for a single depth, then axial resolution is optimized, but the system cannot quickly switch between different depths
Solution Approach 1:
The patent makes the reference arm length dynamically adjustable, allowing the system to quickly switch between different depth positions by changing the reference arm length. This dynamic adjustment capability enables the system to maintain optimal dispersion matching for axial resolution while rapidly transitioning between different depth planes, significantly improving depth switching speed.
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 the generation of interferometric depth sectional images at different depths with improved signal-to-noise ratio and extended measuring depth, facilitating the creation of deep section images with reduced effort and increased reliability.
Implementation Method 1
A linearly movable electrical unit with a mirror is present in the sample path. The sample beam striking the mirror is reflected in the same direction as the mirror.
Data Source
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AI summary
A method and apparatus including an interferometer is provided for sequentially recording interferometric sectional images at different depths, in particular for analyzing an eye. By use of an interferometer, which includes an optical reference path and an optical sample path, a sample beam scans a measuring region of a sample, in particular of an eye, so as to generate a deep sectional image. The optical and geometric paths in a sample arm and/or reference arm of the interferometer can be switched quickly between two or more positions. The path length of the sample beam and/or of the reference beam is changed by way of a path length switching unit, deep sectional images are generated at least at two different depths of the sample, and the change of the path length in the switching unit takes place by deflection of the beam paths to different geometric paths.