Common-Path Interferometric Probe with GRIN Optical Path Compensation
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Solution Overview
Problem
Conventional optical coherence tomography (OCT) systems face issues with optical path differences between light beams due to fiber movement or bending, leading to poor image quality and the need for time-consuming recalibration when probes are replaced, and common-path probes struggle to balance optical path differences and focus reference beams effectively.
Innovation Solution
A common path interferometric probe design incorporating an optical fiber, light guide component, GRIN lens, reflection surface, and beamsplitter surface, where the beamsplitter is positioned at half the length of the collimation part, allowing for equal optical path lengths of reference and sample beams through precise component alignment and reflection, ensuring efficient beam focusing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional common-path probe uses a GRIN lens with the reflection surface at the farthest point from the optical fiber, then the structure is simplified, but the optical path difference between the two light beams cannot be compensated, affecting image quality
Solution Approach 1:
The GRIN lens is divided into two separate components: a collimation lens and a focusing lens. This segmentation allows independent optimization of each lens's function, enabling proper optical path compensation while maintaining structural simplicity. The collimation lens creates parallel light paths, and the focusing lens converges them, achieving the necessary optical path equality without complex adjustments.
Solution Approach 2:
A beamsplitter is introduced as an intermediary component between the optical fiber and the GRIN lens components. This beamsplitter divides the light into reference and sample beams and recombines them, serving as a mediator that enables optical path difference compensation. The beamsplitter's strategic positioning allows it to balance the optical paths while the segmented GRIN lens components focus the beams effectively.
2Manufacturing precision
If the GRIN lens parameters are optimized for sample beam focusing, then the sample beam focusing is improved, but the reference beam focusing spot becomes too large, reducing reference beam collection efficiency
Solution Approach 1:
The GRIN lens system is segmented into two distinct lenses with different functions and parameters. The collimation lens is optimized for creating parallel light paths for the reference beam, while the focusing lens is optimized for concentrating the sample beam. This segmentation allows each lens to be independently optimized for its specific function, resolving the contradiction between sample beam focusing precision and reference beam collection efficiency.
Solution Approach 2:
Different regions of the optical path are given different optical qualities through the use of specialized lens components. The collimation lens provides uniform beam distribution for the reference path, while the focusing lens provides concentrated beam delivery for the sample path. This local optimization of optical properties allows simultaneous achievement of both reference beam efficiency and sample beam focusing precision.
3Ease of operation
If the optical fiber moves or bends during operation, then the probe becomes more flexible and easier to operate, but the optical path difference between the two light beams varies, resulting in bad image quality
Solution Approach 1:
The reference beam and sample beam are merged into a common optical path after the beamsplitter, traveling through the same GRIN lens components and optical fiber. This common-path configuration ensures that any movement or bending of the optical fiber affects both beams equally, maintaining their optical path difference relationship. The merging of paths eliminates sensitivity to fiber disturbances while preserving probe flexibility.
Solution Approach 2:
The interferometric detection mechanism provides feedback on the optical path difference between the reference and sample beams. By monitoring the interference pattern, the system can detect and compensate for any path length variations caused by fiber movement or bending, maintaining stable imaging quality despite physical disturbances to the flexible probe.
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
The design achieves nearly full optical path length compensation, improving image quality by ensuring equal optical path lengths and enhancing reference beam collection efficiency, thus stabilizing imaging performance.
Implementation Method 1
an optical fiber 10, a light guide component 20, a GRIN lens component 30, a reflection surface 40 and a beamsplitter surface 50. The optical fiber has a light transceive end facet 11
Implementation Method 2
The GRIN lens component is configured to focus the light beam and includes a collimation part CP and a focusing part FP connected to each other
Implementation Method 3
The reflection surface is disposed on the first connection end surface of the light guide component and located on one side of the light transceive end facet, and the reflection surface is configured to reflect a reference beam
Implementation Method 4
The beamsplitter surface is disposed in the collimation part and substantially located at half length of the collimation part. The beamsplitter surface and the reflection surface are disposed facing each other, and the beamsplitter surface is configured to reflect the reference beam and allow a sample beam to pass through
Implementation Method 5
When path lengths of the two light beams are equal to each other, there would be interference signals generated for identifying tissues or samples
Data Source
AI summary
A common path interferometric probe for identifying a sample includes an optical fiber, a light guide component, a GRIN lens component and a beamsplitter surface. The optical fiber outputs a light beam. The optical fiber, the light guide component and the GRIN lens component are sequentially connected. The reflection surface is disposed on the light guide component and the beamsplitter surface disposed in the GRIN lens component. When the light beam output from the optical fiber travels through the light guide component and reaches the beamsplitter surface, a part of the light beam is reflected by the beamsplitter surface to form a reference beam, and another part of the light beam passes through the beamsplitter surface to form a sample beam. The reference beam travels back to the optical fiber by undergoing reflections at the reflection surface and beamsplitter surface. The sample beam reaches the sample after traveling through the GRIN lens component, and is reflected by the sample to travel back to the optical fiber.