Spectrally Encoded Endoscope Probe Alignment
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Solution Overview
Problem
The alignment of distal optics in miniature spectrally encoded endoscopic probes is challenging due to their small size, leading to fabrication complexities and optical aberrations, particularly in forward-viewing designs where the illumination fiber is off-axis to the GRIN lens, resulting in obscured areas in the field of view.
Innovation Solution
A method is developed to align the light guiding, focusing, and diffusing components within a drive cable such that at least one wavelength of the dispersed light line goes in the direction of the cable axis, ensuring proper alignment and minimizing obscuration by using active alignment techniques during fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If forward-viewing SEE probe design is used, then imaging capability is improved, but fabrication complexity increases
Solution Approach 1:
The patent combines the illumination fiber, GRIN lens, and diffraction grating into a single integrated distal tip assembly. This merging of components simplifies the overall fabrication process while maintaining the forward-viewing imaging capability, as the components work together in a unified structure rather than requiring separate alignment of multiple independent elements.
Solution Approach 2:
The patent employs preliminary alignment actions during fabrication by pre-positioning the diffraction grating at a specific angle relative to the optical axis before final assembly. This preliminary action ensures that the dispersed light line is properly oriented, reducing the need for complex post-fabrication adjustments and simplifying the overall manufacturing process.
2Ease of operation
If off-axis illumination fiber arrangement is used, then forward viewing is achieved, but optical aberrations increase
Solution Approach 1:
The patent intentionally introduces asymmetry by arranging the illumination fiber off-axis relative to the GRIN lens. This asymmetric configuration enables forward-viewing capability while the subsequent angular positioning of the diffraction grating compensates for the resulting optical aberrations, achieving a balance between operational ease and manufacturing precision.
Solution Approach 2:
The patent changes the angular parameter of the diffraction grating relative to the optical axis. By adjusting this angular parameter, the system compensates for optical aberrations introduced by the off-axis fiber arrangement, maintaining image quality while preserving forward-viewing functionality.
3Reliability
If multiple components are used in forward-view probe, then imaging function is improved, but alignment difficulty increases
Solution Approach 1:
The patent performs preliminary alignment of the diffraction grating at a predetermined angle during the fabrication process itself, rather than requiring complex alignment measurements after assembly. This preliminary action significantly reduces alignment difficulty by establishing the correct geometric relationship between components before final integration.
Solution Approach 2:
The patent replaces complex mechanical alignment systems with a simplified approach where the diffraction grating is positioned at a fixed angular relationship to the optical axis. This substitution eliminates the need for complex alignment mechanisms and measurement systems, reducing alignment difficulty while maintaining imaging function.
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 ensures that the entire field of view is appropriately illuminated, reducing distortion and improving imaging quality, even in small optics, by accurately positioning the spectrally dispersed light line along the probe axis, thereby enhancing the resolution and minimizing fabrication errors.
Implementation Method 1
broadband light is diffracted by a grating at the distal end of an optical fiber to produce a dispersed spectrum of different wavelengths (colors) on a sample
Implementation Method 2
Spectrally-encoded endoscopy utilizes the ability of the diffraction grating that deflects incident light to a diffraction angle according to wavelength
Implementation Method 3
a light focusing component... such that light which is put into the proximal end of light guiding component can emit from the distal end thereof focused by the focusing component onto the light diffusing component
Implementation Method 4
When the deflected light hits an object, light is scattered by the object. Detecting the scattered light intensity at each wavelength is equivalent to detecting the intensity from the corresponding diffraction angle
Data Source
AI summary
A forward-viewing spectrally encoded endoscope (SEE) probe includes a light guiding component, a light focusing component, and a grating component arranged along a longitudinal axis of a drive cable. The SEE probe is configured for guiding light from the light guiding component, through the light focusing component, and to the grating component, and then forwarding a spectrally dispersed light line from the grating component towards an image plane. One or more of the light guiding component, the light focusing component, and the grating component is arranged at an angle with respect to the longitudinal axis of the drive cable so that at least one wavelength of the spectrally dispersed light line goes to the direction of axis of the drive cable.