Ball Lens Angled Surface Corrects Sheath Astigmatism
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Solution Overview
Problem
Current medical imaging technologies, particularly in OCT systems, face challenges with astigmatism and chromatic aberration due to the cylindrical shape of the sheath in optical catheters, leading to image degradation and increased complexity, cost, and vulnerability in multimodality OCT systems.
Innovation Solution
The implementation of a ball lens design with a predetermined diameter and angled surface in the optical probe, which uses total internal reflection or mirror coating to focus light with a balanced astigmatism and achromatic performance between 633±10 nm and 1310 nm wavelengths, eliminating the need for additional optical components with asymmetric power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cylindrical sheath is used to protect the optical probe, then the probe is protected from damage and bodily fluids, but astigmatism is introduced causing beam divergence and image degradation
Solution Approach 1:
The patent introduces an asymmetric optical element (prism or cylindrical lens) with specific optical power to counterbalance the asymmetric astigmatism induced by the cylindrical sheath. This asymmetric correction element is positioned at a precise distance from the distal tip to compensate for the sheath's optical distortion, thereby restoring beam focusing accuracy while maintaining probe protection.
Solution Approach 2:
The patent employs an intermediate optical component (prism or cylindrical lens) placed between the light source and the sample to mediate the optical path. This intermediary element corrects the astigmatic distortion caused by the sheath by introducing compensating optical power, enabling the beam to focus properly despite the protective sheath's presence.
2Manufacturing precision
If additional optical components are added to correct astigmatism, then beam focusing is improved, but device complexity and cost increase
Solution Approach 1:
The patent integrates the astigmatism correction function into existing optical components or combines multiple functions (focusing and astigmatism correction) into a single element. By making the optical system multi-functional, the patent avoids adding separate dedicated correction components, thereby reducing overall device complexity while maintaining beam focusing accuracy.
Solution Approach 2:
The patent merges the astigmatism correction function with the existing focusing optics or protective sheath structure. By combining correction and protection functions into a unified design, the patent reduces the number of discrete components needed, simplifying the overall optical system while achieving both protection and precise focusing.
3Strength
If the sheath thickness is increased for better protection, then probe durability is improved, but astigmatism and chromatic aberration are aggravated
Solution Approach 1:
The patent applies preliminary optical correction through a prism or cylindrical lens positioned before the light exits the sheath. This pre-correction compensates for the astigmatism and chromatic aberration that would otherwise be aggravated by the sheath thickness, allowing the use of thicker, more durable sheath material without sacrificing image quality.
Solution Approach 2:
The patent introduces an intermediate optical element (prism or cylindrical lens) that acts as a mediator between the thick protective sheath and the sample. This intermediary component compensates for the optical distortions introduced by the thick sheath, enabling the system to maintain both high durability and high image quality simultaneously.
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 design improves image quality in MMOCT systems by balancing astigmatism and chromatic aberration, simplifying the optical design, reducing costs, and enhancing the robustness of the imaging system without degrading image resolution.
Implementation Method 1
the light is reflected off from the angled surface by total internal reflection and/or by a mirror coating on the angled surface
Implementation Method 2
the reflected light is focused by the curved surface of the ball lens at a working distance with a predetermined beam waist profile
Data Source
AI summary
An optical probe includes first and second light guiding components, and a ball lens arranged along an optical axis and enclosed in a sheath having asymmetric optical power. The probe transmits at least two light beams including first and second beams each having a different wavelength. The ball lens has a curved surface and an angled surface arranged such that light is reflected off from the angled surface and focused by the curved surface at a working distance with a beam waist profile having lateral and longitudinal directions. Beam waist locations of the first and second beams are different from each other, and the beam waist profiles of the first and second beams in the lateral direction differs less than the beam waist profiles in the longitudinal direction. This ball lens design compensates for the sheath asymmetric optical power and provides balanced astigmatism and substantially achromatic performance.