Optical Cable Radial Gap Stress Isolation for OCT
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Solution Overview
Problem
Optical coherence imaging diagnostic apparatuses face challenges in maintaining a constant light path length due to the weak tensile strength of optical fibers, which are susceptible to bending, expansion, and contraction, leading to disturbances in optical coherence images.
Innovation Solution
An optical cable with a hollow sheath and a filling member that fixes the optical fiber in place, maintaining a radial gap to prevent external stress from being transmitted to the fiber, ensuring the light path length remains constant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the optical fiber is directly inserted into the driving shaft without protection, then the device complexity is reduced, but the optical fiber is susceptible to bending, expansion, and contraction stresses causing light path length variations
Solution Approach 1:
The optical fiber is nested within a hollow sheath structure, creating a protective enclosure that isolates the fiber from external stresses while maintaining a relatively simple overall cable design
Solution Approach 2:
A filling member is introduced as an intermediary substance between the optical fiber and the hollow sheath, completely filling the radial gap to prevent external stresses from being transmitted to the optical fiber while maintaining light path length stability
2Reliability
If the optical fiber is fixed rigidly along its entire length, then the light path length is maintained, but the cable loses flexibility and becomes difficult to operate
Solution Approach 1:
The filling member is applied selectively to completely fill the radial gap between the optical fiber and hollow sheath, creating localized fixation that maintains light path length stability without compromising overall cable flexibility
Solution Approach 2:
The filling member completely fills the radial gap (excessive action) to ensure no stress transmission occurs, providing sufficient fixation while maintaining operational flexibility
3Device complexity
If the radial gap between the optical fiber and sheath is reduced, then the cable structure is simplified, but external stresses are transmitted to the optical fiber causing image disturbances
Solution Approach 1:
The filling member serves as an intermediary that completely fills the radial gap, preventing direct contact between the hollow sheath and optical fiber, thereby blocking the transmission of external stresses while maintaining structural simplicity
Solution Approach 2:
The filling member is positioned beforehand to completely fill the radial gap, providing protective cushioning that prevents external stresses from reaching the optical fiber before they can cause damage
Data Source
AI summary
An optical fiber is positioned in a lumen of a sheath so a gap exists between the sheath and optical fiber. A filling member fills part of the longitudinal extent of the gap and fixes the optical fiber. The gap is devoid of the filling member over a part of the longitudinal extent of the of the optical fiber so that an air gap exists between the optical fiber and the sheath. In the event bending, expansion and/or contraction are applied to the sheath, the stress is inhibited from being transmitted to the optical fiber. If the sheath is expanded and contracted, one end of the optical fiber is open and so the optical fiber is not expanded/contracted like the sheath expansion and contraction. Consequently, stress is not likely to be transmitted to the optical fiber and so it is possible to maintain a constant length of the optical fiber.