Side-Fire Optical Device with Beveled Fused Quartz Cap
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Solution Overview
Problem
Conventional side fire optical fiber devices for medical procedures face issues with thermal stress-induced fracturing, devitrification, and inefficient energy delivery due to residual stresses and high Fresnel reflections, especially with modern high-power surgical lasers, leading to inaccurate and distorted output patterns.
Innovation Solution
A side fire optical device with a solid cylindrical cap made of fused quartz or silica, featuring a beveled surface for orthogonal light redirection, and a metallic shroud for protection, allowing for interchangeable caps and adjustable output spot size and divergence without altering the fiber design, reducing Fresnel and Snell reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a beveled optical surface is machined and polished directly upon the transmitting optical fiber conduit to redirect electromagnetic radiation, then the device can achieve lateral radiation of laser light, but the cap is subjected to thermal cycling stresses that induce fracturing and devitrification
Solution Approach 1:
The device is divided into separate components: the optical fiber conduit and the protective cap are distinct elements that can be assembled together. This segmentation allows the cap to be optimized for thermal resistance while the fiber conduit maintains its optical properties, resolving the contradiction between lateral radiation capability and cap durability.
Solution Approach 2:
An intermediary structure is introduced between the optical fiber conduit and the external environment. The protective cap serves as this intermediary, providing thermal protection and mechanical support to the fiber conduit while enabling lateral radiation through its designed optical interface.
2Power
If high-power surgical lasers are utilized to perform medical procedures, then the energy delivery capability is improved, but thermal stress-induced fracturing and devitrification of the cap occur more frequently
Solution Approach 1:
The material parameters of the protective cap are changed to withstand high-power laser operation. The cap is designed with materials and structures that have higher thermal conductivity and thermal shock resistance, allowing it to dissipate and withstand the thermal stresses generated by high-power surgical lasers without fracturing or devitrifying.
3Reliability
If the cap surface is protected with a circumferential protective cap made of fused quartz or fused silica, then total reflection is maintained, but Fresnel reflections cause energy loss and distorted output patterns
Solution Approach 1:
Different regions of the optical interface are given different optical properties. The local quality of the cap surface is optimized to minimize Fresnel reflections at specific angles while maintaining total internal reflection at the critical angle. This selective optimization reduces energy loss without compromising the reliability of total reflection for lateral radiation.
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 solution enhances the durability and precision of the optical device by minimizing thermal damage and improving energy delivery, allowing for precise control of the output spot and reducing the need for multiple fibers, thus enhancing surgical efficiency and cost-effectiveness.
Implementation Method 1
Conventional side fire optical devices operate by reflecting the electromagnetic radiation off of a beveled optical surface that is machined and polished directly upon the transmitting optical fiber conduit, exploiting total reflection at or below the critical angle as described by Snell's Law.
Implementation Method 2
reflecting the electromagnetic radiation off of a beveled optical surface that is machined and polished directly upon the transmitting optical fiber conduit, exploiting total reflection at or below the critical angle as described by Snell's Law.
Implementation Method 3
Both transient and sustained high temperatures at the transmitting surface of the cap accelerate the endothermic absorption of alkali metal ions within the quartz that form the cap, lowering viscosity sufficiently to permit rearrangement of the amorphous glass into high crystobalite; the cap undergoes devitrification.
Implementation Method 4
a metallic shroud for protection
Data Source
AI summary
Herein is described a side firing optical device for minimal output reflections (scatter) in a one-piece lateral output assembly within which a transmitting optical fiber conduit is disposed providing redirected electromagnetic radiation with operator control of the output beam characteristics. The herein disclosed lateral redirecting device permits ergonomic free rotation of the lateral output beam with positive orientation, provides focus-control of the output beam spot size and/or focus, and provides resposable components, both intraoperatively and interoperatively.