Fiber Optic Splice Using Sapphire Ferrule for Avionics
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Solution Overview
Problem
Existing fiber optic splicing techniques are inadequate for avionics applications due to difficulties in working with limited space and time, high environmental stress, and the need for precise fiber alignment, leading to inconsistent results and increased costs.
Innovation Solution
A multimode mechanical splice method using a glass ferrule with an alignment bore and index matching gel, combined with crimp sleeves and a backlighting system for visual feedback, allowing for secure fiber alignment and crimping without adhesives, and a specialized cleaving tool for precise fiber preparation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard fiber optic splicing techniques are used, then fiber alignment can be achieved, but the splice fails under environmental conditions (temperature, humidity, mechanical forces)
Solution Approach 1:
The patent changes the material parameter of the alignment bore from standard metal to sapphire crystal, which has superior thermal stability, chemical inertness, and mechanical strength. This material substitution enables the splice to withstand extreme temperature ranges, humidity, and mechanical forces that cause standard splices to fail.
Solution Approach 2:
The invention uses a composite structure combining sapphire crystal alignment bore with metal crimp sleeves and adhesive bonding. The sapphire provides environmental resistance while the metal components provide structural support and crimping capability, creating a composite splice assembly that meets both reliability and environmental adaptability requirements.
2Loss of energy
If precise fiber alignment is required, then signal loss is reduced, but the complexity of the splicing process increases
Solution Approach 1:
The sapphire alignment bore is designed with self-aligning features including tapered lead-in surfaces that automatically guide fiber insertion and positioning. The precise geometry of the alignment bore itself provides the alignment function without requiring additional active alignment mechanisms, reducing process complexity while maintaining low signal loss.
Solution Approach 2:
The invention replaces complex active alignment mechanisms with a passive mechanical alignment system based on precision-machined sapphire geometry. The fixed geometric features of the alignment bore provide consistent alignment without requiring motors, sensors, or complex control systems, thereby reducing device complexity while achieving precise fiber alignment.
3Stability of the object's composition
If adhesive is used to secure fibers, then alignment stability is improved, but the splicing time increases
Solution Approach 1:
The sapphire alignment bore is pre-filled with cyanoacrylate adhesive before fiber insertion. This preliminary preparation eliminates the need for adhesive application during the splicing process itself. Fibers are simply inserted into the pre-adhered bore, where they are immediately secured, thereby maintaining alignment stability while reducing splicing time.
Solution Approach 2:
The patent uses cyanoacrylate adhesive as an intermediary substance between the fiber and the sapphire alignment bore. This fast-curing adhesive provides immediate bonding upon contact with moisture, securing the fiber in the precise position established during insertion, thus achieving both alignment stability and rapid fixation.
4Manufacturing precision
If fiber cleaving precision is increased, then splice quality is improved, but the difficulty of the procedure increases
Solution Approach 1:
The fiber cleaving tool is designed with self-positioning features including a V-groove that automatically centers the fiber and reference surfaces that ensure consistent cleave depth and angle. The tool's geometry itself provides the precision needed for high-quality cleaves without requiring operator skill or complex adjustment mechanisms, thereby improving cleaving precision while maintaining ease of procedure.
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 enables reliable, cost-effective, and efficient splicing in tight spaces with improved alignment and reduced signal loss, meeting stringent military performance specifications and minimizing the need for staggered splices.
Implementation Method 1
The alignment bore is filled with an index matching gel to reduce refraction
Implementation Method 2
The backlighted projecting fiber portions are visually inspected through a view port in the outer splice assembly and through the glass ferrule
Data Source
AI summary
A splicing method and splicing kit are suitable for creating a multimode mechanical splice. The splice may be used, for example, in Aircraft Battle Damage Repair operations. The splice utilizes two cylindrical inner crimp sleeves and an outer crimping assembly. The inner crimp sleeves are placed over prepared fiber cable ends, and the fiber core is cleaved. The cable ends are then inserted into an outer cannula of the outer crimping assembly. The cannula guides the inner crimp sleeves, and the cleaved fiber ends enter a glass ferrule in the cannula. The glass ferrule has a triangular bore containing an index matching gel. A window in the cannula and a magnifying viewer are provided to visually confirm the splice quality. The fibers may be cleaved by forming a circumferential score on the fiber.