GRIN Lens Laser Fabrication Pulse Width Control
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Solution Overview
Problem
The existing methods for fabricating gradient-index (GRIN) lenses, such as mechanical polishing, are labor-intensive, expensive, and prone to optical surface variations, which can lead to spherical aberrations and heat accumulation during laser cutting, resulting in non-planar end faces that increase optical losses and require costly and time-consuming processes.
Innovation Solution
The use of laser pulse width duration control to fabricate GRIN lenses by cutting and polishing GRIN rods, preventing heat accumulation and allowing for the creation of planar or substantially planar end faces, which reduces optical losses and facilitates efficient light collimation and bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical polishing is employed to create planar end faces, then optical surface quality is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical polishing system with a laser-based system. Specifically, laser pulses are used to ablate and shape the end faces of optical fibers and GRIN lenses, eliminating the need for mechanical polishing equipment, tools, and manual operations. This substitution maintains optical surface quality while significantly reducing manufacturing complexity and cost.
2Productivity
If laser cutting is employed to create end faces, then manufacturing speed is improved, but heat accumulation causes spherical aberrations
Solution Approach 1:
The patent employs periodic pulsed laser action instead of continuous laser cutting. The laser delivers energy in discrete pulses with specific duty cycles, allowing heat to dissipate between pulses and preventing heat accumulation. This periodic action maintains high manufacturing speed while avoiding spherical aberrations and maintaining optical surface quality.
Solution Approach 2:
The patent dynamically adjusts laser parameters including pulse width, pulse frequency, and duty cycle based on the specific material being processed and the desired end face geometry. This dynamic control allows optimization of both manufacturing speed and optical quality for different scenarios, preventing heat accumulation while maintaining productivity.
3Productivity
If continuous laser exposure is used for polishing, then manufacturing speed is improved, but lens damage or cracking occurs
Solution Approach 1:
The patent uses pulsed laser exposure with controlled duty cycles instead of continuous laser exposure. The periodic on-off nature of the pulsed laser allows heat to dissipate during the off periods, preventing excessive heat accumulation that would cause lens damage or cracking. This maintains manufacturing speed while ensuring lens integrity.
Solution Approach 2:
The patent employs preliminary cooling periods between laser pulses and controls pulse energy levels to prevent heat buildup before it reaches damaging thresholds. This beforehand cushioning approach ensures that thermal energy never accumulates to levels that would cause lens damage or cracking, maintaining both productivity and reliability.
4Reliability
If curved end faces are created through cleaving and polishing, then light coupling is improved, but spherical aberrations increase
Solution Approach 1:
The patent uses pulsed laser ablation to create end faces with optimized curvature profiles. By controlling pulse parameters, the laser can precisely shape the end face to achieve optimal light coupling while avoiding the spherical aberrations that result from traditional mechanical polishing. The periodic pulsed action allows precise control over the material removal process.
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 method enables the production of GRIN lenses with planar end faces, reducing spherical aberrations and optical losses, improving manufacturing throughput, and allowing for easier cleaning and bonding, while avoiding the limitations of mechanical polishing.
Implementation Method 1
controlling the laser to direct a laser beam in pulse width durations in the laser beam path incident to the interface of the GRIN rod to spin cut a planar or substantially planar optical surface end face in the GRIN rod
Data Source
AI summary
Gradient-index (GRIN) lens fabrication employing laser pulse width duration control, and related components, systems, and methods are disclosed. GRIN lenses can be fabricated from GRIN rods by controlling the pulse width emission duration of a laser beam emitted by a laser to laser cut the GRIN rod, as the GRIN rod is disposed in rotational relation to the laser beam. Controlling laser pulse width emission duration can prevent or reduce heat accumulation in the GRIN rod during GRIN lens fabrication. It is desired that the end faces of GRIN lenses are planar to facilitate light collimation, easy bonding or fusing of the GRIN lens to optical fibers to reduce optical losses, polishing to avoid spherical aberrations, and/or cleaning the end faces when disposed in a fiber optic connector, as non-limiting examples.