Sapphire UV Output Mirror Without Multilayer Film Degradation
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Solution Overview
Problem
Existing ultraviolet laser apparatuses face challenges with chromatic aberration due to wide spectral line widths, leading to decreased resolution, and the output mirrors suffer from deterioration with increased output, necessitating a more durable solution.
Innovation Solution
An output mirror for ultraviolet laser beams using a plate-shaped sapphire substrate with a partial reflective surface and a reflection suppressing structure, eliminating the need for dielectric multilayer films, thereby enhancing durability and reducing chromatic aberration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dielectric multilayer film is formed on the output mirror to control reflectivity, then the reflectivity can be precisely controlled, but the mirror deteriorates with increased laser output
Solution Approach 1:
The patent extracts and removes the dielectric multilayer film from the output mirror structure, using only the intrinsic reflective properties of the sapphire substrate. This eliminates the deterioration problem caused by film degradation under high laser output while maintaining the necessary reflectivity control through the substrate's natural optical properties.
Solution Approach 2:
The patent changes the material parameter from a composite structure (substrate + dielectric film) to a single material (sapphire substrate), utilizing the inherent optical parameters of sapphire to achieve the desired reflectivity without additional coatings that would deteriorate under laser irradiation.
2Power
If the spectral line width is widened, then the laser output energy increases, but chromatic aberration occurs in the projection lens
Solution Approach 1:
The patent utilizes the natural spectral properties of the sapphire substrate to maintain a narrow spectral line width while achieving high output energy. The intrinsic optical characteristics of sapphire allow for precise wavelength control, preventing chromatic aberration in the projection lens while maintaining the necessary laser power for exposure.
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 sapphire-based output mirror maintains high durability and reduces chromatic aberration, ensuring stable performance even with high-energy density laser outputs.
Implementation Method 1
reflects a part of the ultraviolet laser beam and transmits another part of the ultraviolet laser beam
Implementation Method 2
the other main surface of the sapphire substrate may be provided with a reflection suppressing structure configured to suppress reflection of the ultraviolet laser beam
Data Source
AI summary
An output mirror for an ultraviolet laser beam includes a plate-shaped sapphire substrate, at least a part of one main surface of the sapphire substrate is a partial reflective surface that is exposed, reflects a part of the ultraviolet laser beam, and transmits another part of the ultraviolet laser beam, and the other main surface of the sapphire substrate is provided with a reflection suppressing structure configured to suppress reflection of the ultraviolet laser beam.