Optical Module Mirror Alignment for Narrow-Linewidth Gas Lasers
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Solution Overview
Problem
Chromatic aberration occurs in gas laser devices due to their large spectral line width, leading to decreased resolution in semiconductor exposure processes, necessitating a method to narrow the spectral line width and maintain optical performance.
Innovation Solution
A manufacturing method involving autocollimators and optical elements to precisely align mirrors in a beam expander, ensuring perpendicular incidence of laser light on reflection surfaces, thereby reducing deviations from designed performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a line narrowing module is provided in the gas laser device to narrow spectral line width, then chromatic aberration is reduced, but device complexity increases
Solution Approach 1:
An optical element (prism or grating) is introduced as an intermediary component between the laser medium and the output coupling mirror to narrow the spectral line width. This intermediary element disperses the light spectrum and enables selection of a narrower spectral bandwidth, thereby reducing chromatic aberration while maintaining the overall laser device structure
Solution Approach 2:
The laser resonator is segmented into functional sections: a laser medium section for light generation and an optical element section for spectral narrowing. This segmentation allows the optical element to be positioned at a specific location within the resonator where it can effectively narrow the spectral line width without interfering with the laser medium's operation, thus reducing chromatic aberration in a structured manner
2Manufacturing precision
If mirrors are precisely aligned using autocollimators and optical elements, then laser light performance matches designed values, but manufacturing process complexity increases
Solution Approach 1:
Autocollimators are used to perform preliminary alignment of mirrors before final assembly and operation. By pre-aligning the mirrors to precise angular positions using optical feedback from the autocollimators, the manufacturing process ensures that the laser resonator is properly configured, thereby achieving designed laser light performance while systematic preliminary actions reduce overall manufacturing complexity
Solution Approach 2:
Autocollimators provide real-time optical feedback during mirror alignment by detecting the reflected light position and angle. This feedback mechanism allows operators to adjust mirror positions and orientations to achieve precise alignment, ensuring that laser light performance matches designed values through a controlled, measurable 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
The method ensures that the laser light performance aligns with designed values, reducing chromatic aberration and maintaining resolution in semiconductor exposure processes.
Implementation Method 1
receiving light, out of the light output from the first autocollimator, reflected by the surface on the incident side
Implementation Method 2
receiving light, out of the light output from the first autocollimator, reflected by the first reflection surface
Data Source
AI summary
A method for manufacturing an optical module may include a step for arranging a first autocollimator such that output light is perpendicularly incident on an incident-side surface of an output coupling mirror; an step for arranging, between the incident-side surface and the first autocollimator, an optical element including a first reflection surface and a second reflection surface facing the incident-side surface as forming an angle of 45° with the first reflection surface such that light output from the first autocollimator is perpendicularly incident on the first reflection surface; a step for arranging a second collimator such that output light is reflected by the second reflection surface and perpendicularly incident on the incident-side surface; and a step for arranging the planar mirror, after removing the optical element, such that light output from the second autocollimator is perpendicularly incident on the reflection surface.