Wedge Beam Splitter Layout for Stray-Light-Free Laser Dimming
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Solution Overview
Problem
Conventional laser beam dimming methods using beam splitters suffer from stray light interference due to back surface reflections, especially when observing laser beams with large numerical apertures, leading to inaccurate image observation.
Innovation Solution
A laser beam dimming device employing a beam splitter with a wedge-shaped cross-section, oriented at a 45° angle, reflects 10% or less of incident light, effectively separating observation light and stray light, even with large numerical apertures, by using reflected light as observation light and minimizing back surface reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a parallel flat plate beam splitter is used to dim the laser beam, then the laser beam can be dimmed to allow observation, but stray light from back surface reflections enters the observation device and distorts the image
Solution Approach 1:
The patent applies asymmetry by using a wedge-shaped beam splitter instead of a parallel flat plate. The wedge shape creates asymmetric thickness distribution, where the incident light side is thinner and the reflected light side is thicker. This asymmetric geometry causes stray light from back surface reflections to exit at different angles than the main reflected beam, preventing it from entering the observation device and thus eliminating image distortion while maintaining beam dimming capability.
2Illumination intensity
If the beam splitter reflectance is increased to improve dimming effect, then the laser beam intensity is reduced sufficiently for observation, but more stray light is generated from back surface reflections
Solution Approach 1:
The wedge-shaped beam splitter with asymmetric thickness distribution separates the main reflected beam from stray light generated by back surface reflections. The different optical paths caused by the wedge geometry ensure that even when reflectance is increased for better dimming, the stray light exits at different angles and does not contaminate the observation image.
3Measurement precision
If a wedge-shaped beam splitter is used to eliminate stray light, then observation accuracy is improved, but the device complexity increases compared to a parallel flat plate
Solution Approach 1:
The wedge-shaped beam splitter uses a simple asymmetric geometric form rather than complex multi-element arrangements. This single asymmetric component achieves stray light elimination that would otherwise require complex optical systems, thus improving measurement precision while minimizing device complexity.
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 device accurately measures laser beam intensity distribution without stray light interference, ensuring precise laser processing by separating observation light and stray light, thereby improving processing quality.
Implementation Method 1
a beam splitter 1 in which reflected light is used as observation light
Data Source
AI summary
To achieve this object, there is provided a laser beam dimming device including a beam splitter in which reflected light is used as observation light, wherein the beam splitter reflects 10% or less of incident light, the beam splitter is disposed such that an incident angle of the incident light at a position of an optical axis is 45° with an X axis as a rotation axis when arbitrary orthogonal coordinate axes whose origin on a plane perpendicular to the optical axis is an optical axis are an X axis and a Y axis, and a cross-sectional shape of the beam splitter on a plane determined by the incident light and the reflected light of the beam splitter is a wedge shape in which an incident light side of the beam splitter is thin and a reflected light side of the beam splitter is thick.