Eye Safety System Using Dichroic Beam Splitter for Laser Retro-Reflection
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Solution Overview
Problem
Existing laser safety devices cannot effectively distinguish between light retro-reflected from an eye and scattered light, leading to potential eye damage due to misdirected laser beams.
Innovation Solution
A dichroic beam splitter and eye safety lens system that collimates and focuses retro-reflected light onto a detector, using a small aperture to capture only light parallel to the laser path and reject scattered light, with a dichroic beam splitter reflecting only the laser emission wavelength to prevent false alarms and terminate laser emission when eye safety is compromised.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a beam splitter is used to detect scattered light, then the device can detect light returned from surfaces, but it cannot distinguish between retro-reflected light from an eye and scattered light from other surfaces
Solution Approach 1:
The patent applies local quality by giving different parts of the optical system different functional properties. The beam splitter is designed to reflect only a specific wavelength band (the laser emission wavelength) while transmitting other wavelengths. This wavelength-selective reflection allows the system to distinguish retro-reflected laser light from other scattered light, thereby improving measurement precision without increasing false alarms
Solution Approach 2:
The patent introduces a wavelength-selective beam splitter as an intermediary element between the laser source and the detector. This beam splitter acts as a mediator that separates the retro-reflected light signal from other scattered light based on wavelength, enabling the detector to specifically identify eye retro-reflections while filtering out false signals from other surfaces
2Area of stationary object
If the laser beam is expanded and collimated to cover a larger area, then the laser can treat larger regions, but the safety system must monitor a larger optical path increasing complexity
Solution Approach 1:
The patent segments the optical system into distinct functional modules: the laser source, collimating lenses, beam expanding optics, dichroic beam splitter, and detection system. Each segment performs a specific function, allowing the overall system to manage large treatment areas while maintaining manageable complexity through modular design. The beam splitter specifically monitors the expanded beam path without requiring the entire system to be overly complex
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
Effectively differentiates between retro-reflected light from an eye and scattered light, reducing false alarms and ensuring immediate shutdown of the laser source to prevent eye damage, while maintaining sensitivity to near-infrared light reflections.
Implementation Method 1
The dichroic beam splitter reflects a narrow wavelength band (that includes the laser emission wavelength) into the eye safety lens
Implementation Method 2
The beam splitter is placed to reflect the retro-reflected light into a collecting eye safety lens with an infinity focus (infinity conjunction) designed to collect and direct the retro-reflected light onto a fast detector
Implementation Method 3
A laser source produces a laser beam which passes through one or more lenses to collimate the divergent beam
Data Source
Figure 1~2
AI summary
An eye safety system, based on retro-reflection from the eye, to shut off a laser source in a short time to avoid approaching the hazard level of the eye. In the event of an accidental direction of laser light toward a nearby eye, the system rapidly collects and detects laser light that retroflects from the retina of the eye. Upon detecting the retroflected light, a comparator/processor assembly signals to switch off the laser source to terminate the hazard to the eye.