Laser Scanner Tilted Window Anti-Reflective Coating
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Solution Overview
Problem
Laser scanners face issues with internally scattered light interfering with measurement capabilities, particularly in safety applications, where it can lead to false alarms or missed detections due to reflective and diffusive components of light entering the housing.
Innovation Solution
A laser scanner design featuring a tilted protective window with anti-reflective coatings and a light absorptive plate to direct internally reflected light into a 'dead zone' and a separation baffle to block light incident on the interference filter at angles below its acceptance angle, reducing internal reflections and improving signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a protective window is used to protect the laser scanner housing, then the structural integrity and protection are improved, but internal reflections and light scattering occur that interfere with measurement capabilities
Solution Approach 1:
The patent applies anti-reflective coatings on the protective window surfaces to convert the harmful reflective property into a beneficial low-reflection property. The coatings reduce internal reflections and light scattering, allowing the protective window to maintain its protective function while eliminating the measurement interference caused by reflections.
Solution Approach 2:
The patent modifies the optical parameters of the protective window by applying anti-reflective coatings that change the reflectivity and transmissivity characteristics of the window surfaces. This parameter change reduces the intensity of internally scattered light while maintaining the window's protective structural function.
2Measurement precision
If light absorptive materials are added to block internal reflections, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines the light absorptive function with existing structural components within the housing. Instead of adding separate dedicated light-blocking components, the absorptive materials are integrated into available spaces and structures, such as lining internal surfaces or placing absorptive elements in dead zones, thereby reducing internal reflections without significantly increasing device complexity.
Solution Approach 2:
The patent introduces light absorptive materials as intermediary elements between the protective window and the detection optics. These materials serve as mediators that intercept and absorb internally scattered light before it can reach the detection system, improving signal-to-noise ratio while maintaining a relatively simple overall structure.
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 configuration effectively minimizes internal reflections, enhancing the accuracy of object detection by reducing false alarms and ensuring reliable detection of objects in the scanning area, particularly in safety-critical applications.
Implementation Method 1
The protective window may have an anti-reflective coating applied to an inner surface and/or an outer surface thereof
Implementation Method 2
At least a portion of the protective window is inclined or tilted at a determined angle with respect to a laser beam emitted from a light source
Implementation Method 3
A bulkhead system which may include a separation baffle is provided to prevent light incident on an interference filter of a receiving optical system
Data Source
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AI summary
A laser scanner which includes a light source which emits a light beam and a scanning mirror rotatable about an axis which reflects the light beam through a tilted protective window toward a scanning area and which directs return light from objects toward receiving optics. The laser scanner may include a collecting mirror which receives the return light, and an interference filter disposed between the collecting mirror and the scanning mirror. The window may include an anti-reflective coating which reduces reflection of internally scattered light. The tilted window may direct the reflective component of internally scattered light into a zone where an energy light absorber is present. A bulkhead system which may include a separation baffle may be provided to prevent light incident on the interference filter at an angle which is below an acceptance angle of the interference filter.