Diffractive Illumination Design for Readable Long-Range Projections
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Solution Overview
Problem
Existing illumination devices using coherent light beams struggle to ensure that information displayed at a distance is correctly recognizable due to beam divergence and non-uniform illumination, leading to potential misinterpretation of projected patterns.
Innovation Solution
An illumination device incorporating a diffractive optical element that diffracts coherent light beams to maintain uniform radiance and luminance, allowing for accurate recognition of information from varying viewpoints and distances, with a design method that calculates diffraction characteristics based on observer positions and light distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If laser light beams are used to display information on a distant road surface, then the beam diameter expansion is smaller compared to LED light beams, but the illumination range extends in the traveling direction, causing the displayed information to be displayed in an extended state that cannot be correctly recognized
Solution Approach 1:
The patent applies local quality by creating different illumination characteristics in different regions of the projection pattern. Specifically, the illumination intensity and beam diameter are locally adjusted across the projection area to compensate for the natural divergence of laser beams over distance, ensuring that information maintains consistent visual characteristics across the entire extended projection range
2Adaptability or versatility
If a diffractive optical element is used to control light distribution, then the width of the illuminated area can be controlled to gradually increase, but the device complexity increases
Solution Approach 1:
The patent replaces complex mechanical adjustment systems with a diffractive optical element that inherently provides the desired illumination control through its diffraction properties. This optical approach eliminates the need for moving parts or complex mechanical mechanisms while achieving precise control over the illuminated area's width and distribution pattern
3Illumination intensity
If laser light beams are used for illumination, then the emission intensity is higher than LED, but the coherent nature of the light causes illumination blurring at edges of characters or patterns
Solution Approach 1:
The patent introduces a diffractive optical element as an intermediary between the laser light source and the projection target. This element mediates the coherent light by diffracting it into a controlled distribution pattern that maintains the high intensity of laser while eliminating the edge blurring effect, producing sharp, well-defined character and pattern edges
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
Ensures clear and uniform projection patterns are visible from different angles and distances, enhancing the visibility of information displayed on surfaces, even when the device is positioned far away.
Implementation Method 1
a diffractive optical element that diffracts the coherent light beam from the light source and projects the projection pattern
Data Source
Figure 1
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Figure 4A~4B
AI summary
An illumination device, which projects a projection pattern including information onto a projection plane, includes a light source that emits a coherent light beam, and a diffractive optical element that diffracts the coherent light beam from the light source and projects the projection pattern. The diffractive optical element has a diffraction characteristic that allow an observer who sees the projection pattern from a viewpoint position in a first line-of-sight direction based on a position and a direction of the diffractive optical element, to visually recognize the information with a predetermined size, a predetermined shape and a predetermined inclination angle.