Diffractive Illumination Pattern Design for Eye-Safe Line Projection
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Solution Overview
Problem
Existing illumination devices project high-intensity light in a narrow area, leading to increased brightness and potential eye safety hazards when viewed at short distances.
Innovation Solution
An illumination system with a diffractive optical element that diffracts light to form a projection pattern with a reduced width in one direction while reducing light intensity at short distances, using a plurality of elemental diffractive optical elements to control light distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the width of the projection pattern is reduced to concentrate light, then the brightness and recognition of the projection pattern is improved, but the light intensity at short distance increases causing eye safety hazards
Solution Approach 1:
The diffractive optical element is divided into multiple elemental diffractive optical elements (first, second, third, and fourth elements) arranged in a specific pattern. Each elemental element diffracts light independently, and their combined effect creates the projection pattern with controlled light distribution, allowing narrow width for brightness while dispersing intensity to reduce eye hazard
Solution Approach 2:
Different regions of the diffractive optical element have different diffraction characteristics. The elemental diffractive optical elements are positioned and sized differently to control where light is concentrated (for brightness in the projection pattern) and where it is dispersed (to reduce intensity at short distances near the device)
2Measurement precision
If the width of the projection pattern is reduced, then the recognition accuracy and visibility of the line shape is improved, but the light intensity concentration increases causing potential eye damage
Solution Approach 1:
The diffractive optical element is segmented into multiple elemental diffractive optical elements that collectively form the narrow projection pattern. This segmentation allows the light to be concentrated in the projection direction for high precision while being managed in intensity through the distributed elemental structure
Solution Approach 2:
The patent controls light distribution not only in the horizontal direction (for pattern width) but also in the vertical direction and depth distribution. The elemental diffractive optical elements are arranged at different positions and orientations to control light propagation in multiple dimensions, achieving narrow width for precision while managing intensity through spatial distribution
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 system effectively reduces the width of the projection pattern and intensity of light at short distances, enhancing visibility and safety by minimizing eye strain and improving recognition of the projection pattern.
Implementation Method 1
a diffractive optical element that diffracts light from the light source to form the projection pattern
Data Source
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AI summary
An illumination system 30 includes a projection surface 40 and an illumination device 50. The projection surface 40 is parallel to a first direction D1 and a second direction D2 orthogonal to the first direction D1. The illumination device 50 projects a projection pattern 41 extending in the first direction D1 onto the projection surface 40. The illumination device 50 includes a light source 51 and a diffractive optical element 55 that diffracts light from the light source 51 to form the projection pattern 41. The diffractive optical element 55 includes a plurality of elemental diffractive optical elements 56 each of which diffracts light from the light source 51. A minimum length Lb1 among the lengths of the projection pattern 41 in the second direction D2 is shorter than a maximum length Lc among the lengths that intersect a plane parallel to the projection surface 40, of the light incident on the diffractive optical element 55 and is longer than a maximum length La among the lengths that intersect the plane parallel to the projection surface 40, of the elemental diffractive optical elements 56.