Diffractive Optical Elements for Laser Illumination

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Solution Overview

Problem

Existing illumination devices that use laser light sources for specific color illumination by additive color mixture face challenges in reducing their size while ensuring safety, as larger hologram elements are required for safety but result in device enlargement.

Innovation Solution

The illumination device employs multiple laser light sources emitting different radiant fluxes, with corresponding diffractive optical elements having planar dimensions proportional to their radiant fluxes, allowing for efficient diffusion and reduced device size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single hologram element with large planar dimension is used to diffract laser light for safety, then the incident area for light source is increased, but the size of the illumination device is enlarged

Engineering Contradiction:

ImprovesafetyVSAvoiddevice size

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The single large hologram element is divided into multiple smaller hologram elements (first hologram element and second hologram element). Each hologram element processes a portion of the laser light, collectively achieving the required incident area for safety while keeping individual element sizes small, thus reducing overall device size.

Inventive Principle:

Principle #1Segmentation

2Illumination intensity

If multiple laser light sources with different radiant fluxes are used for additive color mixture, then specific color illumination is achieved, but the device size enlargement problem becomes more serious

Engineering Contradiction:

Improvecolor illuminationVSAvoiddevice size

Core Design Contradiction:

Illumination intensityVSLength of stationary object

Solution Approach 1:

Each hologram element is designed with specific planar dimensions matched to the radiant flux of its corresponding laser light source. The first hologram element has different planar dimensions than the second hologram element, optimizing the incident area for each light source's power level while maintaining overall compact device size.

Inventive Principle:

Principle #3Local quality

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 approach effectively reduces the size of the illumination device while maintaining safety by adjusting the planar dimensions of diffractive optical elements based on the radiant fluxes of the laser light sources, achieving a balance between power density and device size.

Implementation Method 1

diffractive optical elements provided correspondingly to the respective laser light sources

Methodology Applied

Scientific EffectDiffraction: Diffraction

Data Source

PatentEP3567304B1Illumination device

Publication Date: 2025.01.29 DAI NIPPON PRINTING CO LTD

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AI summary

An illumination device (10) includes: laser light sources (20) having different radiant fluxes; and diffractive optical elements (40) provided correspondingly to the respective laser light sources. A planar dimension of the diffractive optical element, which corresponds to the laser light source that emits a laser light having a minimum radiant flux, is smaller than a planar dimension of the diffractive optical element, which corresponds to the laser light source that emits a laser light having a maximum radiant flux.