Laser Illumination Optical System with Aperture Mirror
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Solution Overview
Problem
LED-based light sources for projectors have large etendue, limiting brightness and efficiency, as increasing light output is difficult without expanding the light-emitting area.
Innovation Solution
An illumination optical system incorporating a laser light source, fluorescent substances, and a mirror with an aperture to concentrate excitation light on fluorescent materials, generating high-brightness, multi-color fluorescent lights with a small etendue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the light-emitting area of LED is increased to increase the amount of light, then the brightness is improved, but the etendue becomes larger which reduces light utilization efficiency
Solution Approach 1:
The patent changes the light source from LED to laser, fundamentally altering the light emission parameters. The laser produces coherent, directional light with small divergence angle, achieving high brightness without increasing etendue. This parameter change resolves the contradiction by decoupling brightness from etendue through the unique properties of laser radiation.
Solution Approach 2:
The patent introduces a fluorescent substance as an intermediary between the laser light source and the display panel. The laser excites the fluorescent substance which then emits light in multiple directions, effectively coupling the small etendue laser source with the display panel requirements. This intermediary enables high brightness projection while maintaining small etendue throughout the system.
2Reliability
If LED light source is used to achieve longer operating life and higher reliability, then the durability is improved, but the brightness and light utilization efficiency deteriorate
Solution Approach 1:
The patent merges the advantages of laser (high brightness, small etendue, long operating life) with fluorescent substances (wavelength conversion, omnidirectional emission). This combination creates a hybrid illumination system that achieves both high brightness and long operating life, resolving the contradiction between reliability and illumination intensity.
Solution Approach 2:
The patent changes the light source from LED to laser, fundamentally altering the emission parameters. Lasers naturally have longer operating lives and higher reliability compared to LEDs, while simultaneously providing much higher brightness and smaller etendue. This parameter change resolves the contradiction by selecting a light source with superior characteristics in both reliability and brightness.
3Loss of energy
If the light-emitting area is kept small to maintain small etendue, then the light utilization efficiency is improved, but the amount of light and brightness deteriorate
Solution Approach 1:
The patent addresses this contradiction by operating in different dimensional spaces. The laser source operates in a highly directional 1D beam mode with small etendue, while the fluorescent substance converts this to 3D omnidirectional emission that fills the display panel aperture. This dimensional transformation enables both small etendue (high efficiency) and high brightness simultaneously.
Solution Approach 2:
The fluorescent substance acts as an intermediary that transforms the laser's directional, small-etendue light into omnidirectional light that can illuminate the entire display panel. This intermediary enables the system to maintain small etendue (preserving efficiency) while delivering sufficient light amount across the projection area (achieving high brightness).
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 achieves a longer operating life and higher brightness by concentrating laser energy on fluorescent substances, producing efficient, multi-color illumination with a reduced etendue.
Implementation Method 1
a laser light source that generates an excitation light
Implementation Method 2
a fluorescent substance that generates a fluorescent light in response to the excitation light
Implementation Method 3
a mirror that is placed within a light path between the laser light source and the light tunnel, and that reflects the fluorescent light
Data Source
AI summary
The present invention seeks to realize a small etendu illumination optical system, a longer operating life and a higher brightness. The illumination optical system comprises: a laser light source that generates an excitation light; a fluorescent substance that generates a fluorescent light in response to the excitation light, a light tunnel that outputs the excitation light input at one end thereof to the fluorescent substance from the other end thereof, and that outputs the fluorescent light generated by the fluorescent substance from the one end thereof; and a mirror that is placed within a light path between the laser light source and the light tunnel, and that reflects the fluorescent light, the mirror having an aperture formed thereon that allows the excitation light to pass through.