Light Source Unit Spectral Member Stray Light Protection
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Solution Overview
Problem
In projectors using semiconductor light emitting devices, light from one source can be inadvertently reflected or transmitted onto the optical device of another source through dichroic mirrors, leading to reduced service life due to exposure to intense light.
Innovation Solution
A light source unit with a dichroic mirror and an optical device featuring a spectral member with a coating that transmits light in one wavelength range while reflecting or absorbing light in another, preventing unwanted light exposure to the second light source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dichroic mirror is used to separate light from different light sources, then light separation efficiency is improved, but stray light from one light source may be reflected onto the optical device of another light source, reducing service life
Solution Approach 1:
A spectral member (optical element with wavelength-selective coating) is introduced as an intermediary component in the optical path between the dichroic mirror and the second light source. This spectral member selectively transmits or reflects specific wavelengths to prevent stray light from the first light source from reaching the optical device of the second light source, while allowing necessary light to pass through.
Solution Approach 2:
The spectral member is positioned specifically at the location where stray light from the first light source intersects with the optical path of the second light source. By applying wavelength-selective coating only to this specific component at this specific location, the patent locally addresses the harmful light exposure problem without affecting the overall light separation function of the dichroic mirror.
2Use of energy by moving object
If semiconductor light emitting devices emit highly intense light, then illumination efficiency is improved, but the intense light reflected by dichroic mirror shortens service life of optical devices
Solution Approach 1:
The patent converts the potentially harmful intense light from the first light source into a beneficial filtering mechanism. The spectral member is designed to selectively transmit or reflect specific wavelengths, transforming the problematic stray light into a controlled optical filtering function that protects downstream optical devices while maintaining the high illumination efficiency of the semiconductor light emitting devices.
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 reduces the impact of stray light on the optical devices, extending their service life by minimizing the effects of intense light exposure, even during prolonged use.
Implementation Method 1
a spectral member to which a coating is applied which transmits the light in the second wavelength range but reflects or absorbs the light in the first wavelength range
Implementation Method 2
a spectral member to which a coating is applied which transmits the light in the second wavelength range but reflects or absorbs the light in the first wavelength range
Implementation Method 3
a dichroic mirror on which light in a first wavelength range and light in a second wavelength range are incident from directions which are different from each other and which reflects or transmits the light in the first wavelength range and the light in the second wavelength range
Data Source
AI summary
A light source unit according to an embodiment has a first light source which emits light in a first wavelength range, a second light source which emits light in a second wavelength range which differs from the light in the first wavelength range, a dichroic mirror to which the light in the first wavelength range and the light in the second wavelength range are incident from directions which differ from each other and which reflects or transmits the light in the first wavelength range and the light in the second wavelength range, and an optical device which is disposed on an optical path between the dichroic mirror and the second light source, and the optical device is a spectral member to which a coating is applied which transmits the light in the second wavelength range and reflects or absorbs the light in the first wavelength range.