Metasurface Projector Phase Modulation for Speckle Reduction
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Solution Overview
Problem
Semiconductor lasers used as light sources in projectors cause speckle noise due to high coherence, which interferes with the observer's retina, and existing solutions require a large installation space, increasing the apparatus size.
Innovation Solution
A projector design incorporating a metasurface element to modulate the phase of light emitted from the light source and a light modulation element to further modulate the phase-modulated light, reducing speckle noise while maintaining a compact size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a phase modulation unit with a cylindrical body and rotation axis is disposed to reduce speckle noise, then speckle noise is reduced, but the installation space increases causing the overall apparatus size to increase
Solution Approach 1:
The patent extracts the essential function of phase modulation from the complex cylindrical body structure and implements it through a thin film metasurface element. This metasurface contains sub-wavelength structures that provide the necessary phase modulation capability without requiring the bulky cylindrical geometry, thereby reducing apparatus size while maintaining speckle noise reduction performance
Solution Approach 2:
The patent replaces the mechanical rotation-based phase modulation system with an optical metasurface approach. Instead of using a rotating cylindrical body with high and low refractive index portions, the invention uses a static metasurface element with sub-wavelength structures that provide phase modulation through optical path differences, eliminating the need for mechanical movement and reducing the overall apparatus size
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
Effectively reduces speckle noise in projected images without increasing the projector's size by using a metasurface element for phase modulation and a light modulation element, enhancing image quality.
Implementation Method 1
a metasurface element configured to modulate a phase of light emitted from the light source
Implementation Method 2
The metasurface element includes a substrate and a plurality of microstructures provided on a surface of the substrate... each microstructure having a width and a height... the height being different for different microstructures
Implementation Method 3
a light modulation element configured to modulate the phase-modulated light emitted from the metasurface element to generate image light
Data Source
AI summary
A projector of the present disclosure includes a light source that emits laser light, a metasurface element that modulates the phase of the laser light emitted from the light source, and a light modulation element that modulates the phase-modulated laser light emitted from the metasurface element to generate projection light.