Laser Speckle Reduction via Phase Modulation
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Solution Overview
Problem
Existing laser-based illumination systems face challenges in reducing speckle artifacts due to their coherent nature, with mechanical despeckling methods causing vibrations, noise, and reducing product lifetime, and being environmentally vulnerable.
Innovation Solution
An electromagnetic radiation system that includes a laser source, a phase-only light modulator, and a control unit generating relative phase shift patterns to modulate the phase of beamlets of light, averaging speckle patterns over time to reduce coherence and eliminate speckle artifacts without mechanical components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If mechanical despeckling methods (moving diffusers, deforming mirrors, vibrating fly-eye arrays) are used to reduce speckle, then speckle patterns are temporally averaged and reduced, but mechanical vibrations are introduced that degrade image quality and device lifetime is reduced due to wear
Solution Approach 1:
The patent replaces mechanical despeckling components (moving diffusers, deforming mirrors, vibrating fly-eye arrays) with a spatial light modulator that uses electrical control to modulate the phase of light. This substitution eliminates mechanical wear, vibrations, and noise while achieving the same speckle reduction effect through phase modulation of the laser beam.
2Object-affected harmful factors
If mechanical components are used for despeckling, then speckle is reduced, but the device becomes environmentally vulnerable due to lightweight fast-moving components
Solution Approach 1:
The patent replaces mechanical despeckling components (moving diffusers, deforming mirrors, vibrating fly-eye arrays) with a spatial light modulator that uses electrical control to modulate the phase of light. This substitution eliminates mechanical wear, vibrations, and noise while achieving the same speckle reduction effect through phase modulation of the laser beam.
3Illumination intensity
If laser's highly coherent nature is utilized for display applications, then unique wavelengths and high brightness are achieved, but speckle artifacts are created as an image artifact
Solution Approach 1:
The patent changes the phase parameter of the coherent laser light by using a spatial light modulator to modulate the phase of different portions of the laser beam. This phase modulation disrupts the coherent interference patterns that cause speckle while preserving the high brightness and wavelength characteristics of the laser light.
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 speckle artifacts in laser-based illumination systems, enhancing image quality and extending device lifetime by eliminating the need for mechanical parts and improving environmental robustness.
Implementation Method 1
a phase-only light modulator that generates beamlets of light and modulates a phase of the beamlets of light
Implementation Method 2
controlling the phase modulation such that a relative phase shift is created between at least two beamlets of light output by the light modulator... averaging speckle patterns over time to reduce coherence and eliminate speckle artifacts
Data Source
AI summary
An illumination system is disclosed, and such system may include a first light modulator (14) that modulates the phase of beamlets of light and generates phase modulated Gaussian beamlets of light (ABC), a light distributor (18) that transforms, the Gaussian beamlets of light to a homogenized rectangular pattern of light, and a second light modulator (56) that utilizes the phase modulated light to form an image.