PLM and Phosphor HDR Projection to Reduce Laser Speckle
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Solution Overview
Problem
Projection-based displays using lasers face challenges with high cost, reduced diffraction efficiency, and increased power consumption due to the use of green and red lasers, along with noticeable speckle and lower photopic efficiency compared to other light sources.
Innovation Solution
Incorporating a phase light modulator (PLM) and a phosphor to modulate and emit multiple color modes, replacing green and red lasers with a blue laser and phosphor, which enhances diffraction efficiency and reduces speckle, while maintaining high dynamic range (HDR) modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If green and red lasers are used in projection-based displays, then color reproduction is achieved, but cost increases and diffraction efficiency decreases
Solution Approach 1:
The patent changes the wavelength parameter from green/red lasers to blue laser (445nm-480nm range), which fundamentally alters the optical parameters of the system. This parameter change enables the use of a single blue laser source with phosphor conversion to generate multiple colors, reducing component count and cost while improving diffraction efficiency through the PLM's optimized optical path for blue light wavelengths
Solution Approach 2:
The patent introduces a phosphor material as an intermediary between the blue laser and the final color output. The phosphor absorbs blue light and converts it to multiple color modes (red, green, yellow), serving as a mediator that enables a single laser source to produce multi-color output, thereby reducing the need for multiple laser diodes and improving overall system efficiency
2Use of energy by moving object
If green and red lasers are used in projection-based displays, then color reproduction is achieved, but power consumption increases
Solution Approach 1:
The patent changes the light source wavelength to blue (445nm-480nm), which has higher photopic efficiency according to the human eye's sensitivity curve. This parameter change in wavelength allows for more efficient energy conversion and reduces power consumption while maintaining or improving color reproduction quality through phosphor conversion
Solution Approach 2:
The phosphor acts as an intermediary that converts the high-efficiency blue laser light into multiple color modes with optimized energy distribution. The phosphor material is selected to maximize energy conversion efficiency from blue to red/green/yellow wavelengths, thereby reducing overall power consumption while maintaining photopic efficiency
3Object-generated harmful factors
If lasers are used in projection-based displays, then color modes are generated, but speckle becomes noticeable
Solution Approach 1:
The phosphor material serves as an intermediary that converts coherent blue laser light into partially coherent multi-color output. This conversion process randomizes the phase relationships between different color modes, thereby reducing the visibility of speckle patterns while maintaining the diffraction efficiency needed for high-quality image projection
Solution Approach 2:
The system uses a composite approach combining blue laser light with phosphor-converted light of multiple color modes. This composite light source combines the advantages of each component: the blue laser provides high coherence and efficiency, while the phosphor conversion introduces spectral diversity that reduces speckle visibility, achieving both high diffraction efficiency and reduced harmful speckle effects
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 solution reduces costs, improves diffraction efficiency, and increases photopic efficiency, providing higher contrast and brighter images with reduced speckle, thus enhancing the overall performance of projection-based displays.
Implementation Method 1
a phosphor optically coupled to the PLM and configured to receive at least a first portion of the first modulated light from the PLM to emit a phosphor light with multiple color modes
Data Source
AI summary
An apparatus for high dynamic range (HDR) modulation includes one or more lasers configured to transmit respective beams of laser light with a single color mode and a PLM optically coupled to the one or more lasers. The PLM is configured to modulate the laser light to produce a first modulated light. The apparatus also includes a phosphor optically coupled to the PLM and configured to receive at least a first portion of the first modulated light from the PLM and to emit a phosphor light with multiple color modes. At least one spatial light modulator (SLM) is also optically coupled to the phosphor and configured to modulate the multiple color modes in the phosphor light and the single color mode to project a second modulated light.