Fluorescent Wheel Diffusion Region Speckle Reduction
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Solution Overview
Problem
Current laser projection technologies face challenges with speckle issues and high costs due to the use of pure laser sources, which are addressed by incorporating a fluorescent wheel with a diffusion component to diffuse and transmit laser, thereby reducing speckle and enhancing brightness.
Innovation Solution
A fluorescent wheel with a transmission region made of a diffusion component material, such as frosted glass, is used to diffuse and transmit blue and red lasers, creating a moving diffusion sheet that undermines laser coherence and alleviates speckle phenomena, while also improving light processing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a pure laser source is used for projection display, then high brightness and strong directivity are achieved, but severe speckle issues and high cost occur
Solution Approach 1:
The patent segments the laser beam into multiple independent sub-beams using a diffuser, which breaks the coherent laser light into numerous incoherent components. This segmentation approach maintains the high brightness of laser while eliminating speckle by preventing coherent interference patterns from forming.
Solution Approach 2:
The patent introduces a temporal dimension by rapidly switching between multiple laser diodes with different wavelengths or characteristics. This time-sequential activation creates a moving diffuser effect that undermines laser coherence over time, effectively reducing speckle while maintaining high brightness through persistence of vision.
2Object-affected harmful factors
If a speckle-removing optical path is added to guarantee light source quality, then speckle is removed, but the volume and complexity of optical architecture increase
Solution Approach 1:
The patent merges the speckle removal function directly into the laser source assembly by integrating a diffuser element and multiple laser diodes at the source level. This consolidation eliminates the need for separate speckle-removing optical paths downstream, thereby reducing overall system complexity and volume while maintaining effective speckle suppression.
Solution Approach 2:
The laser source assembly performs speckle removal autonomously through its internal structure comprising multiple laser diodes and a diffuser. The system self-generates incoherent light at the source without requiring external speckle-removal components, making the source itself service the speckle reduction need.
3Adaptability or versatility
If multiple laser devices are used to enrich variety, then laser source versatility is improved, but speckle phenomenon deteriorates
Solution Approach 1:
The patent segments the multi-laser system into independently controlled laser diodes, each emitting incoherent light relative to the others. By activating these segmented laser sources in a time-sequential manner rather than simultaneously, the system achieves versatility through multiple wavelengths while preventing speckle through inherent incoherence between segments.
Solution Approach 2:
The patent employs periodic activation of multiple laser diodes in a time-sequential pattern, where each laser operates in brief pulses separated by other lasers. This periodic, alternating activation creates a moving diffuser effect that undermines coherence and reduces speckle while maintaining the versatility of having multiple laser types available.
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 effectively reduces speckle interference and enhances the brightness of the light source, simplifying the optical architecture and promoting miniaturization of laser projection equipment by combining laser and fluorescence output in the same direction without the need for additional speckle-removing components.
Implementation Method 1
A fluorescent wheel with a transmission region made of a diffusion component material, such as frosted glass, is used to diffuse and transmit blue and red lasers
Implementation Method 2
create a moving diffusion sheet that undermines laser coherence and alleviates speckle phenomena
Implementation Method 3
fluorescence powder for emitting fluorescence under excitation by excitation laser
Implementation Method 4
green fluorescence powder and red fluorescence powder are coated on a rotating wavelength conversion device, which is typically a fluorescent wheel structure, and sequentially outputs three primary-color light
Implementation Method 5
the inner surface, where the front-side (i.e., the laser incident side) glass comes into contact with the fluorescence powder layer, is coated with a film 3c for transmitting laser and reflecting fluorescence
Implementation Method 6
a substrate where fluorescence powder is coated is made of transparent material, allowing fluorescence resulted from excitation by excitation laser to diverge in an omnidirection covering 360 degrees
Data Source
AI summary
The disclosure provides a fluorescent wheel, including a fluorescent region and a transmission region; the fluorescent region has fluorescence powder for emitting fluorescence under excitation by excitation laser; and the transmission region is for transmitting laser; the fluorescent wheel is for diffusing at least laser to be transmitted. Using fluorescent wheel to diffuse laser enables laser transmission meanwhile removing speckles by diffusion, sparing a separate speckle-removing component, improving light processing efficiency of fluorescent wheel. The disclosure also provides a double-color laser source using the fluorescent wheel, and a laser projection equipment including the double-color laser source, which can output three-primary-color light via fluorescent wheel component, meanwhile removing speckles for double-color laser, thereby reducing usage of optical components, and lowering complexity of optical architecture of double-color laser source, contributing to miniaturization of laser projection equipment. The disclosure is applied in the field of laser illumination display technologies.