Light Source Apparatus Reducing Speckle Noise via Laser-Phosphor Multiplexing
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Solution Overview
Problem
Conventional light source apparatuses face challenges in achieving high-brightness and low-noise output, particularly for red light, due to the short lifetime and temperature quenching of phosphors, and low light density of LEDs, which complicates the production of high-output red light with minimal speckle noise.
Innovation Solution
A light source apparatus utilizing a phosphor with green fluorescence and a red laser light source, where the fluorescence and laser light are spatially multiplexed and demultiplexed using optical multiplexing and demultiplexing optics to separate red and green light components, reducing speckle noise and enhancing brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a red phosphor is used to obtain red light, then the lifetime of fluorescence and temperature quenching are improved, but the brightness and efficiency of red output light deteriorate
Solution Approach 1:
The patent combines red laser light and red phosphor light into a single red light output beam using optical multiplexing. The red laser light source provides high brightness and long lifetime, while the red phosphor contributes to the overall red light output. This merging allows the system to achieve both high brightness and long lifetime without being limited by the weaknesses of individual components.
Solution Approach 2:
The patent creates a composite light source by combining different types of light sources (laser and phosphor) to produce red light. This composite approach leverages the complementary strengths of each component: the laser provides stability and lifetime, while the phosphor enhances the red light output, resulting in a superior red light source that overcomes the limitations of single-component systems.
2Illumination intensity
If a laser light source is used to obtain high-brightness light, then the light density and brightness are improved, but speckle noise increases and image quality deteriorates
Solution Approach 1:
The patent merges coherent laser light with incoherent phosphor light to create a composite light output. The phosphor light acts as a noise-suppressing agent that reduces the speckle patterns generated by the laser, while the laser provides the high brightness and light density. This combination achieves high brightness without the severe speckle noise problems of pure laser systems.
Solution Approach 2:
The phosphor light serves as an intermediary element between the laser light and the final output. It modulates the coherent laser light, reducing its harmful speckle noise properties while preserving its high brightness characteristics. The phosphor acts as a mediator that transforms the pure laser light into a hybrid light source with improved image quality.
3Object-generated harmful factors
If LED light source is used to avoid speckle noise, then the image quality is improved, but the light density and brightness deteriorate
Solution Approach 1:
The patent combines the noise-free characteristics of LED/phosphor light with the high light density of laser light. By merging these two light sources, the system achieves both low speckle noise and high light density, overcoming the limitations of pure LED systems that lack sufficient brightness and light concentration.
4Device complexity
If conventional light source apparatus is used to obtain red light, then the structure is simple, but the brightness and efficiency of red output light deteriorate due to phosphor limitations
Solution Approach 1:
The patent merges red laser light and red phosphor light using optical multiplexing components. This addition of merging capability increases the device complexity slightly, but enables the system to achieve high brightness and efficiency in red light output that cannot be obtained with simple single-component systems.
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 approach allows for high-brightness and low-noise red and green light output, improving image quality by using incoherent fluorescence and reducing speckle noise, while maintaining a long lifetime and being mercury-free.
Implementation Method 1
a phosphor having, as a main wavelength region of fluorescence, wavelengths of green excited by excitation light emitted from the excitation light source
Implementation Method 2
an optical multiplexer that multiplexes fluorescence emitted from the phosphor and red laser light emitted from the red laser light source
Implementation Method 3
color demultiplexing optics that demultiplexes the light multiplexed by the optical multiplexer into two light beams
Data Source
AI summary
A light source apparatus includes: an excitation light source; a phosphor having, as a main fluorescence wavelength region, wavelengths of green excited by excitation light emitted from the excitation light source; a red laser light source that oscillates in a red wavelength region; an optical multiplexer that multiplexes fluorescence emitted from the phosphor and red laser light emitted from the red laser light source; and color demultiplexing optics that demultiplexes the multiplexed light into two light beams. A cutoff wavelength of the color demultiplexing optics is a wavelength in the wavelength region of fluorescence, and is shorter than the red wavelength region.