Tunable Liquid Lens Speckle Reduction in Laser Projection
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Solution Overview
Problem
Laser image projection systems face the challenge of speckle phenomenon, which degrades image sharpness due to coherent light interference, making speckle reduction highly desirable.
Innovation Solution
A projection system incorporating a tunable liquid lens and a spatial light modulator that varies the lens's focal length, alignment, light-diffusing ability, and polarization properties to mitigate speckle by creating quasi-independent speckle configurations that the human eye can average, reducing speckle contrast without degrading image sharpness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If laser coherent light is used for projection, then vibrant images with extensive color coverage are achieved, but speckle phenomenon degrades image sharpness
Solution Approach 1:
The patent applies dynamics by making the liquid lens parameters variable rather than fixed. The liquid lens continuously changes its focal length, curvature, and other optical properties in response to control signals, creating time-varying speckle patterns that the human eye averages to reduce perceived speckle contrast while maintaining laser projection quality
Solution Approach 2:
The patent changes physical parameters of the liquid lens including focal length, curvature radius, refractive index distribution, and lens shape. These parameter variations modify the speckle pattern characteristics without changing the fundamental laser projection function, thereby reducing speckle visibility while preserving image quality
2Object-affected harmful factors
If speckle reduction techniques are applied, then speckle contrast is reduced, but image resolution may be degraded
Solution Approach 1:
The patent employs periodic action by causing the liquid lens to oscillate or vary its parameters at frequencies above the human visual flicker fusion threshold (typically >50 Hz). This creates rapidly changing speckle patterns that appear averaged to the human eye, reducing speckle contrast without creating visible temporal artifacts or degrading spatial resolution
Solution Approach 2:
The dynamic adjustment of liquid lens parameters creates temporal variation in speckle patterns while maintaining spatial coherence necessary for sharp images. The human visual system integrates these rapid changes, perceiving reduced speckle contrast without loss of image sharpness or resolution
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 contrast by averaging quasi-independent speckle configurations, improving image sharpness and viewer experience without significant loss of resolution.
Implementation Method 1
The system incorporates a tunable liquid lens and a spatial light modulator adapted to modulate light generated by the laser source to project an image on a viewing screen. The system is adapted to vary the focal length, alignment, light-diffusing ability, and/or light-polarizing properties of the tunable liquid lens
Implementation Method 2
varying at least one of the lens' characteristics to mitigate speckle in the projected image... varying the lens's focal length, alignment, light-diffusing ability, and polarization properties to mitigate speckle by creating quasi-independent speckle configurations
Implementation Method 3
vary the focal length, alignment, light-diffusing ability, and/or light-polarizing properties of the tunable liquid lens to mitigate speckle in the projected image
Data Source
AI summary
A representative embodiment of the invention provides a projection system having a laser source that incorporates a tunable liquid lens and a spatial light modulator adapted to modulate light generated by the laser source to project an image on a viewing screen. The tunable liquid lens is adapted to vary focal length, alignment or position with respect to an optical element that is external to the lens, ability to diffuse light, and/or polarization rotation angle.