Laser Display Speckle Reduction via Image Displacement
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Solution Overview
Problem
Projection display systems using laser illumination suffer from speckle, a random spatial intensity modulation that is undesirable and varies with the viewer's position, limiting image quality and brightness.
Innovation Solution
A method and apparatus that includes a laser light source, a spatial light modulator, and an optical element, such as a displacement device, to displace images by a selected amount in a specific direction, reducing speckle by creating a second image that is displayed sequentially with the original image, typically within a frame time, to minimize visible speckle on the display medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a laser light source is used to increase brightness, then image brightness is improved, but speckle noise is generated
Solution Approach 1:
The patent segments the coherent laser light into multiple independent speckle patterns by using multiple displacement amounts. Each displacement creates a separate speckle realization, and when these multiple patterns are combined (typically through temporal or spatial superposition), the random speckle noise averages out, reducing its visibility while preserving the bright laser illumination.
Solution Approach 2:
The patent introduces dynamic displacement of the image along the shear direction by an amount that varies over time or across different regions. This dynamic variation in displacement amount ensures that the speckle patterns change and do not remain static, allowing multiple independent speckle realizations to be combined, thereby reducing overall speckle visibility while maintaining laser brightness.
2Object-affected harmful factors
If image displacement is applied to reduce speckle, then speckle noise is reduced, but image resolution may be affected
Solution Approach 1:
The patent applies local quality by using different displacement amounts in different regions or for different portions of the image. This allows optimization of speckle reduction in specific areas while maintaining higher resolution where displacement has minimal impact. The displacement is tailored locally rather than applied uniformly, preserving resolution where possible while reducing speckle where needed.
Solution Approach 2:
The patent employs partial displacement rather than full-image displacement, applying the shear and displacement selectively to portions of the image where speckle reduction is most beneficial. This partial action approach minimizes the impact on overall image resolution while still achieving speckle reduction in critical regions, balancing the trade-off between speckle suppression and resolution maintenance.
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 in laser-illuminated projection systems, improving image quality and brightness while maintaining the advantages of using a coherent light source like lasers, without significantly increasing system cost, size, or weight.
Implementation Method 1
an optical element between the laser and the display medium for displacing the plurality of images so as to reduce speckle associated with the projection of the plurality of images on the projection medium
Data Source
AI summary
An apparatus and method of reducing speckle in projection of images is provided that includes the elements or features of producing a first image and displacing the first image to produce a second image that will reduce speckle relating to the first image when the first image and the second image are displayed on a display medium.