Laser Speckle Reduction via Dynamic Spot Superposition
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Solution Overview
Problem
Current methods for reducing speckle in laser projection, such as offsetting beam spots or intermittently turning off the light source, are limited in effectiveness and efficiency, particularly for high-definition projections, as they either restrict the number of available positions for beam spots or reduce image clarity and prolong projection time.
Innovation Solution
The method involves using a laser to produce multiple secondary light spots with different input currents, which are then superposed to form a single primary light spot, ensuring that the sum of their powers matches the desired primary light spot power, and these secondary light spots are aligned and overlapped to reduce speckle by averaging their interference patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If multiple beam spots are offset positioned to reduce speckle, then speckle reduction is achieved, but the number of available positions is limited for high-definition projection
Solution Approach 1:
The patent applies dynamics by sequentially shifting beam spots to different positions within a pixel area over time. Instead of using multiple fixed offset positions simultaneously, the system dynamically moves beam spots through multiple positions sequentially, allowing effective speckle reduction through temporal averaging while accommodating high-definition projection requirements with limited spatial positions.
Solution Approach 2:
The patent employs periodic action by repeatedly scanning beam spots through a sequence of positions within each pixel area. The beam spots are modulated to visit multiple positions in a periodic manner, and the human eye integrates these periodic variations to perceive reduced speckle while maintaining the required positional precision for high-definition projection.
2Object-affected harmful factors
If the light source is turned off intermittently to reduce speckle, then speckle reduction is achieved, but projection time increases
Solution Approach 1:
The patent maintains continuity of useful action by keeping the light source continuously on while modulating the beam spot positions. Instead of turning the light source off and on, the system continuously projects light but varies the spatial distribution of beam spots within pixels over time, achieving speckle reduction without interrupting the projection process and thus avoiding increased projection time.
3Object-affected harmful factors
If the light source is turned off intermittently to reduce speckle, then speckle reduction is achieved, but image clarity decreases
Solution Approach 1:
The patent uses dynamics to maintain image clarity by ensuring that beam spots are continuously projected and dynamically redistributed within pixel areas. The continuous light projection with temporal spatial modulation ensures sufficient illumination intensity for clear images while the dynamic position variation achieves speckle reduction through temporal averaging.
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 effectively reduces speckle in projected images by averaging the interference patterns of secondary light spots, improving image clarity while maintaining efficient projection times, as the human eye integrates the light spots within a specific time frame, making the method suitable for high-definition imaging.
Implementation Method 1
Speckle is a phenomenon created with laser light sources, due to the fact that laser light is coherent
Implementation Method 2
When the light hits the surface, it creates constructive and destructive interference
Implementation Method 3
superposing the secondary light spots
Implementation Method 4
the positions of each of the beam spots which define a pixel to be different... will cause an averaging of the speckle over the whole pixel
Data Source
AI summary
According to the present invention there is provided a method of reducing speckle in a primary light spot which is projected onto a surface by a projection device which comprises a laser, wherein a primary light spot is defined by two or more secondary light spots, the method comprising the steps of (a) consecutively providing the laser with “n” different input currents so that the laser consecutively outputs “n” different light beams, wherein each one of the “n” different light beams defines a secondary light spot on the surface, wherein “n” is an integer value greater than one; and (b) superposing the secondary light spots. There is further provided a corresponding method of projecting a pixel.