Laser Beam Diameter-Converting Optical System for Laser Projectors
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Solution Overview
Problem
Projection-type image display devices using laser light for coherent light sources face challenges in maintaining focus across different screen positions, leading to reduced convenience and difficulty in achieving high-definition images due to the need for larger scanning mirrors and increased scanning speed, which complicates the formation of clear images with sufficient margin.
Innovation Solution
An image display device that incorporates a laser beam diameter-converting optical system to ensure the beam diameter at the scanner is larger than the mirror size, with the beam waist positioned to prevent pixel overlap, using a combination of convex and concave lenses or mirrors to achieve a full width at half maximum intensity smaller than the pixel pitch, allowing for high-definition image display without user focusing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the scanning speed is increased and mirror size is reduced to achieve high-definition imaging, then the pixel count and image quality are improved, but the margin between beam diameter and scanner dimension is insufficient causing pixel overlap
Solution Approach 1:
The patent applies preliminary action by introducing a beam diameter converting optical system before the scanner to pre-adjust the beam parameters. This system converts the beam diameter to an appropriate size for the scanner operation, ensuring that the beam is properly sized before it reaches the scanning element, thereby preventing pixel overlap while maintaining high image definition.
Solution Approach 2:
The patent uses an intermediary approach by inserting a beam diameter converting optical system between the light source and the scanner. This intermediary system acts as a mediator that transforms the beam characteristics to match the requirements of the scanning element, enabling high-definition imaging without pixel overlap by properly sizing the beam before scanning.
2Reliability
If the beam diameter at the scanner is made larger than the scanner dimension to ensure margin, then pixel overlap is prevented, but the beam waist position and intensity distribution become difficult to control
Solution Approach 1:
The patent applies parameter changes by using the beam diameter converting optical system to adjust the beam diameter, waist position, and intensity distribution parameters. By changing these parameters through the optical system, the patent achieves both sufficient margin at the scanner and precise control over beam characteristics, preventing pixel overlap while maintaining image quality.
3Stability of the object's composition
If a laser beam with larger beam diameter is propagated over projection distance to locate beam waist at projection surface, then the beam can be collimated on projection surface, but the beam diameter becomes too large causing loss of definition
Solution Approach 1:
The patent applies preliminary action by converting the beam diameter to an appropriate size before the scanner using the beam diameter converting optical system. This pre-adjustment ensures that the beam is properly sized for scanning and projection, maintaining collimation while preventing the beam from becoming too large and losing image definition.
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
Enables clear image display with no pixel overlap and maintains a margin relative to the beam deflector even when the scanning element is downsized, supporting high-definition projections across various screen sizes and distances without the need for user focusing.
Implementation Method 1
a laser beam diameter-converting optical system that determines the position of a beam waist and the diameter of the beam waist
Implementation Method 2
the intensity distribution of the laser beam according to a Fresnel diffraction integral is smaller than a pixel pitch
Data Source
AI summary
The present image display device is an image display device that scans laser beams emitted from light sources 101, 102 and 103 to form an image on a projection surface, and includes laser beam diameter-converting optical systems 104 that shape a beam waist of a laser beam, and horizontal scanner 106 and vertical scanner 107 for scanning a laser beam. Beam diameter-converting optical systems 104 adjust the beam diameter at the position of mirror 26, which is a beam deflector for scanner 106 and 107, to be smaller than the mirror diameter. Also, beam diameter-converting optical systems 104 shape beam waist 110 so that a full width at half maximum of the intensity, which corresponds to beam diameter 114 or 116, is always smaller than pixel pitch 115 or 117 in projection range 118 defined between first projection surface 112 and second projection surface 113.