Beam-Shaping Lens Pair for Laser Display Spot Size Control
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Solution Overview
Problem
In laser phosphor displays, the use of multimode lasers with increased power results in a beam footprint that violates the required pixel size, leading to issues such as RGB color crosstalk and non-square pixels, which affect the display's resolution and fill factor.
Innovation Solution
A cylindrical or toroidal lens pair is used between the magnification lenses and the screen to adjust the beam footprint. The lens pair, comprising a negative and a positive lens, adjusts the magnification in the single mode and multimode directions independently, ensuring the beam is focused correctly on the screen without magnifying the beam itself.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the laser diode emitter height is increased to obtain more power, then the laser power is improved, but the beam footprint on the screen becomes larger than the required pixel size
Solution Approach 1:
The patent divides the magnification control into two independent segments: one for the single mode direction and another for the multimode direction. This is achieved by using separate cylindrical lenses for each direction, allowing independent adjustment of beam dimensions without affecting the other direction. The segmentation enables the beam footprint to be precisely controlled within pixel boundaries while maintaining high laser power.
Solution Approach 2:
The patent introduces independent magnification control in two orthogonal dimensions (single mode direction and multimode direction) rather than using a single scalar magnification factor. By applying different magnification values (Msm and Mmm) along different axes through cylindrical lenses, the system can reshape the elliptical beam footprint to fit square pixel geometries while maintaining high power output.
2Area of stationary object
If separate magnifications are used in single mode and multimode directions, then the beam footprint can be controlled, but the pixel geometry becomes non-square affecting fill factor
Solution Approach 1:
The patent applies different optical properties and magnification values to different spatial directions (single mode vs. multimode directions). By tailoring the magnification specifically for each direction based on the laser emitter's characteristics and the desired pixel geometry, the system can transform the beam footprint into a square shape that matches the pixel geometry, ensuring optimal fill factor.
3Object-affected harmful factors
If the beam height is reduced to decrease effective beam width, then color crosstalk is reduced, but the laser power decreases
Solution Approach 1:
The patent segments the beam dimension control into independent directions, allowing the multimode direction (which affects color crosstalk) to be optimized separately from the single mode direction (which carries the power). By controlling only the necessary dimension while maintaining the other, the system reduces color crosstalk without sacrificing laser power.
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 solution effectively reduces the spot size of the light beam in the multimode direction, addressing issues like color crosstalk and non-square pixels, while maintaining the required beam focus on the screen, thus enhancing the display's resolution and fill factor.
Implementation Method 1
A cylindrical or toroidal lens pair is used between the magnification lenses and the screen to adjust the beam footprint. The lens pair, comprising a negative and a positive lens, adjusts the magnification in the single mode and multimode directions independently, ensuring the beam is focused correctly on the screen
Implementation Method 2
One of the lenses of the lens pair is negative while the other lens is positive. In so doing, then lens pair provides the light beam in a focal point at the screen
Data Source
AI summary
Lenses can be used to compact and/or shape a beam of light from any variable multimode light source such as a laser that has a larger beam footprint. The lenses are a cylindrical or toroidal pair that is disposed between any magnification lenses and the screen so that the magnified light beam can be appropriately directed to the screen. The lenses are different from magnification lenses in that the lens pair does not magnify the light beam, but rather, adjusts in the single mode (SM) direction and one dimension in the multimode (MM) direction. One of the lenses of the lens pair is negative while the other lens is positive. In so doing, then lens pair provides the light beam in a focal point on a non-uniform two-dimensional portion of the screen.