Microlens Array Diffuser Plate for Laser Light
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Solution Overview
Problem
Existing diffuser plates struggle to achieve desired diffusion properties for spot-like incoming light, such as laser light, due to increased coherence and manufacturing process limitations, particularly in suppressing diffracted light components and ensuring durability under high light intensity.
Innovation Solution
A microlens array diffuser plate design with specific vertex-to-vertex distance and radius of curvature variations, combined with a manufacturing method using dry etching and an antireflection layer, to optimize the microlens structure and material selection for improved diffusion and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If irregular microlens array structure is used to suppress diffracted light, then diffusion property is improved, but manufacturing complexity and data amount increase enormously
Solution Approach 1:
The patent divides the microlens array into multiple unit cells, where each unit cell contains a specific arrangement of microlenses with irregular pitches and heights. This segmentation allows the complex irregular pattern to be broken down into manageable repeating units, reducing the overall data amount and manufacturing complexity while maintaining the diffusion performance through the cumulative effect of multiple unit cells.
Solution Approach 2:
The patent applies different pitch and height variations to different regions within unit cells. Specifically, adjacent microlenses have different pitches, and microlenses at different positions have different heights, creating local irregularities that suppress diffraction. This local quality approach maintains diffusion performance without requiring entire surfaces to be completely irregular, thus reducing manufacturing complexity.
2Reliability
If completely irregular pattern is used to suppress diffraction, then diffusion property is improved, but evaluation time and production cost increase due to inability to narrow down evaluation spots
Solution Approach 1:
By dividing the diffuser into repeating unit cells with specific irregular patterns, the patent enables evaluation to be focused on representative samples of these unit cells rather than the entire large-area irregular surface. This segmentation allows for narrowed down evaluation spots, significantly reducing evaluation time and production cost while maintaining confidence in the overall diffusion performance.
3Productivity
If step and repeat exposure method is used to manufacture large area diffuser, then productivity is improved, but pattern discontinuity occurs at joints
Solution Approach 1:
The patent designs unit cells with specific boundary characteristics that ensure continuous patterns when multiple unit cells are joined through step and repeat exposure. The segmentation into standardized unit cells with controlled boundary conditions allows for seamless tiling, eliminating pattern discontinuity at joints while enabling efficient large-area manufacturing through repeated exposure cycles.
4Reliability
If microlens array is used for spot-like coherent light, then diffusion is achieved, but diffracted light components increase due to high coherence
Solution Approach 1:
The patent creates local irregularities in pitch and height among adjacent microlenses within unit cells. These local variations in optical path lengths and phase relationships disrupt the coherence of diffracted light components, suppressing unwanted diffraction patterns. This local quality approach is particularly effective for coherent light sources like lasers, where maintaining diffusion performance while suppressing diffraction is critical.
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 enables a diffuser plate with enhanced diffusion properties and durability for coherent light sources, while improving productivity through optimized manufacturing processes.
Implementation Method 1
a mechanism that utilizes light refraction resulting from the surface shape of the diffuser plate
Implementation Method 2
a mechanism that utilizes scattering by a substance existing inside a bulk body and having different refractive index from the circumference
Data Source
Figure 1~2
Figure 3A~3B
Figure 4A~5
AI summary
[Object] To manufacture a diffuser plate with better productivity, the diffuser plate exhibiting an excellent diffusion property and having excellent durability with respect to light having large coherence. [Solution] The microlens array diffuser plate according to the invention includes a microlens group positioned on a surface of a transparent substrate. The diffuser plate includes two or more unit cells that are continuously set in array, the unit cell includes a plurality of microlenses positioned on the surface of the transparent substrate, and ridge lines between the microlenses adjacent to each other are nonparallel to each other, and are nonparallel to the transparent substrate.