Microlens Array Pitch Variation for Controlled Light Diffusion
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Solution Overview
Problem
Conventional microlens arrays face challenges in achieving good cutoff characteristics while suppressing the generation of diffracted bright spots, particularly when there is a variation in the pitch of the lenses.
Innovation Solution
The microlens array is designed with a specific inflection point density and controlled pitch variation. The inflection point density is set to 0.50 to 0.80 [/μm] in at least one row of the array, and the pitch variation is kept less than 7.5% to achieve the desired characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the pitch of the lenses is varied to suppress diffracted light in specific directions, then the cutoff characteristics are improved, but the generation of diffracted bright spots increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the pitch variation of the microlens array to be within 7.5% and setting the inflection point density to 0.50-0.80 /μm. These specific parameter ranges resolve the contradiction by enabling good cutoff characteristics while suppressing diffracted bright spots, as demonstrated in the simulation results where different pitch variation levels produce different diffusion profile characteristics.
Solution Approach 2:
The patent introduces local quality by varying the depth of the microlenses in different regions while maintaining controlled pitch variation. The inflection point density parameter controls the local shape characteristics of the lenses, creating regions with different optical properties that work together to achieve both good cutoff characteristics and suppression of diffracted bright spots simultaneously.
2Manufacturing precision
If the pitch variation is reduced to improve cutoff characteristics, then the diffusion profile becomes more uniform, but the suppression of diffracted bright spots becomes insufficient
Solution Approach 1:
The patent resolves this contradiction by establishing specific parameter ranges: pitch variation of 7.5% or less and inflection point density of 0.50-0.80 /μm. These parameter settings simultaneously achieve uniform diffusion profiles and effective suppression of diffracted bright spots, as verified through simulation comparisons of different parameter combinations.
Solution Approach 2:
The patent effectively uses a composite approach by combining controlled pitch variation with inflection point density control. This composite parameter control strategy allows the system to achieve both good cutoff characteristics and suppression of diffracted bright spots, as the two parameters work synergistically rather than independently.
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 design effectively suppresses the generation of diffracted bright spots and enhances the cutoff characteristics of the diffusion profile, resulting in a more uniform and controlled light diffusion.
Implementation Method 1
light is diffused using a phenomenon of refraction of light
Data Source
AI summary
A microlens array includes: a substrate transparent to a used wavelength; and a plurality of aspheric lenses formed on a first face of the substrate, wherein an inflection point density N is 0.50 to 0.80 [/μm] in at least one row of the aspheric lenses in a desired one-dimensional direction in a plane of the first face, and a pitch variation with respect to an average of entire pitches of a region excluding 25% of the aspheric lenses at both ends is less than 7.5%, the aspheric lenses being arranged in a desired one-dimensional direction in the plane of the first face.