Microlens Array Non-Periodic Design for Uniform Light Diffusion

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Solution Overview

Problem

Existing microlens arrays suffer from unevenness in light intensity distribution due to diffraction at the aperture of individual microlenses and interference from periodic structures, which limits their application in achieving smooth and high-transmittance light diffusion for various optical systems.

Innovation Solution

A microlens array design where the distance between adjacent microlenses is varied to reduce diffraction-induced unevenness, with specific relationships between lattice spacing, curvature radius, and focal length ensuring optimal light distribution, and vertex positions are displaced to minimize dark spots and interference effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If microlenses are arranged at small intervals to achieve high transmittance and wide angle of light distribution, then transmittance is improved, but wave fronts of rays from respective microlenses interfere with one another producing diffracted waves due to the periodic structure, generating unevenness in light distribution

Engineering Contradiction:

ImprovetransmittanceVSAvoiduniformity of light distribution

Core Design Contradiction:

Loss of energyVSEase of operation

Solution Approach 1:

The patent applies asymmetry by intentionally introducing non-periodic deviations in the microlens array structure. The microlens positions are displaced from regular lattice points by random amounts, and the lens shapes are perturbed from perfect symmetry. This asymmetric, non-periodic structure eliminates the periodic diffraction effects that cause uneven light distribution, while maintaining high transmittance through close spacing.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent applies local quality by allowing each microlens to have slightly different properties - random positional deviations from lattice points, varying aperture shapes, and perturbed surface profiles. This local variation prevents coherent interference patterns while maintaining overall functional consistency, achieving both high transmittance and uniform light distribution.

Inventive Principle:

Principle #3Local quality

2Illumination intensity

If curvature radius of microlens is reduced to achieve wide angle of light distribution, then angle of divergence is improved, but diffraction at the aperture itself of microlens causes unevenness in light intensity distribution

Engineering Contradiction:

Improveangle of divergenceVSAvoiduniformity of light intensity distribution

Core Design Contradiction:

Illumination intensityVSEase of operation

Solution Approach 1:

The patent applies composite approach by combining multiple microlens elements with slightly varying properties into an array. The collective behavior of these composite elements, with random positional and shape variations, produces a uniform overall light distribution pattern while maintaining wide divergence angles through appropriate curvature radius selection.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies parameter changes by systematically varying multiple parameters - curvature radius, aperture size, positional deviations, and shape perturbations - to optimize the balance between divergence angle and uniformity. By adjusting these parameters within specific ranges and combining them with random variations, the patent achieves wide angle distribution without aperture diffraction unevenness.

Inventive Principle:

Principle #35Parameter changes

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 design achieves a more uniform light intensity distribution and reduced diffraction effects, enhancing the transmittance and smoothness of light diffusion across a wider angle of divergence, suitable for applications requiring high flexibility and minimal surface texture.

Implementation Method 1

A Gaussian diffuser that realizes a Gaussian intensity profile distribution of diffused light by refraction of incident lights

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

diffraction at the aperture itself of a microlens causes unevenness in light intensity distribution of diffused light

Methodology Applied

Scientific EffectDiffraction: Diffraction

Implementation Method 3

wave fronts of rays from respective microlenses interfere with one another so that diffracted waves due to the periodic structure of the arrangement are produced

Methodology Applied

Scientific EffectInterference: Interference

Data Source

PatentUS10443811B2Microlens array and optical system including the same

Publication Date: 2019.10.15 NALUX CO LTD

AI summary

A microlens array includes N microlenses arranged in a predetermined direction on an x-y plane. A projection onto the x-y plane of the vertex of each microlens is arranged in the vicinity of a lattice point of a reference lattice on the x-y plane, the lattice spacing of the reference lattice in the predetermined direction being D/M (millimeters) where M is a positive integer. A distance between two sides of a lens facing each other is approximately equal to D, and a distance between the projection onto the x-y plane of the vertex of the lens and the projection onto the x-y plane of a side of the lens is D/2+εi. Letting n represent the refractive index of the material of each microlens and letting f (millimeters) represent the focal length of each microlens, the following relationships are satisfied.0.0042D<D2⁢⁢f=D⁡(n-1)2⁢⁢R0.0048⁢f⁢{1+(D/2⁢⁢f)2}<σ<0.014⁢f⁢{1+(D/2⁢⁢f)2}σ2=∑i=1N⁢(ɛi-ɛ_)2Nɛ_=∑i=1N⁢ɛiN=0