Microlens Array Diffuser Plate for Luminance Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional microlens arrays used in diffuser plates suffer from unevenness of luminance and color due to periodicity, which can lead to speckle noise and deteriorated image quality, and existing solutions either fail to sufficiently mitigate these issues or introduce new problems like increased diffracted light density.
Innovation Solution
A diffuser plate with a microlens array featuring NxN lenses arranged in a two-dimensional basic periodic structure, creating an optical path length difference, where each microlens has the same effective diameter and curvature, and is arranged based on a specific periodic structure that reduces the sine interval of diffracted light, thereby minimizing unevenness and speckle noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a typical microlens array with periodic structure is used, then the diffusion function is achieved, but unevenness of luminance occurs due to diffraction spot caused by periodicity
Solution Approach 1:
The microlens array is segmented into multiple blocks, where each block contains microlenses with different optical path length differences. This segmentation allows the periodic structure to be divided into smaller units with varying characteristics, reducing the overall diffraction effects while maintaining the diffusion function.
Solution Approach 2:
Different blocks of the microlens array are assigned different optical path length differences locally. This local variation in optical properties ensures that while each block contributes to diffusion, the cumulative effect reduces periodic diffraction patterns, thereby improving luminance uniformity.
2Illumination intensity
If randomness is imparted to the shape and/or position of the lens to mitigate unevenness of luminance, then overall luminance uniformity improves, but speckle noise occurs and image quality deteriorates due to random phase difference
Solution Approach 1:
Instead of random arrangement, the invention uses a periodic block structure where microlenses are systematically arranged in blocks with specific optical path length differences. This periodic yet structured approach mitigates luminance unevenness while avoiding the random phase differences that cause speckle noise, thereby maintaining image quality.
3Illumination intensity
If a second periodic structure is imparted to create optical path length difference, then unevenness of luminance is mitigated, but density of diffracted light increases only several times and differences in luminance occur among individual diffracted light beams
Solution Approach 1:
The invention introduces optical path length differences in an additional dimension by varying the lens shape or material properties within blocks, rather than relying solely on positional arrangement. This dimensional approach to creating optical path differences significantly increases diffracted light density while maintaining luminance uniformity across all beams.
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 effectively mitigates unevenness of luminance and color while suppressing speckle noise, achieving a higher density of diffracted light and improved image quality by increasing the diffracted light density up to N times in each direction.
Implementation Method 1
the microlenses have the same effective diameter and substantially the same curvature and have a structure that creates an optical path length difference for transmitted light or reflected light
Implementation Method 2
unevenness of luminance or unevenness of color due to the diffracted light caused by periodicity of the microstructure
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
Provided is a diffuser plate that makes it possible to mitigate unevenness of luminance or unevenness of color while suppressing speckle noise of transmitted light or reflected light. The diffuser plate of the present invention includes a microlens array having a structure that creates an optical path length difference for incident light or reflected light, the microlenses having the same effective diameter. The microlens array constitutes a basic block structure in which periodic arrangement is provided with a period of an integer multiple of the effective diameter, a two-dimensional second periodic structure having a period that is N times the period of the microlens array in the basic periodic structure is configured by a repetitive arrangement of the basic blocks, and the microlenses are set to create an optical path length difference based upon a specific arrangement within the basic block structure.