Dual-Surface Microlens Diffusion Plate for Speckle Reduction
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Solution Overview
Problem
Conventional diffusion plates suffer from speckle noise, which degrades image quality in optical devices due to periodic microlens arrays, and using two diffusion plates to mitigate this issue reduces transmittance.
Innovation Solution
A diffusion plate with microlens arrays on both surfaces, where the first array is formed on one surface and the second array on the reverse side, allowing light from the first array to pass through and be incident on the second array, with irregular arrangements to suppress diffraction and maintain high transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single diffusion plate with periodic microlens array is used, then the device structure is simple, but speckle noise appears causing deterioration of image quality
Solution Approach 1:
The diffusion plate is segmented into multiple functional layers: a first microlens array layer and a second microlens array layer with different periodicities. This segmentation allows each layer to contribute differently to light diffusion, reducing speckle noise while maintaining structural feasibility.
Solution Approach 2:
The patent introduces asymmetry by using microlens arrays with different periodicities on the two surfaces. The first microlens array has a different period than the second microlens array, breaking the symmetry that causes periodic speckle noise while maintaining the overall diffusion function.
2Object-affected harmful factors
If two diffusion plates are used to reduce speckle noise, then speckle noise is reduced, but transmittance decreases
Solution Approach 1:
The patent merges two microlens array functions into a single integrated diffusion plate structure. The first and second microlens arrays are combined in one component rather than using two separate diffusion plates, maintaining speckle noise reduction while minimizing the number of air-glass interfaces that would reduce transmittance.
Solution Approach 2:
Instead of adding diffusion plates in the optical path direction (one dimension), the patent adds diffusion functionality in the thickness direction of a single plate (another dimension). This approach reduces speckle noise without increasing the number of separate components that light must pass through.
3Object-affected harmful factors
If microlens arrays with different periodicities are used on both surfaces, then speckle noise is reduced, but manufacturing complexity increases
Solution Approach 1:
The diffusion plate structure serves multiple functions: the first microlens array provides primary diffusion, the second microlens array with different periodicity provides secondary diffusion to reduce speckle noise, and together they maintain high transmittance. This multi-functionality in a single component simplifies the overall system while addressing multiple requirements.
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 configuration effectively reduces speckle noise while maintaining high transmittance, improving image quality and brightness in optical devices.
Implementation Method 1
A diffusion mechanism of incident light in the diffusion plate is roughly classified into a mechanism that uses refraction of light resulting from a surface shape of a diffusion plate
Implementation Method 2
a mechanism that uses scattering by a substance having a refractive index different from that of the surroundings, present inside a bulk body
Data Source
AI summary
In order to provide an optical device and a diffusion plate which has high transmittance and is capable of reducing speckle noise, the present it is a diffusion plate 1 in which a plurality of microlens cells 11 are arranged on both surfaces of a transparent substrate 10, the diffusion plate 1 having a first microlens array 12A which is formed on one surface of the transparent substrate 10 and comprises a plurality of concave or convex microlens cells 11, and a second microlens array 12B which is formed on the other surface on the reverse side from the one surface and comprises a plurality of concave or convex microlens cells 11, and the diffusion plate 1 being configured so that light emitted from the microlens cells 11 constituting the first microlens array 12A is incident on the microlens cells 11 constituting the second microlens array 12B.