Microlens Array Speckle Reduction in Optical Assemblies
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing projection systems, such as those used in head-up displays, suffer from a speckle effect due to the randomization of coherent light by diffusers, which reduces the resolution and quality of the projected image.
Innovation Solution
An optical assembly comprising a telecentric lens in optical communication with a microlens array, where the microlens array is designed to diffuse light without randomizing its phase, using semi-cylindrical or semi-spherical lenses, and optionally a pin hole array or Fresnel lens to control light diffusion and reduce speckle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a diffuser is used to diffuse light beams and create a field of view, then the field of view is provided and defined, but the phase of coherent light is randomised inducing a speckle effect that reduces resolution and image quality
Solution Approach 1:
The patent divides the light diffusion function into discrete microlens elements arranged in an array. Each microlens acts as an independent light-guiding element that directs light to specific regions, replacing the continuous random diffusion of traditional diffusers. This segmentation allows controlled light distribution without phase randomization.
Solution Approach 2:
The patent replaces the mechanical/scattering-based diffuser with an optical lens-based system. Instead of using materials that randomly scatter light through micro-structures, the invention uses microlenses that optically guide and direct light beams through refraction, eliminating the speckle effect while maintaining field of view.
2Adaptability or versatility
If a diffuser is used to enable light scattering in all directions within the field of view, then viewers can see the image from different locations, but the coherent light becomes randomised in phase reducing image quality
Solution Approach 1:
The patent assigns different optical functions to different regions of the microlens array. Each microlens is positioned and oriented to guide light to specific angular directions, creating local variations in light guidance. This local quality differentiation enables viewers to see the image from multiple locations while maintaining coherent light phases throughout the system.
3Illumination intensity
If traditional diffusers are used to provide field of view, then light is scattered effectively, but the speckle effect reduces the brightness uniformity and clarity of the projected image
Solution Approach 1:
The patent employs microlenses with curved surfaces (spheroidal or aspherical geometry) to control light scattering. The curved surfaces of the microlenses enable precise control over light ray directions through refraction, achieving effective light scattering while maintaining image clarity and eliminating the speckle effect associated with flat or rough-surfaced diffusers.
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 increases the quality of the projected image by diffusing light without inducing speckle, providing a larger field of view and improving image clarity while maintaining brightness uniformity.
Implementation Method 1
The light diffusers are used to diffuse light beams which they received. The diffusion of light beams in a projection system is done so as to create a field of view
Implementation Method 2
an optical assembly which comprises a telecentric lens arranged to be in optical communication with a microlens array
Implementation Method 3
a pin hole array which arranged adjacent to the second surface of the microlens array
Data Source
AI summary
An optical assembly, and in particular an optical assembly which uses a microlens array or a micromirror array to reduce speckle. It further concerns an optical component which comprises a micromirror array.