Dual Microlens Array Beam Homogenizer for 3D Mapping
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Solution Overview
Problem
Optical projection systems face challenges in achieving homogeneous illumination beams, leading to spurious intensity variations and degraded accuracy in 3D mapping applications due to factors like laser speckle and inhomogeneities.
Innovation Solution
A beam homogenizer comprising a matrix of light sources with a predetermined uniform spacing, utilizing dual microlens arrays with different pitches and a collection lens to collimate and mix light, reducing speckle contrast and achieving uniform intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single microlens array is used for beam homogenization, then the structure is simple, but the illumination homogeneity is insufficient
Solution Approach 1:
The single microlens array is divided into multiple sub-arrays with different pitch values. Each sub-array processes a portion of the light from the light source array, and the combined effect achieves superior homogenization that would not be possible with a single uniform pitch array.
Solution Approach 2:
Different regions of the microlens array have different local properties (different pitch values in different sub-arrays). This allows each region to optimize for its specific function while contributing to the overall homogenization goal, resolving the contradiction between structural simplicity and illumination quality.
2Illumination intensity
If multiple optical elements are added to improve beam homogeneity, then illumination quality improves, but device complexity increases
Solution Approach 1:
Multiple microlens sub-arrays with different pitch values are integrated into a single optical component. This merging approach achieves the homogenization benefits of multiple separate elements while maintaining a compact, unified structure that does not significantly increase system complexity.
Solution Approach 2:
The microlens array component performs multiple functions simultaneously: it collimates light, homogenizes the beam profile, and maintains a compact form factor. This multi-functionality resolves the contradiction by achieving superior illumination quality without proportionally increasing device complexity.
3Use of energy by moving object
If microlens pitch matches light source spacing, then light collection efficiency is high, but speckle contrast is reduced
Solution Approach 1:
The microlens array is segmented into sub-arrays with different pitch values. The first sub-array with pitch matching the light source spacing optimizes light collection efficiency, while subsequent sub-arrays with different pitches further process the light to reduce speckle contrast, thus resolving the contradiction between these two opposing requirements.
Solution Approach 2:
The pitch parameter of the microlens array is varied across different sub-arrays. By changing this critical parameter from a single fixed value to multiple values, the system simultaneously achieves high light collection efficiency (through the matching pitch sub-array) and speckle reduction (through the non-matching pitch sub-arrays).
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 provides compact, cost-effective generation of homogeneous projection beams, significantly reducing speckle contrast and enhancing the accuracy of 3D mapping by averaging out intensity variations across the projected area.
Implementation Method 1
A first microlens array, which has a first pitch equal to the spacing between the light sources and which is aligned with the matrix so that a respective optical axis of each microlens in the array intercepts a corresponding light source in the matrix and transmits light emitted by the corresponding light source
Implementation Method 2
A second microlens array, which is positioned to receive and focus the light transmitted by the first microlens array and which has a second pitch that is different from the first pitch
Implementation Method 3
significantly reducing speckle contrast and enhancing the accuracy of 3D mapping by averaging out intensity variations across the projected area
Data Source
AI summary
Optical apparatus includes a matrix of light sources arranged on a substrate with a predetermined, uniform spacing between the light sources. A beam homogenizer includes a first optical surface, including a first microlens array, which has a first pitch equal to the spacing between the light sources and which is aligned with the matrix so that a respective optical axis of each microlens in the array intercepts a corresponding light source in the matrix and transmits light emitted by the corresponding light source. A second optical surface, including a second microlens array, is positioned to receive and focus the light transmitted by the first microlens array and has a second pitch that is different from the first pitch.