Chirped Microlens Array Homogenizes Radiation
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Solution Overview
Problem
Existing radiation homogenization devices are adjustment-critical, sensitive to impurities, and limited in their ability to achieve uniform homogeneity across large areas, especially when the input intensity distribution varies, due to interference patterns and wavelength dependence.
Innovation Solution
A device utilizing a plurality of non-identical lens systems with parallel optical axes, where each lens system can have different numerical apertures and geometries, arranged in a chirped microlens array configuration to achieve uniform radiation homogenization, with optional Fourier lenses for beam deflection and overlap, allowing for complete coverage and improved homogeneity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If regular microlens arrays (rMLA) are used for homogenization, then the device structure is simple and manufacturing is easier, but interference patterns occur leading to intensity maxima and zeros that deteriorate homogeneity
Solution Approach 1:
The patent applies asymmetry by using chirped microlens arrays where lenses have different parameters (radius of curvature, free diameter, vertex position) rather than being identical. This asymmetric design eliminates the regular interference patterns that occur with identical lenses, removing intensity maxima and zeros while maintaining manufacturing feasibility through systematic parameter variation.
Solution Approach 2:
The patent implements local quality by allowing each lens in the array to have different local parameters tailored to its position. The parameters of each lens can be determined by functions dependent on the position of the cell or lens in the array, enabling optimized local performance that collectively achieves superior homogeneity across the entire output area.
2Device complexity
If refractive beam shaping elements are used, then the device structure is simple, but the device is adjustment-critical and sensitive to impurities
Solution Approach 1:
The patent applies segmentation by dividing the beam shaping function into multiple discrete microlenses arranged in an array. Each microlens processes a portion of the input beam independently, so that impurities or misalignments in one lens do not critically affect the entire system. The collective action of many segmented lenses produces the homogenized output.
3Manufacturing precision
If diffractive beam shaping elements are used, then homogenization can be achieved, but the efficiency depends on wavelength and surface relief increases scattered light
Solution Approach 1:
The patent substitutes diffractive optical elements with refractive microlens elements. Instead of relying on diffraction and surface relief structures that cause wavelength dependence and scattering losses, the system uses geometric refraction through curved lens surfaces. This mechanical/refractive approach eliminates the harmful effects of diffraction while maintaining the beam shaping and homogenization function.
4Manufacturing precision
If the number of individual lenses in regular microlens array is increased to improve homogeneity, then homogenization improves, but the numerical aperture constraint becomes more limiting and device complexity increases
Solution Approach 1:
The patent applies parameter changes by systematically varying the parameters of each lens in the array (radius of curvature, free diameter, vertex position) according to position-dependent functions. This chirped parameter distribution allows the system to achieve superior homogeneity with a practical number of lenses, avoiding the need for extremely large arrays while eliminating interference patterns through parameter diversity.
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 achieves uniform radiation homogenization largely independent of input intensity distribution, minimizing interference patterns and wavelength dependence, thereby enhancing homogeneity and reducing manufacturing costs.
Implementation Method 1
The incident radiation hits this microlens array so that its lenses focus the radiation. The maximum angle of the focused radiation depends on the numerical aperture (NA) of the lenses. Behind the focus of the lenses, individual radiation beams diverge divergently, with the angle of divergence corresponding to the numerical aperture of the lenses.
Implementation Method 2
A Fourier lens is now arranged in the beam path behind the microlens array, which deflects the individual bundles in such a way that the partial bundles generated by the individual microlenses of the microlens array lie one above the other in the focal plane of the Fourier lens.
Implementation Method 3
A Fourier lens is now arranged in the beam path behind the microlens array, which deflects the individual bundles in such a way that the partial bundles generated by the individual microlenses of the microlens array lie one above the other in the focal plane of the Fourier lens.
Implementation Method 4
Since all power components that run through individual lenses are superimposed on the same area in the focal plane, the radiation is homogenized.
Data Source
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Figure 3~4
AI summary
The invention relates to a device for homogenizing radiation, preferably light, with the help of chirped microlens arrays (cMLA) which, unlike standard regular microlens arrays (rMLA), are an arrangement of non-identical lenses in an array. Non-identical means that the lens parameters in the array, e.g. the radius of curvature, free diameter, vertex position, and other parameters, can vary from one lens or cell to another. The parameters of each lens or cell can be (analytically, numerically) determined by means of functions which are preferably dependent on the position of the cell or lens within the array.