Aspherical Convex-Lens Array Homogenizer for Laser Illumination
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Solution Overview
Problem
Conventional homogenizers struggle to achieve an even light-intensity distribution on irradiation planes when using laser light sources, particularly with Gaussian intensity distributions, and are limited by the cosine fourth power law, leading to uneven illumination and reduced light utilization efficiency.
Innovation Solution
A homogenizer design featuring a pair of convex-lens arrays with each lens having a common symmetry axis, where the first convex-lens array has an average internal transmission angle greater than 1.3 times that of a spherical lens, and the second array has a larger numerical aperture, allowing for a maximum diffusion angle of 12° or more while maintaining high condensing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional homogenizers with spherical convex lenses are used, then the structure is simple and easy to manufacture, but the light-intensity distribution on irradiation planes becomes uneven when using laser light sources
Solution Approach 1:
The invention changes the key parameter of lens shape from spherical to aspherical. The aspherical convex lenses have a surface curvature that varies with distance from the optical axis, allowing precise control of light transmission angles. This parameter change enables the homogenizer to achieve even light-intensity distribution (85% or higher) on irradiation planes when using laser light sources with Gaussian intensity distributions, resolving the contradiction between manufacturing simplicity and illumination quality.
Solution Approach 2:
The aspherical lenses exhibit local quality variations across their surface - the curvature radius changes depending on the radial distance from the optical axis. This allows different regions of the lens to transmit light at different angles, with the average internal transmission angle being 1.3 times or more that of spherical lenses. This local differentiation enables precise control over light distribution to achieve uniform illumination while maintaining reasonable manufacturability.
2Loss of energy
If the numerical aperture of the second convex-lens array is increased to achieve wider diffusion angle, then the light utilization efficiency improves, but the manufacturing precision requirements increase
Solution Approach 1:
The invention increases the numerical aperture of the second convex-lens array to achieve a maximum diffusion angle of 12° or more, which improves light utilization efficiency. The aspherical lens design allows this increased numerical aperture while maintaining manufacturability through controlled variations in surface curvature. The average internal transmission angle of 1.3 times or more that of spherical lenses enables efficient light diffusion without requiring excessive manufacturing precision.
3Ease of manufacture
If conventional spherical lenses are used, then the manufacturing process is simpler, but the average internal transmission angle is insufficient for achieving even illumination with laser sources
Solution Approach 1:
The invention modifies the lens parameter by transitioning from spherical to aspherical geometry, achieving an average internal transmission angle that is 1.3 times or more that of spherical lenses. This parameter enhancement improves light utilization efficiency and achieves even illumination with laser sources, while the aspherical surfaces can still be manufactured using conventional precision molding or grinding techniques, maintaining reasonable ease of manufacture.
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 enables a homogenizer that achieves an even light-intensity distribution of 85% or higher on irradiation planes, effectively addressing the limitations of conventional designs and improving light utilization efficiency for laser light sources.
Implementation Method 1
The convex lenses of the convex-lens array 52a condense incident light so as to strike on the convex lenses of the convex-lens array 52b
Implementation Method 2
fluxes of incident light which differ in light-intensity distribution on the surface of the convex-lens array 52a are emitted from the convex lenses 521a of the convex-lens array 52a and the convex lenses 521b of the convex-lens array 52b and superimposed at the irradiation plane
Data Source
AI summary
A homogenizer includes a convex-lens array pair including a first convex-lens array disposed on a light entrance side and a second convex-lens array disposed on a light emission side. The first convex-lens array and the second convex-lens array are disposed so as to face each other such that each of the convex-lens arrays has a lens surface opposed to each other outward or inward. The first convex-lens array includes a plurality of first convex lenses in an array arrangement. The second convex-lens array includes a plurality of second convex lenses in an array arrangement. The first convex lens has an average internal transmission angle for incident light entering a lens-surface center region in the lens cross-section and being in parallel with the symmetry axis being equal to or more than 1.3 times an average internal transmission angle of a spherical convex lens.