Laser Homogenizer With Light Pipe and Microlens Array for Top-Hat Profiles
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Solution Overview
Problem
Existing laser systems struggle to achieve a uniform, even intensity distribution (top hat profile) for applications requiring uniform illumination, leading to inefficiencies and energy waste in Gaussian profile outer regions.
Innovation Solution
A laser beam homogenizer using a light pipe and a second stage integrator, combined with custom surface engineered diffusers and microlens arrays, to achieve a top-hat intensity profile by redistributing the irradiance and phase profile, minimizing light loss and speckle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a Gaussian beam source is physically cut by an aperture to form a pseudo-flat top profile, then the device complexity and cost are minimized, but there is significant energy waste in the outer regions of the Gaussian profile
Solution Approach 1:
The patent introduces a light pipe as an intermediary optical element between the Gaussian beam source and the output. The light pipe acts as a mediator that transforms the Gaussian intensity distribution into a uniform top-hat profile through total internal reflection, thereby eliminating the need for aperture cutting while preventing energy waste in the outer regions.
Solution Approach 2:
The patent changes the intensity distribution parameter from Gaussian to uniform by utilizing the light pipe's optical properties. The light pipe modifies the beam parameters (intensity profile, spatial distribution) through its specific geometry and total internal reflection characteristics, transforming the input Gaussian beam into an output top-hat beam.
2Loss of energy
If refractive beam shapers with field-mapping phase elements are used to achieve uniform intensity distribution, then the output beam is highly efficient and wavelength independent, but the device complexity increases
Solution Approach 1:
The patent replaces complex refractive optical elements (lenses, diffractive components) with a simple light pipe based on total internal reflection. This substitution eliminates the need for field-mapping phase elements while achieving the same uniform intensity distribution, thereby reducing device complexity while maintaining high beam efficiency and wavelength independence.
Solution Approach 2:
The light pipe utilizes its own geometric structure and total internal reflection properties to automatically transform the Gaussian beam into a uniform profile without requiring external control mechanisms or complex optical components. The system is self-contained and self-regulating, achieving beam shaping through the inherent optical properties of the light pipe itself.
3Manufacturing precision
If a light pipe is used to transform non-uniform light source output into uniform illumination through total internal reflection, then the beam homogenization is achieved, but potential hotspots and interference patterns may appear
Solution Approach 1:
The patent segments the light pipe into multiple internal reflection zones and uses a microlens array to divide the beam into multiple sub-beams. This segmentation approach distributes the light more evenly across the output profile, preventing hotspot formation while maintaining uniform homogenization quality.
Solution Approach 2:
The patent introduces a microlens array as an intermediary element between the light pipe and the final output. This additional mediator further uniformizes the intensity distribution by redistributing light through the microlens array, eliminating residual hotspots and interference patterns while preserving the homogenization achieved by the light pipe.
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 system provides accurate beam shaping with minimal light loss, achieving a near top-hat intensity profile with no visible hot spots or interference patterns, suitable for various applications including spectroscopy, material processing, and entertainment.
Implementation Method 1
Through the process of total internal reflection (TIR), a light pipe can transform the output of a highly non-uniform light source into a highly uniform or homogenized illumination
Implementation Method 2
A second integrator based on a microlens array is added downstream to further improve the homogenization as a second stage of this invention
Implementation Method 3
To eliminate potential hotspots and achieve an even more uniform distribution profile, the beam can be diffused with an holographic refractive diffuser
Data Source
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AI summary
Provided is an invention related to laser beam shaping with the goal to achieve a controlled intensity profile, usually top-hat distribution, created by several laser beam sources with incident non-uniform beam intensity profile (incident gaussian laser beam/s or other higher order multi-transverse modes, in the visible, IR or UV spectrum). The laser beam homogenizer-expander uses a main beam shaper element or Light Pipe (light integrator), and a second beam shaper element or microlenses array (MLA), that is, second light integrator which defines the top-hat intensity distribution output, thus providing a second homogenization stage. The invention also includes several optics like light diffusers, mirrors, dichroic filters, beam shaping lenses, light pipe and microlenses, to achieve a good homogenization at the desired output angle. The invention is designed to fully integrate/blend one or several wavelength laser sources, like red, green, and blue as an example, but other wavelengths in the visible/non-visible spectrum can be integrated as well. If multi-wavelengths are used as initial laser source, the light engine output provides a good homogenization and color blend, with almost no noticeable speckle, near top-hat intensity profile and no visible hot spots or interference patterns. The invention is useful for many applications, like microscopy, material processing, fluorescence, lighting fixtures, holography, fiber coupling etc., where spectral properties of laser light is required (narrowband, monochromaticity) but a uniform distribution of the intensity is necessary at the same time.