Koehler Integrator Microlens Layout for Uniform Multi-Wavelength Spots
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Solution Overview
Problem
Conventional Koehler integrators are limited in generating a uniform array of excitation spots at multiple wavelengths and suffer from power loss, making them unsuitable for multi-focal confocal microscopy and other applications requiring efficient illumination.
Innovation Solution
A Koehler integrator device comprising a collimating lens, planar micro-lens arrays, and a Fourier lens, with a third micro-lens array arranged in the Fourier lens front focal plane to create a wavelength-independent array of light spots, ensuring telecentric illumination and high power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a single mode laser beam with Gaussian intensity profile is used to generate an array of excitation spots, then the excitation spots can be created, but the relative intensities of the spots follow a Gaussian distribution causing significant intensity variation across the field of view and significant power loss when only the central part is used
Solution Approach 1:
The patent segments the single Gaussian beam into multiple spatial modes by introducing a micro-lens array that divides the beam into multiple sub-beams, each forming an excitation spot. This segmentation allows the entire beam cross-section to be utilized rather than just the central part, reducing power loss while maintaining uniform spot intensities through the structured illumination pattern.
Solution Approach 2:
The patent transitions from using a single spatial mode (1D Gaussian profile) to utilizing multiple spatial modes by adding structural dimensionality through a micro-lens array. This dimensional change enables the system to convert the radial intensity distribution of the Gaussian beam into a uniform 2D array of excitation spots, eliminating intensity variation across the field of view.
2Illumination intensity
If conventional Koehler integrators are used to generate a uniform array of excitation spots, then uniform illumination can be achieved, but significant power loss occurs and they are limited in generating uniform arrays at multiple wavelengths
Solution Approach 1:
The patent creates a multi-functional illumination system where the micro-lens array configuration can generate uniform excitation spot arrays at multiple wavelengths simultaneously. The system is designed to be wavelength-agnostic, allowing the same optical structure to function across different spectral ranges, thereby eliminating the limitation of conventional Koehler integrators that are optimized for specific wavelength ranges.
Solution Approach 2:
The patent changes the fundamental parameters of the illumination system by replacing the conventional Koehler integrator's complex lens system with a micro-lens array that directly shapes the Gaussian beam. This parameter change in the optical configuration enables both uniform illumination and high power efficiency by maintaining a direct optical path without the multiple transformations and losses inherent in conventional designs.
3Shape
If a pinhole array is used in the conjugate image plane to create an array of excitation spots, then an array of spots can be generated, but significant power loss occurs since light is not efficiently transmitted through the pinhole array
Solution Approach 1:
Instead of using a pinhole array to block unwanted light and form spots (conventional approach), the patent inverts the approach by using a micro-lens array to actively focus and shape the light into the desired spot array pattern. This inversion from a blocking mechanism to a focusing mechanism fundamentally improves light transmission efficiency while achieving the same array spot formation.
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 the generation of uniform, wavelength-independent arrays of light spots with high power efficiency, suitable for multi-focal confocal microscopy and other applications, overcoming limitations of conventional Koehler integrators.
Implementation Method 1
a collimating lens (11) adapted for collimating a light field created by a light source device (110)
Implementation Method 2
a pair of planar first and second micro-lens arrays (12, 13) arranged with a mutual distance along said optical axis, wherein said distance is equal to a common micro-lens focal length
Implementation Method 3
Both micro-lens arrays extend perpendicular to said optical axis and are arranged for relaying portions of said collimated light field through separate imaging channels
Implementation Method 4
a Fourier lens (14) superimposing light from all imaging channels in a Fourier lens front focal plane
Data Source
AI summary
A Koehler integrator device includes a collimating lens for collimating a light field from an incoherent or partially coherent light source, planar first and second micro-lens arrays for relaying portions of the collimated light field along separate imaging channels, wherein all the micro-lenses have equal focal length and pitch and the arrays are arranged with a mutual distance equal to the focal length, and a collecting Fourier lens having a Fourier lens diameter and focal length defining front and back focal planes, wherein the Fourier lens is for superimposing light from all imaging channels in the front focal plane and wherein the second micro-lens array is in the back focal plane, wherein a third micro-lens array is in the front focal plane for creating a wavelength independent array of illumination spots. Furthermore, a confocal microscope apparatus, including the device, and a method of using the apparatus are described.