Stacked Rhomboidal Waveguides for Aspect Ratio Transformation
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Solution Overview
Problem
Existing optical transformation methods fail to efficiently convert a nominally circular input to a high aspect ratio output without significant loss of brightness, particularly for applications like diffraction-grating based spectrometry, as they are either inefficient, complex, or difficult to compactify.
Innovation Solution
The use of stacked rhomboidal slab waveguides with 45° mirrors to transform the aspect ratio of an optical input, where each rhomboid has a different length but similar width and thickness, allowing for a compact and efficient conversion of a near-unity aspect ratio spot to a high aspect ratio output, with optional slit masks to define the equivalent slit width for spectrometers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If anamorphic prism pairs are used to transform aspect ratio, then the transformation can be achieved, but the device becomes difficult to compactify and requires collimated beams which increases system complexity
Solution Approach 1:
The patent transitions from 2D prism-based aspect ratio transformation to 3D waveguide-based transformation. The waveguides propagate light through their length, adding a spatial dimension to the transformation process. This allows compact integration of the transformation function within the waveguide structure itself, eliminating the need for separate prisms and collimation optics.
Solution Approach 2:
The waveguide acts as an intermediary medium that performs both light propagation and aspect ratio transformation simultaneously. Instead of using prisms to deflect light and separate optics for propagation, the waveguide's evanescent field interaction with the sample provides both functions in one component, simplifying the overall system.
2Shape
If fiber bundles are used to convert near-unity aspect ratio spots to high aspect ratio outputs, then the transformation is achieved, but collection efficiency is reduced and the device becomes difficult to compactify
Solution Approach 1:
The patent replaces the mechanical fiber bundle arrangement with an optical waveguide system. Instead of physically rearranging light paths through bundled fibers with air gaps and connection losses, the waveguide uses total internal reflection to guide light through its structure, maintaining higher collection efficiency while achieving the same aspect ratio transformation.
3Volume of moving object
If non-imaging elliptical concentrators are used, then compactification is achieved, but angular distribution of input radiation is not preserved
Solution Approach 1:
The waveguide structure provides different optical paths for different spatial locations. Light entering at different positions and angles through the waveguide face experiences locally optimized propagation paths that preserve the angular distribution information. This local quality control maintains the relationship between input angle and output position, which is critical for spectroscopic applications.
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
This approach enables a large factor change in aspect ratio without substantial brightness loss, resulting in a compact and efficient optical transformation suitable for high-resolution spectrometry applications, preserving angular distribution and maintaining high numerical aperture.
Implementation Method 1
The radiation, upon being launched in the slabs is reflected by a first 45° mirror which is one angular face of the rhomboid. The reflected radiation propagates in the waveguides and then encounters the second angular face of the rhomboid which is a second mirror also disposed at 45°.
Implementation Method 2
The radiation, upon being launched in the slabs is reflected by a first 45° mirror which is one angular face of the rhomboid. The reflected radiation propagates in the waveguides and then encounters the second angular face of the rhomboid which is a second mirror also disposed at 45°.
Data Source
AI summary
An apparatus consisting of stacked slab waveguides whose outputs are vertically staggered is disclosed. At the input to the stacked waveguides, the entrances to each slab lie in approximately the same vertical plane. A spot which is imaged onto the input will be transformed approximately to a set of staggered rectangles at the output, without substantial loss in brightness, which staggered rectangles can serve as a convenient input to a spectroscopic apparatus. A slit mask can be added to spatially filter the outputs so as to present the desired transverse width in the plane of the spectroscopic apparatus parallel to its dispersion.