Biased Fast Axis Retarder System for Broadband Wavelength Coverage
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Solution Overview
Problem
Conventional Berek and Non-Berek-type retarders are limited in the range of significant retardance they can provide between orthogonal components of an electromagnetic beam, failing to achieve significant retardance over a range of about 0.3 to 3.0 microns.
Innovation Solution
A retarder system comprising at least one pair of plates, where each plate has parallel sides and a fast axis at a biased angle between 0.0 and +/-90 degrees relative to the plate surfaces, allowing for a phase angle change between orthogonal components of the electromagnetic beam without being perpendicular or parallel to the plate surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional Berek or Non-Berek-type retarders are used, then the device structure is simple and well-defined, but the range of significant retardance is limited and cannot achieve 0.3 to 3.0 microns
Solution Approach 1:
The retarder is divided into multiple sequential plates (at least two plates) with different fast axis orientations. Each plate contributes to the overall retardance in a specific wavelength range, and by combining multiple plates with different orientations (e.g., 0 degrees and 45 degrees relative to the beam plane), the system achieves extended retardance coverage from 0.3 to 3.0 microns that cannot be obtained with a single conventional plate
Solution Approach 2:
The system uses composite optical structures by combining multiple retarder plates with different fast axis orientations and potentially different materials. This composite approach allows the system to provide significant retardance across a broad wavelength range by leveraging the complementary retardance characteristics of each plate in the sequence
2Adaptability or versatility
If multiple sequential Berek or Non-Berek-type retarders are used, then the device complexity increases, but the range of significant retardance remains limited
Solution Approach 1:
The invention changes the orientation parameter of the fast axis relative to the beam plane. By setting fast axes at specific angles (0 degrees, 45 degrees, or other orientations) rather than the conventional perpendicular or parallel orientations, each plate provides optimized retardance for specific wavelength ranges. This parameter optimization allows achieving extended broadband retardance with a practical number of plates
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 significant retardance over a range of wavelengths from 0.3 to 3.0 microns, enhancing the capability of retardance compared to conventional systems, particularly beneficial in ellipsometer applications.
Implementation Method 1
an incident beam of electromagnetic radiation entering the first side of the first plate is refracted thereby so that it exits the second side of the first plate at a location offset from the incident beam
Implementation Method 2
entering phase delay between orthogonal components of a polarized beam of electromagnetic radiation
Data Source
AI summary
A retarder that comprises at least two plates, each of which comprise two surfaces that are parallel to, or substantially parallel to one another, said plates being tipped with respect to one another so that the surfaces of one thereof are not parallel to the surfaces of the other, each said plate further comprising a biased fast axis that is neither parallel to, or perpendicular to surfaces of said plates.