Spectrally Controlled Light Source for Interferometry
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Solution Overview
Problem
Conventional spectrally controlled interferometry faces limitations due to the trade-off between spectral resolution and useful energy in spectrally filtered beams, particularly with single-slit spectrometers, which result in reduced light intensity and inefficiency.
Innovation Solution
A spectrally controlled light source with a periodic modulating element, such as a Ronchi ruling or Digital Mirror Device, is used to create multiple copies of the spectral distribution, allowing for resonance effects that enhance the utility of the source by matching the spatial period of the light source with the filter period, thereby increasing energy efficiency and spectral resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single-slit spectrometer is used for spectral filtering, then spectral resolution can be achieved, but light intensity is reduced and energy efficiency deteriorates
Solution Approach 1:
The single slit is segmented into multiple slits arranged in a periodic array. Each slit contributes to the spectral filtering function, and their combined effect produces multiple spectral copies that can be constructively interfered to enhance both resolution and intensity simultaneously, resolving the contradiction between spectral resolution and energy efficiency
Solution Approach 2:
Multiple spectral copies generated by the periodic slit array are merged through constructive interference at specific angles. This merging process concentrates the energy from multiple slits into enhanced spectral lines, achieving both high spectral resolution and improved light intensity/energy efficiency
2Measurement precision
If spectral filtering is applied to achieve localized interference, then measurement accuracy improves, but light intensity decreases
Solution Approach 1:
The filtering function is segmented across multiple slits in a periodic array. Each slit produces a spectral copy, and the periodic arrangement ensures these copies are spatially separated and can be selectively enhanced, maintaining measurement accuracy while increasing total light throughput
Solution Approach 2:
The periodic arrangement of slits creates periodic spectral copies that can be selectively enhanced through constructive interference. This periodic structure allows the system to maintain precise spectral filtering (for measurement accuracy) while accumulating light from multiple periodic elements (for increased intensity)
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 results in an extended, high-power light source with improved spectral modulation capabilities, enabling efficient localized interference in spectrally controlled interferometry, overcoming the limitations of single-slit systems and facilitating the use of common-path designs in white-light interferometry.
Implementation Method 1
All copies are propagated through dispersive optics to produce equally dispersed spectra on an image plane
Implementation Method 2
A periodic modulating element with a given filter period is applied to each of the dispersed spectra
Implementation Method 3
the spatial period of the light source on the image plane and the filter period of the modulating element are selected so as to produce a resonance effect
Implementation Method 4
SCI enables the formation of localized interference in an unbalanced OPD interferometer
Data Source
AI summary
A spectrally controlled light source includes a light source with a spectral distribution repeated with a predetermined spatial period along an input plane so as to produce multiple copies of the spectral distribution separated by the spatial period. All copies are propagated through dispersive optics to produce equally dispersed spectra on an image plane. A periodic modulating element with a given filter period is applied to each of the dispersed spectra to produce corresponding modulated outputs. According to the invention, the spatial period of the light source on the image plane and the filter period of the modulating element are selected so as to produce a resonance effect that greatly enhances the utility of the spectrally modulated source.