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Metal mesh interference filters for the far infrared
1Aerospace Corporation, P.O. Box95085, Los Angeles, California 90045, USA.
Applied Optics
|January 12, 2010
Summary
Researchers fabricated improved far infrared Fabry-Perot interference filters using metal meshes. These filters achieve higher finesse and peak transmittance, enabling applications across a wide frequency range.
Area of Science:
- Physics
- Optical Engineering
- Materials Science
Background:
- Fabry-Perot interference filters are optical devices utilizing resonant cavities.
- Previous designs using metal meshes had limitations in performance and frequency range.
Purpose of the Study:
- To fabricate improved far infrared (FIR) Fabry-Perot type interference filters.
- To enhance filter finesse and peak transmittance using advanced techniques.
- To characterize filter performance and explore their frequency applicability.
Main Methods:
- Fabrication of FIR filters using parallel, closely spaced metal meshes.
- Characterization of transmittance curves using the Aerospace lamellar grating interferometer.
- Analysis of transmittance peaks to determine filter finesse and limitations.
Main Results:
- Achieved filters with significantly larger finesse (up to 100) and peak transmittance.
- Identified beam convergence angle (8 degrees) as a primary limitation on peak sharpness.
- Demonstrated filter applicability for frequencies from 10 cm⁻¹ to over 200 cm⁻¹.
Conclusions:
- Improved fabrication techniques yield high-performance FIR Fabry-Perot filters.
- These filters offer broad frequency coverage for spectroscopic applications.
- Absorbing components are necessary to mitigate harmonic interference in practical applications.
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