20 October 2004 Mid-infrared spatial filter fabrication using laser chemical etching
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Feedhorns like those commonly used in radio-telescope and radio communication equipment couple very efficiently (>98%) to the fundamental Gaussian mode (TEM00). High order modes are not propagated through a single-mode hollow metallic waveguides. It follows that a back to back feedhorn design joined with a small length of single-mode waveguide can be used as a very high throughput spatial filter. Laser micro machining provides a mean of scaling successful waveguide and quasi-optical components to far and mid infrared wavelengths. A laser micro machining system optimized for THz and far IR applications has been in operation at Steward Observatory for several years and produced devices designed to operate at λ=60μm. A new laser micromachining system capable of producing mid-infrared devices will soon be operational. These proceedings review metallic hollow waveguide spatial filtering theory, feedhorn designs as well as laser chemical etching and the design of a new high-NA UV laser etcher capable of sub-micron resolution to fabricate spatial filters for use in the mid-infrared.
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Christian Y. Drouet d'Aubigny, Christian Y. Drouet d'Aubigny, Christopher K. Walker, Christopher K. Walker, Dathon R. Golish, Dathon R. Golish, } "Mid-infrared spatial filter fabrication using laser chemical etching", Proc. SPIE 5491, New Frontiers in Stellar Interferometry, (20 October 2004); doi: 10.1117/12.552671; https://doi.org/10.1117/12.552671

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