Evaporation of uniform antireflection coatings on hemispherical lenses to enhance infrared antenna gain
Abbreviated Journal Title
Infrared Phys. Technol.
Keywords
Infrared antennas; Immersion lens; Antenna-coupled detectors; Antireflection coatings; SURFACE; Instruments & Instrumentation; Optics; Physics, Applied
Abstract
Infrared dipole-coupled bolometers receive radiation more efficiently when illuminated through a high permittivity, antireflection (AR) coated, hemispherical immersion lens. To maintain the enhanced responsivity for all illumination angles, the AR coating Must be uniform over the hemispherical surface. An evaporation method for depositing a uniform AR coating on the hemispherical surface is presented. The lens is tilted relative to the source, which can be either electron-beam or thermal, and rotated throughout the deposition. Evaporation at an angle of 70 degrees yields a uniform film with less than 10% thickness variation over a 120 degrees full angle of the hemispherical Surface. A theoretical model is developed and compared to profilometer measurements. In all cases, there is general agreement between theory and measurement. A single dipole is fabricated onto the flat surface of an AR-coated germanium immersion lens and the responsivity is measured for both substrate-side and air-side illumination. With a zinc sulfide (ZnS) single-layer AR coating, substrate-side illumination yields a broadside antenna response 49 +/- 2.7 times greater than air-side illumination. (C) 2009 Elsevier B.V. All rights reserved.
Journal Title
Infrared Physics & Technology
Volume
53
Issue/Number
2
Publication Date
1-1-2010
Document Type
Article
Language
English
First Page
89
Last Page
93
WOS Identifier
ISSN
1350-4495
Recommended Citation
"Evaporation of uniform antireflection coatings on hemispherical lenses to enhance infrared antenna gain" (2010). Faculty Bibliography 2010s. 806.
https://stars.library.ucf.edu/facultybib2010/806
Comments
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