Title

Evaporation Of Uniform Antireflection Coatings On Hemispherical Lenses To Enhance Infrared Antenna Gain

Keywords

Antenna-coupled detectors; Antireflection coatings; Immersion lens; Infrared antennas

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° yields a uniform film with less than 10% thickness variation over a 120° 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. © 2009 Elsevier B.V. All rights reserved.

Publication Date

3-1-2010

Publication Title

Infrared Physics and Technology

Volume

53

Issue

2

Number of Pages

89-93

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1016/j.infrared.2009.10.001

Socpus ID

76449115175 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/76449115175

This document is currently not available here.

Share

COinS