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Title: Antireflection Coatings 1: BASICS

Abstract

Reflections off windows, eyeglass lenses, computer and television screens, and optical components can be very annoying and sometimes dangerous. Reflection of light incident on an optical window or optical component can degrade the performance of the window and the optical system associated with the window over its operating spectral range, whether it is the human eye or an optical device. Thin films can help us with this problem.

Authors:
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
876984
Report Number(s):
PNNL-SA-47317
VT0402000; TRN: US200608%%352
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Vacuum Technology & Coating; Journal Volume: 6; Journal Issue: 11
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANTIREFLECTION COATINGS; COMPUTERS; EYES; LENSES; OPTICAL SYSTEMS; PERFORMANCE; REFLECTION; SCREENS; TELEVISION; THIN FILMS; WINDOWS

Citation Formats

Martin, Peter M. Antireflection Coatings 1: BASICS. United States: N. p., 2005. Web.
Martin, Peter M. Antireflection Coatings 1: BASICS. United States.
Martin, Peter M. Tue . "Antireflection Coatings 1: BASICS". United States. doi:.
@article{osti_876984,
title = {Antireflection Coatings 1: BASICS},
author = {Martin, Peter M.},
abstractNote = {Reflections off windows, eyeglass lenses, computer and television screens, and optical components can be very annoying and sometimes dangerous. Reflection of light incident on an optical window or optical component can degrade the performance of the window and the optical system associated with the window over its operating spectral range, whether it is the human eye or an optical device. Thin films can help us with this problem.},
doi = {},
journal = {Vacuum Technology & Coating},
number = 11,
volume = 6,
place = {United States},
year = {Tue Nov 15 00:00:00 EST 2005},
month = {Tue Nov 15 00:00:00 EST 2005}
}
  • Coatings of refractive index that vary between 1.22 and 1.44 were prepared from combinations of a colloidal silica suspension and a polysiloxane solution. The polysiloxane acted both as a binder and a filler for the colloidal silica particles. Increasing ratios gave coatings of lower porosity, hence higher refractive index, and better abrasion resistance. This variation in refractive index allowed high-efficiency quarter-wave antireflection coatings to be prepared on substrates whose index varied from 1.45 to 2.1. The laser damage thresholds of all the coatings were {lt}50 J/cm{sup 2} at a wavelength of 1.06 {mu}m with a 10-ns pulse length.
  • The construction of achromatic coatings of quarter- and half-wave layers, obtained by the electron-beam evaporation method in vacuum without heating the items being coated and providing a reflection of less than 1% in the spectral region from lambda/sub 1/ to lambda/sub 2/ = (1.6--1.85)lambda/sub 1/, is investigated.
  • Calculations are presented for the optimal parameters of antireflection coatings of two types of photoelectric converters with inversion layers: a single-layer SiO/sub 2/ film and a two-layer film with SiO/sub 2/ inner layer. The magnitude of the photocurrent is taken as the optimization criterion. The dispersion of the refractive index of silicon and the spectral sensitivity of the photoelectric converter are taken into account. Values are found for photocurrent as a function of single-layer oxide coating thickness and for losses due to reflection. It is shown that the double-layer coating makes it possible to reduce photocurrent losses to 5%.
  • The optimum thickness and index of refraction film parameters are established for a wide range of InGaAsP lasers emitting at 1.3 microns. The minimum theoretical power reflectivity is higher for the TM polarization than for the TE by a factor of about 3. Film parameter tolerances are calculated for a power reflectivity of 0.001, where the laser in question has a spot size of 0.5 microns. The processing of high quality antireflection coating films on InGaAsP devices is possible according to the tolerances obtained through the use of sputtered Si3N4, which allows a very slow deposition rate as well asmore » the tailoring of the film index through adjustment of plasma nitrogen pressure. 11 references.« less