ROCKY MOUNTAIN SECTION OPTICAL SOCIETY OF AMERICA
                              &
           IEEE LASERS AND ELECTROOPTICS SOCIETY


                        May Meeting

Date:  Thursday, 16 May 2002
Time:  6:30 PM pizza, 7:30 PM talk
Place: National Center for Atmospheric Research
       Mesa Lab
       1850 Table Mesa Drive, Boulder, CO
       Damon Room


Title: Optical Coatings

       Prof. Angus Macleod
       Thin Film Center, Inc.
       2745 E Via Rotonda
       Tucson, AZ 85716-5227


Abstract:

Optical systems consist largely of a series of specular 
surfaces that reflect and refract the light to define the 
path of the light through the system. These surfaces define 
the direction of the light but their other attributes, like 
reflectance, transmittance, induced phase change, and 
polarization sensitivity, are determined by the materials 
used to define the surfaces and are rarely satisfactory. The 
correct values of these attributes are assured by the 
addition of optical coatings. The optical coatings do not 
change the direction of the light but they have an influence 
on virtually everything else. Coatings reduce the reflection 
losses of transmitting lenses. They increase the reflectance 
of mirrors. They modify the spectral qualities. They even 
modify the shape of short pulses. They are essential 
components of wavelength division multiplexers in 
telecommunication systems. They equalize the gain of fiber 
amplifiers. They protect sensors from damaging laser 
radiation. They form the sensing element in biochemical 
detectors. They are even used as decoration. They are 
essential components in virtually every optical system. 
Without them few modern optical systems could possibly 
function.

The great expansion in optical coating use belongs to the 
second half of the 20th Century but interference effects have 
always fascinated scientists. We have no idea how long ago it 
was when the colorful fringes in thin layer systems first 
excited curiosity. The most vivid early account of these 
colors appears in Newton's Optiks. Almost 250 years of 
continuing progress in optics were to pass after that 
description, before the effects were effectively harnessed.

Most optical coatings today are deposited by vacuum 
deposition processes. Machines for deposition range from 
enormous machines for coating architectural glass to small 
batch coaters for spectacle lenses. Coatings range in 
complexity from one or two layers to several hundred.

This is a big field. The talk will review topics in the 
history of the subject, the principles of optical coatings, 
their manufacture and their application.

Not all problems have been solved, and as optics advances so 
the demands on optical coatings become greater. It is an 
exciting time for thin film practitioners, but it has always 
been an exciting time.


Biography:

Angus Macleod has 40 years of experience in optical coatings, 
both in manufacturing and in research. He was born and 
educated in Glasgow, Scotland, and worked both in industry 
and academia in Great Britain before joining the University 
of Arizona as Professor of Optical Sciences in 1979. Since 
1995, he has been full time with Thin Film Center, Inc., a 
software, training and consulting company in Tucson that he 
co-founded in 1986. He is the author of "Thin Film Optical 
Filters," 3rd edition (Institute of Physics Publishing, 
2001).