|MadSci Network: Engineering|
The term popcorn denotes a type of random shot noise and was given the name
because of its similarity to the sound of popping corn when heard over a
loudspeaker. Several technologies suffer from “popcorn noise” including
operational amplifiers, thin film magnetic recording heads, motion picture sound
tracks and various electromagnetic wave detection devices including optical
detectors. In general popcorn noise has been related to various problems in the
processing of semiconductor materials and in particular to their metalization for
electrical contacts. One of the reasons that you will find that there is little
reference to popcorn noise in the literature is that in general it is a form of highly
filtered flicker noise (1/f noise) that rolls off at low frequencies and does not
extend to DC. Some books call it pink noise.
A recent book that is available at Amazon.com includes a section on the causes of
popcorn noise in general is:
T. I, Bajenescu, M. I. Bazu, T.I. , Reliability of Electronics Components,
Springer, 1999, 509 pages.
An excellent collection of papers on the basic physics of detector parameters,
including noise, and pyroelectric detectors, is:
F. R. Arams, Infrared to Millimeter Wavelength Detectors,
Airtech House, Inc, 1973.
The Airtech publication does discuss noise, but does not specifically discuss popcorn
noise in pyroelectric detectors. The main focus in the development of these devices
has been to increase the speed of response of the detectors to higher power laser
energy and not to reducing their noise floor. In my experience, applying uniform low
resistance, low noise contact metalization to ferroelectric and pyroelectric materials
has been a very difficult processing problem. I will continue to look for specific information on popcorn noise in pyroelectric devices and what ever I find I will forward it to you.
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