Page 126 - Photodetection and Measurement - Maximizing Performance in Optical Systems

Source: Photodetection and Measurement

Chapter
6

Useful Electronic Circuits

and Construction Techniques

to Get You Going

6.1 Introduction

So far we have covered some of the theoretical basics involved in making good
optical laboratory measurements and in the electronic circuitry needed. We
know a little about sources and detectors, their noise, and the added noise of
amplifiers and about the beauty and power of modulation and synchronous
detection. Circuit diagrams, calculations, and simulations are all very necessary,
but whatever measurements you want to do, at some point you must put the
theory into practice and build something! Sure, things will go wrong and not
work as you hoped, so it is important to learn about the limitations and prac-
tical problems of electronics and optoelectronics in this environment, debug-
ging the problems and figuring out what caused them. In my experience this
means making lots of circuits, so you don’t want to waste time searching for
circuit fragments to do the job or actually constructing them. In general, the
same needs and problems crop up time and again. Hence it is useful to have a
collection, initially just designs but over time a physical collection, of the key
circuits. Source drivers, synchronous detectors, clock oscillators and so on will
be very useful in quickly assembling experiments; it is the flux of these exper-
iments, properly evaluated, that generates experience. Later in this chapter we
give a small collection of the “electronic clichés” you will need, together with
some suggestions for actual components. Generally the circuits are rather
trivial, but not if you need to search hours for them or spend time getting them
to work.

6.2 Circuit Prototyping and PCBs

There are many different ways to rapidly prototype small circuits. For
instance, the hobby catalogs offer “pluggable” circuit boards for through-hole

119
Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com)
Copyright © 2004 The McGraw-Hill Companies. All rights reserved.
Any use is subject to the Terms of Use as given at the website.