Radiometry is an essential part of the optical design of virtually every optical instrument, and key to many applications. It is also used to measure the radiation of various objects. This tutorial examines both the techniques of calculating radiative transfer and the measurement of fluxes and radiometric properties of various sorts.
Mathematics is often called the queen of the sciences. Radiometry should then be called the waiting maid or servant. It is not especially elegant; it is not very popular, has not been trendy; but it is essential in almost every part of optical engineering. The infrared devices I described in Introduction to Infrared System Design (SPIE Press, 1996) cannot be designed without an understanding of the amount of power that impinges on the detector from the target, and the radiation of the target cannot be understood without a radiometric measurement. Similar statements can be made about photography, movies, TV, medical instrumentation, and industrial quality control.
Radiometry appears to be a simple subject, and the basics are indeed uncomplicated. The devil is in the details. These details include the language, which is special, but is essential for good understanding. Units and dimensions need to be followed assiduously, and everything must be considered for its pertinence and significance in measurements and calculations.
I have tried to address these issues in this text by discussing nomenclature in Chapter 2, by listing a taxonomy of measurements in Chapter 11, and by describing the most important techniques of measuring the major radiometric properties of flux and materials.
This text is the result of notes that I have used for an SPIE tutorial and from a three-hour course I have taught at the University of Arizona for a quarter century.
I am indebted to George Zissis, for whom I first worked in radiometry at The University of Michigan, and to Don O'Shea and Jim Palmer for their incisive criticisms of this text. I thank Eric Pepper, who thoroughly edited the text and caught a number of errors. The remaining misteaks are mein!
Of course I offer my gratitude to my wife of almost 45 years, who now knows what I do in front of the computer, and what I do with her telephone - and puts up with it.
I dedicate this book to the memory of my parents, who would have been pleased.
William L. Wolfe