This chapter introduces the physics of lighting. It can be read as

a whole, you can dip into it to read about topics that are

unfamiliar, or you can skip it altogether and use it as a reference

later. It is structured in a way that allows you to look up a particu-

lar point, and go into the detail only as far as you need. If you

read the fi rst part of each section, you should gain a working

knowledge of the main ideas and the words used to describe

them; if you work through the chapter as a whole, you will

cover much of the theoretical basis of illumination engineering.