Relations of photometry. Part 2.
The most general photometric definitions are presented and the origins of Lamberts's law and the cosine (or inverse square) law of illumination are shown. These derivations are made possible through the use of a simple diagram relating emitting and illuminated surfaces. Several classical problems are solved to illustrate the theory and use of the diagram, and the problems of the photometric microscope and telescope are discussed in detail.
Gravely
B T
BT