
RADIOMETRY AND PHOTOMETRY 371
ABCD matrix from the front focal point to the back focal point which we have calculated in
Equation 9.45:
M
FF
=
0 f
−
1
f
0
,
det M
FF
=1 =n
/n leads to Equation 12.19, and thus to the radiance theorem, Equation
12.20.
12.1.2.2 Summary of the Radiance Theorem
The key points in this section bear repeating:
• The radiance theorem (Equation 12.20) is valid for any lossless optical system
• In such a system, basic radiance, L/n
2
, is conserved
• Loss can be incorporated through a multiplicative constant
12.1.3 Radiometric Analysis: An Idealized Example
We have introduced ve precise denitions of radiometric terms, radiant ux or power ...