Page 237 - Phase Space Optics Fundamentals and Applications

218 Chapter Seven

qualities of Lambertian sources. Section 7.4 introduces the mutual
coherence function and statistical quantities that play a central role
in connecting the radiometric quantities of conventional radiometry
to those of generalized radiometry. Section 7.5 examines the concept
of stationary phase, an important tool in determining the radiome-
try of diffracting systems. Section 7.6 brings together the radiometric
concepts of the previous sections to establish generalized radiome-
try. Section 7.7 examines specific examples of generalized radiometry
in the context of blackbody radiation, partially coherent sources, and
coherent sources.

7.2 Conventional Radiometry
This science is largely empirical. Several workers having to deal with
the detection of radiation under different experimental conditions
have found it necessary to define and use quantities applicable to
their cases. A notable attempt to unify these concepts was made by
1
Jones (1963).
In this chapter, we define the radiometric quantities in common use
and show their interrelationships. Basically, we have sources, illumi-
nation, and detection.
Can make visual observations of radiation in the visible region
and/or quantitative measurement by radiation detectors. Radiom-
etry provides a defined vocabulary for describing the properties of
sources and various experimental arrangements for observations or
detections.
We begin with the (total) radiant power in units of watts (W).
ˆ
The spectral radiant power is generally expressed as a function of
wavelength or frequency . We define it as a function of frequency
−1
with units of W Hz . Its integral over all frequencies yields the total
radiant power
∞

ˆ
= ( ) d (7.1)
0
With respect to a source, we speak of radiation emanating from it. We
−2
use the term radiant exitance M with units of W cm . It is a function
of position ,
r
∞

ˆ
r
M( ) = M( r, ) d (7.2)
0
ˆ
In this equation, M( r, ) is the spectral radiant exitance with units of
−2
−1
Wcm Hz .