
51-1
51.1 Introduction
For nearly 50 years, turbidity measurements have been used to perform a wide variety of physical mea-
surements. ese include the determination of particle concentration per unit volume when the scatter-
ing
cr
oss
se
ction
pe
r
pa
rticle
is kn
own,
th
e
de
termination
of pa
rticle
siz
e
(s
cattering
cr
oss
se
ction)
wh
en
th
e
co
ncentration
of pa
rticles
is kn
own
[1
–4],
an
d
th
e
de
termination
of so
me
of th
e
cr
itical
ex
ponents
as
sociated
w
ith
s
econd-order
a
nd
n
early
s
econd-order
p
hase
t
ransitions
[
5–9]
.
e ba
sic
id
eas
ne
cessary
to un
derstand
tu
rbidity
me
asurements
ar
e
fa
irly
sim
ple
. In th
e
ab
sence
of
re
ection
lo
sses,
wh
en
a we
ak
be
am
of ...