Zuzi 300 Serie Manual De Instrucciones página 28

Figure 4
The sample of liquid to be analysed is pla-
ced on the prism and then it is illuminated
with monochromatic or natural light (white
light). The light beam goes through the sam-
ple and the prism; then in the eyepiece we
can observe the prism surface up to find the
BOUNDARY LINE (the boundary line is the
refracted ray coming from a ray that has inci-
ded with an angle of 90º with the normal).
The reading is carried out dividing the
eyepiece field in a dark zone and a light zone.
The boundary line will determine both
zones. All the refracted rays come from inci-
dent rays with an incident angle less than 90º.
Figure 5
incident
normal
rays
Once the eyepiece field has been divided,
the value of the refractive index can be read
directly on the scale.
Before making any measurement, the ins-
trument must be calibrated with distilled
water (refractive index 1). For this purpose, a
drop of water must be placed on the prism of
the refractometer and make the necessary
correction by turning the scale adjustment
screw.
A refractometer is an instrument that mea-
sure the concentration of aqueous solutions
by measuring the refractive index. All
aqueous solutions can be crossed by light.
The path length is proportional to its concen-
tration.
Page 28
prism
sample
boundary line
Manual 5030XXXX
dark zone
light
zone
Version 7 Feb-2011