4
Propylene Glycol determinations are made by measuring the refractive index of a solution. Refractive
Index is an optical characteristic of a substance and the number of dissolved particles in it.
Refractive Index is defined as the ratio of the speed of light in empty space to the speed of light in
the substance. A result of this property is that light will “bend”, or change direction, when it travels
through a substance of different refractive index. This is called refraction.
When passing from a material with a higher to lower refractive index, there is a critical angle at
which an incoming beam of light can no longer refract, but will instead be reflected off the interface.
The critical angle can be used to easily calculate the refractive index according to the equation:
sin (
θ
critical
) = n
2
/ n
1
Where n
2
is the refractive index of the lower-density medium; n
1
is the refractive index of the
higher-density medium.
In the
HI 96832
refractometer, light from an LED passes through a prism in contact with the sample.
An image sensor determines the critical angle at which the light is no longer refracted through the
sample. Specialized algorithms then apply temperature compensation to the measurement and
convert the refractive index to: % Volume or Freezing Point.
PRINCIPLE OF OPERATION
Battery Type / Life:
1 X 9V / 5000 readings
Auto-Off:
After 3 minutes of non-use
Dimensions:
19.2(W) x 10.2(D) x 6.7(H) cm
Mass:
420 g