7
In the
HI96801
, 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. The
HI96801
automatically applies
temperature compensation to the measurement and converts the refractive
index of the sample to sucrose concentration in units of percent (by weight) Brix.
The Brix determination is 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.
PRINCIPLE OF OPERA
TION