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Lambert Beer Law:
= intensity of incident light beam
I
o
I = intensity of light beam after absorption
= molar extinction coefficient at wavelength l
e
l
c = molar concentration of the substance
d = optical path through the substance
5.5. OPTICAL SYSTEM
The internal reference system (reference detector) of the
drifts due to power fluctuations or ambient temperature changes, providing a stable source of light for
your blank (zero) measurement and sample measurement.
LED light sources offer superior performance compared to tungsten lamps. LEDs have a much higher
luminous efficiency, providing more light while using less power. They also produce little heat, which
could otherwise affect electronic stability. LEDs are available in a wide array of wavelengths, whereas
tungsten lamps have poor blue / violet light output.
Improved optical filters ensure greater wavelength accuracy and allow a brighter, stronger signal to be
received. The end result is higher measurement stability and less wavelength error.
A focusing lens collects all of the light that exits the cuvette, eliminating errors from cuvette
imperfections and scratches, eliminating the need to index the cuvette.
-log I/I
= e
c d
o
l
or
A = e
c d
l
Instrument Block Diagram
HI83325
photometer compensates for any
11
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