INTRODUCTION
Ultraviolet (UV) radiation constitutes a portion of the electromagnetic spectrum from 100 to 400 nm, and is further
subdivided into three wavelength ranges: UV-A (315 to 400 nm), UV-B (280 to 315 nm) and UV-C (100 to 280 nm).
Much of the UV-B and all of the UV-C wavelengths from the sun are absorbed by the Earth’s atmosphere. There
are also many artificial UV light sources available that output a select wavelength range or offer a broadband UV
radiation source.
Most UV sensors designed for sunlight measurements are sensitive to UV radiation in the UV-A and UV-B ranges.
Apogee Instruments SU-100 UV sensors detect UV radiation from 250 to 400 nm and are calibrated in photon flux
units of micromoles per square meter per second (µmol m
-2
s
-1
). The output can also be expressed in energy flux
units of watts per square meter (W m
-2
, equal to Joules per second per square meter).
Typical applications of UV sensors include incoming UV radiation measurement in outdoor environments (not
recommended for continuous outdoor deployment) or in laboratory use with artificial light sources (e.g.,
germicidal lamps).
Apogee Instruments SU-100 UV sensors consist of a photodiode and signal processing circuitry mounted in an
anodized aluminum housing, and a cable to connect the sensor to a measurement device. Sensors are potted solid
with no internal air space, and are designed for UV radiation measurement in indoor or outdoor environments.
The SU-100 outputs an analog voltage that is directly proportional to UV radiation incident on a planar surface
(does not have to be horizontal), where the radiation emanates from all angles of a hemisphere.
