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
Earth’s atmosphere. There are
also multiple artificial UV light sources available.
Most UV sensors designed for sunlight measurements are sensitive to UV radiation in the UV-A or UV-B ranges.
Apogee Instruments MU-200 series UV-A meters detect UV radiation from 300 to 400 nm and are calibrated in
energy flux density units of watts per square meter (W m
-2
, equal to Joules per second per square meter). The
output can also be expressed in photon flux density units of micromoles per square meter per second (µmol m
-2
s
-
1
).
Typical applications of UV meters include incoming UV radiation measurement in outdoor environments or in
laboratory use with artificial light sources (e.g., germicidal lamps).
Apogee Instruments MU-200 series UV-A meters are connected by cable to an anodized aluminum housing (MU-
250). Separate sensors consist of a photodiode and filter, and are potted solid with no internal air space. MU series
meters provide a real-time photon flux or energy flux (menu selectable) reading on the LCD display that
determines the UV radiation incident on a planar surface (does not have to be horizontal), where the radiation
emanates from all angles of a hemisphere. MU series meters include manual and automatic data logging features
for making spot-check measurements or calculating integrated daily total values.
