LPUVA02
- 4 -
V2.0
2
WORKING PRINCIPLE
LPUVA02 radiometer is based on a solid state sensor, the spectral match with the de-
sired curve is obtained using a special filter. The relative spectral response is reported
on figure 2.1.
Fig. 2.1
The radiometer is provided with a 50 mm external diameter dome in order to supply a
suitable protection of the sensor to the weather agents.
The response in accordance with the cosine law has been obtained thanks to the par-
ticular shape of the diffuser and of the housing. The deviation between the theoretical
response and the measured one is shown in the Fig. 2.2.
Angle
Fig. 2.2
The excellent relation between the response of the radiometer and the cosine law al-
lows using the instrument also when the sun has a very low raising (the UVA diffuse
radiation increases as the sun moves away from the zenith, therefore the error on the
direct radiation, due to the imperfect response according to the cosine law, becomes
negligible on the measurement of the global radiation).
R
e
la
ti
v
e
s
p
e
c
tr
a
l
re
s
p
o
n
s
e
%
d
e
v
ia
ti
o
n
f
ro
m
t
h
e
o
re
ti
c
a
l
re
s
p
o
n
s
e
