PASCO CI-9784 UVA LIGHT SENSOR - Manual

Instruction Sheet
for the PASCO
Model CI-9784
UVA LIGHT SENSOR
012-07185B
Introduction
The PASCO CI-9784 UVA Light Sensor is designed to
be used with a PASCO computer interface to make
measurements of relative intensity of electromagnetic
radiation in the UVA band.
The UVA Light Sensor uses a fairly broad band Si
Photodiode for a sensing element. It is sensitive to
electromagnetic energy ranging from visible light to
above the UVA band. Since the radiation to be measured
by this sensor is the UVA band, the sesnor is furnished
with a UVA filter. This filter can be removed if broader
band measurements are to be made.
The Ultraviolet (UV) radiation band in the
electromagnetic spectrum extends from very short
wavelengths of 100 nm, just below the X-ray band, to
400 nm, which is just above violet light in the visible
region of the spectrum. This can be observed in Table 1.
The UV band is divided into four smaller bands according
to the nature of the radiation. The shortest wavelengths are
designated as the vacuum UV band (
λ = 100-200 nm) so
called because energy in this band can only be studied in a
vacuum. This is because oxygen and other gas molecules
in air absorb radiation in this band.
The UVC band ranges from 200-280 nm. Essentially all
UVC radiation from the sun is absorbed or scattered by
ozone in the earth’s upper atmosphere and does not reach
the surface. UVB radiation (
λ = 280-315 nm) from the sun
is also absorbed or scattered by the upper atmosphere but
under some conditions can reach the surface of the earth.
Table 1
Ultraviolet Spectrum
UV
A
LIG
HT
SE
NS
OR
CI-9
78 4 10 1
100
GAIN
collimator
DIN connector
CI-9784
UVA Light Sensor
interface cable
with 8-pin DIN
connectors
to computer
interface
vacuum UV UVC UVB UVA
100-200nm 200-280nm 280-315nm 315-400nm
far UV near UV
< > Ultraviolet Band ( l = 100 - 400nm)