PASCO CI-9784 User Manual

Instruction Sheet
for the PASCO
Model CI-9784

UVA LIGHT SENSOR

DIN connector

012-07185B

interface cable

with 8-pin DIN

connectors

G

A

I

N

1

1

0

1

0

0

collimator

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.

4

8

7

I-9

C

A

V

T

U

H

R

O

IG

S

L

N

E

S

UVA Light Sensor

CI-9784

to computer

interface

Table 1

Ultraviolet Spectrum

<>

vacuum UV UVC UVB UVA

100-200nm 200-280nm 280-315nm 315-400nm

far UV near UV

Ultraviolet Band (l = 100 - 400nm)

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.

UVA Light Sensor

Interface

500

1

2

GAIN

=

1,10:ISOLATED

GAIN

=

1,10: REF TO GND

GAIN

=

1: REF TO GND

A

s

C

ON

ANALOG CHANNELS

B

n

DIGITAL CHANNELS

ScienceWorkshop



U

V

A

L

I

G

H

T

S

E

N

S

O

R

C

I-9

7

84

10

1

1

0

0

G

A

IN

P

R

E

S

S

T

O

L

O

G

®

s

n

E

1240

(nm)

E

1240

315

eV

012-07185B

Vacuum UV, UVC and UVB radiation has harmful, high
photon energies and can initiate chemical processes
including changes in biological tissue called photo­biological reactions.

Reaction-causing UV is also called actinic ultraviolet. It is
characterised by photon energies above about 4 electron
volts (eV). To compute the photon energy in eV from the
wavelength in nanometers (nm) the following formula
can be used:

eV

=

λ

For example 315 nm radiation has a photon energy:

=

≈ 3.9

UVA is the least hazardous ultraviolet radiation and its
band extends from 315-400 nm.

It is worthwhile noting that ordinary glass cuts off some
UV radiation with wavelengths less than about 300 nm.
Thus UVA and some UVB can pass through glass.

In addtion to the CI-9784 UVA Light Sensor, an
appropriate UV light source is required in order to
perform some experiments and demonstrations. The use
of a source which radiates in the UVA band is
recommended because it is the least hazardous UV
radiation to work with. A small fluorescent “black” light
makes a suitable UVA source.

Other good sources of UVA radiation are:

ADDITIONAL RECOMMENDED

• UVA Light Sensor Accessory Kit (PASCO
part no. CI-9792)

• 365nm Filter Accessory (PASCO part no.
CI-9841)

Operation

Setting up the Equipment

Connect the UVA Light Sensor unit to analog channel A,
B, or C of the PASCO interface using the cable with the
DIN connectors (Figure 1). Alternatively, the unit can be
plugged directly into the analog channel jack.

A

Plug into

any analog

channel.

Figure 1

Connecting the Light Sensor and the computer interface

Using the Filter With Retaining Cap

B

ANALOG CHANNELS



ScienceWorkshop

®

A

C

500

Interface

E

S

R

S

1

P

T

G

O

O

L

DIGITAL CHANNELS

G
AIN

1
1
0

4

100

8
7
9

I­C

UVA
LIGHT

SENSOR

B

2

ON

=

GAIN

=

GAIN

1,10:ISOLATED

1,10: REF TO GND

Plug into

any analog

channel.

=

GAIN

1: REF TO GND

• the sun (best on clear days - but some UV when
overcast)

• sun lamps for tanning

• halogen lamps which are not “UV-protected”

• fluorescent lamps

Equipment

INCLUDED

• UVA Light Sensor

• UVA filter and retaining cap

• collimator

• 6-foot cable with 8-pin DIN connectors

ADDITIONAL REQUIRED

• PASCO Interface

• PASCO Data Acquisition Software

The UVA Light Sensor is shipped with the filter installed
in the retaining cap. When the filter is removed from the
retaining cap, light from a wider source can be detected.
Simply unscrew the retaining cap from the photodiode
assembly as neededto remove the filter. See Figure 2. Be
careful not to damage the filter.

photodiode

assembly

retaining

cap

UVA filter

Figure 2

Assembly of the Filter and Retaining Cap

2