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1. Purpose of the device
This dosimeter is used to measure ionizing radiation in processes such as cross-linking of paints or
plastics.
As a measurement instrument, it is extremely simple to use: a measuring film is exposed to radiation
and then evaluated using the dosimeter in a matter of seconds. The measured value is displayed in
kGy. By offsetting optical components, performing measurements using a 10-Bit A/D converter and
averaging values over several measurements, the dosimeter offers a very high degree of accuracy.
Measurement errors only occur if there are irregularities in the measuring film (thickness and color
distribution). Thanks to these features, the dosimeter is a valuable tool in quality assurance.
1.1
Electron beam irradiation
When using electron beam equipments a three-dimensional determination of dose distribution is
a must for reproducible production procedures.
In the case of low-energy electron beam equipment, the short range of the electrons causes
considerable alteration in the absorbed dose with the penetration depth. One useful dosimeter
employs polyvinyl butyral (PVB) with pararosaniline cyanide: this colors on irradiation with
electrons or UV (red discoloration).
This very thin film (approx. 20 µm or 20 g/m
2
) has good resolution in depth doses for
measurements with low-energy electrons. As the film is supplied by the meter, it is also possible
to measure the dose distribution across the effective width at high resolution, as follows:
Radiation is directed onto a strip which corresponds to the beam width and evaluation then
performed at cm intervals, for example.
2. Device
design
The dosimeter is accommodated in a sealed high-grade steel housing which effectively shields
it from interference. A keyboard overlay on the function keys and the display protects against
dirt.
To allow a better view while working, you can tilt the device at an angle using the retractable
stands. Just three keys are necessary to activate all of the device functions; all necessary data
is shown on a 2 x 20 character display screen.
The measuring head, which has a measurement slot 0.5 mm in width, contains the transmitter
and receiver optical components.
A processor the size of a check card is located inside the device: this controls all of the
functions and dose calculation.
3. Power
supply
The power is supplied by a standard power supply unit. The measurement device is designed
for continuous operation. The device can be switched off with the power switch located on the
device.
The serial interface can be used to read the stored values into a PC for further processing.
