Method and device for measuring the distribution of radioactivity on a flat sample

In a device for effecting a location-sensitive measurement of a flat sample of radiation emitting material having a plurality of partial areas, the flat sample lying substantially in a sample plane, which device includes:

• radiation detector means;
• a screen plate having radiation passage openings, the screen plate being disposed between the detector means and the flat sample and the radiation passage openings being oriented for directing radiation from the sample to the detector means and the detector means being arranged for detecting radiation emanating from one group of the partial areas in accordance with the shape of the screen plate openings;
• signal evaluation means for processing and storing information based on radiation detected by the detector means;
• and means operatively associated with the sample for effecting a relative displacement between the sample and the detector means and for detecting radiation and storing information for another group of partial areas, to produce a total measurement composed of a plurality of successively performed partial measurements which provide a measurement of the total distribution of radiation emitted by the sample, the improvement wherein:
• said screen plate has a width and is provided with a plurality of slits which extend in parallel with one another in a first direction substantially parallel to the sample plane, essentially across the entire width of the screen plate, and which constitute said passage openings;
• and
• said detector means are operative for effecting a simultaneous, location-sensitive detection of strip-like partial areas of the sample which are in line with the slits;
• said means for effecting a relative displacement are operative for causing the relative displacement to occur exclusively in a second direction which is transverse to the first direction and which is substantially parallel to the sample plane;
• said device has a desired spatial detection resolution in the second direction;
• said signal evaluation means comprise an electronic evaluation unit with a memory device and a display device for displaying measured radiation intensity distribution Z (x, y) of the radiation;
• with respect to the first direction, radiation from the sample is detected in a location-sensitive manner;
• said slits in said screen plate each have a width dimension, which is in the second direction, with a value that at least approximately corresponds to the desired spatial detection resolution in the second direction;
• and
• said means for effecting a relative displacement are operative for producing successive displacements through a distance not greater than the slit width dimension between successive measurements effected by said detector means.