The analysis of nuclear tracks with confocal microscopy and image restoration

To measure radiation damage of particles with high energy and charge in space, radiosensitive plastics are used, in which particles leave damage tracks where they pass. These tracks are then etched, after which they have a typical cone shape. The geometrical parameters of these cones give information about energy and charge of the particles. To measure these parameters, the tracks are recorded in three dimensions with a confocal microscope, which is a special kind of microscope that can make threedimensional images of an object. To reduce blur in the recorded images of the tracks, image restoration is used. But with blur removal, the risk is that noise is amplified. Three techniques that handle this problem are compared: the wienerfilter, iterative constrained Tikhonov-Miller and Richardson-Lucy. The first two methods increase sharpness of the image, but also fit noise as data. Richardson-Lucy is the best method, but has a very slow convergence rate. After the image is restored, the geometrical parameters of the damage cones are extracted from the image by fitting cone models to the image. Key-Words: Confocal microscopy, nuclear tracks, space environment, image restoration.