To detect even a gap between illumination pixels by shifting a module, e.g. a perforated plate, through an adjusting element and shifting a measuring point raster through a probe.

Light from a light source 11 illuminates the illumination raster of a light transmitting layer existing on an illumination face 11b having small holes arranged like a raster. The illumination raster is focused through lenses 13o, 13u onto a focal plane 13f and an object 14 is illuminated with a raster-like light spot. A reflected light beam is focused through the lenses 13u, 13o and a beam splitter 16 onto a receiver face 17b and the signal from a receiver array 17 is evaluated by a computer 18 before being displayed graphically on a display 18b. The illumination raster, the beam splitter 16, the receiver array 17, and the like, constitute a compact module and an adjusting element 24a, being connected with the computer 18 through a supporting arm 21 and a control line 18w, shifts the module by a distance corresponding to the interval of light spot under control of the computer. The object 14 can be moved in all three spatial directions through an adjuster 15.