A device and method for checking surfaces in the interior of holes,
depressions, or the like. The device and method are developed in such a
manner that a multicolor light beam can be produced with a light source,
wherein a light beam, due to the chromatic aberration of the imaging
optics, can be focused onto several points at different distances from
the imaging optics, such that the distance to the surface can be
determined from the spectrum of the detected light beam.