1. An apparatus for fast, quantitative, non-contact topographic investigation of samples, comprising: a light source; a collimating concave mirror structured and arranged to produce a parallel beam and to direct the parallel beam to a sample to be investigated; a structured mask located between said light source and said concave mirror; and an image sensor structured and arranged to receive a beam reflected from the sample and said concave mirror, wherein relative positions of said mask and said sensor to other elements of the apparatus are chosen to provide an essentially sharp image of the mask on the sensor.