An optical detector (110) is disclosed, the optical detector (110) comprising: at least one spatial light modulator (114) being adapted to modify at least one property of a light beam (136) in a spatially resolved fashion, having a matrix (132) of pixels (134), each pixel (134) being controllable to individually modify the at least one optical property of a portion of the light beam (136) passing the pixel (134); at least one optical sensor (116) adapted to detect the light beam (136) after passing the matrix (132) of pixels (134) of the spatial light modulator (114) and to generate at least one sensor signal; at least one modulator device (118) adapted for periodically controlling at least two of the pixels (134) with different modulation frequencies; and at least one evaluation device (120) adapted for performing a frequency analysis in order to determine signal components of the sensor signal for the modulation frequencies.