A lighting device (100, 200, 300, 400) is disclosed. The device comprises a plurality of light sources (111, 119, 120, 211, 219, 220) providing light in different wavelengths, a collimating means (104, 204) having a receiving end (103, 203, 407) and an output end (114, 214, 409), wherein said light sources are arranged at said receiving end. The collimating means comprises a set of wavelength selective filters (109, 110, 115, 116, 117, 118, 215, 217) arranged as sub-collimators (106, 107, 108, 206, 207, 208) to each of said plurality of light sources such that, for each light source, said sub-collimator collimates the light from its light source, and said wavelength selective filter of said each light source is translucent for light from adjacent light sources of different wavelength, wherein said wavelength selective filters are high pass or low pass filters.