An optical system as subject of the present invention comprises at least one packaged spatial light modulator comprising a front side for facing incident light. The optical system further comprises projection optics for projecting an image formed by the packaged spatial light modulator, there being a sealed gas space in between the front side of the packaged spatial light modulator. The optical system comprises a first heat transporting means being thermally coupled to the frontside of the packaged spatial light modulator, the first heat transporting means comprising a thermally conductive frame contacting the front side of the packaged spatial light modulator along an edge thereof. A second heat transporting means being thermally coupled to the package back side may be provided as well. The first and second heat transporting means are thermally separated by the package. The device may further comprise a control means for controlling the heat flow in at least one of the first heat transporting means and the second heat transporting means.