Intraoral scanner with optical system for minimizing stray light

An optical system for an intraoral scanning device, the optical system comprising:

• a light source for emitting light;
• a beam splitter configured to split an incident beam of light into two beams, wherein at least one of said beams is linearly polarized, wherein the beam splitter is made from two glass prisms attached together to form an interface, the beam splitter comprising:
• a coating on the interface, wherein the coating is configured to separate unpolarized light into two different polarizations, whereby light of a first polarization state is transmitted through the interface and light of a second polarization state is reflected at the interface;
• a long pass filter having a predefined cut-off wavelength, such that wavelengths below said cut-off wavelength are blocked by the filter, wherein the long pass filter is arranged on a first surface of the beam splitter;
• and
• a light absorbing unit comprising an absorbing layer for absorbing light, wherein the light absorbing unit is arranged on a second surface of the beam splitter.