Systems and methods to acquire three dimensional images using spectral information

A system for use in optical topographical and/or tomographic 3D imaging of a sample, comprising:

• a lens unit, chromatically dispersive so that its focal length varies depending on a light wavelength, said lens unit being configured to pass therethrough polychromatic light arriving from and originated at a sample, while selectively collimating those spectral components of the polychromatic light which are in focus based on their wavelengths and origins,
• an etalon structure accommodated in an optical path of light being output from the lens unit to receive the collimated light, said etalon structure being configured to operate with multiple resonant wavelengths and to provide respective spectral transmittance peaks at said resonant wavelengths;
• and
• an optical detector configured to detect an output of the etalon structure consequential to said polychromatic light arriving from and originated at the sample and generate measured data indicative thereof, thereby enabling to determine, from said measured, a distance from the lens to a location at the sample, based on a spectral signal from said optical detector.