Patent ID: 8547557

Claim:
An apparatus for determining a height map of a surface in an interferometric mode and in a non-interferometric mode, the apparatus comprising: positioning means for positioning an object having the surface to be measured; a light source; an optical detector adapted to convert received light into electrical signals; first optical means for directing light from the light source to the surface and for directing the light reflected by the surface to the optical detector; a beam splitter located between the first optical means and the surface; and a reference mirror that reflects the light from the beam splitter back to the beam splitter; wherein the beam splitter is a polarizing beam splitter; a controllable polarization controller is located between the light source and the first optical means, the controllable polarization controller polarizing the light from the light source and forming polarized light having only one component with a first angle in the non-interferometric mode so that the polarized light passes through the polarizing beam splitter and the controllable polarization controller polarizing the light from the light source and forming polarized light having two components with the first angle and a second angle, respectively, in the interferometric mode so that the polarized light having the polarization component with the first angle passes through the polarizing beam splitter and the polarized light having the polarization component with the second angle is reflected by the polarizing beam splitter; and an analyzing polarizer is located between the first optical means and the optical detector.