The inventive concept provides apparatuses and methods for monitoring semiconductor fabrication processes in real time using polarized light. In some embodiments, the apparatus comprises a light source configured to generate light, a beam splitter configured to reflect the light toward the wafer being processed, an objective polarizer configured to polarize the light reflected toward the wafer and to allow light reflected by the wafer to pass therethrough, a blaze grating configured to separate light reflected by the wafer according to wavelength, an array detector configured to detect the separated light and an analyzer to analyze the three-dimensional profile of the structure/pattern being formed in the wafer.