By the use of simple algorithms and measurement techniques, we attempt to demonstrate the use of two differential phase contrast techniques for measurement of micron and sub-micronfeatures in several different structures representative of those used in the semiconductor industry. The technique makes use of a scanning laser interference microscope (SLIM) operating in one of two modes. The first mode uses a segmented detector placed in the Fourier plane of the microscope objective. The second mode is a differential detector scheme using a Nomarski-like optical system. Both offer the benefits of high speed video rate scanning and highly automated operation with near shot noise limited detection. © 1991.