A compact, low noise magnetic force microscope has been constructed. It utilizes an ac interferometric detection scheme sensitive to the magnetic force gradients above a sample. It is similar to the design proposed by Rugar et al.1 A variety of magnetic recording medias, both longitudinal and vertical with written patterns, have been investigated. The studies have been made using etched Ni cantilevers. Contrast and resolution of the microscope as a function of cantilever scan heights will be discussed.