The development of a grating interferometer with application to the angular measurement of a hard disk drive actuator arm for application to the servo-track writing process is presented. A brief discussion of the operating principle of the grating interferometer is presented. This principle is then extended to the case of the measurement of the angular displacement of a hard disk drive actuator arm. A vector based diffraction technique has also been developed as a tool for visualization and analysis of the grating interferometer design. Finally, experimental setups and results from an implementation of the grating interferometer design are presented and discussed.