The ultrahigh-speed PhaseCam 4000 interferometer system from 4D Technology Corp. of Tucson, Ariz., captures high-accuracy, quantitative optical phase measurements. It uses a computer-generated holographic diffraction grating and a polarization phase mask to simultaneously create four phase-shifted interferograms on a single, high-resolution detector array. The system can acquire data 10,000 times faster than conventional systems, eliminating the need for bulky vibration isolation equipment and enabling the capture and study of transient or dynamic events. A significant revision of the original PhaseCam, the 4000's rms accuracy and repeatability have been improved by a factor of 10, and it can accommodate a detector that is four times larger at 4 million pixels. It offers remote focus ability, vacuum compatibility, user-adjustable beam ratio and focus, and high-power laser options. The 4Sight software provides the user interface for PhaseCam data acquisition and analysis. This entirely new application features a high-speed burst acquisition mode, diffraction and geometrical surface analysis, and a remote ActiveX interface that allows control of the instrument from third-party programs. Other features include parametric vibrational modal analysis, customizable 2- and 3-D data displays, an easy-to-use data simulator and a robust Zernike aberration fitting tool. Multiple formats are supported to simplify data transfer with a variety of other software programs. Applications include measurement of transient gas density (e.g., aerodynamic flow fields and atmospheric turbulence), testing of large aerospace and astronomy optical systems, and vibration analysis of specular and diffuse surfaces such as deformable mirrors and turbine blades.