The POD-101D is a DSP (digital signal processor) powered in-line polarimeter specially designed for high-speed polarization analysis and monitoring. The instrument uses four channels to simultaneously obtain the four Stokes parameters and measure the instantaneous state of polarization (SOP) and degree of polarization (DOP) of an input light beam. A simple USB interface enables data to be transferred directly to a computer without the need for any additional hardware. Thanks to the high speed DSP electronics, this polarimeter easily monitors and analyzes fast polarization changes with a sampling rate of up to 625 kS/s. The POD-101D comes with PolaView™ software for real-time graphic display of polarization state either on a Poincaré Sphere window for viewing SOP traces or on an oscilloscope window for tracking polarization changes over time. The oscilloscope window has three operation modes: continuous scan mode, for instantaneous display of various polarization parameters; external trigger mode, for capturing transient events; and long term monitoring mode, for recording only the polarization changes above a predetermined threshold, in order to save hard drive space. This instrument can be quickly and easily calibrated using its built-in self-calibration program to optimize DOP and SOP measurement and control at special wavelengths and temperatures. The POD-101D is ideal for PMD compensation, polarization stabilization, system polarization monitoring, polarization analysis, and sensor analysis.