Using a patented maximum & minimum search technique, this DOP meter can measure and display the Degree of Polarization (DOP) of a light source in real time with high accuracy and wide dynamic range. Other, polarimeter-based, systems are expensive and measure the DOP less accurately for low DOP sources, while polarization scrambler-based instruments are less accurate for high DOP sources. Surprisingly, our low cost DOP meter provides simple and accurate DOP measurement for both low and high DOP sources. It is ideal for DOP characterization of depolarizers and depolarized light sources, such as ASE and SLED sources, and the pumps for Raman amplifiers. It can also be used to monitor the OSNR and PMD of optical signals, and to measure the noise figure of optical amplifiers. Another attractive feature is that no calibration is needed for a wide operating wavelength range, including the S, C and L bands. Finally, the instrument also simultaneously measures the optical power level of the light source under test, a feature attractive for measuring DOP power dependence and for ensuring that a good optical connection is made to the instrument.