The magneto‐optical Faraday effect associated with certain paramagnetic ions has been utilized to construct an optical magnetometer suitable for studying the magnetic properties of hollow cylinder superconductors. As an instantaneous field detector, the response of the system in general is limited only by the spin‐bath relaxation time of the paramagnetic ion‐host crystal system being used. The magnetometer has the advantage of requiring no moving parts and also avoids the necessity of having to extract a low level voltage signal from the low temperature environment. Also, since the detector is an insulator, there are no undesirable time derivative of field signals generated in its use. The operating field range is limited by the sensitivity desired in a given experiment. For fields up to 13.5 kOe at a temperature of 2.15 K, the sensitivity for the analyzer oriented at 45° with respect to the plane of polarization of the emergent light is at worst ±9.3 Oe. The text lists the sensitivity at various other fields and temperatures in tabular form. Initial results on superconducting hollow cylinder niobium are also presented.