The Swift & son polarized light microscope has been in use from 1880 to 1950, and has been used in the study of minerals as well as for the study of materials and fibers in forensic investigation and also by the police. Modern versions of these models are still used in medicine. The light before reaching the eyes of the observer undergoes a polarization. This is what is achieved when a prism passes through the beam of light and vibrates the sample when it hits. The manufacturer was established at 81 TotenhamCourt Road in London, an area with many optical establishments due to the proximity of the University College Hospital, the University of London and the British Museum. It measures 30 cm high.