Optical measurement using polarized and unpolarized light

摘要

Physical quantities such as pressures, accelerations and electrical currents including dc currents are measured by alternately passing polarized and unpolarized light through an optical-sensor which modifies the polarization of the poralized light in proportion to the magnitude of the physical quantity while passing the unpolarized light unaltered by the physical quantity. Light emerging from the optical sensor is converted into an electrical signal by an analyzer and a photodetector. The difference between the electrical signal generated by the polarized light and a reference signal is proportional to the magnitude of the physical quantity.