Optical Method of Measuring Temperature in Hot Glass

An optical method of temperature measurement, developed for semitransparent media, was tested using molten glass. The beam from a helium‐neon laser was passed through glass, and the attenuation of the beam was measured. Since the monochromatic absorptivity of the glass was a monotonic function of temperature, the attenuation of the beam indicated the temperature of the glass. The optical method was used to measure the one‐dimensional temperature profile in a slab of molten glass with an accuracy of ±5°F. The temperature gradient within the slab was of the order of 200°F/in. The method is useful when the medium is isothermal along the length of the laser beam, the medium does not significantly scatter radiation, and the monochromatic transmissivity of the medium based on the laser path length is 0.1.