Immersion infrared thermometer for molten materials

A temperatuare measuring system for molten materials comprising a hollow tubular dipstick having a closed end adapted to be inserted in the molten material with said dipstick being constructed of a material having a melting or deformation temperature higher than the estimated temperature of the molten material, infrared detecting means operatively connected to said dipstick for receiving infrared radiation from said end of said dipstick to provide an output signal indicative of the temperature of the molten material adjacent said end and infrared transmission means within said hollow dipstick for transmitting infrared radiation from an interior surface of said closed end to said infrared detector means, wherein said infrared transmitting means within said hollow dipstick include lens means mounted in said hollow dipstick in alignment with said closed end and having a focal point located on the inside surface of said closed end and an intermediate infrared transmitting rod disposed in alignment with said lens means for transmitting infrared radiation from said lens means to said infrared detector means.