Apparatus for determining correct pyrometer readings with steam interference present

Claim 1

Apparatus for determining the true temperature of a surface from the radiation emitting from the surface where radiation from the surface received by a detector is attenuated by an interfering substance causing erroneous detection comprising a first radiation detector having a known error characteristic caused by the interfering substance and aligned to receive radiation from the surface for providing a first signal responsive to radiation received from said surface; a second radiation detector having a known error characteristic caused by the interfering substance, a different wave length response characteristic than said first detector, an error response substantially a constaNt multiple of the error response in said first signal and aligned to receive radiation from the same location on said surface as said first detector for providing a second signal response to radiation received from said surface; means connected to said means for providing a second signal for providing a third signal by changing said second signal by said multiple; and means connected to said first detector and said means for providing a third signal and responsive to said first and third signals for combining said first and third signals and said known error characteristics thereby providing a fourth signal representative of the true temperature.