Pyrometer for measurement of surface temperature distribution on a rotating turbine blade

A conceptual optical method and some test results are presented for measuring the surface temperature distribution on one of the rotating turbine blades with a surface resolution of 0.05 cm spot diameter at a tip speed of 400 m/sec. The blade is scanned line-by-line by a fixed optical system. During each line-scan, the detector analog output signal is converted to two hundred consecutive digital values that are temporarily stored in a high speed buffer memory, and then transferred at a slower rate to a computer for processing. The signal-to-noise ratio of the silicon avalanche detector is large enough to obtain an accuracy of one percent at 1050 K blade temperature. By averaging 25 scans of the same line the same accuracy can be obtained at 900 K.