Pyrometric temperature measurements in flameless atomic absorption spectroscopy

Circuitry for automatically adjusting the calibration of a first pyrometric radiation detector for extended temperature range measurements of a heated atomic absorption spectroscope graphite tube independently of the radiation emission factor of said tube, said first radiation detector being positioned to receive radiation from said tube and generating an output signal indicative of the temperature thereof, said circuit including:

• a variable gain amplifier coupled to said radiation detector and responsive to the signal generated therefrom;
• a second radiation detector positioned to sense the radiation emitted by said graphite tube, said second detector being accurate within a limited wavelength range and generating a second output signal that is independent of the emission factor of said graphite tube;
• and
• circuitry means responsive to said second output signal for adjusting the gain of said variable gain amplifier whereby the output signal of said amplifier represents the temperature sensed by said first radiation detector corrected for emission factor;
• the improvement comprising:
• said second radiation detector being sensitive to a limited radiation wavelength range, the center of which is a shortwave with respect to a radiation emitted by said graphite tube, said second detector including said first radiation detector and a short wavelength transmitting filter interposable in the radiation beam from said graphite tube.