Bichromatic pyrometer

A bichromatic pyrometer for performing successive temperature measurements on a succession of surface elements of a surface, said surface being in fast motion relative to said bichromatic pyrometer, wherein temperature radiations emitted by said surface elements pass successively in front of said bichromatic pyrometer and vary at a high frequency temperature variation rate, said bichromatic pyrometer comprising:

• an optical element having a sight for detecting said temperature radiations emitted by said surface elements passing successively in front of said sight;
• an optical fiber system coupled to said optical element and to a first photodiode and a second photodiode, said optical fiber system having divider means for dividing said detected temperature radiations into a first part and a second part and for transmitting said first part to said first photodiode and said second part to said second photodiode, said first photodiode and said second photodiode being made of a semiconductor material having a large forbidden band, and said first photodiode and said second photodiode being sensitive to radiation in given sensitivity ranges of wavelengths, said forbidden band of said first photodiode being greater than said forbidden band of said second photodiode, said forbidden band of said second photodiode being greater than or equal to the forbidden band of silicon, said sensitivity range of wavelengths of said first photodiode being different from said sensitivity range of wavelengths of said second photodiode, said first photodiode and said second photodiode having a conversion rate in accordance with said high frequency temperature variation rate for converting said first part and said second part of said detected temperature radiations into respective electrical signals without deformations;
• amplifier means connected to each of said first photodiode and said second photodiode, said amplifier means having a gain and a passband in accordance with said high frequency temperature variation rate for amplifying said respective electrical signals without attenuation or deformations;
• and
• transmitter means for transmitting said respective amplified electrical signals to a recorder means for recording said respective amplified electrical signals.