Fiber optic pyrometry with large dynamic range

The method for optically measuring a wide band of work environ temperatures comprising the steps of:

• transducing a work environ temperature into an intensity modulated black body radiance optical signal;
• selecting a predetermined spectral band of said black body radiance signal as an intensity signal representation of said work environ temperature band;
• splitting said intensity signal into a plurality of intensity range segregated optical signal components;
• converting each of said component optical signals into an electrical signal, a plurality of said electrical signals each corresponding to a component optical signal and representing a range of work environ temperatures thereby resulting;
• and
• generating a temperature indication signal from a selected sequence of said plural electrical signals.

Apparatus for optically measuring a wide band of work environ temperatures comprising:

• means for transducing a work environ temperature into an intensity modulated black body radiance optical signal;
• means for selecting a predetermined spectral band of said black body radiance signal as an intensity analog signal representation of said work environ temperature band;
• means for splitting said intensity analog signal into a plurality of intensity range segregated optical signal components;
• means for converting each of said component optical signals into an electrical signal, a plurality of electrical signals each corresponding to a component optical signal resulting;
• and
• means for generating a temperature indication signal from selected of said plural electrical signals.

Apparatus for optically measuring fluctuating work environ temperatures in the range of 500 to 2300 degrees Kelvin comprising:

• an irridium black body transducer member capable of being immersed in said work environ and of generating a black body radiance signal when heated by said environ;
• an optical beamsplitter member capable of dividing a radiance signal sample into ten and ninety percent intensity components;
• an optical transmission member including optically coupled sapphire fiber and glass fiber portions located intermediate said work environ and said beamsplitting members respectively, and capable of transmitting optical radiance signal samples therebetween;
• optical filter means located in the path of said optical radiance signal sample for rejecting radiance signal spectral components external of a band between 1.5 and 1.8 micrometers of spectral wavelength;
• a first neutral density attenuation member of density factor between four-tenths and six-tenths located in the ninety percent intensity component path of said beamsplitter;
• a second neutral density attenuation member of density between three and three and one-half located in the ten percent intensity component path of said beamsplitter;
• a first optical signal to electrical signal detector member comprised of a room temperature maintained gallium indium and arsenic compound photodiode capable of converting said four-tenths to six-tenths density attenuated beamsplitter ninety percent component into a first electrical signa;
• said detector member diode having a linear dynamic transducer range between 1E5 and 1E6;
• a second optical signal to electrical signal detector member comprised of a room temperature maintained gallium indium and arsenic compound photodiode and capable of converting said three to three and one-half density attenuated beamsplitter ten percent component into a second electrical signal, said detector member diode having a linear dynamic transducer range between 1E5 and 1E6;
• and
• means responsive to a selected one of said first and second electrical signals for generating a measured temperature indication.