Fiber optic pyrometry with large dynamic range

Claim 2

Large temperature range optical pyrometer apparatus comprising: optical beamsplitting means for segregating photon flux optical signals into first and second component optical signals of predetermined segregated intensity range ratio; optic means for transmitting photon flux optical transmission signals from adjacent an elevated temperature work environ to said beamsplitting means; first optical attenuation means for generating from said first component optical signal a first attenuated optical signal of first intensity ratio relationship with said first component optical signal; second optical attenuation means for generating from said second component optical signal a second attenuated optical signal of second intensity ratio relationship with said second component optical signal; first optical-to-electrical transducer means, of smaller dynamic range capability than said photon flux energy optical signal, for generating first electrical signals amplitude responsive to said first attenuated optical signal intensity; second optical-to-electrical transducer means of smaller dynamic range capability than said photon flux energy optical signal, for generating second electrical signals amplitude responsive to said second attenuated optical signal intensity; and means responsive to the amplitude of a selected one of said first and second electrical signals for generating a pyrometer output temperature indication signal.

Claim 3

The apparatus of claim 1 further including optical filter means for limiting the spectrum of said first and second attenuated optical signals to a predetermined spectral band.

Claim 4

The apparatus of claim 2 wherein said optical filter means includes a limiting spectral response in said optic transmission means.

Claim 5

The apparatus of claim 3 wherein said optic transmission means limiting spectral response lies on one spectral wavelength side of said predetermined spectral band and said optical filter means further includes an optical filter element of limited spectral response lying on the opposite spectral wavelength side of said predetermined spectral band.

Claim 6

The apparatus of claim 4 wherein said spectral band includes the spectral wavelength of 1.6 micrometers.

Claim 7

The apparatus of claim 1 further including a black body transducer element located within said work environ intermediate said environ and a work environ terminus of said optic means.

Claim 8

The apparatus of claim 6 wherein said black body transducer element is comprised of a metal taken from the group of platinum and irridium.

Claim 9

The apparatus of claim 7 wherein said black body transducer element includes a protective film of oxide material disposed over the metal surface adjacent said work environ.

Claim 10

The apparatus of claim 1 wherein said optic transmission means includes a transmission element comprised of sapphire.

Claim 11

The apparatus of claim 9 wherein said optic transmission means includes a high temperature sapphire transmission element adjacent said work environ and low temperature fiber optic means intermediate said sapphire transmission element and said beamsplitting means.

Claim 12

The apparatus of claim 1 wherein said first and second optical-to-electrical transducer means each include a transducer element comprised of indium gallium arsenide.

Claim 13

The apparatus of claim 1 wherein said means for generating a pyrometer output temperature indication signal includes selection means responsive to the amplitude of said first and second electrical signals for selecting between said electrical signals in generating said pyrometer output indication signal.

Claim 14

The apparatus of claim 1 wherein said beamsplitting means includes a beamsplitting pellicle member, said first component signal is transmitted through said pellicle member, said second component optical signal is reflected from said pellicle member and said second component reflected optical signal is of lesser intensity than said first component transmitted optical signal; whereby said transmitted first component signal correlates with a low intensity, low temperature portion of the dynamic range of said pyrometer and said reflected second component signal, correlates with a high intensity high temperature portion of said dynamic range of said pyrometer.

Claim 15

The apparatus of claim 13 wherein said first optical attenuation means is of smaller attenuation capability than said second optical attenuation means; whereby said second lower intensity component optical signal is attenuated by a greater degree than said first component optical signal and the portions of said pyrometer dynamic range correlating with said component signals are further segregated.

Claim 16

The apparatus of claim 2 wherein said spectral band is located at a spectral wavelength of limited optical signal intensity dynamic range.

Claim 17

The apparatus of claim 15 wherein said optical-to-electrical transducer means includes a transducer element comprised of indium, gallium, and arsenic, said selected spectral band includes the wavelength of 1.6 micrometers, one of said attenuation means is capable of attenuation greater than one thousand times and the other of said attenuation means is capable of attenuation less than one hundred times.

Claim 20

The method of claim 17 further including attenuating each of said component optical signals by a differing predetermined amount in inverse correspondence with said segregated intensity ranges; whereby the dynamic range of each said component signal converted into an electrical signal is similar and within the linear dynamic range of means performing said converting.

Claim 21

The method of claim 17 wherein said step of selecting a predetermined spectral band includes rejecting the black body spectral band of maximum signal dynamic range: whereby optical signals of large dynamic range and transducer physical damage capability are excluded from said converting step and limited dynamic range converting is enabled.

Claim 22

The method of claim 19 wherein said step of splitting said intensity signal into a plurality of signal components comprises splitting said intensity signal into two signal components of dissimilar intensity range.

Claim 23

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.

Claim 24

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.

Claim 25

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.

Claim 26

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.

Claim 27

The apparatus of claim 22 wherein said optical filter means is comprised of a first limited spectral passband residing in said optical transmission member and a filter member of second limited spectral passband.