Infrared inspection system and method employing emissivity indications

Claim 2

Apparatus for analyzing a unit in the form of a device or a structure having differing thermal emissivities at differing regions thereof comprising an infrared camera for monitoring infrared emission from the unit and for deriving a signal having magnitudes representing the infrared emission from multiple pixels in a field of view of the camera, a computer responsive to the signal including: means storing data representing emissivity and standard temperature of the unit at each of the pixels, the stored emissivity and standard temperature data for some of the pixels of the unit differing from the stored emissivity and standard temperature indication of others of the pixels of the unit, means for: (a) combining indications of the infrared emission from the pixels and the stored data representing emissivity of the pixels to derive an indication of monitored temperature of the pixels, (b) comparing the stored data representing standard temperature of each pixel and the indications of monitored temperature of the pixels, and (c) deriving an indication of the deviation between the magnitude of the standard temperature and monitored temperature at the pixels; and means responsive to the indication of the deviation at each pixel for indicating a property of the unit, the property being related to the deviations at the pixels.

Claim 3

The apparatus of claim 1 wherein the means for indicating includes a two-dimensional display for displaying an image of the deviation at each pixel, the image spatially corresponding with an image of the unit.

Claim 4

The apparatus of claim 2 wherein the means for indicating responds to a deviation in excess of a predetermined value at any pixel for signaling that the unit is unacceptable for its intended purposes.

Claim 5

The apparatus of claim 1 wherein the signal is derived for each pixel of a single analyzed unit at plural times, the computer deriving the deviation indication for each pixel at each of the plural times, the property indicating means for the single analyzed unit responding to the deviation indication for each pixel at each of the plural times.

Claim 8

The method of claim 5 wherein the pixels for which the deviation magnitudes are derived are first pixels, the unit having a standard pixel with known radiation emissivity, the standard pixel being spatially displaced from

Claim 9

The method of claim 6 wherein the method is performed to derive the data representing the standard temperature for the first pixels by performing said steps of claim 6 on Q units having second pixels corresponding to said first pixels and further pixels having the known emissivity and corresponding with said standard pixels, where Q is at least several, deriving indications of the detected intensities from the corresponding second pixels and the further pixels of the Q units, the computer combining the derived indications of the detected intensities from the corresponding second pixels and the further pixels of the Q units to derive the data representing the standard temperature of the first pixels.

Claim 10

The method of claim 7 wherein the computer derives the data representing the standard temperature for the first pixels in response to ##EQU8## where: I T1 =intensity of radiation from the second pixels at the first temperature I T2 =intensity of radiation from the second pixels at the second temperature I STDT1 =intensity of radiation rom the further pixels at the first temperature I STDT2 =intensity of radiation from the further pixels at the second temperature 1/3 STD =the known radiation emissivity Q=the number of the at least several units q=is successively each of 1, 2 . . . Q B=average value of B for the Q units C=average value of C for the Q units S B =standard deviation of B for the Q units S C =standard deviation of C for the Q units.

Claim 11

The method of claim 8 wherein the steps of claim 5 are performed on the first pixels of a monitored unit and on the standard pixel of the monitored unit, the computer deriving the indication of the temperature of the first pixels in response to ##EQU9## I T1 (test) =intensity of radiation from the first pixels of the monitored unit at the first temperature I T2 (test) =intensity of radiation from the first pixels of the monitored unit at the second temperature I STDT1 (test) =intensity of radiation from the standard pixel of the monitored unit at the first temperature I STDT2 (test) =intensity of radiation from the standard pixel of the monitored unit at the second temperature.

Claim 12

The method of claim 7 wherein the computer derives indications of (a) the standard temperature for the first pixels in response to B·r(B,C) and (b) the monitored temperature for the first pixels in response to B test ·r tested (B,C), and (c) the deviations between the indications of standard temperature for the first pixels and the monitored temperatures for the first pixels of the monitored

Claim 13

The method of claim 7 wherein the computer derives the data representing the standard temperatures for the first pixels by (a) determining first and second measures of the average infrared intensity from the second pixels of the O units at said first and second temperatures, (b) determining a third measure of the deviations of the infrared intensity from the second pixels of each of the O units at the first temperature from the first measure, (c) determining a fourth measure of the deviations of the infrared intensity from the second pixels of each of the O units at the second temperature from the second measure, (d) non-linearly combining the third and fourth measures for each of the O units to derive a first resultant, (e) linearly combining the first resultant, (f) determining first and second indications of the spread of values of the detected intensities from the first pixels at the first and second temperatures, respectively, and (g) combining the second resultant with the first and second indication of the spread of values.

Claim 14

The method of claim 7 wherein the computer obtains the standard temperature data for the first pixels from a statistical function of (a) the known emissivity and (b) the detected intensities at the further pixels and at the second pixels of the O units while the O units are at the first and second temperatures.

Claim 15

The method of claim 12 wherein the computer combines a value derived from the statistical function with a measure of the detected intensity for the first pixel to provide the indication of the standard temperature for the first pixels.

Claim 16

The method of claim 13 wherein the computer derives the statistical function value by determining the average values and the standard deviations of the intensities from the second pixels of the O units at the first and second temperatures, and combining the determined average values and standard deviations.

Claim 17

The method of claim 6 wherein the unit includes plural components and the method is performed to detect the expected lifetime of the unit, each of the components occupying a plurality of said first pixels and having known pixel locations on the unit, further comprising using the camera to monitor the intensity of infrared radiation emitted from the first pixels forming the components while the components are stimulated to a higher temperature than ambient temperature of the unit, the computer responding to the radiation indications for the first pixels of each particular component and an indication of the particular component radiation emissivity to derive an indication of expected operating temperature of each particular component, responding to the indication of expected operating temperature of each particular component and a stored value relating expected operating temperature of each particular component to the lifetime of the particular component to derive a second indication representing the expected lifetime of each particular component, and combining the second indications for all of the components to derive the indication of the unit expected lifetime, the temperature indication of each particular component being derived by combining the indications of (a) the monitored radiation intensity from all of the first pixels occupied by the particular component and (b) the radiation emissivity of the first pixels occupied by the particular component.

Claim 18

The method of claim 5 wherein the unit includes plural components and the method is performed to detect the expected lifetime of the unit, each of the components occupying a plurality of said pixels and having known pixel locations on the unit, further comprising using the camera to monitor the intensity of infrared radiation emitted from the pixels forming the components while the components are stimulated to a higher temperature than ambient temperature of the unit, the computer responding to the radiation indications for the pixels of each particular component and an indication of the particular component radiation emissivity to derive an indication of expected operating temperature of each particular component, responding to the indication of expected operating temperature of each particular component and a stored value relating expected operating temperature of each particular component to the lifetime of the particular component to derive a second indication representing the expected lifetime of each particular component, and combining the second indications for all of the components to derive the indication of the unit expected lifetime, the temperature indication of each particular component being derived by combining the indications of (a) the monitored radiation intensity from all of the pixels occupied by the particular component and (b) the radiation emissivity of the pixels occupied by the particular component.

Claim 19

The method of claim 16 wherein the intensity of the infrared radiation for the pixels is monitored while the unit is at first and second displaced temperatures, and further including monitoring the intensity of infrared radiation emitted from a standard pixel of the unit while the unit is at the first and second temperatures, the standard pixel having known radiation emissivity, and combining indications of the monitored intensity of the infrared radiation of the pixels and the standard pixel while the unit is at the first and second temperatures with an indication of the emissivity of the standard pixel to provide an indication of the temperature of each pixel.

Claim 20

The method of claim 5 wherein the indicated property is an indication of worthiness of the unit for its intended use.

Claim 21

The method of claim 5 wherein the camera monitors the emission at plural times while the unit is being transiently stimulated.