Methods and systems for measurement and estimation of normalized contrast in infrared thermography

Patent metadata

Field	Value
Publication number	US-9787913-B1
Application number	US-201514727383-A
Country	US
Kind code	B1
Filing date	Jun 1, 2015
Priority date	Jan 8, 2010
Publication date	Oct 10, 2017
Grant date	Oct 10, 2017

Abstract

Methods and systems for converting an image contrast evolution of an object to a temperature contrast evolution and vice versa are disclosed, including methods for assessing an emissivity of the object; calculating an afterglow heat flux evolution; calculating a measurement region of interest temperature change; calculating a reference region of interest temperature change; calculating a reflection temperature change; calculating the image contrast evolution or the temperature contrast evolution; and converting the image contrast evolution to the temperature contrast evolution or vice versa, respectively.

First claim

The invention claimed is:

1. A method for converting an image contrast evolution of an object to a temperature contrast evolution, the method comprising:
calculating a measurement region of interest temperature change ΔT;
calculating a reference region of interest temperature change ΔT;
calculating a reflection temperature change ΔT ref ;
calculating the image contrast evolution C W t ; and
converting, using a processor, the image contrast evolution C W t to the temperature contrast evolution C t according to the equation of

C
_

t

≅

[

1
+

2
⁢

(

1
ɛ

-
1

)

⁢
Δ
⁢

⁢

T
refl

(

Δ
⁢

⁢
T

+

Δ
⁢

⁢

T
ref

)

]

⁢

C
_

W
t

wherein ε is the emissivity of the object.

2. The method of claim 1 , where calculating the image contrast evolution comprises:
measuring a measurement region of interest temperature T;
measuring a reference region of interest temperature T ref ;
measuring a reflection temperature T refl ; and
calculating the image contrast evolution according to the equation of:

C
_

W
t

≅

ɛ
⁡

(

(

T
4

-

T

0
4

)

-

(

T
ref
4

-

T
ref

0
4

)

)

(

ɛ
⁡

(

(

T
4

-

T

4
0

)

+

(

T
ref
4

-

T
ref

0
4

)

)

+

2
⁢

(

1
-
ɛ

)

⁢

(

T
refl
4

-

T
refl

0
4

)

)

,

wherein ε is the emissivity of the object, T 0 is the measurement region of interes

Assignees

• Koshti Ajay M
• Nasa

Inventors

• Koshti Ajay M

Classifications

• G01N25/18 Primary

  by investigating thermal conductivity (by calorimetry G01N25/20; by measuring change of resistance of an electrically-heated body G01N27/18) · CPC title

• G01J5/0003

  for sensing the radiant heat transfer of samples, e.g. emittance meter · CPC title

• H04N5/32

  Transforming X-rays (cameras or camera modules for generating image signals from X-rays H04N23/30; circuitry of SSIS for transforming X-rays into image signals H04N25/30) · CPC title

• H04N3/09

  for electromagnetic radiation in the invisible region, e.g. infrared · CPC title

• B41M5/26

  Thermography (B41M5/20, B41M5/24 take precedence); {Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used (B23K takes precedence; thermographic or photothermographic systems using noble metal compounds G03C1/494)} · CPC title