What are the wavelength boundaries of infrared radiation?
The infrared radiation is the electromagnetic radiation where wavelengths are between 700 nanometres and 1 millimetre. Thus, it is located between the red limit of visible spectrum and the shortest microwaves.
However, taking into account the major applications of thermal sensors, the main considered spectral range is between 1 µm and 50 µm including 3 major sub spectral ranges corresponding to the atmosphere transmission windows:
- 1 µm to 3 µm or Short Wave Infrared (SWIR) or band I
- 3 µm to 5 µm or Middle Wave Infrared (MWIR) or band II
- 8 µm to 14 µm or Long Wave Infrared (LWIR) or band III.
Why do you place a target in front of a blackbody?
An IR camera is sometimes sensitive to the temperature difference between an object and its background. Consequently, some tests require to simulate an object and its background and to have a simultaneous and accurate measurement of both.
What is an infrared target?
An infrared target is a thin sheet coated with high emissivity coating with stuck patterns. The object is made by the blackbody seen through the holes and the background is the solid part of the sheet.
Consequently the temperature of the object is the temperature of the blackbody while the temperature of the background is measured by inserting a temperature sensor into the mount of the target.
What is a differential blackbody?
As some IR cameras specifications depends on the temperature difference between an object and its background, it is necessary to have the object temperature adjusted with respect to the background temperature. A differential blackbody allows this function by adjusting the temperature of the object in real time to a fixed temperature difference (positive or negative) with respect to the floating temperature of the background.
What kind of tests can I perform on my IR camera using a blackbody?
The tests which can be performed on an IR camera using a blackbody can be divided into 4 categories:
- Correction and calibration tests: thermal calibration of the signal, non-uniformity correction, dynamic range, linearity measurement, etc.
- Noise measurement: thermal resolution, temporal noise, NETD, fixed pattern noise, spatial noise, NEI, etc.
- Spatial resolution and geometrical specifications: LSF, MTF, Field of View, IFOV, alignment, magnification, etc.
- Range evaluation: MRTD, MDTD, TOD, Detection, Recognition, Identification ranges, etc.
EOI offers an efficient solution to the test of IR Cameras through the INFRATEST software