Thermal Imaging

Thermography is a type of imaging achieved with thermal cameras that are sensitive to parts of the infrared ratiation spectrum.

The intensity of their emitted energy varies with temperature and wavelength and for objects cooler than 500 ℃, the emitted radiation lies completely within the IR wavelengths []. Depending on the detector material, the camera is sensitive to a certain part of the electromagnetic spectrum [Figure 1]. The camera detectors are of two types: thermal detectors and quantum detectors. The main thermal camera used in this research (FLIR A65sc) uses a microbolometer type thermal detector and it is sensitive to the LWIR (long wavelength IR) part of the spectrum.

ir spectrum detector materials graph
Figure 1: Detector Types and the IR spectrum ranges where they are sensitive

Detailed description of Figure 1: 
Figure 1 shows on left hand side of image PtSi and InSb detectors which are sensitive within the MWIR (medium wavelength IR between 3 and 5 micrometres wavelength) and on the right hand side of the image MCT, QWIP and Microbolmeter detectors which are sensitive within the LWIR (long wavelength IR between around 7 and 14 micrometres wavelength) 

The FLIR A65sc it an uncooled microbolometer type thermal camera usef for measuring temperatures of solid objects in a non-invasive manner. The main technical specifications of the camera are presented in the table below. The full specifications can be found here:

Main FLIR A65sc specifications
IR resolution 640 x 512 pixels
Thermal sensitivity/NETD <0.05 ℃; @30 ℃/50 mK
Field of view 45˚ x 37˚
Focal Length 13 mm
Image frequency 7.5 Hz
Spectral range 7.5 – 13 um