Research and Development in Digital Infrared Cameras
Research in thermal imaging systems targets overcoming the restrictions of human vision beyond short length waves. The basic underlying principle is using the light emitted by objects with high temperature to allow humans to see what cannot be observed with bare eye. A human eye has limited capability in the absence of short length waves. Hence, special thermal imaging devices need to be used to view images at night at the same quality of images viewed in daylight.
One of the most important devices in this area is the Digital Infrared Camera. The idea behind digital infrared camera to use infrared in place of the visible light. The word infrared is a combination of the word “infra,” which means below, and red, which is the light with the largest wavelength visible to human eyes.
Most digital cameras use a filter called, IR-Blocking filter, that is used to separate infrared light waves from visible light waves. In order to convert a regular digital camera into a digital infrared camera, the IR-Blocking filter needs to be removed.
The challenges involved in designing an effective digital infrared camera can be appreciated by thinking of the perfection of images produced by a human eye. While human eye produces images based on reflection differences, a digital infrared camera produces images using thermally self-generated energy patterns. Hence, the quality of the produced image depends largely on the temperature of the observed object. Objects temperature and reflectivity distributions induce distribution of the points in the scene recorded by a digital infrared camera.
Recent research efforts in building advanced digital infrared camera make use of the distribution of temperature of warm objects in addition to the geometrical characteristics of objects’ surfaces to measure different wavelengths emitted by the objects. The recorded wavelengths are digitally stored in a computer system which employs a texture-mapping technique to perform digital reconstruction of the 3-D temperature distribution of the object, which allows tracking object’s motion or tracking changes in object's temperature.
Some other recently proposed systems use eye contact sensing to improve focus selection in a digital infrared camera. The process of focus selection can be difficult since the selection buttons in the digital infrared camera place the focus in a device-specific modality. This process can be facilitated using digital eye contact sensors. The sensors allow setting the focus target by looking at its sensor. The proposed system uses a central server to interpret commands provided by remote controller, key buttons or voice. This system is implemented using a calibration-free digital eye contact sensing method that allows determining user's point of sight.
by Mike William
About the Author:
Mr. William is an Electrical Engineering Researcher
References:
BOOKS:
1. Lloyd J. Michael. Thermal imaging systems. Springer, May 31, 1975.
MAGAZINE ARTICLE:
1. Xiao Hai, Zhang Yibing, and Wang Anbo. “Multispectral three-dimensional digital infrared thermal imaging”. Optical Engineering. April, 2003, pp. 560-2303
2. Vertegaal Roel, Mamuji Aadil, Sohn Changuk and Cheng Daniel. “Media eyepliances: using eye tracking for remote control focus selection of appliances”. Extended abstracts on Human factors in computing systems, 2005, pp. 1861-1864.
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