Infrared Imaging Sensors

Basic Description

Infrared imaging sensors, or thermal imaging sensors, are those which can detect objects using infrared radiation. Similar to visible light, infrared radiation is electromagnetic radiation with a wavelength of 750 nm to 1 mm (Fig-1). Thermal infrared radiation occupies wavelengths from about 3 to 30 microns. This radiation is generated by any object with a temperature higher than absolute zero. It cannot be seen by the human eye, but it is readily detected by electronic sensors designed for that purpose. One popular use of thermal infrared image sensors in vehicles is to enable the driver to see pedestrians or animals at nighttime.

Generally, there are two types of infrared imaging sensors: cooled and uncooled. Cooled infrared sensors are manufactured with individual cooling systems and operate at a very low temperature (4° K - 180° K). The low temperature operation improves the imaging resolution and sensitivity, but increases the cost and response time of these systems. Uncooled infrared sensors operate at ambient temperature, or a stabilized temperature close to ambient. Uncooled infrared sensors are generally smaller and cost less making them the sensors of choice for automotive and other mobile applications.

A typical infrared imaging sensor consists of an optical system, a CCD or CMOS detector, a signal processing module and a display interface as illustrated in Fig-2. An optical imaging system project the image on to a CCD or CMOS focal plane array (FPA) detector, where the image is converted to an electrical signal. A signal processing module calibrates and conditions the image before sending it to the display.

Manufacturers

Aptina, Autoliv, Bosch, FLIR, Lapis, L-3, LumaSense, Teledyne, ULIS

For More Information

[1] Thermographic Camera, Wikipedia.

[2] Thermal Imaging Camera, Wikipedia.

[3] Flir Systems - "Path Finder" Automotive Infrared Camera, YouTube, April 5, 2008.

[4] ICU: Infrared Imaging Components for use in Automotive Safety Applications, YouTube, June 10, 2010.

[5] Autoliv's Second Generation Night Vision with Pedestrian Detection, YouTube, Aug. 15, 2010.

[6] How Thermal Imaging Infrared Technology Works, MoroVision website.