Near Infrared

Near-infrared imaging is centered in the 700-1000nm region of the electromagnetic spectrum. This wavelength is slightly outside the range of normal vision and visible (VIS) cameras. However, NIR often shares the same technology as VIS. A typical NIR camera uses a visible sensor material (CCD, CMOS) that is also sensitive in the NIR. Certain sensors simply have a better response to NIR as can be indicated by reading the wavelength graph from the sensor manufacturer or camera provider. For example, cameras using a Sony CCD sensor with an Ex-view had CCD can perform quite well with quantum efficiency even detectable by a 1050 laser.

NIR cameras are commonly used in military or outdoor surveillance applications although the range is limited based on light conditions. A typical remedy is the addition of NIR illuminators, gain amplification, and pairing of NIR cameras with other cameras such as thermal imagers. When NIR cameras are used in visible industrial applications they may need to have the NIR blocked or filtered using an IR cut filter so that the image is not distorted. Conversely, when NIR cameras are used for NIR only applications the visible portion must be blocked. For example, applications involving inspection of vegetation with an IR signature, or wafer defect inspection – may require visible filters. Most of the sensors options and accessories for VIS still apply for NIR, including many lenses, unless a more NIR-oriented optical path is required.