Spirit Photography
Full-spectrum photography is a subset of full-spectrum imaging, defined currently among photography enthusiasts as imaging with consumer cameras the full, broad spectrum of a film or camera sensor bandwidth. In practice, specialized broadband/full-spectrum film captures visible and near infrared light, commonly referred to as the “VNIR”. Modified digital cameras can detect some ultraviolet, all of the visible and much of the near infrared spectrum, as most digital imaging sensors are sensitive from about 350nm to 1000nm. An off-the-shelf digital camera contains an infrared hot mirror filter that blocks most of the infrared and a bit of the ultraviolet that would otherwise be detected by the sensor, narrowing the accepted range from about 400nm to 700nm[2]. Replacing a hot mirror or infrared blocking filter with an infrared pass or a wide spectrally transmitting filter allows the camera to detect the wider spectrum light at greater sensitivity. Without the hot-mirror, the red, green and blue (or cyan, yellow and magenta) colored micro-filters placed over the sensor elements pass varying amounts of ultraviolet (blue window) and infrared (primarily red, and somewhat lesser the green and blue micro-filters). A converted full-spectrum camera can be used for ultraviolet photography or infrared photography with the appropriate filters.
Uses of full-spectrum photography are for fine art photography, geology, forensics & law enforcement, and even some claimed use in ghost hunting.
Source: Wikipedia, the free encyclopedia