Kirlian photography is a collection of photographic techniques used to capture the phenomenon of electrical coronal discharges. It is named after Semyon Kirlian, who, in 1939 accidentally discovered that if an object on a photographic plate is connected to a high-voltage source, an image is produced on the photographic plate.
Kirlian photography is a technique for creating contact print photographs using high voltage. The process entails placing sheet photographic film on top of a metal discharge plate. The object to be photographed is then placed directly on top of the film. High voltage is momentarily applied to the metal plate, thus creating an exposure. The corona discharge between the object and the high voltage plate is captured by the film. The developed film results in a Kirlian photograph of the object.
Color photographic film is calibrated to faithfully produce colors when exposed to normal light. Corona discharges can interact with minute variations in the different layers of dye used in the film, resulting in a wide variety of colors depending on the local intensity of the discharge. Film and digital imaging techniques also record light produced by photons emitted during corona discharge (see Mechanism of corona discharge).
Photographs of inanimate objects such as a coins, keys and leaves can be made more effectively by grounding the object to the earth, a cold water pipe or to the opposite (polarity) side of the high voltage source. Grounding the object creates a stronger corona discharge.
Kirlian photography does not require the use of a camera or a lens because it is a contact print process. It is possible to use a transparent electrode in place of the high voltage discharge plate, allowing one to capture the resulting corona discharge with a standard camera or a video camera.