Projector

PROJECTOR, a device in which a carbon-arc is used for local treatment with light. The scientific basis of this method belongs to Finsen and his school. The projector consists of an arc lamp of 15–30 A, at least 30 V of direct or alternating current. Alternating current devices are less powerful. The voltaic arc is obtained by passing an electric current through carbons impregnated with salts of various metals. An automatic device for bringing the carbons closer together as they burn is placed above the carbons, which makes it possible to maintain a steady arc for a long time. Behind the carbons is a nickel-plated reflector, easily movable, so that the arc can always be placed in its focus. The arc lamp is mounted in a metal cylinder so that it can easily rotate in any plane. The arc light, reflected from the reflector, takes a parallel direction and can be directed to any part of the body. The energy of the projector, in its physical and chemical properties, is very close to the solar spectrum. The thermal energy of the projector penetrates deeply into the tissues. A projector of 15 A at a distance of 2 m gives 66°, and a 25 A projector gives 93°. In intensity, the chemical energy of the projector even exceeds that of the sun. According to Vermel, the light of the projector retains the ability to cause photochemical and bactericidal effects after passing through a considerable thickness of tissues. Before the procedure, the reflector should be moved forward or backward so that the voltaic arc falls in its focus, i.e., so that a bright uniform circle is obtained on the screen. The latter is directed to the part of the body being illuminated. The procedure is performed with the patient sitting or lying at a distance of 2–3 m from the projector, depending on their tolerance to heat. The number of sessions is usually 3–12. In Germany, a combined method of light treatment is used, in which the projector is directed to different areas of the skin of the patient sitting in a light bath. Sometimes treatment with the projector is performed using monochromatic light, for which red and blue light filters are placed in front of the voltaic arc (see figure). The projector acts analgesically, bactericidally, and resorptively, causing a light tan on the skin after several sessions. Indications for the use of the projector: neuralgias and myositis of various origins, dry pleurisy, and exudates in the pelvic cavity. Symptomatically, as an analgesic, the projector is prescribed for gastrointestinal neuroses, hepatic and renal colic, bronchitis, and bronchial asthma. A disadvantage of the apparatus is the contamination of the room air with products of the combustion of the carbons. Therefore, in recent times the projector is gradually being displaced by more convenient and simple apparatuses that give radiation rich in both the right and left parts of the spectrum (Jupiter lamps, Ultrason lamps, Ultrabalk lamps, etc.).

E. Pasynkov