A high intensity discharge lamp, especially for optical projection systems, in one embodiment uses an anode electrode, a cathode electrode and a cylindrical envelope of single crystal (SC) sapphire. The fill may contain hydrogen, chlorine, sodium, scandium, sulfur and selenium and is under pressure exceeding 20 atmospheres. The lamp produces a continuous non-flash arc and generates a correlated color temperature between 6500 and 7000 degrees Kelvin and an efficacy exceeding 60 lumens/watt.
A short-arc high-pressure mercury vapor discharge lamp includes a pair of electrodes in an arc tube and encloses mercury, a rare gas, and so forth in the arc tube. The lamp is so constructed as to be operated at a lamp current of, for example, about 1.5 A or higher, or at a lamp voltage/lamp current ratio of about 37.5 (V/A) or lower. In addition, the distance between the electrodes, and the like are set so that the rated power per unit arc length P/d.gtoreq.88 (W/mm) and the tube wall loading Pw (rated power P/internal surface area of the arc tube).ltoreq.1.0 (W/mm.sup.2). Thus, a lamp is constructed having, even with a relatively low lamp voltage, a high lamp power of, for example, 125 W or higher, having a short arc length and a high luminous flux per unit arc length, and furthermore being one in which damage to the arc tube does not occur.
An apparatus, system, and method are disclosed for replacing an incandescent lamp with a ceramic metal halide ("CMH") lamp in a framing projector. A CMH base is connected to a framing projector body at a connection for an incandescent lamp base for an incandescent lamp. The CMH base positions a CMH lamp relative to a focal point of a reflector within the framing projector body. The CMH lamp is plugged into a CMH socket on the CMH base and the framing projector body includes an opening and connection for an incandescent base holding an incandescent lamp relative to the focal point. A CMH ballast for the CMH lamp is included and is connected to the CMH base and to an electrical connection of the incandescent lamp base.
A thru-hull fitting assembly is connected to the forward end of a hollow lamp housing for mounting to a hole in the hull of a vessel in a water-tight fashion. An HID or other lamp is mounted in the lamp housing and is surrounded by a reflector which may have an outer elliptical section and an inner parabolic section. A protective transparent window extends across the forward end of the lamp housing and is sealed thereto. The window may be made of sapphire to provide improved heat dissipation and to resist scratching during hull cleaning and breakage due to thermal shock and wave slap. A circuit may be connected to the lamp to provide over-heat protection, leak detection, as well as fault and power status indicators. Alternate embodiments utilize a solid light pipe or a hollow reflective tube to convey light from the lamp to the protective window.
