Abstract: A metal-halide discharge lamp for photooptical purposes has a small electe spacing of less than 15 mm, preferably 2-8 mm, to provide an essentially pin-point light source, and a fill which contains AlI.sub.3 in an amount between 0.1 and 4.5 mg/cm.sup.3. Other filling components may in particular be halides of mercury, indium, thallium or cesium; up to 2 mg/cm.sup.3 of AlBr may be added. The lamp is particularly adapted for combination with a, preferably parabolic, reflector.

Abstract: A metal halide high-pressure discharge lamp has a discharge vessel of comt construction, with a fill of mercury, at least one noble gas, typically argon, and a metal halide, with an excess of halogen. The halogen component of the metal halide is formed by iodine and/or bromine. An average light density in excess of 30 ksb, with a specific arc power of between 400 to 5000 W/cm is obtained over an average lifetime of 250 hours with a color rendering index Ra of at least 85 by utilizing cadmium and lithium as the metal component in the metal halide of the fill. Preferably, holmium also is used as a metal for the metal halide, the fill including between 0.1 and 5 mg cadmium, up to 0.05 mg lithium, and 0.05 to 1 mg holmium in a preferred form, halogen and bromine being present in a mol relation of between 0.5 to 2 within the discharge vessel. The excess halogen may be up to about 35 micromol per cubic centimeter of volume of the discharge vessel.

Abstract: A-C high-pressure discharge lamp and reflector combination assembly in which the reflector and the lamp are each separately and individually cemented into a base, but are not cemented together. Ventilation openings are formed between the lamp and the reflector in the base, to permit air to pass between the base and the lamp, and between the lamp and the reflector. Preferably, the reflector at the end remote from the base is surrounded with a ceramic end ring, at the inner circumference of which extends a metallic ribbon or strip which has radially extending connecting portions to the electrical terminals of the lamp, placed edgewise with respect to the light radiation to provide for essentially shadowless electrical connection and high-voltage insulation between the lamp terminals. Constructing the lamp as an a-c lamp permits lifetimes in the order of hundreds of hours for a lamp of comparable power and size with respect to d-c high-pressure lamps.