W.c. Heraeus Gmbh

Helmut Lochmann

Jurgen Witt

Gunter Thomas

Werner Schwarz

Horst Kremmling

To protect the quartz of a quartz glass bulb (2) from attack by alkaline earth oxides emitted from electrodes (6) of the lamp, and prevent deterioration of the quartz in use of the lamp with respect to transmission of ultraviolet (UV) radiation, particularly in the short wave length range of 200 nm to 250 nm, boron silicate glass or glass-like aluminum oxide, or a mixture of boron silicate glass and glass-like aluminum oxide is interposed between the quartz bulb (2) and the electrodes. Boron oxide can be applied to the interior of the quartz bulb, and fired thereon to form, for example, a boron silicate glass layer (4) or diffuse into the quartz glass to form a diffusion layer (4') by suitable selection of firing temperatures. Alternatively, an aperture support element (35, 45) can retain a disk of boron silicate glass or glass-like aluminum oxide positioned between the electrodes and the quartz glass bulb. Such disk elements may be planar or of lensetic shape, positioned transverse to the radiation beam axis (10, 310) or at an angle thereto, to provide for partial transmission and reflection, for example in a dual-beam control or measuring system.

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Hofheim, Germany

Helmut Lochmann