Abstract: The invention relates to a low-pressure mercury vapor discharge lamp having a tubular discharge vessel which is sealed in a vacuum-tight manner, a filamentary body, consisting for example of glass wool, which is thinly distributed over the volume of the discharge vessel being provided near the electrodes to increase the radiance in those portions of the discharge vessel.

Abstract: Low-pressure mercury vapor discharge lamp suitable for use in photo-therapy and having a glass discharge tube which is opaque to shorter wavelength ultraviolet radiation and bears a luminescent layer on its inside surface. A problem in such lamps is to produce a useful quantity of radiation which is effective for photo-therapy in combination with as low a quantity of erythema-producing radiation as possible. The luminescent layer comprises a luminescent material having the characteristic line emission of gadolinium at 312 nm, and the glass has an absorption edge located between 280 and 305 nm.

Abstract: A low-pressure mercury vapor discharge lamp for radiation purposes having a discharge tube made of glass with selective transmission, the tube being coated on the inside with a luminescent layer. This layer contains a luminescent material which has the characteristic line emission of gadolinium at 312 nm. The discharge tube is made of glass having an absorption edge located between 260 and 280 nm and the tube has at 312 nm a transmission of at least 80%.

Abstract: Low pressure mercury vapor discharge lamp having a cylindrical discharge vessel the inner surface of which is, at least partly, coated with a luminescent layer, a reflecting layer containing titanium dioxide being provided between the said surface and the luminescent layer over a portion of the circumference between the ends of the discharge vessel. The reflecting layer contains up to 10% by weight of fine-grained silicon dioxide, thereby increasing the luminous flux emitted by the lamp.