Abstract: A discharge vessel with a ceramic wall is filled with inert gas and metal and is ignited and operated by an electronic circuit including a half bridge converter with an LC circuit which, when the lamp is not ignited, enters an oscillation state near a resonance frequency which lies near the third harmonic of the switching frequency of the half bridge converter. The vessel encloses a cylindrical discharge space of diameter D and length L, wherein L.ltoreq.D.ltoreq.1.2 L.

Abstract: The invention relates to a switching arrangement for operation of a high-pressure sodium discharge lamp by means of an adjustable power. Control of the adjustable power takes place by means of a control signal generated by optical sensing means for registering the spectral power of light emitted by the lamp. Registration of spectral power takes place in a first wavelength range between 350 nm and 800 nm.

Abstract: The invention relates to a high-pressure sodium discharge lamp provided with a discharge vessel having a ceramic wall and enclosed with intervening space by an outer bulb. The discharge vessel is provided with two electrodes whose respective tips have a mutual distance D. The discharge vessel has a substantially circular cross-section with an interior diameter d.sub.i over the distance D. Under nominal operating conditions, according to the invention, the wall has a wall load of at least 60 W/cm.sup.2, the space between the outer bulb and the discharge vessel contains a gas filling, and D/d.sub.i being >6.

Abstract: The invention relates to a switching arrangement for operating a high-pressure sodium lamp which radiates white light in stable operating conditions. The switching arrangement is provided with switching means for switching current through the lamp by means of a drive signal generated in a drive circuit, which signal is based on a comparison between a reference value C and drive signal V+.beta.I, in which V is the lamp voltage, I is the lamp current, and .beta. is a constant. According to the invention, C may be adjusted in steps in dependence on the lamp voltage. Thus the duration over which the lamp radiates white light can be prolonged and brought into better accordance with the electrical lamp life.

Abstract: The invention relates to a high-pressure sodium discharge lamp which under nominal operating conditions radiates white light with a maximum color rendering index R.sub.a of more than 80. Since the wall load is above 80 W/cm.sup.2 under nominal operating conditions, a color temperature T.sub.c of at least 2800.degree. K. can be achieved with a luminous efficacy of more than 40 lm/W.

Abstract: A gas discharge laser in which at least the inner wall of the laser tube is manufactured for the greater part from a gehlenite glass thereby providing a laser having a long life. The gehlenite glass can better withstand the eroding effect of the gas discharge so that the rate at which the optical elements are contaminated is greatly reduced.

Abstract: A gas discharge laser in which the light beam emanating from said laser is linearly polarized by applying a transverse magnetic field in which reflectors are used which are more or less anisotropic and the anisotropy axes of which have a precise orientation relative to the magnetic field so that a high degree of polarization is obtained.