Abstract: A metal halide lamp includes a luminous tube which is sealed and filled with predetermined rare gases and metal halide, a pair of electrodes provided in the inner portion near both ends of the luminous tube, an outer tube which encloses the luminous tube, and a pair of socket connectors electrically connected with the electrodes, wherein the luminous tube cross-section forms an uneven pattern and is pleated along outer and inner surfaces of the luminous tube. The atmospheric pressure in the luminous tube is stabilized to prevent the bending of the arc. Accordingly, the lifetime of the luminous tube is prolonged and high vapor density is obtained, thereby improving luminous efficiency and color rendering by far.

Abstract: A semiconductor wafer can be exposed by arranging a combination of electrodes in an opposed relation with an interelectrode distance of not more than 15 mm in a closed discharge cavity, enclosing, within the cavity, mercury as a light-emitting discharge component in an amount such that the vapor pressure of mercury reaches 0.4-5 atms during discharge lighting, forming a discharge between the combination of electrodes while controlling the discharge current at not less than 10 A, and irradiating light, which has been radiated as a result of the discharge and contains at least one of light components having wave-lengths of 405 nm and 436 nm respectively, onto the surface of a photoresist applied on the semiconductor wafer through a photomask or reticle and a lens which permits transmission of the light having wavelength of 405 nm or 436 nm therethrough.

Abstract: A high pressure discharge lamp with a starting circuit contained therein includes an arc tube provided with a pair of opposed electrodes at the hermetically sealed opposite ends thereof. The interior of the arc tube is filled with at least a luminous metal and gas. The discharge lamp further includes a series circuit consisting of a thermo-responsive switch and a resistor and shunted to the electrodes of the arc tube, and an outer envelope for containing therein the series circuit and the arc tube. The resistance value of the resistor is set such that a sufficient current to induce a pulse of higher voltage than the starting voltage flows through the series circuit while, on the other hand, the current flowing through the series circuit is substantially equal to or less than the lamp current during the stable state of the lamp.