Abstract: A method for controlling electrical conductivity to a work piece by irradiating pulse light from a light source onto the work piece, the method comprising a step of controlling the light irradiation index S of the pulse light in a 400?S?900 range, wherein light energy, pulse width and light irradiation index are represented by E J/cm2, ? sec, and S, and the S is defined as E/?1/2.

Abstract: A method for controlling electrical conductivity of a work piece by emitting pulse light from a light source onto the work piece, the method comprising a step of controlling the light emission index S of the pulse light in a 400≦S≦900 range, wherein light energy, pulse width and light emission index are represented by E J/cm2, &tgr; sec, and S, and the S is defined as E/&tgr;1/2.

Abstract: The invention relates to a discharge lamp with a discharge vessel of silica glass which has a higher operating pressure than atmospheric pressure, where the high temperature viscosity (VA) in the outer surface area of the arc tube portion of the discharge vessel is lower than the high temperature viscosity (VB) at a depth of 100 microns from the outer surface of the arc tube portion. Since the high temperature viscosity (VA) in the outer surface area of the arc tube portion of the discharge vessel is lower than the high temperature viscosity (VB) at a depth of 100 microns from the outer surface of the arc tube portion, formation of thermal distortion in the vicinity of the outer surface of the arc tube portion can be suppressed. This prevents the discharge vessel from being damaged or from breaking by thermal distortion even after operation for a long time.

Abstract: An improved cermet for hermetically sealing a discharge vessel in a ceramic discharge lamp where the cermet includes a material having a coefficient of linear expansion which is at least equal to a coefficient of linear expansion of a translucent ceramic, and a material having a coefficient of linear expansion which is smaller than the coefficient of linear expansion of the translucent ceramic, where the cermet has an average coefficient of linear expansion in a range of E±1.0×10−6 (K−1) at a temperature range of 25 to 300° C., where E (K−1) is an average coefficient of linear expansion of said translucent ceramic at a temperature range of 25 to 300° C. In addition, a ceramic discharge lamp utilizing such a cermet.