US Patent 7312563 Short arc lamp

According to the present invention, a short arc lamp comprises a lamp main body having a reflective surface therein, a first opening on an optical axis thereof, and a second openings, a window member provided so as to close the second opening and to define a discharge space between the lamp main body and the opening, a first electrode and a second electrode that are arranged so as to face each other, wherein a tip portion of each of the electrodes extends into the discharge space, and a base disposed approximately at a back end portion of the lamp main body, wherein a hole is formed in the base, the first electrode is held in a burying portion of the base, and a diameter of the first electrode in the burying portion is larger than that of the tip portion of the first electrode.