Light source device

A light source device, comprising:

• an alternating current high-pressure mercury lamp having a roughly spherical light-emitting part containing at least 0.15 mg/mm3 of mercury and halogen within a range of 10−6 μmol/mm3 to 10−2 μmol/mm3, and cylindrical hermetically sealed portions extending from both ends of the light-emitting part;
• a pair of electrodes arranged opposite each other within the light-emitting part;
• and external leads that protrude from ends of the light-emitting part for receiving alternating current;
• a reflecting mirror comprising a concave reflecting part arranged so as to surround the light-emitting part and a cylindrical neck part;
• an adhesive for mounting of the lamp in the light source device, the adhesive surrounding the periphery of a portion of one of the hermetically sealed portions in an area in which the external leads are located;
• and
• feed wires connected to the external leads,
• wherein the relationship L1/R≧0.5 is fulfilled, where L1 (mm) is a length filled with an adhesive in a direction in which the hermetically sealed portions extend and R (mm) is a diameter of the hermetically sealed portions.