Patent ID: 7104654

Claim:
A light source unit comprising: an ellipsoidal mirror having an ellipsoid mirror surface and a flange disposed so as to surround the mirror surface, a plurality of pairs of first fitting parts being disposed on a surface of the flange, the first fitting parts in each pair facing one another across a light axis of a lamp; the lamp disposed in a space surrounded by the ellipsoidal mirror such that rays emitted from the lamp are reflected on the mirror surface so as to be irradiated as parallel rays; a holder having second fitting parts disposed so as to face the first fitting parts, the second fitting parts fitting one-to-one with the first fitting parts, the holder and the ellipsoidal mirror thereby being integrated; and a lens held by the holder so as to face the lamp, wherein (i) the first fitting parts are prism-shaped projections and the second fitting parts are depressions corresponding to the shape of the projections, or (ii) the second fitting parts are the projections and the first fitting parts are the depressions, and when the first fitting parts and the second fitting parts are fitted together, a light axis of the ellipsoidal mirror and a light axis of the lens substantially coincide wherein each of the prism-shaped projections is positioned in a manner that a center line in a lengthwise direction thereof is in a direction intersecting with the light axis of the lamp, and each of the prism-shaped projections has a plane inclining at an angle of 30 degrees to 60 degrees with respect to a surface of the flange.