Light source and projector

A light source used for a projector for modulating a light irradiated from a source lamp to form an optical image in accordance with image information and enlarging and projecting the optical image, comprising:

• a source lamp;
• a reflector for aligning and emitting the light irradiated from the source lamp;
• and
• a case for accommodating the source lamp and the reflector,
• wherein a light-emitting surface of the reflector is covered by a light-transmissive plate and a pair of openings is formed on a contact surface of the light-transmissive plate and the reflector, the pair of openings being symmetrically disposed around an optical axis of the reflector and respectively having a dust filter, and
• wherein the case includes a cooling channel for introducing a cooling air to the source lamp through the pair of openings and a cooling channel shutter for shutting the cooling channel when the case is detached from the projector and for opening the cooling channel shutter when the case is attached to the projector.