Projection aligner

A projection aligner for transferring an image of a mask having a predetermined pattern onto an object to be exposed, said projection aligner comprising:

• a light source that emits a collimated light beam to the mask to illuminate the mask;
• an optical system that projects the light beam passed through the mask to the object to form the image of the mask on the object;
• and
• an image magnifying/contracting system that changes the magnification of said optical system to change the size of the image projected onto the object,
• wherein said optical system includes:
• a first mirror that deflects the light beam emitted by said light source and passed through the mask;
• a lens unit having a positive power, the light beam deflected by said first mirror being incident on said lens unit;
• a reflector that reflects the light beam passed through said lens unit, the reflected light beam being incident on said lens unit;
• and
• a second mirror that deflects the light beam reflected by said reflector and passed through said lens unit, the light beam deflected by said second mirror being incident on the object, the object being arranged in parallel with the mask, an image being formed on the object;
• and wherein said image magnifying/contracting mechanism includes:
• a reflector driving mechanism that moves said reflector along an optical axis of said lens unit;
• and
• a position adjuster that adjusts the position of said first and second mirrors such that the mask and the object are displaced from the focal points of said lens unit while keeping a conjugate relation of the mask and the object with respect to said lens unit.