PROJECTION OPTICAL SYSTEM, PROJECTION APPARATUS, AND PROJECTION SYSTEM

摘要

An optical system includes a reflective optical system on a magnification side along an optical path of the projection optical system and a refractive optical system on a reduction side along the optical path. The reflective optical system includes one reflective optical element having a power. The refractive optical system includes a front group on the magnification side and a rear group on the reduction side. The front group having, in order from the magnification side toward the reduction side, a first lens group with a positive or negative refractive power, a second lens group, and a third lens group with a positive refractive power. The rear group has a positive refractive power. The first lens group moves to the magnification side, and the second lens group and the third lens group move to the reduction side in a change in focus from a long distance to a short distance.

主权项

1. A projection optical system to enlarge and project an image displayed on an image display element onto a projection surface, the projection optical system comprising:
a reflective optical system on a magnification side along an optical path of the projection optical system, the reflective optical system including at least one reflective optical element having a power; and a refractive optical system on a reduction side along the optical path, the refractive optical system including:
a front group on the magnification side; anda rear group on the reduction side having a positive refractive power,the front group including in order from the magnification side toward the reduction side:
a first lens group with a positive or negative refractive power;a second lens group with a negative refractive power; anda third lens group with a positive refractive power, wherein the first lens group moves to the magnification side, and the second lens group and the third lens group move to the reduction side in a change in focus from a long distance to a short distance.