OPTICAL SYSTEM AND IMAGE PROJECTION APPARATUS

摘要

PURPOSE: An optical system and image projection device applied with the same are provided to add a zoom function in a projector in which a projection distance is shorts. CONSTITUTION: An optical system comprises a first optical group(110), a second optical group(120) and a third optical group(130). The first optical group performs a zoom function by using a first lens. The second optical group performs a focus function by using a second lens. The third optical group performs a reflection function by using first and second optical groups. A middle ground is formed between the first and second optical groups. The first optical group, and the second optical group and the third optical group are successively arranged.