ULTRA SHORT FOCUS PROJECTION LENS

摘要

PROBLEM TO BE SOLVED: To provide an ultra short focus projection lens for imaging a first image displayed by a display unit as an enlarged second image.SOLUTION: An ultra short focus projection lens has: a first lens unit that is arrayed back and forth along an optical path and adapted to image a first image as a first intermediate image; an aperture stop that is arranged at an image formation position of the first intermediate image; a second lens unit that is adapted to image the first intermediate image as a second intermediate image; and a reflecting mirror that is adapted to reflect the second intermediate image to form an enlarged second image. The first lens unit, the aperture stop and the second lens unit have the same principal optical axis. Transmittance of the ultra short focus projection lens is 0.2 to 0.25, and a focal length thereof is -3.2 mm to -2.9 mm, and an amount of shift of the first image relative to the principal optical axis is greater than 120%. The present invention can project a large-sized image at a short distance and exhibit a high image quality.SELECTED DRAWING: Figure 1