Patent ID: 6310736
Filing Date: 2001-10-30
Classification: G02B

Abstract:
An image-forming optical system for forming an image of an object, said image-forming optical system comprising:a first prism and a second prism, each of said first prism and second prism being formed from a medium having a refractive index (n) larger than 1 (n>1), said second prism being placed closer to the object than said first prism;said second prism having three optical surfaces that transmit or reflect a light beam, said three optical surfaces including:a first surface through which a light beam from an object side of said second prism enters said second prism;a second surface that reflects the light beam entering through said first surface in said second prism;said first surface also reflecting the light beam reflected from said second surface in said second prism; anda third surface through which the light beam reflected from said first surface exits from said second prism;wherein at least one of said first surface and second surface has a curved surface configuration that gives a power to a light beam, said curved surface configuration having a rotationally asymmetric surface configuration that corrects aberrations due to decentration;said first prism having at least:a decentered reflecting surface having a curved surface configuration and internally reflecting a light beam in said medium, said reflecting surface having a rotationally asymmetric surface configuration that gives a power to a light beam and corrects aberrations due to decentration;an entrance surface through which a light beam enters said first prism; andan exit surface through which the light beam exits from said first prism;wherein an intermediate image surface is formed between the first surface of said second prism and the exit surface of said first prism.