Patent ID: 6178042
Filing Date: 2001-01-23
Classification: G02B

Abstract:
A real image mode finder comprising, in order from an object side:an objective optical system comprising, in order from an object side, an objective unit, a first prism, and a second prism; andan eyepiece optical system having at least one reflecting surface,wherein said first prism has an entrance surface which transmits a light beam emerging from said objective unit and a transmission surface which is optically inclined with respect to the entrance surface so that a ray travelling along an optical axis of said objective unit is obliquely incident on the transmission surface,wherein said second prism has a reflecting surface which is situated nearly opposite to the entrance surface of said first prism and which obliquely reflects the light beam transmitted through said first prism toward the object side, a transmitting-reflecting surface which is located substantially parallel with the transmission surface of said first prism, at a minute distance away therefrom, to transmit the light beam transmitted through said first prism and to totally reflect the light beam from the reflecting surface, and an exit surface; andwherein said objective unit, said first prism and said second prism form an immediate image plane adjacent to the exit surface of said second prism.