LENS WITH TAKEN-OUT ENTRANCE PUPIL Russian patent published in 2003 - IPC

FIELD: optics. SUBSTANCE: lens includes four components. First component is negative meniscus facing object space with concavity, second component is positive meniscus facing object space with concavity, third component is positive component of positive lens and negative meniscus facing object space with concavity bonded together, fourth component is positive meniscus facing image space with concavity and glued together from positive and negative lenses. Thickness of first component is equal to 0.4 focal distance of lens or more and ratio of focal powers of first and third components in absolute value does not exceed 1.03 and amounts to 0.2 optical power of entire lens. Optical power of fourth component amounts to 0.14 optical power of entire lens. Entrance pupil is removed from first surface of first component of lens to distance not less than 1.3 focal distance of lens. EFFECT: increased aperture ratio of lens, increased removal of entrance pupil, improved quality of image thanks to raised gain factor of modulation over entire vision field. 6 dwg