Multi-focus condenser lens

Abstract

Abstract PURPOSE:To prevent a deficiency in the quantity of light at the circumference of a visual field even when lenses are changed by forming such a Fresnel surface that cycle refracting surfaces having at least two kinds of converging power are arranged periodically from the center of the optical axis. CONSTITUTION:A condenser lens 1 is such a Fresnel type that cycle refracting surfaces having at least two kinds of converging power is arranged periodically from the center of the optical axis, and alternate cycle refracting surfaces correspond to lens surfaces R1 and R2 having different radii of curvatures. When this condenser lens 1 is used as a focal plate, exit pupils of lenses L and L' having different focal lengths are made coincident to an eye point E, and a deficiency in the quantity of light at the circumference of the visual field is prevented even if lenses are changed.

Inventors

• 👤 Hideo Shizume
• 👤 鎮目　秀雄

Bibliographic Details