Patent ID: 6204978
Filing Date: 2001-03-20
Classification: G02B

Abstract:
An optical system in which rays of light from an object pass through a first lens unit having at least one off-axial curved surface, a second lens unit and a third lens unit having at least one off-axial curved surface in the named order, characterized in that when the route of a ray of light passing from the object through the center of a stop to the center of the last image surface is defined as a reference axis and the converted principal point interval between said first lens unit and said second lens unit is defined as e1 and the converted principal point interval between said second lens unit and said third lens unit is defined as e2 and the power of said second lens unit at a certain azimuth angle is defined as .phi.2 (.xi.), the condition that ##EQU26##is satisfied, and when the powers of said first lens unit and said third lens unit at a certain azimuth angle are defined as .phi.1 (.xi.) and .phi.3 (.xi.), respectively, the conditions that ##EQU27##are satisfied.