REFLECTING OBJECTIVE SYSTEM INCLUDING A NEGATIVE OPTICAL POWER SECOND MIRROR WITH INCREASING NEGATIVE OPTICAL POWER OFF-AXIS

摘要

A reflecting objective system comprising three or more spherical reflecting mirrors arranged symmetrically with regard to an optical axis common thereto and has spherical aberration corrected very favorably. By using a single or plural aspherical surfaces, this reflecting objective system can be modified so as to comprise two or more reflecting mirrors and correct not only the spherical aberration but also the offaxial aberrations.