| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a stereoscopic optical system having a short overall optical length, which is suitable for an electron image microscope. <P>SOLUTION: The stereoscopic optical system comprises, in order from the object side, an objective lens OB, an afocal zoom optical system AZ, an afocal relay optical system AL, a plurality of aperture stops AS, and a plurality of imaging optical systems IL. The afocal relay optical system comprises a front group GF and a rear group GR and has an intermediate image IM between the front group and the rear group. When a focal length of the front group in the afocal relay optical system is denoted as fF and a maximum value of a distance from a surface closest to the object side to a surface closest to the image side of the afocal zoom optical system is denoted as Lz, 0.5<fF/Lz<0.9 is satisfied. <P>COPYRIGHT: (C)2013,JPO&INPIT |
