Patent ID: 6930831
Filing Date: 2005-08-16
Classification: G02B

Abstract:
1. A vari-focal polar alignment scope comprising; an objective optical system, a relay optical system which relays an image formed through said objective optical system to form a secondary image, and an eyepiece optical system for observing said secondary image, in that order from the object side; wherein said relay optical system comprises an erecting vari-focal viewing optical system, including a positive condenser lens element constituting a first relay lens group, a positive second relay lens group, and a positive third relay lens group, wherein said second and third relay lens groups relatively move in a direction along the optical axis thereof so as to vary the magnification of said polar alignment scope, wherein the following conditions (1), (2) and (3) are satisfied: f fe designates the focal length of said eyepiece optical system; M M