Optical device for determining angles by measuring the orientation of one image with respect to another

Claim 1

AN OPTICAL DEVICE FOR DETERMINING ANGLES COMPRISING: (A) A CASING ADAPTED TO BE HELD IN THE HAND OF AN OBSERVER FOR PERMITTING LIGHT RAYS FROM A REMOTE OBJECT TO TRAVEL ALONG A FIRST LONGITUDINAL SIGHTING AXIS DIRECTLY TO THE OBSERVER; (B) FIRST REFLECTOR MEANS FIXEDLY DISPOSED WITH RESPECT TO SAID FIRST SIGHTING AXIS AND BEING PROVIDED WITH MEANS TO COMBINE LIGHT RAYS ALONG SAID FIRST WITH AXIS AND A SECOND SIGHTING AXIS WHICH IS PERPENDICULAR TO AND WHICH INTERSECTS SAID FIRST AXIS; (C) SECOND REFLECTOR MEANS SPACED FROM SAID FIRST SIGHTING AXIS AND ROTATABLE ABOUT SAID SECOND SIGHTING AXIS TO PROVIDE A THIRD SIGHTING AXIS IN THE PLANE PARALLEL TO SAID FIRST SIGHTING AXIS FOR REFLECTING ALONG SAID SECOND AXIS ADDITIONAL LIGHT RAYS ARRIVING FROM SAID OBJECT WHEN SAID FIRST AND THIRD SIGHTING AXES ARE PARALLEL AND FOR REFLECTING ALONG SAID SECOND AXIS LIGHT RAYS ARRIVING FROM A SECOND REMOTE OBJECT WHEN SAID SECOND REFLECTOR MEANS IS ROTATED; (D) A TRANSPARENT MEMBER FIXEDLY DISPOSED WITH RESPECT TO SAID SECOND REFLECTOR MEANS AND LOACTED ON SAID THIRD SIGHTING AXIS AND PERPENDICULAR THERETO SO THAT THOSE LIGHT RAYS STRIKING SAID SECOND REFLECTOR MEANS MUST PASS THERETHROUGH, (E) SAID TRANSPARENT MEMBER HAVING ANGULARLY SPACED GRADUATIONS THEREON LOCATED CIRCUMFERENTIALLY ABOUT SAID THIRD SIGHTING AXIS PROVIDING AN INDICATION OF THE ANGULAR DEGREE OF INVERSION OF THE IMAGE ALONG SAID THIRD SIGHTING AXIS AND THEREFORE THE ROTATIVE POSITION OF SAID SECOND REFLECTOR MEANS.