Adaptor for measuring length optically for endoscope

Claim 1

An optical adaptor for measuring length of an object viewed to be attached to an endoscope, the endoscope comprising: an elongated insert member capable of being inserted through a body cavity; a handle member connected to a trailing end of said insert member; an illuminating optical system arranged at a tip portion of said insert member; an objective optical member arranged at the tip portion of said insert member adjacently to said illuminating optical system, said objective optical member for imaging the object illuminated by said illuminating optical system; and observation means for observing the object from the handle member side by transmitting the image from said objective optical system to said handle member side; the adaptor comprising a body, attaching means including a bore in said body for receiving detachably a tip portion of said insert member, a projecting optical system arranged in said adaptor so that when said adaptor is attached to said tip portion said projecting optical system is attached to said illuminating optical system in a confronting relation with said illuminating optical system, a view field-changing optical system arranged in said adaptor so that when said adaptor is attached to said tip portion said view field-changing optical system is attached to said objective optical system in a confronting relation with said objective optical system, and at least one index attached to said projecting optical system to be projected on the object through said projecting optical system for providing a datum length.