Intraocular length measuring instrument having phase compensating means

An intraocular length measuring instrument, comprising:

• a light source portion for emitting a measuring beam of light;
• a measuring optical system for projecting said measuring beam onto an intraocular object to be measured;
• a beam splitter for separating a part of said measuring beam from said measuring beam;
• a reference optical system for guiding said separated part of light to a reference mirror;
• an interference optical system for making interference between measuring beam of light reflected from the eye fundus and a beam of light reflected from said reference mirror;
• a light receiving portion for receiving said interference light made by said interference optical system;
• and
• phase compensating means for setting a compensation value in consideration of birefringence of the intraocular object in order to cause a beam of light reflected from said intraocular object to have a given phase difference with respect to said measuring beam of light projected onto said intraocular object, said phase compensating means being disposed between the eye to be measured and said beam splitter.