Intraocular length measuring instrument with rotary optical path length variator

An intraocular length measuring instrument including:

• a light source having a short coherent length;
• a beam splitter for forming a measuring optical path via the interior of an eye to be tested and a reference optical path within said instrument, and guiding a beam of light from said light source to both said measuring optical path and said reference optical path;
• a first light receiving means for interfering light reflected by an intraocular object to be measured after passing along said measuring optical path with light coming through said reference optical path and receiving a resultant interference light;
• an intraocular object position measuring means for finding an optical path difference from the reference optical path and the measuring optical path according to a peak position of a signal coming from said first light receiving means and an optical path length of the reference optical path;
• a light irradiating optical means for irradiating a light beam to the cornea of said eye to be tested;
• a light receiving optical means for introducing a reflected light from said cornea to a second light receiving means;
• and
• a corneal position measuring means for finding a position of said cornea from an output of said second light receiving means;
• a rotatable optical path length variable means for varying the optical path length of the reference optical path in accordance with an angle of rotation;
• and
• a rotary means for rotating the optical path length variable means to vary the optical path length of the reference optical path sequentially.