A holographic camera with motorized x,y,z patient positioner has been constructed and used to estimate tensile strength of corneal wounds in patients who had previously under-gone corneal transplantation. The technique using a krypton ion laser gives high contrast fringes which readily localize to regions of the wound and suture sites, revealing weak or partially healed areas. This will hopefully serve to indicate when the sutures can safely be removed. Intraocular pressure stressing is supplied by the patient every time his heart beats. Double exposure holography is synchronized to occur when the pulse of blood reaches the eye. Thus, no external stress need be applied to the eye; and, since the retinal light exposure is typically 1/10,000th of that received during a conventional fundus photograph, the technique is truly non-invasive. The illuminating system consists of a large hemispherical reflector imaging a diffusely reflecting disk onto the cornea. An expanded laser beam illuminates the disk which is thereby specularly reflected by the cornea into the holographic imaging lens.1Rigid body movement of the eye due to microsaccades occurring between exposures have produced bothersome artifacts. A dual reference beam technique for fringe control has partially overcome this.
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