OPHTHALMOLOGICAL INSTRUMENT

PROBLEM TO BE SOLVED: To provide an ophthalmological instrument which permits both Z-alignment driving over a wide range and accurate driving control to a focusing position to be consistently performed by appropriately changing the detection information of an ultrasonic distance measuring means and an optical Z-alignment sensing means. SOLUTION: The ophthalmological instrument is provided with: an XY-alignment detection means to detect upward, downward, rightward and leftward alignment information of the instrument with respect to an examinee's eye E; an optical Z-alignment detection means to optically detect the Z-alignment information of the instrument with respect to the examinee's eye E by a light receiving element; an ultrasonic wave transmission means to transmit ultrasonic waves to the examinee's eye E on the basis of the XY-alignment detection information; an ultrasonic wave Z-alignment detection means to detect the reflected waves of ultrasonic waves transmitted to the examinee's eye E; a sonic velocity correction means to correct the sonic velocity varied by temperature; a Z-alignment detection signal selection means to select one of detection signals detected by two Z-alignment detection means; and a Z-axis driving means to drive the instrument on the basis of the selected Z-alignment detection signal. COPYRIGHT: (C)2008,JPO&INPIT