Non-contact type tonometer

摘要

A non-contact type tonometer for measuring intraocular pressure of a human eye. The tonometer includes a fluid ejection nozzle to eject a fluid toward a cornea of an eye to be tested and an alignment control apparatus. The alignment control apparatus comprises a pair of alignment control systems disposed in a manner as to intersect the respective optical axes at one point on the central axis of the fluid ejection nozzle and to be symmetrical about the central axis. The alignment optical systems each include an index projection optical system for projecting an index spot light toward the cornea and an index detection system for forming a virtual image of the index spot light produced by means of corneal specular reflection from the eye on an observation system as an index image through a part of an index projection optical system of the other alignment optical system. Alignment control between the eye to be tested and the fluid ejection nozzle is determined by confirming a superposed relation of the pair of index images formed on the observation system.