Eye-refractometer device

Claim 1

An eye-refractometer device for measuring the refractive power of an eye to be examined comprising: a first beam splitter; a second beam splitter disposed on that side of said first beam splitter which is adjacent to the eye; a projection optical system provided in one light path of said first beam splitter for projecting a slit-like light beam into the pupil of an eye to be examined by way of said first beam splitter and scanning said slit-like light beam in a direction perpendicular to the lengthwise direction of said slit-like beam; a condenser optical system provided in the other light path of said first beam splitter for receiving the reflected light from the retina of said eye by way of said first beam splitter, said condenser optical system including a fixed condenser lens, a diaphragm member fixedly disposed substantially at a focus position of said condenser lens, and a light-receiving member fixedly disposed rearwardly of said diaphragm member, said diaphragm member having a slit-like opening parallel to the lengthwise direction of said projected slit-like beam, and said light receiving member having two light-receiving elements fixedly disposed off the optic axis of said condenser lens and symmetrical with respect to the optic axis in a direction coincident with the scanning direction of said slit-like beam; a signal processing system for processing the signal from said light-receiving member and having phase difference detecting means for detecting the phase difference between the output signals from said two light-receiving elements and having averaging means for generating the average value signal of the plurality of signals from said phase difference detecting means; a target optical system for directing the target light to the eye by way of said second beam splitter; and light beam rotating means disposed between said first beam splitter and said second beam splitter for rotating said light beam about the center of the light path, whereby the scanning direction of the slit-like light beam supplied by said projection optical system is rotated at the eye by means of said light beam rotating means, while the scanning direction of the slit-like beam which is reflected by the fundus of the eye, passes again through said light beam rotating means and reaches said condenser optical system, is kept constant without being subject to the rotation by said light beam rotating means, and whereby all members constituting said condenser optical system are kept fixed and no servo system is needed, thus precise and quick refractive power of the eye being measured.