Ophthalmic measurement apparatus
AssigneeKowa Company, Ltd.
InventorsTadashi Ichihashi, Koichi Akiyama
Life of this patent
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Abstract
An ophthalmic measurement apparatus is provided in which a laser beam is converged at a selected point in a measurement zone within an eye and light scattered therefrom is photoelectrically detected via a measurement mask having an aperture of a prescribed size for ophthalmic measurement. During alignment the measurement zone is scanned at high speed by the laser beam with the same scanning width as the scanning width used during measurement. This makes it possible to observe any harmful light rays that will actually appear during measurement at those settings and to align the apparatus so that the harmful light rays do not come within the limiting aperture of the measurement mask, thereby enabling measurement to be conducted under optimum conditions.
Claims15
An ophthalmic measurement apparatus in which a laser beam is projected at a selected point in a measurement zone within an eye to be examined and light scattered therefrom is photoelectrically detected for ophthalmic measurement, comprising:
- a laser source for producing a laser beam;
- projecting means for projecting the laser beam to converge it to the point in the measurement zone;
- a light receiving section provided with a photosensor for photoelectrically detecting scattered laser light from the measurement zone via a measurement mask having an aperture of a prescribed size and positioned conjugate with the point of convergence of the laser beam;
- deflecting means for deflecting the laser beam in a prescribed direction for scanning the area of the measurement zone during alignment of the eye and during measurement;
- processing means for processing signals received from the light receiving section to perform the ophthalmic measurement;
- and
- arranging means for arranging an alignment index at a position that is conjugate with the measurement mask so that during alignment an image of the alignment index appears superimposed on an image of the measurement zone formed at the aperture of the measurement mask;
- wherein during alignment the measurement zone is scanned at high speed by the laser beam having the same scanning width as the scanning width used during measurement.
An ophthalmic measurement apparatus in which a laser beam is projected at a selected point in a measurement zone within an eye to be examined and light scattered therefrom is photoelectrically detected for ophthalmic measurement, comprising:
- means for converging the laser beam to the selected point in the measurement zone;
- receiving means for detecting the scattered light via a measurement mask having an aperture and disposed at a position that is conjugate with the selected point;
- deflecting means for deflecting the laser beam for scanning an area of the measurement zone during alignment of the eye and during measurement, the deflecting means including means for scanning the measurement zone during alignment of the eye at high speed and having a same scanning width as a scanning width used during measurement;
- and means for arranging an alignment index at a position that is conjugate with the measurement mask so that an image of the alignment index appears superimposed on an image of the measurement zone formed at the aperture of the measurement mask during alignment of the eye.
Dependencies are inferred from the claim text.