| 摘要 |
<p>A scanning keratometer for the rapid and accurate measurement and mapping of the corneal curvature is disclosed. The keratometer has a monochromatic light source directing light to a scanner, preferably controlled by a microcomputer. The scanner directs the light to a holographic element functioning as a lens which in turn focuses the light to a fixed focal point forward of the holographic element independent of the area of the holographic element being illuminated. The subject's eye is position with respect to the fixed focal point so that a part of the light incident to the eye is reflected from the surface thereof again passing through the holographic element, to be deflected from the main optical axis of the system to a suitable area sensor. Assuming the subject's eye is properly positioned and the cornea surface matches the shape of an ideal cornea, the light incident to the cornea will be reflected in the same direction as the incident light, ultimately impinging on the center of the sensor. If, on the other hand, the local area of the cornea being illuminated is not matching, the light reflected from the cornea will be at an angle with respect to the incident light, ultimately impinging on the sensor at a position dependent upon the shape of the local area of the cornea then being illuminated. Various methods of eye positioning, scanning and other aspect of the system are disclosed.</p> |
