Keratoscope, Cornea, Surface
Monday, September 11, 2006
A Keratoscope has been designed and developed that provides minimum sensitivity to instrument misalignment relative to the eye. The design configuration provides for the measuring of the entire corneal surface simultaneously (FOV angle 160°).
A collimator is combined as a lens and conic mirror to provide cornea illumination. The optical axes of the lens and the conic mirror are coincident. The radius of the meniscus concave surface is chosen to coincide with the focal surface of the lens. Part of each light beam of the parallel rays falls directly on the cornea. Other parts of the light beam are reflections from the conic mirror.
The Keratoscope uses a telecentric optical system. The aperture stop center is placed at the lens focus. The projecting lens is placed near the aperture stop. The chief rays of the light beam reflected from the cornea are parallel to the optical axis in the space between the cornea and the collimator lens. This provides an image independence of the lateral and longitudinal misalignments of the cornea. If any eye misalignments occur, the virtual image formed by the reflecting cornea image is motionless relative to the corneal surface and is also undistorted.
Source: “New Keratoscope Optical System”, by A. V. Laskin and D. T. Puryayev, Optics & Laser Technology, Vol 27, No 3, 1995; A. V. Laskin and D. T. Puryayev, Moscow Bauman State Technical University, 2-ya Baumanskaya st., 5, 107005, Moscow, Russia
Reference:
1) US Patent Numbers: 3797921, 4569576, 4666269, and 4863260
2) Russian Patent Numbers: 1292727, 1337042, 1397021, and 1762894
Industrial Products
posted by JD52 @ 7:26 PM,
