Resolution enhancement of tomographic images using the row action projection method.

The row action projection (RAP) method is used to increase the spatial resolution of images reconstructed via the filtered back projection (FBP) algorithm. An implementation of RAP is introduced which is computationally efficient and facilitates local adaptation of the projection operators. The local mean value as well as minimum and maximum bounds are used as constraints. The method is proposed to provide zoom-in capability, which yields a high-resolution estimate of a specified region of the image. Computer simulations demonstrate the new method to be very effective in recovering high-order spectral components of designated regions of the reconstructed image.

3-D corneal modeling system.

New surgical procedures have been introduced recently that provide refractive correction to replace the use of eyeglasses or contact lenses. The procedures involve reshaping the cornea to compensate for the optical anomalies of astigmatism and nearsightedness. Although thousands of operations are currently performed in the U.S., there are no instruments available for monitoring the results. Thus, a critical need has arisen to inspect and measure the cornea's surface both before and after surgery. In this paper an instrument is presented which provides a detailed topographical model of an individual's cornea. The method uses a novel structured light source. The cornea is modeled as a convex mirror which forms a virtual image of the structured light source. A single image is recorded from the patient's cornea. The depth is obtained from triangulation between the acquired image and a reference image of a sphere. The reconstruction of the depth map is complicated by the fact that the magnification used in recording the image varies with the radius of curvature of the cornea. An iterative method is presented which solves for the radius of curvature despite the variation in magnification. The virtual image is digitized and the instantaneous curvature of the cornea is obtained. The instantaneous curvature is displayed in units of optical power (diopters). This display provides the ophthalmologist or optometrist with the essential optical properties of the cornea.

Improving material properties by a simple gas-treatment procedure.

A simple, easy-to-use, room-temperature gas-treatment procedure improves the surface and bulk physical, chemical, and electrical properties of materials in a number of applications. Water wettability and a number of dielectric properties of various polymers, thin metal films, and porous carbon-based cathodes can be markedly changed by exposure for a few minutes to this gas treatment. This inexpensive technique can be used to chemically modify surface, and even bulk, electrical and physical properties of materials. These changes can then improve device performance. The technique can be easily inserted into ordinary manufacturing procedures.