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Proceedings Paper

Dynamic point shifting in null screen videokeratometry
Author(s): M. I. Rodríguez-Rodríguez; A. Jaramillo Núñez; R. Díaz Uribe
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Paper Abstract

For obtaining the shape of the corneal surface through the Null Screen method, a numeric integration procedure must be carried out; perhaps, the simplest integration method is the trapezoid rule. This method, however, is limited by the truncation error. It has been shown previously [1-6] that the point shifting method allows the reduction of this error by adding many more evaluation points so reducing the average spacing between evaluation points. To do so, an array of LCD's must be used to display the moving Null Screen. In this paper we propose to use three LCD forming a triangular prism, instead of a cylindrical Null Screen [3] for measuring the shape of the human corneas. The null screen design will be described and some experimental results obtained with calibration spheres used to simulate the corneal surface will be presented.

Paper Details

Date Published: 3 November 2011
PDF: 8 pages
Proc. SPIE 8011, 22nd Congress of the International Commission for Optics: Light for the Development of the World, 80119H (3 November 2011); doi: 10.1117/12.903320
Show Author Affiliations
M. I. Rodríguez-Rodríguez, Instituto Nacional de Astrofísica, Óptica y Electrónica (Mexico)
Univ. Nacional Autónoma de México (Mexico)
A. Jaramillo Núñez, Instituto Nacional de Astrofísica, Óptica y Electrónica (Mexico)
R. Díaz Uribe, Univ. Nacional Autónoma de México (Mexico)


Published in SPIE Proceedings Vol. 8011:
22nd Congress of the International Commission for Optics: Light for the Development of the World

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