New null screen design for corneal topography

Manuel Campos-García; Amilcar Estrada-Molina; Rufino Díaz-Uribe

doi:10.1117/12.903397

25 October 2011 New null screen design for corneal topography

Manuel Campos-García, Amilcar Estrada-Molina, Rufino Díaz-Uribe

Proceedings Volume 8011, 22nd Congress of the International Commission for Optics: Light for the Development of the World; 801124 (2011) https://doi.org/10.1117/12.903397
Event: International Commission for Optics (ICO 22), 2011, Puebla, Mexico

Abstract

In this work we report the design of a null screen for corneal topography. Here we assume that the corneal surface is an ellipsoid with a diameter of 12 mm and a curvature radius of 7.8 mm. To avoid the difficulties in the alignment of the test system due to the face contour (eyebrows, nose, or eyelids), we design a conical null-screen with spots (similar to ellipses) drawn on it in such a way that its image, which is formed by reflection on the test surface, becomes an exact radial array of circular spots if the surface is perfect. Additionally, we performed a numerical simulation introducing Gaussian random errors in the coordinates of the centroids of the spots on the image plane, and in the coordinates of the sources (spots on the null-screen) in order to obtain the conical null-screen that reduces the error in the evaluation of the topography.

Citation Download Citation

Manuel Campos-García, Amilcar Estrada-Molina, and Rufino Díaz-Uribe "New null screen design for corneal topography", Proc. SPIE 8011, 22nd Congress of the International Commission for Optics: Light for the Development of the World, 801124 (25 October 2011); https://doi.org/10.1117/12.903397

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