24 September 2015 Advances in corneal topography measurements with conical null-screens
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In this work we report the design of a null-screen for corneal topography. 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 a novel radial points distribution drawn on it in such a way that its image, which is formed by reflection on the test surface, becomes an exact array of circular spots if the surface is perfect. Additionally, an algorithm to compute the sagittal and meridional radii of curvature for the corneal surface is presented. The sagittal radius is obtained from the surface normal, and the meridional radius is calculated from a function fitted to the derivative of the sagittal curvature by using the surfacenormals raw data. Experimental results for the testing a calibration spherical surface are shown. Also, we perform some corneal topography measurements.
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Manuel Campos-García, Manuel Campos-García, Cesar Cossio-Guerrero, Cesar Cossio-Guerrero, Oliver Huerta-Carranza, Oliver Huerta-Carranza, Víctor Iván Moreno-Oliva, Víctor Iván Moreno-Oliva, } "Advances in corneal topography measurements with conical null-screens", Proc. SPIE 9628, Optical Systems Design 2015: Optical Fabrication, Testing, and Metrology V, 96281B (24 September 2015); doi: 10.1117/12.2192137; https://doi.org/10.1117/12.2192137


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