Null Hartmann screen for measuring the spherical aberration in a plane-convex lens.
Author(s): M. Avendaño-Alejo, D. M. González-Utrera, V. I. Moreno-Oliva and R. Díaz-Uribe.
Affiliation(s): Universidad Nacional Autónoma de México, Centro de Ciencias Aplicadas y Desarrollo Tecnológico
Topic: 1. Interferometry & Optical Testing Techniques
Traditionally the Hartmann test uses a screen with a uniform distribution of holes which produces a non-uniform distribution of bright spots at the detection plane. For a lens, it is well know that the transverse spherical aberration depends on the refractive index, the radii of curvature, the object distance, and the ray height . We consider that the object point is at infinity so that the incident rays are parallel to the optical axis, in this way we can calculate the caustic surface for the refracted rays through the lens under test. In this work we design a Hartmann-test like screen in such a way that we have a uniform distribution of bright spots of the same size spots; that is what we called a null Hartmann screen. The design of this screen is based on the knowledge of the caustic surface. This design is intended to make straightforward the detection of the spots for the measurement of the spherical aberration of the lens. Acknowledgments: This work has been partially supported by PAPIIT-UNAM projects IN119508 and 114507-2  F. A. Jenkins and H. E. White, Fundamentals of Optics, 4th, (Mc Graw Hill, 1976), Chap. 9.