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Autre Publication Scientifique Année : 2014

Metrology of micro-optical components quality using direct measurement of 3D Intensity Point Spread Function

Résumé

High-resolution miniature imaging systems require high quality micro-optical elements. Therefore, it is essential to characterize their optical performances in order to optimize their fabrication. Usually, basic evaluation of micro-optical elements quality is based on the measurement of their topography since their optical properties are largely defined by their shape. However, optical characteristics have to be derived from the measured geometry using optical propagation algorithms. An alternative method is the direct measurement of their optical properties. Unlike topography measurement, it allows characterization of high numerical aperture components. Moreover, it can be applied to single elements but also to optical systems composed of several microlenses. The most popular method of direct optical measurement concerns the wavefront measurement that is complicated when it concerns micro-optical elements. In this work, we propose a simple method based on the measurement of the 3D intensity point spread function (IPSF). IPSF is defined by the 3D shape of the focal spot generated by the micro-element. The direct characterization of focusing response through the measurement of PSF allows very precise estimation of micro-structures quality. The considered method consists in imaging different slices of the focal volume generated by the focusing component. It is easier to implement than wavefront-based methods since it is less affected by probing beam quality and less demanding in terms of alignment accuracy. The employed setup is simple and requires only a microscope objective and a camera that are moved along the propagation axis. It allows, depending on the configuration, characterizing both transmissive and reflective micro-optical components. If additional data analysis is performed, the wavefront or the 3D topography can be calculated from the IPSF data. Moreover, the Strehl ratio and the radius of curvature of the optical element can be also calculated. Advantages of this technique are demonstrated on micro ball lenses and micro-mirrors.
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Dates et versions

hal-00982942 , version 1 (24-04-2014)

Identifiants

  • HAL Id : hal-00982942 , version 1

Citer

Stéphane Perrin, Maciej Baranski, Nicolas Passilly, Luc Froehly, Jorge Albero Silvestre, et al.. Metrology of micro-optical components quality using direct measurement of 3D Intensity Point Spread Function. 2014. ⟨hal-00982942⟩
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