Recently, multi-layer surface profiling and inspection has been considered an emerging topic that can be used to solve various manufacturing inspection problems, such as graded index lenses, TSV (Thru-Silicon Via), and optical coating. In our study, we proposed a gated wavefront sensing approach to estimate the multi-layer surface profile. In this paper, we set up an experimental platform to validate our theoretical models and methods. Our test bed consists of pulse laser, collimator, prism, well-defined focusing lens, testing specimen, and gated wavefront sensing assembly (e.g., lenslet and gated camera). Typical wavefront measurement steps are carried out for the gated system, except the reflectance is timed against its time of flight as well as its intensity profile. By synchronizing the laser pulses to the camera gate time, it is possible to discriminate a multi-layer wavefront from its neighbouring discrete layer reflections.

Date Published: 7 January 2015
PDF: 6 pages
Proc. SPIE 9442, Optics and Measurement Conference 2014, 94421K (7 January 2015); doi: 10.1117/12.2176174

Published in SPIE Proceedings Vol. 9442:
Optics and Measurement Conference 2014
Jana Kovačičinová; Tomáš Vít, Editor(s)