B8.3 - Simultaneous Measurement of Thickness and Refractive Index by Chromatic Confocal Coherence Tomography (CCCT)
- Event
- AMA Conferences 2017
2017-05-30 - 2017-06-01
Nürnberg, Germany - Band
- Proceedings Sensor 2017
- Chapter
- B8 - Optical Measurement Systems II
- Author(s)
- T. Boettcher, M. Gronle, W. Osten - ITO, Universität Stuttgart (Germany)
- Pages
- 294 - 296
- DOI
- 10.5162/sensor2017/B8.3
- ISBN
- 978-3-9816876-4-4
- Price
- free
Abstract
One of the main problems for optical inspection in precision manufacturing is to handle unknown layers on the specimen correctly, especially to achieve the goal of high-resolution topography measurement of underlying surfaces without prior cleaning. We introduce a new hybrid scheme for simultaneous measurement of thickness and refractive index of layered specimens. Confocal systems underestimate the layer’s thickness depending on the refractive index, while interferometers evaluate the optical path length, which is an overestimation due to the refractive index of the material. By a combination of a chromatic confocal and an interferometric channel, it is possible to measure topography trough contamination layers without prior knowledge in a single shot. In this contribution, theoretic background and evaluation strategies are discussed as well as the possible range of
applications.