Abstract
We use digital holography to quantify surface topography of rough objects in full-field. We calculate the variance of the intensity image as a focus metric over a set of reconstruction distances for each pixel, which results in a focus metric curve. The distance where the variance peaks is an estimate for the depth. First we analyze the lateral resolution of this method using the Talbot effect and argue that sub-mm axial resolution is feasible. Then, using a Michelson setup without magnifying optics or lateral scanning we experimentally demonstrate that sub-mm FWHM width of the focus curve can be achieved. This is significantly better than what was previously reported using digital holography and could make this technique useful for characterising objects in art and machine vision.
Original language | English |
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Title of host publication | Digital Optical Technologies 2017 |
Editors | Bernard C. Kress, Wolfgang Osten, H. Paul Urbach |
Publisher | SPIE |
Number of pages | 7 |
ISBN (Print) | 978-1-5106-1115-3 |
DOIs | |
Publication status | Published - 2017 |
Event | SPIE Digital Optical Technologies 2017 - Internationales Congress Center Munich, Munich, Germany Duration: 25 Jun 2017 → 29 Jun 2017 https://spie.org/about-spie/press-room/-spie-digital-optical-technologies-2017-news-and-photos |
Publication series
Name | Proceedings of SPIE |
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Volume | 10335 |
ISSN (Electronic) | 1605-7422 |
Conference
Conference | SPIE Digital Optical Technologies 2017 |
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Country/Territory | Germany |
City | Munich |
Period | 25/06/17 → 29/06/17 |
Internet address |
Keywords
- Digital holography
- metrology
- Talbot effect
- depth from focus