Axial-resolution in depth from focus digital holography

van Rooij, J.; Kalkman, J.

doi:10.1117/12.2270295

Axial-resolution in depth from focus digital holography

Title

Axial-resolution in depth from focus digital holography

Author

van Rooij, J. (TU Delft ImPhys/Quantitative Imaging)
Kalkman, J. (TU Delft ImPhys/Quantitative Imaging)

Contributor

Kress, Bernard C. (editor)
Osten, Wolfgang (editor)
Urbach, H. Paul (editor)

Date

2017

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.

Subject

Digital holography
metrology
Talbot effect
depth from focus

To reference this document use:

http://resolver.tudelft.nl/uuid:b37ac3df-c086-4a8c-8700-cf1554c48786

DOI

https://doi.org/10.1117/12.2270295

Publisher

SPIE

ISBN

978-1-5106-1115-3

Source

Digital Optical Technologies 2017