Nonmechanical parfocal and autofocus features based on wave propagation distribution in lensfree holographic microscopy

authored by
Agus Budi Dharmawan, Shinta Mariana, Gregor Scholz, Philipp Hörmann, Torben Schulze, Kuwat Triyana, Mayra Garcés-Schröder, Ingo Rustenbeck, Karsten Hiller, Hutomo Suryo Wasisto, Andreas Waag
Abstract

Performing long-term cell observations is a non-trivial task for conventional optical microscopy, since it is usually not compatible with environments of an incubator and its temperature and humidity requirements. Lensless holographic microscopy, being entirely based on semiconductor chips without lenses and without any moving parts, has proven to be a very interesting alternative to conventional microscopy. Here, we report on the integration of a computational parfocal feature, which operates based on wave propagation distribution analysis, to perform a fast autofocusing process. This unique non-mechanical focusing approach was implemented to keep the imaged object staying in-focus during continuous long-term and real-time recordings. A light-emitting diode (LED) combined with pinhole setup was used to realize a point light source, leading to a resolution down to 2.76 μm. Our approach delivers not only in-focus sharp images of dynamic cells, but also three-dimensional (3D) information on their (x, y, z)-positions. System reliability tests were conducted inside a sealed incubator to monitor cultures of three different biological living cells (i.e., MIN6, neuroblastoma (SH-SY5Y), and Prorocentrum minimum). Altogether, this autofocusing framework enables new opportunities for highly integrated microscopic imaging and dynamic tracking of moving objects in harsh environments with large sample areas.

External Organisation(s)
Technische Universität Braunschweig
Tarumanagara University
Gadjah Mada University
Type
Article
Journal
Scientific reports
Volume
11
ISSN
2045-2322
Publication date
05.02.2021
Publication status
Published
Peer reviewed
Yes
ASJC Scopus subject areas
General
Electronic version(s)
https://doi.org/10.1038/s41598-021-81098-7 (Access: Open)