Autofocusing method for tilted image plane detection in digital holographic microscopy

作者：Kostencka Julianna^*; Kozacki Tomasz; Lizewski Kamil

来源：Optics Communications, 2013, 297: 20-26.

DOI：10.1016/j.optcom.2013.01.078

• Autofocusing to a tilted plane
• Numerical propagation between tilted planes
• Digital holography
• Digital holographic microscopy
• Focus evaluation algorithms

A rapid autofocusing technique is a fundamental element for a vast range of applications of digital holography. In this paper we propose a new autofocusing method that permits to detect a tilted optimal focus plane. The method is based on estimation of focusing condition of the optical field by evaluating the sharpness in its amplitude distribution. The developed algorithm is fully automated. It consists of two major steps, first the rotation axis is localized from the map of local sharpness and then the angular orientation of the image plane is derived by maximizing the focus of optical fields reconstructed in many subsequent tilted planes. In our study six image sharpness quantification methods are investigated and the numerical propagation between inclined planes is performed with an efficient band limited angular spectrum algorithm. The utility of the proposed method for autofocusing to a tilted image plane is experimentally confirmed in a digital holographic microscopy setup by carrying out a successful reconstruction of holograms of the exemplary amplitude (the 1951 USAF positive target) and phase (a matrix of microlenses) objects.

• 出版日期2013-6-15