For digital holographic microscopy applications, we modify the focus criterion based on the integration of the amplitude modulus to make possible its use regardless of the phase or amplitude nature of the objects under test. When applied on holographic data, the original criterion gives, at the focus plane, a minimum or a maximum, for amplitude or phase objects. The criterion we propose here operates on high-pass filtered complex amplitudes. It is shown that the proposed criterion gives a minimum for both types of objects when the focus plane is reached. Experimental results on real samples and simulations are provided, illustrating the efficiency and the potential of the method.
© 2014 Optical Society of America
Original Manuscript: March 28, 2014
Revised Manuscript: June 10, 2014
Manuscript Accepted: June 10, 2014
Published: July 16, 2014
Frank Dubois, Ahmed El Mallahi, Jérôme Dohet-Eraly, and Catherine Yourassowsky, "Refocus criterion for both phase and amplitude objects in digital holographic microscopy," Opt. Lett. 39, 4286-4289 (2014)