Digital holographic microscope with automatic focus tracking by detecting sample displacement in real time.
We propose a new method for focus tracking during the recording of a sequence of digital holograms while the sample experiences axial displacement. Corrected reconstruction distances can be automatically calculated, and well-focused amplitude and phase-contrast images can be obtained for each digitized hologram. The method is demonstrated for inspection of microelectromechanical systems subjected to thermal load. The method can be applied as a quasi-real-time procedure.
Ferraro
Pietro
P
Istituto per la Microelettronica e Microsistemi del Consigilio Nazionale delle Ricerche, Via P. Castellino 111 80134 Naples, Italy. p.ferraro@cib.na.cnr.it
Coppola
Giuseppe
G
De Nicola
Sergio
S
Finizio
Andrea
A
Pierattini
Giovanni
G