Digital in-line holography for dynamic micro-metrology

Abstract

In this paper in-line digital holography has been explored for dynamic micro metrological applications. In in-line digital holography, full CCD sensor area is utilized for real image reconstruction of the objects with less speckle noise. Numerical evaluation of the amplitude and phase information during reconstruction process finds promising applications in optical micro-metrology. Vibration analysis of the smaller object has been performed by combining the time average principle with in-line digital holographic methods. A double exposure method has been explored for measurements, which is simultaneously used to suppress the overlapping of zero-order and twin image wave with real image wave. The vibration amplitude and mean static state deformation of the harmonically excited object are analysed separately from time average in-line digital holograms. The experimental results are presented for a thin aluminium membrane of 5mm diameter.