Digital Holography Used for Shape Measurement of Microscopic Object

Digital holography is an emergent imaging technique which provides complete three-dimensional information of an object. An off-axis Fresnel digital holographic system with pre-magnification is built. The recording and numerical reconstruction of digital hologram is analyzed. Experimental investigations have been performed for a USAF test target. The focal plane is determined automatically by Fourier spectrum algorithm. The accurate phase image is obtained based on the automatic phase aberration compensation procedure. The lateral resolution with better than 1 and the axial resolution of no larger than 10 nm have been achieved experimentally. The results show that digital holography is very suited for imaging and measurement of microscopic object.