Digital holographic testing of the optical fiber at welding area

A method to analyse of optical fibers inhomogeneity in welding junction using digital holography is proposed. The method utilizes lens-less Gabor scheme for recording of a digital hologram with numerical reconstruction by angular spectrum approach. Qualitative image analysis applied on the intensity distribution of specimen after hologram reconstruction enables to evaluate the structural defects inside the fiber core and cladding after welding procedure, which are not observable with conventional microscopy. The possibilities of the presented method were tested on an optical fiber with axial displacement in the welded area. A compact digital holographic recording installation for express and reliable analysis of optical fiber was also developed. It is shown how the axial displacement of the welding fibers leads to a change in the intensity distribution around the joint in the reconstructed image.