A step-frequency fault locator was constructed as a new diagnostic tool for integrated optics devices. The wavelength of the light was swept stepwise from 1.5 to 1.6 μm in steps less than 1 nm. The image of the target was processed using a neural network algorithm. Detailed comparisons between the results using the neural network algorithm and FFT algorithm have been presented. Obtained resolution
was of the order of microns. The overall dimensions were reduced to 7 x l0 x 2 in. by replacing bulk optic elements with fiber-optic elements.