A microprism array as shearing device for speckle shearing interferometry

In most speckle shearing interferometers image shearing is performed by means of a Michelson interferometer or by means of a wedge prism covering half of the aperture of the camera objective. We present a speckle shearing interferometer which utilizes a microprism array for this purpose. It is placed between the test specimen and the camera. In comparision with a wedge prism it exhibits some advantages: it needs no exact alignment, it works with any camera lens, the shearing distance and direction of shearing can be easily changed by changing position (resp. angular orientation) of the element. Phase stepping for computer evaluation of the speckle shearing interferograms is performed by the translation of the shearing element. A special translation stage was developed. Experimental results are presented. The interferometer is suited for microcomponent and microsystem testing.     

Microprism for Wide-Angle Low-Loss Y-Junction Waveguide

A wide-angle low-loss Y-branch waveguide with butterfly-shaped microprisms is designed. The microprisms not only compensate the phase difference but enhance the mode-conversion evolution in the branching region. Simulation results predict that a mode separation with low branching losses can be achieved in the wide-angle Y-branch. The transmitted power efficiency can be as high as 89 % for the branching angle up to 20 .