Heterodyne readout system for dual plate speckle photography: analysis of error sources and performance evaluation.

We describe the design, construction, and testing of a dual plate specklegram heterodyne readout system. The choice of the optical layout and mode of operation is based on the results of a detailed discussion on the sources of error associated both with optical noise and misalignments. Noise analysis includes the conventional scintillation noise and a recently described additional source, the speckle grain noise. Stability and reproducibility tests have been conducted and the accuracy of displacement measurement is 10(-6) of the recorded specklegram size, approximately five times worse than the ultimate noise limited value.