Efficiency measurements for a digital-holography system

摘要

This paper compares efficiency measurements to predictions for a digital-holography system operating in the off-axis image plane recording geometry. We use a highly coherent 532 nm laser source, an extended Spectralon object, and an Si focal-plane array to perform digital-holographic detection, which provides access to an estimate of the complex-optical field and is of utility to long-range imaging applications. In the experiments, digital-holographic detection results from the interference of a signal beam with a reference beam. The signal beam was created from the active illumination of the extended Spectralon object and the reference beam from a local oscillator which is split off from the master-oscillator 532 nm laser source. To compare efficiency measurements to predictions, an expression was developed for the signal-to-noise ratio, which contains many multiplicative terms with respect to total-system efficiency. In the best case, the measured total efficiency was 15.2% ± 5.8% as compared to the predicted 16.4%. The results show that the polarization and the fringe-integration efficiency terms play the largest role in the total-system efficiency.