Heterodyning time resolution boosting for velocimetry and reflectivity measurements

David J. Erskine

doi:10.1117/12.582723

17 March 2005 Heterodyning time resolution boosting for velocimetry and reflectivity measurements

David J. Erskine

Proceedings Volume 5580, 26th International Congress on High-Speed Photography and Photonics; (2005) https://doi.org/10.1117/12.582723
Event: 26th International Congress on High-Speed Photography and Photonics, 2004, Alexandria, Virginia, United States

Abstract

A theoretical technique is described for boosting the temporal resolving power by several times, of detectors such as streak cameras in experiments that measure light reflected from or transmitted through a target, including velocity interferometer (VISAR) measurements. This is a means of effectively increasing the number of resolvable time bins in a streak camera record past the limit imposed by input slit width and blur on the output phosphor screen. The illumination intensity is modulated sinusoidally at a frequency similar to the limiting time response of the detector. A heterodyning effect beats the high frequency science signal down a lower frequency beat signal, which is recorded together with the conventional science signal. Using 3 separate illuminating channels having different phases, the beat term is separated algebraically from the conventional signal. By numerically reversing the heterodyning, and combining with the ordinary signal, the science signal can be reconstructed to better effective time resolution than the detector used alone. The effective time resolution can be approximately halved for a single modulation frequency, and further decreased inversely proportional to the number of independent modulation frequencies employed.

Citation Download Citation

David J. Erskine "Heterodyning time resolution boosting for velocimetry and reflectivity measurements", Proc. SPIE 5580, 26th International Congress on High-Speed Photography and Photonics, (17 March 2005); https://doi.org/10.1117/12.582723

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