Detection of optical targets using laser illumination has become an increasingly valuable military tool. In order to better understand typical detection scenarios for a laser illumination system and to improve target detection performance, intensity probability density functions of retroreflected near-infrared laser light were experimentally measured over a near-ground line-of-sight optical path. Returns from a corner cube and a simple lens-mirror system were recorded under a variety of atmospheric conditions, as measured by changes in the refractive-index structure parameter C 2 n . In addition to its applicability to target detection, this work is relevant to atmospheric propagation research and to free-space laser communication studies.

Abstract. Bunch length is of prime importance to beam driven plasma wakefield acceleration experiments due to its inverse relationship to the amplitude of the accelerating wake. We present here a summary of work done by the E167 collaboration measuring the SLAC ultra-short bunches via autocorrelation of coherent transition radiation. We have studied material transmission properties and improved our autocorrelation traces using materials with better spectral characteristics.

The E163 laser acceleration experiments conducted at SLAC have stringent requirements on the temporal properties of two regeneratively amplified, 800nm, Spitfire laser systems. To determine the magnitude and cause of timing instabilities between the two Ti:Sapphire amplifiers, we pass the two beams through a crosscorrelator and focus the combined beam onto a Hamamatsu G1117 photodiode. The photodiode has a bandgap such that single photon processes are suppressed and only the second order, two-photon process produces an observable response. The response is proportional to the square of the intensity. The diode is also useful as a diagnostic to determine the optimal configuration of the compression cavity.

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