<title>Measuring atmospheric dispersion employing avalanche photodiodes</title>

Abstract

The accuracy of today's satellite laser ranging systems (SLR) is limited to a few cm. A significant part of this range error is due to the limitations of the atmospheric correction model. A dual color ranging experiment has been designed to investigate this source of error. When ranging to satellites at the fundamental and second harmonic frequency of a Nd:YAG laser, two different pulse round trip times are obtained simultaneously. The infrared pulse is detected by an avalanche photodiode, operated in the "Geiger mode" , while the green pulse is recorded by a microchannel plate photomultiplier (MCP).For a given satellite pass, the jitter in recording the time of flight of the pulse is too high to calculate an atmospheric correction from individual measurements. Due to the many shots per satellite pass, the scatter can be significantly reduced by applying a nonlinear least squares fitting procedure to the data. The results of a large number of satellite passes are compared with the predictions of the Marini-Murray model.

<title>Dual color modulo satellite ranging operating a synchro scan streak camera</title>

“…2581 /29 whereas target scatter does not. The wavelength dependence of phase fluctuations is given in Strohbehn [6] Ds(p) = 1.46Ck2Lp, (4) where Cn denotes the refractive index structure constant, k the wavenumber, L the propagation distance and p corresponds to the separation between two points where the phase is evaluated. Since Ds is proportional to the square of the wavenumber one should find a dependence on wavelength when detecting infrared and green satellite echos.…”

“…There have been several attempts [4] [2] [1] to utilize streak cameras in satellite laser ranging in order to derive the atmospheric correction. As their time resolution can be pushed beyond 1 ps, these devices seem to offer a good approach to improve the accuracy of laser ranging instrumentation.…”