from 28 June 2015 to 3 July 2015 (Africa/Johannesburg)
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SAIP2015 Proceeding published on 17 July 2016
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An Integrated Software Based Analytical Model for the Signal Path Efficiency of the HartRAO Lunar Laser Ranger Optical System

Presented by Mr. Sphumelele NDLOVU on 2 Jul 2015 from 11:50 to 12:10
Type: Oral Presentation
Session: Space
Track: Track D2 - Space Science


The Lunar Laser Ranger (LLR) system under development at HartRAO will accurately measure the Earth-Moon distance by the use of laser pulses. We would like to ensure that the transmitted pulses reaches the retro-reflectors located on the Moon and a signal is returned to the Earth-fixed receiving telescope. We start by discussing the hardware components and software used in HartRAO’s LLR system to achieve optimal signal path efficiency. This includes thorough descriptions of the laser source, optical components used throughout the coudé path, atmospheric transmission efficiency and retro-reflector’s optimal reflectance value. The use of the link budget equation in this work estimates the number of photons that are expected to be received; this result has a direct relationship with total system efficiency. An integrated model for HartRAO’s LLR is an essential tool to enable optimal signal path (optical and electrical) efficiency and is useful in estimating the expected number of photon returns for given observational parameters. An improved system will reduce adverse effects (beam divergence) on the transmitted laser beam that result from atmospheric thermal and density fluctuations. Adverse effects cannot be easily minimised, therefore the software based analytical model for HartRAO’s LLR will enable evaluation of specific portions of the receive and transmit path, as well as certain atmospheric parameters. This will lead to an understanding of the effects of the numerous variables on the total system efficiency.






Prof Ludwig Combrinck





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