Silicon infrared diffuser for wireless communication.
We show what we believe to be a novel way to use silicon in infrared radio communication as a suitable material for the realization of optical diffusers in the range of 850-1600 nm. A crystalline silicon wafer is made porous by means of electrochemical etching. The porous silicon produced is optically characterized, and measurements report a high reflectance in the band of interest. We also study the angular distribution of diffused radiation by the porous silicon surface at different angles of incident radiation. Measurements show that radiation diffuses in a quasi-Lambertian manner, confirming the good performance of this material as an incident radiation diffuser.
Integrating-sphere diffuser for wireless infrared communication
The application of an integrating sphere (IS) as a diffuser in a wireless infrared (IR) network is investigated. Going beyond the simplified analytical model, it is shown that ray-tracing simulations provide realistic data for the optical insertion loss: the transfer function and the far-field light distribution. As an example, a sphere diffuser for a 155 Mbit/s 16-PPM IR transmitter is investigated with an insertion loss of 0.66 dB, a cutoff frequency of 570 MHz and a 104/spl deg/ full width at half-maximum (FWHM) angle of the intensity distribution. The device has also been manufactured using a proprietary material and good agreement between simulation and experimental data is found. A method to increase the FWHM angle and some aspects of eye safety are discussed.
Heritage Sites of Astronomy and Archaeoastronomy in the context of the UNESCO World Heritage Convention: A Thematic Study
"Following the publication of the first ICOMOS–IAU Thematic Study (“TS1”) in 2010, the IAU requested its Working Group on Astronomy and World Heritage to develop particular case studies in greater detail, so as to explore further and clarify some of the key issues highlighted in TS1 that can arise in the particular case of astronomical heritage sites. In doing so, it would further encourage and aid State Parties in the development of nominations. In collaboration with ICOMOS, nine “extended case studies” were duly prepared for discussion at a workshop held at Mount Cook, New Zealand, in June 2012 and presented at the IAU General Assembly in August of that year. 
 
A particularly complex issue is the recognition and protection of dark skies. Dark sky areas cannot in themselves be considered as potential World Heritage Sites, but a thematic chapter by Michel Cotte considers a range of ways in which dark sky values can be interrelated with broader cultural or natural values of a place and thereby contribute to its overall cultural or natural value and potential OUV. Other issues explored in TS2 include the need to balance archaeoastronomical considerations in the context of broader archaeological and cultural values; the potential for serial nominations, for example among groups of monuments whose astronomical significance is only evident from the group as a whole; and management issues such as preserving the integrity of astronomical sightlines through the landscape. 
 
The case studies included in TS2 include seven-stone antas (prehistoric dolmens) in Portugal and Spain, the thirteen towers of Chankillo in Peru, the astronomical timing of irrigation in Oman, Pic du Midi de Bigorre Observatory in France, Baikonur Cosmodrome in Kazakhstan, and Aoraki–Mackenzie International Dark Sky Reserve in New Zealand. A case study on Stonehenge, already a World Heritage Site, focuses on preserving the integrity of the solstitial sightlines." 
 
Source: UNESCO portal to the heritage of astronomy