Laser-induced diffraction patterns in germanium diselenide amorphous films.
We report the characterization of changes produced on germanium diselenide amorphous semiconductor thin films by a focused He-Ne laser beam. The diffraction pattern produced by the laser spot on the sample is studied as a function of the intensity and the irradiation time. At low intensities the state of polarization of the incident beam generates an asymmetry in the induced diffraction pattern. Moreover, if the polarization of the incident beam is rotated, the corresponding asymmetry rotates as well. These results show the difference between thermal and electromagnetic effects on the material. This system may be used as a high density recording medium.
Photodarkening and light induced anisotropy in chalcogenide glasses
Abstract A unified description of photodarkening and light induced anisotropy in chalcogenide glasses is presented in terms of bistable atomic configurations
Geography, Cartography and Military Intelligence: The Royal Geographical Society and the First World War
This essay examines the connections between geography, cartography and military intelligence in Britain during the First World War. It focuses on the Royal Geographical Society (RGS) and its wartime activities on behalf of the British intelligence service. Evidence is presented on the role of the RGS in the dispute between the so-called 'westerners', committed to an all-out clash with Germany on the western front, and the 'easterners', who argued that the key to deadlock in western Europe lay in the Ottoman Empire. For a short period, the RGS became a significant metropolitan focus for those advocating a British intervention in the Middle East coupled with an Arab revolt against the Turks, the campaign popularly associated with T E Lawrence. The essay concludes with an assessment of the significance of geography to the British war effort and an evaluation of the impact of the war on the institutions and prestige of the discipline. Some final comments are offered on the moral and ethical questions raised by the mobilization of geographical expertise in wartime.