The plasma mirror - A subpicosecond optical switch for ultrahigh power lasers

Plasma mirrors are devices capable of switching very high laser powers on subpicosecond time scales with a dynamic range of 20–30 dB. A detailed study of their performance in the near-field of the laser beam is presented, a setup relevant to improving the pulse contrast of modern ultrahigh power lasers ~TW–PW!. The conditions under which high reflectivity can be achieved and focusability of the reflected beam retained are identified. At higher intensities a region of high specular reflectivity with rapidly decreasing focusability was observed, suggesting that specular reflectivity alone is not an adequate guide to the ideal range of plasma mirror operation. It was found that to achieve high reflectivity with negligible phasefront distortion of the reflected beam the inequality csDt,lLaser must be met (cs : sound speed, Dt: time from plasma formation to the peak of the pulse!. The achievable contrast enhancement is given by the ratio of plasma mirror reflectivity to cold reflectivity.

The Sound of Becoming: Moving Towards a Virtual Music

In 1985 Jacques Attali proposed a new modality for music. He suggests that there be “not a new music, but a new way of making music... a radically new form of the insertion of music into communication” (Attali 134). What Attali foretold has become a firm reality in contemporary musical practice. One has only to look at any current musical activity to encounter work that relies heavily on real-time interaction and dynamic generation and/or modification of materials. But why is this ontologically different ‘mode of essentially interactive and transformative existence’ (Ziarek 195), this ‘new way of making music’, so attractive to contemporary artists? What is motivating artists to abandon a production model in favor of a model of real-time interactive exploration? I will argue that at the foundation of this new artistic ontology lies Deleuze’s concept of the virtual. It is a recognition of the virtual power of music, that music making can be an act of invention, a process where one can discover something never before experienced.