SCANNING AUDIENCES AT LASER SHOWS: THEORY AND PRACTICE

摘要

For more than three decades, the technique of "audience scanning" has been routinely used at laser light shows outside of the United States. Visible beams from continuous-wave lasers are projected towards viewers, to put them inside cones, fans and other moving light shapes set to music. Most commonly, irradiance levels have not been measured by operators; instead they have been set by eye to look "OK". Since MPE-level irradiance at the audience is somewhat dim, most shows have exceeded the MPE. Estimated irradiance levels range from 5-10 times the MPE, to 100 times or more.rnDespite this, there have been remarkably few proven or even claimed reports of injuries from deliberate audience scanning. A number of possible reasons are presented, including the greater distance to the audience (e.g., wider beam), the use of moving beams, and viewers who actively take action to reduce exposure. Finally, a compromise proposal is presented for regulators and venue operators, in order to allow audience scanning at measured, reasonable irradiance levels, in return for banning truly unsafe or unknown levels.