Vol. 16, No. 3, Oct-December 2005 

Audience Scanning: Let's Do It Right
By Dirk Baur, MediaLas Laserprodcuts GmbH

May 1999: What's the finest and most exciting thing a laserist can do? Create a nice audience scanning beam show and bring three-dimensional dreams into the viewer's heart! That's what all laserists are striving for, and it is the way many Europeans do their shows. But there are differences in the way audience scanning can be done: it can be safe, or it can be uncomfortably bright. I hope ILDA can promote a method of doing safe audience scanning.

An important step in bringing so-called "European-style" audience scanning to ILDA members occurred in November 1998 at the Amsterdam conference. Stephen Heminover, master of ceremonies for the Awards presentation, made a good point: "Amsterdam, the nicest place on earth: Sex, drugs and audience scanning—everything's legal!" He's right. But as we found out in Amsterdam, audience scanning is legal everywhere — even in the United States! Here's why.

At the 1997 ILDA Conference in Nebraska I was curious to find out more about the differences between European and American safety standards. A few times I was told, "There is no difference. The Europeans just measure it wrong!" And my thought was, "No, the US measures it wrong!" At the 1998 ILDA Conference, laser safety experts from several countries sat together and talked about safe audience scanning. And you wouldn't believe it: the list of differences is very small!

In Amsterdam, we invited safety experts from several countries to attend a meeting on audience scanning safety. Each expert arrived with his own opinion and his own measurement system: John O'Hagan (UK) with the "MPE-meter;" LOBO electronic (Germany) brought an LMS-2 meter; Dr. Wolfgang Kirchner (Germany) used a Coherent power meter; and Greg Makhov (USA) brought his own measurement system. The group privately tested a simple figure (a circle) scanned over a distance of 10 meters with an output power of 200 mW at the scan aperture. The initial results were disappointing. Every measuring system had a different analysis of the MPE, sometimes with a difference of more than 10 times! Later, we discovered the reasons for this difference.

Almost 20 ILDA members found their way to the public safety seminar held the following day. After the first break, three people left the discussion to drive to the facility where the Lase-Off and the Awards Banquet would take place. The plan was to measure the audience scanning beam show scheduled for that evening. John O'Hagan and Wolfgang Kirchner were chosen to take measurements and I had the task of coordinating between all the parties.

I was very eager to see the results between the two officers, and this time I experienced a wonder. Both John O'Hagan and Wolfgang Kirchner came to the same results. After decreasing the output power of the laser to 3.75 watts, the MPE-meter was in the safe range. All parties came to an agreement to stay at this level and to provide ILDA members with a safe and exciting audience scanning show.

What I want to emphasize is the common ground discovered in Amsterdam. Although the initial measurements of the scanned circle varied considerably, we discovered the differences were caused by using different units of measurements. There was, in fact, no significant difference in the MPE standards used by Germany, Britain or the U.S.

It is not impossible to do safe and exciting audience scanning shows, which confirm to both European and US laws. I talked to several people who reported the comfortable feeling they had watching the safe beam shows during the beginning of the Lase-Off. It is now ILDA's job to develop a way of bringing this knowledge to its members. Perhaps we will see fantastic audience shows in the United States sometime in the future—at full legal power!