I ran across these old photos in my archives from around 1980 and thought you all might enjoy them. A recent thread here on the forum discussed how difficult it is to photograph the laser mirror ball effect. I think I had one of the first if not the first audience scan variances around 1979/80.
Here is the Canadian power trio "Triumph" and the little ole' band from Texas "ZZ Top" with the mirror ball effect.
The BRH wouldn't allow me to scan the mirror ball with galvos so I used spinning mirrors on two motors with flywheels and built in tachometers to scan a lissajou pattern on the ball which was spun by a third motor/tach. The three tachs fed comparator circuits in series so if any one failed the shutter would close. A slip clutch on the mirror ball together with the inertia of the ball insured that it could not stop instantly. The effect duration was only about 30 seconds and during testing it took the BRH over five minutes to finally capture and measure one pulse.
The "rear" projected graphic through a 30ft scrim was during the song "Legs". There was no blanking and the only animation was me inverting the Y axis slider. When the girl turned upside down the audience went crazy.
The ZZ Top Sphinx with fiber optic laser eyes was used in the show opener. The curtains parted to reveal the band gear covered with a large white sheet (looking like a big pile of white powder). With a loud "snort" sound (pre-recorded by Billy Gibbons), the sheet was yanked up and disappeared through the sphinx's nostrils to reveal the band and stage set.
After one show during load-out, I assigned two stagehands to bring down the 4ft mirror ball. I thought it would be obvious to them to lower the ball into the case. I was coiling up some cable with my back to them when I heard the sound of crunching glass and turned to see them rolling the mirror ball across the arena floor towards the case. Fortunately I carried a bunch of spare mirror squares.
Lotsa fun!