Laser growing up

[laserist]

Time marches on, things change, which is good and sorrowful to some extent, but there was no better illusionary back drop for a 45-50 minute laser show than a planetarium with a start ball, any planetarium any star ball. I applaud your rational for wanting to fully document what Laserium achieved. I, too, have always preferred and found huge value in RYGB pairs of scanners, be they open-loop or closed-loop for presentations. But now RGB 30K pairs would still be terrific. Fixed rotation is the one biggy, the one thing I always wanted to do like Laserium but never figured out a practical way to do it back then, and I lacked the math skills to help.

snip

Fixed rotation is easy. You just use two resistors one for the x input and one for the y input to generate the non-orthogonal axes. Laserium's fixed rotation as I recall was 0, 90, 135, 225 degrees. The 135 and 225 just used 14.1K resistors into a summing amp with a 10k feedback resistor. You just have to get the inverting amps in the right place...

[Greg]

Fixed rotation is easy. You just use two resistors one for the x input and one for the y input to generate the non-orthogonal axes. Laserium's fixed rotation as I recall was 0, 90, 135, 225 degrees. The 135 and 225 just used 14.1K resistors into a summing amp with a 10k feedback resistor. You just have to get the inverting amps in the right place...

The module I think about building for the purpose of getting back to where Laserium was with the four scan pairs would have routing of 4 input xy signals to 4 ilda out ports, and would apply the functions of joystick positions and rotations to the channels. Routing, gains, inversions, and rotations would be under the control of low level signals which could come from the panel or from another module of the system: a bunch of DACs under timeline control. It seems to me fortunate that ilda allows basically +-10V control signals directly from any one of Laserium's classic modules with nothing more than wires needed.

Laserist is trying to make something sound easy that some of us find not so: image rotation circuitry. I expect there are great reference threads on PL already on this topic. Pointers welcome.

Here is the link to the dogloids catalog video:
https://youtu.be/fJ7kAR7D8yU

[lasermaster1977]

The module I think about building for the purpose of getting back to where Laserium was with the four scan pairs would have routing of 4 input xy signals to 4 ilda out ports, and would apply the functions of joystick positions and rotations to the channels. Routing, gains, inversions, and rotations would be under the control of low level signals which could come from the panel or from another module of the system: a bunch of DACs under timeline control. It seems to me fortunate that ilda allows basically +-10V control signals directly from any one of Laserium's classic modules with nothing more than wires needed.

Laserist is trying to make something sound easy that some of us find not so: image rotation circuitry. I expect there are great reference threads on PL already on this topic. Pointers welcome.

Here is the link to the dogloids catalog video:
https://youtu.be/fJ7kAR7D8yU

That's cool, Greg. The 6502 and 65C02 programming I am very familiar with and actively updating some of my recently updated RGB DAC machine code drivers.
Edit: 4 XY channels feeding 4 ILDA projector inputs is one of my projects as well as my old LaserMaster system has 4 XY DAC outputs.

Mixedgas already shared the schematic for a 4QMM circuit for image rotation in "Analog Scan Rotator" post.

[laserist]

The module I think about building for the purpose of getting back to where Laserium was with the four scan pairs would have routing of 4 input xy signals to 4 ilda out ports, and would apply the functions of joystick positions and rotations to the channels. Routing, gains, inversions, and rotations would be under the control of low level signals which could come from the panel or from another module of the system: a bunch of DACs under timeline control. It seems to me fortunate that ilda allows basically +-10V control signals directly from any one of Laserium's classic modules with nothing more than wires needed.

Laserist is trying to make something sound easy that some of us find not so: image rotation circuitry. I expect there are great reference threads on PL already on this topic. Pointers welcome.

Here is the link to the dogloids catalog video:
https://youtu.be/fJ7kAR7D8yU

Yeah, thats a good start. So you've got a joystick, which needs a couple of fixed rotation options -so four x/y outputs, and needs 8 summing amps (x/y for each color) to add the joystick to 4 ILDA (fixed rotated or not) outputs. You're going to want gain of the ILDA signals before the summing amps, and ideally master gain and symmetry. You're going to want joystick overrides and master gain. (individual gains would be a PITA) And if you have a joystick (or two) throw in a set 4 - 4 quadrant multipliers (laserium used AD732's) and two op-amps to make a z axis rotation circuit to rotate the ILDA input signal. That would be a cool start. Then we can start talking about color mod...

It's not that laserium was hard, there were just a lot of simple circuits that were put together to make art.

[laserist]

One of the early Iconic laserium Lumia effects was the Dimple Tube, often referred to as a torture tube because there wasn't much sharing back then. Another whole genre of effects that were born at the same time involved the fiber turret. Charlie Rau remarked back in 2014 that he'd never seen anything like that in a laser projector. Imagine a 3 foot long incoherent fiber bundle that's fed a very tight lumia via a lens focusing the RYGB beams almost on the lumia wheel and placing one end of the fiber bundle right at the output of the lumia wheel. What you get is random individual fibers in a random but reoccurring way since there is a direct correlation between the input fibers and the output fibers. Now attach the other end of the fiber bundle to a rack and pinion focusing mount like used on a microscope. Build a servo drive that allows the laserist to focus the output fiber to the effect, and you've got a fiber turret...

[lasermaster1977]

Veeery nice share. Way cool!

[Greg]

I remember how well that fiber turret effect worked to mimic any tinkling sounds that appeared in songs such as 10cc's I'm Not In Love and Floyd's Is There Anybody Out There. I remember the feel of operating the focus dial. I think the fiber turret effects were accessible without the 351.

When I get home next month I'll post a photo of my ridiculous attempt to build the dimple tube using a harmonic drive, which is a component usually used on spacecraft for pointing antennas. It turned incredibly smoothly but WAY to slow. Later I bought a 1:100 gear box and a dc motor speed control from China, which gave good results, and can be seen in this video. The dimple tube effect comes in at 3:41. Not exactly like the Laser Images dimple tube, but similar.

https://www.youtube.com/watch?v=verZM6mDXz8

Laserist previously explained how the Crystal Dimple worked. Looking forward to building that and seeing the effect again.

[laserist]

I remember how well that fiber turret effect worked to mimic any tinkling sounds that appeared in songs such as 10cc's I'm Not In Love and Floyd's Is There Anybody Out There. I remember the feel of operating the focus dial. I think the fiber turret effects were accessible without the 351.

When I get home next month I'll post a photo of my ridiculous attempt to build the dimple tube using a harmonic drive, which is a component usually used on spacecraft for pointing antennas. It turned incredibly smoothly but WAY to slow. Later I bought a 1:100 gear box and a dc motor speed control from China, which gave good results, and can be seen in this video. The dimple tube effect comes in at 3:41. Not exactly like the Laser Images dimple tube, but similar.

https://www.youtube.com/watch?v=verZM6mDXz8

Laserist previously explained how the Crystal Dimple worked. Looking forward to building that and seeing the effect again.

The fixed dimple was used with any number of lumina wheels beneath the dimple. One was an acetone wheel. Just Plexiglas etched with acetone. The was another thin sort of crinkled Plexiglas wheel, and another that had the crystalline lacker that used to be sold for fish tanks.

One of the cool effects since I left in '84 was a made with a special effect filter for a camera.. it had a clear center and outer concentric grooves like fresnel lens. Nice effect for straight lumina and scan through.

[Greg]

I'm under the impression that Ron has many noteworthy specimens of what we are talking about.

Here's something I'd like to know. What were the three effect glasses used in the Laserock2 version of Tank.

Tank was an unusual number because it was done entirely with dots and a joystick. There is a video of Tank available but it's not the version I'm remembering. The drum solo part had the yellow, green, and blue dots only. Each was projected through an effect that gave some size and shape to the dot, but didn't refract lumia all over the dome as the dot moved around. Green was a sand dollar nebula like thing, blue was a roundish thing similar to green but one quarter in size, and yellow was a baton like bar that always pointed away from the origin, and collapsed in length as it approached the origin.

The simplicity of using these three characters to play off each other was an effective way to visually express the beloved nuances of Carl Palmer's brilliant abstract acoustic narrative.

I'm now remembering licks from that number that really shouldn't be lost. The yellow tapping the blue when the cymbal goes ting ting ting tating tating tating, the blue only meandering with a ghostly colormod for the quiet run on the snare, and near the end of the drum solo, during the powerhouse groove before the final round of crashes that precedes the sweep that is the beginning of the synth part, the laserist would cycle the joystick around-and-round-and-round-and-round with a slight color mod, and play the offset enable levers with the left hand. What an effect! A ring of lumia with a colormod pattern of bars that looked like a turntable speed adjust thing appeared, with each of the three characters taking turns snapping to the origin to sit there for an instant on each snare accent.

Those were fun days.

[Greg]

Come to think of it, I now remember teachers becoming concerned when I'd be spotted blinking and rolling my eyes wildly. It wasn't easy to explain that I was playing with lissajous, chop, and offsets using a point source reflection and persistence of vision.