Back then...this is what we did...

[lasermaster1977]

Thanks for the pointer, Steve. Interesting reading, most of which I'm familiar with, after 10 years of ion laser R&D + show experience. I've already built the rest of my 3 projector system, but only need a circuit to convert audio signals into ILDA standards, cause I'm critically lacking in the analog electronics lobe of my grey matter. But, I can twiddle knobs purdy good. Of course, that was way back in the day, long before the rheumatism set in. CBD helps with that, too.
Lasermaster1977 is graciously being very helpful for achieving my goals.
Nevertheless, I have no doubt that RTFMin' the pdf's will help in that respect.
BR
😎

@TheHermit: This or a variation of this circuit may help you to convert audio signals to ILDA standards. I just posted it today in another thread on PLF as well. (Question about X and Y differential ILDA signals) If the DC offset 10K input and the 50K variable resistor are eliminated entirely then the circuit becomes a single-ended (unbalanced) inverting amp with a gain of 2 (change the gain via Rf to suit your needs), the output which becomes the input to the final ILDA differential (balanced) outputs for X & Y. Shown here are X and Y channel circuitry.

[lasermaster1977]

Here is an update to this thread, related to my mentioning back at the beginning of this thread when I first added computer DAC generated imagery to my analog console capabilities. Computer generated imagery was for both abstract and real world line drawings.

On July 1, a few days ago, I heard from an old friend, Mike. He had some laser related articles he wanted to mail me. It turned out to be some 35mm color slides I had sent him in August of 1979 of the first computer graphics images I had created with his help. My jaw dropped when I saw these slides. And if I ever had other copies of these slides in the past, they had long disappeared!

Mike, a good friend of my brother, and my brother designed my first DAC card for use with my first Apple II Rev. 0 computer. Mike worked for Motorola and his job was to figure out cool things to do with Rockwell's new 6500 series CPUs. When I approached my brother to help me find a solution for digital graphics, it was Mike who suggested that I buy an Apple II and use it for this purpose since it had I/O expansion slots and used the 6502 CPU. Mike did the digital design of my 1st XY DAC card while my brother did the analog design (op amp circuits). Mike also wrote the binary DAC driver along with several simple BASIC programs for entering, modifying, listing X,Y coordinates of images and together they debugged this first hardware/software project.

It was delivered to me in June or July of '79. I could draw via the DACs ANY image I wanted provided it used less than 127 XY coordinates! Wow! What freedom, right? I started learning to use this new technology straight away. By then I had also acquired one floppy disk drive for the Apple II for Mike to use during development and to store his programs to.

Forgive me if I've mentioned what follows in other threads, but even though I now had a nifty 8-bit, 1MHz computer with up to 48K of DRAM AND Integer Basic. To create an image I had to use blue grid paper with 1" major divisions and .1" minor divisions (but in order to minimize grid paper size we mentally subdivided the .1" squares in half for .05" true minor divisions) to draw out my desired image shapes with pencil and eraser. My maximum useable grid size was 254 squares x 254 squares, roughly a one foot square piece of paper.

The first image I drew was the scripted word "Laser", which was about 4 inches tall and 8 or so inches wide. We then had to determine the best beam path sequence to follow from the start of the word to its end as well as considering any retrace lines. At this time, beam blanking was just a dream. Next looked where the pencil drawn lines of the word "Laser" crossed XY grid intersections, marked that intersection with a pencil dot then counted the XY minor grid lines along the X and Y axes to derive XY coordinate values between 1 and 127, and wrote on another piece of paper 1. 40,64, etc. It was tedious for sure. The first Byte of the image was the image point count, followed by "n" number of XY pairs where n<=127. Images were loaded into memory from floppy drive storage on 256 Byte boundaries with a key code assigned to each image loaded. I could load up to 10 images, 10!

At the time, I only had GSI G115 open-loop scanners, so this is how the first laser rendered computer DAC image looked at about 3-7 fps, scanned on the dome of a 40 foot diameter planetarium. The dome aluminum panels had small hole perforations for acoustic transparency as there were four audio speakers behind the dome. The red laser beam penetrated some of these holes and hit the inner dome ceiling that was about 3 feet from the dome's true screen. This resulted in a dim offset image ghost seen in the photo.



This Kodachrome 64 slide image was taken sometime in Aug 1979. And this had to have been just prior to my first commercial, product reveal gig that also happened in August '79.
Notice at the end of the "r" you can see the "inductive ringing" inherent in the open-loop galvos at the start of a "Step" response.

People from the Weedeater company in Houston had seen my Dallas planetarium laser shows and hired me to help with a new product reveal for their executives and wholesalers at a hotel ballroom in Houston at the end of August 1979. I was to draw the outline of their new XR model two-cycle nylon weed whacker on a blacked out stage, black background, just slightly larger than the real thing. Its engine housing was green plastic so naturally we used the green line of my mixed gas laser for this. Again, the image was done in 127 XY points and scanned at around 3-7 fps. This was a good example of how frame-rate flicker added to the dramatic reveal, since in a fairly darkened ballroom the green beam seemed akin to a laser light sword action. The laser effect only lasted a few second then a spot light came on illuminated the new weed whacker where the laser scan had just happened. ...and the crowd roared!



I mean...yeah the images aren't perfect but pretty darn good for open-loop scanners of that day.

[I did a few minor edits today for better readability.]

[MountainGoat]

Thanks for sharing your awesome story and memories.
I’m sure it took some time to jot that down and wanted to let you know I appreciate it and found it very interesting and inspiring. I am sure others do as well!

[Greg]

Mike, a good friend of my brother, and my brother designed my first DAC card for use with my first Apple II Rev. 0 computer. Mike worked for Motorola and his job was to figure out cool things to do with Motorola's new 6500 series CPUs.

Thanks for the post. I love historical recounts of successful use of lasers back in the days when that was difficult and expensive. Am I correct though, you mean MOS and not Motorola?

[lasermaster1977]

Thanks for the post. I love historical recounts of successful use of lasers back in the days when that was difficult and expensive. Am I correct though, you mean MOS and not Motorola?

Glad you caught my error. I meant Rockwell's new 6500 CPU series. Correction made. (MOS was the chip technology used ;-), correction MOS Technology who designed the 6502 was made up of many of the same Motorola engineers that designed the 6800 CPU. The 6502 was a simplified and cheaper version of the 6800...see https://en.wikipedia.org/wiki/MOS_Technology_6502)

[lasermaster1977]

I had a single XY multiplying, quadrature DAC Apple II system that also became used when the IIe came out. Soon after its inception more capabilities were added, including dynamic frame-rate control, rope-draw, image blanking using the Apple's Game I/O port, etc.. I began referring to it as Laser Master (two words with a space in between). Back then software soon came on 5-1/4" floppy disks, such as the Apple DOS 3.3 boot disk. The original disk was often referred to as the Master disk, aka the original copy. It was always recommended to make copies of the master disk and use the copies. The software we wrote for laser show purposes had labels with the name "Laser Master" which contained the binary DAC driver, floating-point basic programs for creating images, image block loads with image key code assignments, etc. The master could be filled up with quite a few images but a 2nd disk would be used for more images and was often referred to as the image master, like Pink Floyd Image Master, etc. Many copies of the Laser Master would be made and the name implied "everything you need to create and do". This system was an augmentation to the ubiquitous analog oscillators, phase-locked and free-running, 2 x 4 mixer, AM oscillators w/inverter switches, four quadrant, four channel joystick, analog tape XY inputs.

5 years later and two prototypes later, the Apple IIe Lasermaster system was developed. After five years went by it dawned on me to drop the "space" and make it one word as the system name for the 5 6502 CPU conglomerate made up of the Apple IIe, dual floppy controller & floppy drives, 1.5MB memory expansion card, and real-time clock card and 4 Apple DAC Laser Controllers (ALDC) each with a 65C02 CPU. The Apple IIe was the 5th CPU. It was after all a master controller of RYGB laser outputs and the console's programmable analog mixer, channel selector and digital switches.

The memory expansion card provided 80-column text ability PLUS 6 RAMDrives 5 of which had 5 times the storage capacity of the standard 140KB floppy and far, far faster file read/write ability. As many as four full-to-capacity floppy disks, containing images, waveform, shape and scale parameter tables, host software, ALDC drivers, time-based show command scripts would be uploaded to RAMDrives prior to a performance. Everything was transferred from RAMDrives to the Apple IIe and ALDC cards from then on. On each ALDC card there were 4 DACs, X & Y out, Xscale, Yscale. The scale DACs could be slow speed for zooming up/down and image or for amplitude modulation, and were controlled by soft switches that could switched out for remote XY scaling inputs (like external modulation).

The real-time-clock (RTC) was used to create a synchronous link between the Apple IIe's manual or scripted program control and the ALDC display cards function. The system could use 1 to 4 ALDC cards. The Apple's clock was used for the Apple's CPU and the 4 ALDC CPUs, the details of which I will not go into. From tests we determined that a 1/16th of a second was an ideal time interval for the RTC to generate Interrupt Requests to the Apple IIe' CPU. Normally the Apple would be reading the time script on noting when the next time scripted command or commands to act upon needed to happen, note the RTC time and if the two matched the Interrupt would cause the Apple to stop what it was doing and run a different program to fetch the command(s) that needed to be sent to one or more of the ALDC card(s) and send them, all in less than 1/16th of a second. This also caused the IRQ line of affected ALDC CPUs to quickly check their command buffers, fetch and execute the commands sent them. (The ALDC cards would only execute commands at the end of a frame.) Then return to reading the show command script up to the next timed event, and repeat until "time is gone, the show is over."

These are the high points of both systems.

[lasermaster1977]

I was chatting with @TheHermit recently and I mentioned the cool "resonant frequency ringing" effect produced by the G-115 open-loop galvos. I sent him photos I had taken of examples of this, and in the process found they came from digitized video from 16mm film tests I and a cinematographer friend, Phillip Thomas, did in my Dallas studio back in 1982. We also discussed several prominent composers of the time, Tomita, Vangelis, Wendy Carlos, and that reminded me of Terrry Riley's "A Rainbow In Curved Air" also from back then.

When Phillip got back all the reels of processed Kodak positive 16mm film he shot that day, he spliced them all together into one big reel. He had a small viewing room and dual 16mm projection booth in his house. He invited me over to see the results of our collaboration one evening. We adjusted our altitudes with some most excellent Columbian 'something", he but on this album that I wasn't familiar with and rolled the film. We were both blown away at how amazing temporal changes in the laser effects matched this music.

Today, I imported these digital video files into Pinnacle Studio 26 and with two exceptions, the beginning and the end and a wee crossfade around 2min 30 sec, did nothing to synchronize the laser to the music mentioned here (that will be apparent in many places).

For more detailed insights to this video and how it was shot please read the YouTube Description. Enjoy! And watch for my studio room lights to come on/off at 9mintues:05seconds.

https://www.youtube.com/watch?v=9Ea1L18DQek

[Greg]

How did the red dot with lumia bursts seen around three and a half minutes work? Is that the amazing symmetrical quad scan pair turret you built seen producing the tunnel effects?

[lasermaster1977]

How did the red dot with lumia bursts seen around three and a half minutes work?

By creatively placing a rotating lumia disc near the red XY scanner pair without completely blocking the scan area and fully in the green/blue scanner pair outputs that had stationary, centered beams. The red 647nm beam REALLY over-saturated the film, eh? The actual beam size was no where near what came out on film. But a cool effect nonetheless. Afterthought: There is slightly more to it for how the red beams glides smoothly but that shouldn't be hard to figure out...it is using a joystick with variable dampening.

Is that the amazing symmetrical quad scan pair turret you built seen producing the tunnel effects?

Used in these film footages was my 1st generation symmetrical quad mount roughly dimensioned for four G-115 scanner pairs and not quite as nearly densely packed together as the 3rd generation version for the G-120Ds, which is shown on PLF. The 1st and 2nd generation quad mount versions were done using only a machine square w/scribe, 6" digital caliper, a drill press, table saw and machine thread taps. The 2nd generation mount had two G-115s pairs and two G-120D scanner pairs. The 3rd generation mounts used four G-120D scanner pairs and was machined out using a manual Bridgeport style vertical mill and was dimensioned for a far more tightly packed scanner array as dimensionally practical.

The 2nd generation mount is pictured in post #18 of this thread. The projector used for this filming is a slightly early version than the one shown in post #18. How the beams were directed onto the X scanner mirrors were identical in the 1st and 2nd generation mounts.



In the 3rd generation mount, shown in post #19 of this thread, I took into account the ability to replace mirror mounts and/or scanners, in place, while the 1st and 2nd generation had plenty of room to do these things.

[absolom7691]

I mean...yeah the images aren't perfect but pretty darn good for open-loop scanners of that day.

This is so nostalgic for me. Especially the red "Laser" image. Back when lasers were prohibitively expensive for me, I was limited to G124s and a PC LITE ISA card from Laser Illusions. I could only make simple graphics and only had the default abstract "frames" available (which were my favorite) but it was the closest I could get to a graphics show. Running on an old 386 machine and pushing about 6k~8k (I'm only estimating the speed) and a 12mW HeNe with no blanking... I had so much fun. Thanks for sharing!