Microscopes can see video on a laserdisc

Tech Tangents is one of the best retro channels on youtube but by retro I dont mean glorified nostalgia either. Shelby puts a lot of work into his videos and likes to showcase what awesome engineering went into some of the early tech that was practically magic. Love the channel and glad to see it on HN.

I'm not that familiar with CED but the fact that we can see the images with microscopes is because these are analog discs? And that was because computing power back then was non-existent so they didn't use any kind of compression?

Is there a version that doesn't require watching a video please? This would be 10x faster and easier as a text blob

Here's a screen capture of the end credits visible on the disc the videos worth it but I do think sometimes you need to start with the money shot https://ibb.co/v4KK88fF

The live stream of this had more interesting things as well, such as looking at the ink on mimeographs compared to inkjet printing. Long and rambly as live streams tend to be, but it is there if anyone cares.

https://m.youtube.com/watch?v=zIsCswtkozI (mimeograph around 3:36:00 mark)

Not nearly as cool, but I was able to show a colleague the letters in a raster image section of a pdf using xxd by varying the output width

So CAV (constant angular velocity) is an encoding format for laser disks. When something is written with CAV, it is basically analogue data and therefore repeating patterns can be recognized on the disk.

But the opto mechanical parts of a laserdisc reader are way more interesting than a microscope.

Fun fact about laser discs. They are analogue not digital. CD’s store digital information with the presence or absence of pits. Fairly ancient but still fundamentally feels like a very old version of a thumb drive.

Laser discs are not digital. They encode the analogue video signal’s value as the length of the pit. It is digitized in the time domain - sampled at some frequency, but the “vertical” signal value is stored entirely analogue. In terms of encoding it’s more similar to a VHS tape than a CD. Kinda crazy.

Actually amazing being able to read the text like that, and on two different types of discs. Great video, was much better than I was expecting it to be from the title!

Very cool but, I was hoping he was going to spin it and align with the camera’s refresh rate.

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That’s not a LaserDisc, it’s a CED video disk. Totally different technology.