Tech Tangents (TT) surprised themselves by looking at the surface of a CED ‘LaserDisc’ under a microscope and felt compelled to purchase a new device, with a built-in screen and HDMI out, to share what they had discovered. Spoiler alert: You can clearly see some of the analog imagery stored on a CED surface.
Though the media looks quite a lot like a LaserDisc, a CED (Capacitance Electronic Disc) is an unusual video distribution format that existed for a time alongside the far better known VHS and BetaMax videotape era. It consisted of a vinyl-like disc, distributed and maintained for its own protection in a caddy, and it was read by a needle-loaded cartridge just like ye olde music LPs and singles.
Like its tape format rivals, the video content stored on a CED was in a standard-definition quality analog form. So, looking extremely closely at the grooved surface can actually give you more than a clue to the content of the disc.
Enjoying the new microscope
After introducing his new microscope and its capabilities, TT finally gets down to some close-up disc scrutiny at around the 14mins mark. Specifically, he zooms in on the surfaces of two samples of actual CEDs. These contain generally better quality (though still analog) video tracks, which were read by a laser pickup. Some of the later LaserDiscs were enhanced with digital PCM audio tracks.
One of the CEDs examined closely was a CAV (Constant Angular Velocity) disc, with its data evidenced by a consistent geometric pattern, whereas a CLV (Constant Linear Velocity) disc under the microscope looks simply colorfully streaky.
“I found an image!”
Now studying the CED surface more earnestly, something caught TT’s eye. “It's not going to happen. We're not going to find an image.” Then, almost immediately, “I found an image.”
The video host explains what we are seeing and that, due to the nature of the CED recording and media, it is possible to see a “meaningful” image on the surface, if and when the video slowly pans across the x or y axis. The first evidence of this phenomenon comes from some video text shown at around 22min 30sec in the video (see image, above).
CED QED
The main event takes place around 25 minutes into the video. A CED disc is (at last) placed under the microscope. After a bit of zooming, focusing, and angling of light sources, TT blurts, “Oh my gosh. We just nailed it. Bang. Right there.”
Again, it is some text, but this time a much clearer representation of the disc content. The CED surface text is almost as clear as a stored video frame on some old film.
After that excitement, the video host moves along to look at a couple of other tech-related artifacts under the microscope. The extras include a surface study of a mixed-mode audio/data CD, and a smartphone screen close-up where the OLED (sub) pixels are clearly visible.
If you reckon the demonstrated desktop digital microscope is a good one, it is the Andonstar AD246S model. We have noticed it is currently 13% off and available for $139 on Amazon.
