whilst fooling around while bored, I pointed a cat laser at a vinyl disk, and when I held up a piece of paper to the reflection, I could kinda see the individual grooves, but no detail. I then continued experimenting, where the farther away I saw the reflection the more pronounced the grooves got.
However I could not see the individual bumps inside the groove, so I got an idea, if I could take three lasers, two of them are focused on the angled sides of an individual groove, and one that points directly at the groove and reflects off of it to track it, with all these reflections pointed at photodiodes.
I know this has already been done, but, if I could, what would that entail? This is purely hypothetical, I know it’s not exactly simple. I have an excess of CD and DVD players about, all with lasers I could steal, but would a CD or DVD laser make it so I could actually see the grooves? The cat laser does not let me see what’s in the grooves, only the grooves themselves. Do I just need to focus the cat laser better? Or is this way out of the scope of things I can haphazardly hack together.
However I could not see the individual bumps inside the groove, so I got an idea, if I could take three lasers, two of them are focused on the angled sides of an individual groove, and one that points directly at the groove and reflects off of it to track it, with all these reflections pointed at photodiodes.
I know this has already been done, but, if I could, what would that entail? This is purely hypothetical, I know it’s not exactly simple. I have an excess of CD and DVD players about, all with lasers I could steal, but would a CD or DVD laser make it so I could actually see the grooves? The cat laser does not let me see what’s in the grooves, only the grooves themselves. Do I just need to focus the cat laser better? Or is this way out of the scope of things I can haphazardly hack together.
Vinyl is black and absorbs perhaps > 90% of the light incident - you risk local melting with a tightly focussed beam (and very little laser light will be reflected to your sensors anyway). This is why CDs, DVDs and Bluray are metalized discs. A further problem is the variation in angle of the reflected beam is substantial - although this is itself could encode useful information (perhaps not easy to decode though). For 15kHz on a 33rpm disc at outer edge you have a groove wavelength of about 35µm, so you need to focus to <= 10µm diameter beam to capture the detail.
You would need a sensor to cut the lasers if the disc slows/stops otherwise it will melt a hole...
Elliptical diamond stylus technology seems much more tractable by comparison I fear... Still fun to experiment..
You would need a sensor to cut the lasers if the disc slows/stops otherwise it will melt a hole...
Elliptical diamond stylus technology seems much more tractable by comparison I fear... Still fun to experiment..
No published specifications? Suggests its a very hard problem and the results aren't superb (apart from lack of wear of course)...
Yeah, I'd read anecdotes that it wasn't a very successful method of reproduction. There were a few commercial attempts I believe.
Watch The Expanse (sci-fi series on Amazon Prime), end of series 3 to learn all about the dangers of pointing powerful lasers at things😂
Don't need to, I've seen the state of the Vulcan petawatt laser's target chamber, sputter-coated in copper from the target backstop... Petawatt class lasers outdo cat lasers by 18 orders of magnitude! When the power source is a warehouse full of capacitors you know its a good one!