laser analog format?

bizmark · 02-27-2002, 02:35 AM

Something that I've been curious about...

We have all of these analog-lover people moaning and groaning about how they hate the sound of digital audio. While I am aware of the mathematics behind sampling, and I certainly don't think that I could hear any difference between a really good analog master and a normal CD of the same recording, the idea of keeping things analog still has a certain appeal.

So would it be possible to have essentially an analog CD? Or, put another way, an LP that you read with a laser? Maybe where the laser was bounced off of the disc at an an angle so that it's reflected to a sensor, which is set up in such a way that it could capture even the tiniest variation in the height of the reflecting surface, thereby achieving the so-called infinite resolution of analog while still being read with the precision of a laser? (and the protective effect of a polymer coating that kept the actual recording-encoded surface free from dust, scratches, and other problems?)

Does anybody know if this has been tried, or if it's in the works by someone who's still making a killing selling analog systems?

Superdoopercooper · 02-27-2002, 06:04 AM

Hmmm... I don't see why not. You'd have problems with Laser scatter and stuff, though. Plus, I think the circuitry would have to compensate for the laser focal point change when the laser transistion from a "mountain" to a "valley" on the CD. If the laser pickup is held constant, there will be some places where the focal point of the laser is just above the pickup, meaning that the power of the light at the sensor will be slightly decreased, I think. I say this because I don't think CD's use highly collumated lasers, but I could be wrong.

So, I believe the CD player circuitry would be more complex and quirky than any of the normal CD players today. Think about it... you can get a CD walkman for like $20. Everythign would be in the analog domain... which makes accuracy, stability, and power consumption much more difficult to come by.

Not to mention the manufacturing process of the CD itself would be much more complicated... instead of two levels of info on the CD... there'd be a continual variation in height of the reflecting material. Any slight defects would kill the sound quality. And think.... a disc would not be able to be quickly tested coming off the line like it is now (if they even are tested). A computer can easy zip through and compare a Disc full of 1 & 0, but a no such comparison for analog. I'm not even sure how they made sure the records were ok, since records were big until I was only 10 or so... Then tapes became popular.

RSMemphis · 02-27-2002, 11:10 AM

Most music these days (at least high quality music, not necessarily pop crap) is recorded digitally, albeit with higher resolution than a CD.

The new DVD music formats really do not leave anything to desire - extremely crisp and not discernible from a perfect analog recording for 99.999% of the population.

Now, to answer your question: Yes it would be possible, however:
You'd need a die that reacts permantly to the Laser and has almost infinite shades of "grey". However, certain impurities may cause a die to react stronger or less strong to your laser.
No laser will ever work 100% stable, especially not in "cheap" consumer electronics. Reading and writing will induce some variation.

In other words, you lose any chance of ever reproducing it 1:1, and in all likelihood no two consumer players would replay a piece the same way.

It can be done, but there is really no reason to implement a very expensive system like that.

bizmark · 02-28-2002, 03:42 AM

Thanks, that's kind of what I figured. (i.e. that it was possible but not worth the cost and that there would be a few technical problems with mastering the discs and ensuring that the laser can read properly through a varying depth of the substrate which protects the disc which would cause problems with refraction/scatter/focal changes or whatever.)

CSoup · 02-28-2002, 04:19 AM

just call it analog even though it is digital and all those people will be happy. Just like how some of those people still prefer laserdisc over DVDs because they are "analog". I don't understand how these people can say that. They claim that the pulse FM conversion is not an analog to digital conversion. Come on, your transforming the analog waveform and clipping it to get a form that can be represented by pits on a disc, I certainly consider that analog to digital.

Goosemaster · 03-01-2002, 02:57 AM

<< Or, put another way, an LP that you read with a laser? >>

It's been done

It is supposed to be very good, but at 10 grand, i'l lstick with my appearantly crappy cds

It actually can play alot of normal LPs too..not much of a problem..then again, a lot of LPs don't work on it either...(they have to be in PERFECT...EXTREMELY PERFECT>>. condition..

It does prevent damage over time that needles are infamous for....

Sahakiel · 03-01-2002, 03:01 AM

<< It does prevent damage over time that needles are infamous for.... >>

ooo, kinky.... needles and vinyl...

wait a minute...

bizmark · 03-01-2002, 03:21 AM

wow that's so cool... heh I guess I could've done a Google search for it before I posed the question, but I thought "nahhh... why would anybody do something like that?"

<< Over a period of seven years, with financial backing (about twenty million dollars US) from people who shared his vision, he developed the basic technology.. >>

:Q That's a lotta time and money to spend working on a laser reader for LPs!

<< they have to be in PERFECT...EXTREMELY PERFECT>>. condition.. >>

Actually:

<< The Laser Turntable can play broken, cracked and heavily warped records >>

That's pretty cool... I guess the laser can correct for problems.

Funny.... they misspelled "monaural" on one of their figures! You'd think that at 13 grand a pop, they'd be able to spell basic audio terms correctly....