watch a dvd-burner burn.. dvds!

[Tw15t3r]

Quite interesting experiment you did really!
Btw I believe that lasers tht burn DVDs and CDs don't burn the surface underneath. A typical DVD/CD has a coating on the top (I shall refer to top being the side the label is printed on, and bottom as the other side). What happens for these discs are that the laser is actually focused in such a way that the burn occurs just underneath of the top side. My dad tested this by scratching away the label part till the disc looked clear on just a small fraction of the whole disc. All the while, the underside was not scratched.

And lo and behold! the old disc was unreadable after that!

So I think it proves that the burning doesn't occur on the surface of the discs. (Apparently Blu ray discs are slightly different in that the surface which is burnt is closer to the underside, but still not directly on the surface)


PS: Where'd you get that drive! PEACE THROUGH POWER!

 

[Krutz]

Tw15t3r, you are absolutely right with your conclusion, thank you for mentioning it here!
therefore, scratches on the top(label) side are almost instantly fatal, whereas "data-side" scratches arent that bad. if its a small scratch, the laser wont bother at all. the dot reaching the surface is relatively big, and focuses more until it reaches the datastructure on the labelside.
all three media (cd, dvd, br) are different, if i remember correctly. cd being the data right on the label-side, dvd/br having it in between two plasticdiscs. br has a much smaller focus-size and distance between lens and media. therefore, dust and scratches get worse and worse from cd to dvd to br. when br was developed, the plan was to put them into cartridges, just like minidiscs. to cut costs, they opted for (more) scratchresistant surfaces. which doesnt help from dust and fingerdips.

got my drive from ebay germany, was around 20€ shipped. considered thats the most powerful red laserdiode buyable (from drives, anyway), thats a absulitely ridiculously low price..
well, we'll talk again about this in a year, lets see.. hehe

manuel

 

[oinker]

you are right, KANE LIVES!

hmm, i guess 22x dvd is about the end.. i was surprised to see anything higher than 16x actually! the limiting factor being the rotation of the media, therefore there isnt anything higher than 52x cd.. except that one drive which used more than one laser/pickup/sensor or whatever. it was more than 52x, but with the same rotational speed.
any higher, and cds just explode. and sometimes do already..

manuel

mythbusters blew this 'exploding cd's' myth ages ago...

and i also remember reading in a 'supposedly reputable' magazine once upon a time that there was no chance of cdroms ever reaching speeds over 4x, and im thinking this myth was blown a while ago as well

 

[thesk8nmidget]

nice krutz you rock! you always have good sets of pictures!

 

[Tw15t3r]

mythbusters blew this 'exploding cd's' myth ages ago...

and i also remember reading in a 'supposedly reputable' magazine once upon a time that there was no chance of cdroms ever reaching speeds over 4x, and im thinking this myth was blown a while ago as well  

Yea, I remember them proving that the myth was false. Although there were one or two reported cases of cds "exploding" (really rare). But I guess, that's why they didn't go higher than 52x. Mythbusters always has the two part thing, replicate the conditions, replicate the result. All they did to replicate the result was to spin the disk faster than what it already was and yes, it did "explode". The significance is that they didn't need to go that much faster, which implies that we are already reaching the limit of the disc.