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A DVD diode and some questions about it's ability

daem0n

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So I was harvesting a DVD-R diode and it got me wondering about a couple of things.  First of all, this thing must have different modes...one for CD-R, one for DVD-RW, and then DVD-R, etc.  I've heard that CD-R is infrared so you most likely wouldn't see it, but when we power these diodes, we're just giving it generic power, etc.  Is there a way to know how you can select the different burning capabilities of it or figure out what else a diode can do?  Is the difference pulsed and un-pulsed or something else?  I have no idea but the question came to mind...

Also, the faster the drive burns DVD-R media, does that mean that the laser's output power is higher (since the disc is spinning faster)?
 

pullbangdead

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Re: A DVD diode and some questions about it's abil

There will be separate diodes for DVD and CD burning. You're right that the CD burning diode will be IR, while the DVD burning diode will be red. The wavelength of the diodes depends on the materials in the diode, specifically the bandgap (roughly) in the materials used in the diode, and thus one diode can't emit more than 1 wavelength. The Blu-Ray "diode" that can emit all three is actually 3 diodes packaged together in 1 can, but they are separate diodes and have to be supplied power separately (if I understand correctly)

And yes, the faster burners have more powerful diodes in general. The 18x and 20x burners are often the "open can" type, at least from what I've read on here.
 

Gazoo

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Re: A DVD diode and some questions about it's abil

All of the DVD burners I know of have two diodes. One is infrared and the other is red...they are not combined into one can.
 

daem0n

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Re: A DVD diode and some questions about it's abil

Ah ok, thanks a lot for those replies. They cleared-up all of my questions and should help me with my next project. I guess choosing the 1x DVD-R burner for my first harvest wasn't the best idea lol.
 

LarryQ

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Re: A DVD diode and some questions about it's abil

No....unfortunately..if you want the best diode..they happen to come wrapped in the fastest burners...

Larry
 

Things

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Re: A DVD diode and some questions about it's abil

yup! have a look at senkat's GB for diodes, they are 16x and are very powerful and cheap! he doesn't have any ATM, but he is getting more in!
 

o_DEATH_ANG3L_o

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Re: A DVD diode and some questions about it's abil

I am currently using an LD from a 4x burner. It is pretty powerful believe it or not. But yes LarryQ is correct, if you want a powerful burning laser, get a fast dvd burner.
 

Hemlock_Mike

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Re: A DVD diode and some questions about it's abil

You also asked about writing to the disk --- That's when the LD is pulsed at high power and high speed to record the 1's and 0's onto the disc. Don't ask me how they erase !!!

Mike
 

styropyro

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Re: A DVD diode and some questions about it's abil

daem0n said:
.  I've heard that CD-R is infrared so you most likely wouldn't see it, but when we power these diodes, we're just giving it generic power, etc.  
Actually, the CD burner diode does put out a fairly visible dot considering it's near-IR. The wavelength is 780nm, I have an 80mW 780nm module I bought from Aixiz for $15 and the brightness is comparable to the Cheap pointers at stores, exept the color is different.
 

pullbangdead

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Re: A DVD diode and some questions about it's abil

Hemlock Mike said:
You also asked about writing to the disk --- That's when the LD is pulsed at high power and high speed to record the 1's and 0's onto the disc. Don't ask me how they erase !!!

Mike
The -RW part of a DVD-RW works through a phase change in the material on the disk. The disk is coated with GST, Ge2Sb2Te5, or germanium antimony telluride (I think this is right, it's at least close) or a similar material. Hitting a certain spot with a laser heats it up (clearly). Very high heat for a short time and a quick cool down will give 1 phase of the material, whereas a lower heat for possibly a slightly longer time (or possibly the same amount of time, not sure how they program it with the burners) will give a different phase. These phases will have different properties, such as reflectivity (which is how the information is read back off). Heating the cell again by hitting it with the laser again will simply change the phase the same way it did the first time, thereby rewriting the data.
 




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