What do Blu ray Players use to Play other formats?

[Meatball]

I'm just curious really, if anyone has opened up a dedicated blu ray player - say, a Sony BDP series unit - and peeked inside.

These dedicated Blu ray players are also able to play CDs, and regular DVDs.

Does this backward compatability for playback alone require a separate diode for each format since each format requires a different wavelength for disc burning?

Put simply, can Blu ray diodes be used to read DVDs and CDs?

I haven't been inside one of these players to see for myself, but I wouldn't be surprised to find that they use the 405nm diode for reading everything, since its wavelength would allows it's smaller dot to fit inside the larger pits on DVDs and CDs. Do you suppose the 405nm dot would have to be focused to a larger diameter to accomodate the larger pits if this is the case?

In the name of curiousity,

-Tyler

 

[ilikeadabox]

Re: Can What do Blu ray Players use to Play other formats?

Umm If i'm not mistaken I have seen in laptops and stuff that is that blu ray drives have multiple diodes including a Blu Ray and a red one.

 

[nikokapo]

Re: Can What do Blu ray Players use to Play other formats?

Put simply, can Blu ray diodes be used to read DVDs and CDs?

Yes. They can also write them.
These kinds of technology are usually backwards compatible.

The problem relies on formats and not on the ability to read files. For example, you can't read an .mkv file on a DVD player, simply because they don't support the format (container in this case).

 

[pseudolobster]

Re: Can What do Blu ray Players use to Play other formats?

Yep, every bluray player or burner that also reads or writes cds and dvds will also have a red diode and an infrared diode. Some times both red and ir diodes will be in one can, or in the case of the PS3, all three diodes are in one can.

 

[Meatball]

Re: Can What do Blu ray Players use to Play other formats?

I guess what I might be getting at, would be referring to Blu ray players only. The kind of blu ray player that you might actually have set up with your TV and such. Do they only need one 405nm diode to be backwards compatible with DVDs and CDs?

Thanks!

 

[pseudolobster]

Re: Can What do Blu ray Players use to Play other formats?

Yes, they need all three diodes in order to read all three formats. A playstation 3 (one of the examples I gave) is a reader only device, it cannot burn discs, and you plug it into your TV. It has all 3 diodes in one can. The PHR-803T sled is from an xbox 360 hd-dvd player, again, a playback device you plug into your TV, and it has a violet diode in one can, and the red and IR diodes in another can.

If you ever found a bluray player that *only* played bluray, and didn't play dvd's or cd's, then yes, it would only have the violet diode, otherwise all players and burners, for the computer or the TV, all have three different lasers inside.

 

[LaserRX]

Re: Can What do Blu ray Players use to Play other formats?

CD's, DVD's Blu Ray disks and most optical media similar to these store data in the form of flats and lands. Because a 405nm laser can be focused to a much smaller area then the 780nm or 650nm lasers used in CD's and DVD's they are able to have more of these flats and lands on the area of the disk. This is why a CD player can't read a DVD, 780nm just can't focus small enough to read them properly.

Roughly light can be focused to 1/2 its wavelength without going into more complicated math.

780nm ~ 390nm
650nm ~ 325nm
405nm ~ 202.5nm

Technically the Blu Ray player could read all three with just one laser, the 405nm, but this would require a device to focus the laser according to the media type. It is much cheaper to use additional laser diodes, 780nm and 650nm instead to read these disks.

 

[photonaholic]

Re: Can What do Blu ray Players use to Play other formats?

all 3 in one can, possibilities abound....

With a good heatsink or TEC, couldn't you fire all 3 at once???

 

[StridAst]

Re: Can What do Blu ray Players use to Play other formats?

I couldn't give you links, (mostly as I am in a hurry) however I have read a thread someone started on a magenta laser. they were running the red and violet at the same time from the ps3 diode (I think it's called a kes-400aaa or something close). problems were the red and violet lasers need a lens at a different location. the ps3 apparently adjusts the lens position according to which laser is being used. the end result was a cool looking laser, but the beams aren't focused well together, and one was spreading out much faster then the other. I remember reading that he was running the two lasers off a single driver, but running for 30 seconds max as he didn't have a heatsink. could be fascinating to play around with though.

StridAst

 

[pseudolobster]

Re: Can What do Blu ray Players use to Play other formats?

Yeah, you can run more than one of the ps3 diode's lasers at a time, though even with a TEC you're going to run into heat problems, since the dies are stacked on top of each other, the heat generated by one laser has to pass through another diode before it can be sunk away by the TEC. Also, as mentioned before, since they're different wavelengths coming out of one can, it's impossible to focus both beams at once using a lens. In theory you could use some sort of parabolic mirror to focus it instead of a lens and the wavelengths wouldn't separate, but that's getting kinda silly.

Also, they're very low powered, and fairly expensive.. The violet is capable of 15-30mW, and the red is maybe 50mW tops. Last time I checked they were still $50 per sled.

 

[Gryphon]

Re: Can What do Blu ray Players use to Play other formats?

^ I remember people doing that for a nice magenta color from one diode, too bad it couldn't be focused propery :undecided:

Those diodes were THE easiest extraction of any sled i've done, just glued to a plate around the can :crackup: