Do Blu-Ray / DVD readers have two heads?

[WyomingKnott]

Does a device that can play both Blu-Ray and DVD video need two different lasers? Are they combined into one head, in two separate heads on the same mechanism, or completely independent?

Thanks.

 

[COLGeek]

2 lasers (different wavelengths), usually on one "head" to minimize the number of moving parts and costs, while increasing reliability.

 

[Dark Lord of Tech]

2 lasers in the blueray ^ optical drive

While a DVD uses a 650 nm red laser, Blu-ray Disc uses a 405 nm "blue" laser diode. Note that even though the laser is called "blue", its color is actually in the violet range.

 

[COLGeek]

For more:

http://en.wikipedia.org/wiki/Blu-ray_Disc

 

[Dark Lord of Tech]

Plus 1 ^

 

[COLGeek]

Plus 1 ^

Great minds think alike!

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[WyomingKnott]

Tough choice for best. First right answer or picture? Too bad I can't split it.

COLGeek: I had already read that on Wikipedia, but gave up after reading "Backward compatibility

Though not compulsory, the Blu-ray Disc Association recommends that Blu-ray Disc drives be capable of reading standard DVDs and CDs, for backward compatibility. A few early Blu-ray Disc players released in 2006 could play DVDs but not CDs."

One of my favorite half-witticisms is "Great minds think alike. So do you and I."

 

[WyomingKnott]

Best answer selected by WyomingKnott.

 

[Dark Lord of Tech]

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