What is "Numerical aperture" ? - Blu-ray Forum

achilles · 12-13-2004, 08:33 PM

Can somebody explain to me what is "Numerical aperture" which has been changed to 0.85 in Blu-ray and is 0.65 in HD-DVD? :? What is this in normal DVD and why does it make a difference in storage?

I am writing a paper on optical media and I need to mention this.

Thanks for your help in advance

achilles · 12-13-2004, 09:12 PM

No worries

I found it…

http://en.wikipedia.org/wiki/Numeric...8microscopy%29

its amazing what you can find in the internet!

MeGaBlitz · 03-05-2006, 11:17 AM

My english is too bad to understand that on wikipedia. Can someone probably discribe it for me, please?

Thanks!
meGa

Marwin · 03-05-2006, 11:44 AM

Numerical Aperture (NA)
A unitless measure of the ability of a lens to gather and focus light. A numerical aperture of 1 implies no change in parallel light beams. The higher the number, the greater the focusing power and the smaller the spot.

All you need to know is basically that the lens focuses the laser beam with greater precision when reading/writing data, which allows more data to be stored in less space.

MeGaBlitz · 03-05-2006, 06:58 PM

Thank you for this informations!

meGa

12-13-2004, 08:33 PM	#1
achilles New Member Member since:Dec 2004	What is "Numerical aperture" ? Can somebody explain to me what is "Numerical aperture" which has been changed to 0.85 in Blu-ray and is 0.65 in HD-DVD? :? What is this in normal DVD and why does it make a difference in storage? I am writing a paper on optical media and I need to mention this. Thanks for your help in advance

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12-13-2004, 09:12 PM	#2
achilles New Member Member since:Dec 2004	No worries I found it… http://en.wikipedia.org/wiki/Numeric...8microscopy%29 its amazing what you can find in the internet!

03-05-2006, 11:17 AM	#3
MeGaBlitz Junior Member Member since:Feb 2006	My english is too bad to understand that on wikipedia. Can someone probably discribe it for me, please? Thanks! meGa

03-05-2006, 11:44 AM	#4
Marwin Developer Top contributor Member since:May 2003 Blu-ray collection:10 DVD collection:5 iTunes collection:1	Numerical Aperture (NA) A unitless measure of the ability of a lens to gather and focus light. A numerical aperture of 1 implies no change in parallel light beams. The higher the number, the greater the focusing power and the smaller the spot. All you need to know is basically that the lens focuses the laser beam with greater precision when reading/writing data, which allows more data to be stored in less space.

03-05-2006, 06:58 PM	#5
MeGaBlitz Junior Member Member since:Feb 2006	Thank you for this informations! meGa

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