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geoffkait
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Joined: Apr 29 2008 - 5:10am
The truth about the Green Pen revealed

The green pen was an audiophile tweak from Audio Prism that came out about 25 years ago. The green pen was used around the outer edge of CDs to improve the sound. The green pen appears to work by absorbing stray scattered CD laser light that might other wise be detected as “real signal” by the photodetector. The green pen is a very good CD tweak as far as it goes. The reason I say that is because the green pen can only absorb visible red light which accounts for only a fraction of the scattered laser light inside the CD transport. Most of the scattered light is actually invisible, in the range 700-850 nanometers. Only the light just below 700 nm (visible red) can be absorbed by the color green or green blue (cyan). Thus the problem of scattered laser light is only partially solved by the Green Pen. Around 2/3 of the scattered light still has the potential to enter the photodetector even with the Green Pen. Oh, dear!

Addendum: the CD laser appears red to the naked eye only as a safety precaution. Most of the laser bandwidth is invisible. The nominal wavelength of the CD laser is 780 nm, which is near infrared.

Yes, I know what you’re thinking - “I always thought the laser was monochromatic.”

geoffkait
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Last seen: 18 hours 33 min ago
Joined: Apr 29 2008 - 5:10am
So, the punch line to this OP

So, the punch line to this OP is there’s an audiophile product now that absorbs all (rpt all) scattered laser light - invisible and invisible light. So this product works 3 times better for CDs than ye olde Green Pen, which only absorbs visible red light and red light only comprises about 30% of the scattered light inside the CD transport. And since the product absorbs all wavelengths of light it works for SACD and BLU-RAY too. I am considering writing a paper explaining how this product (New Dark Matter) works.

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