For those who are interested in this topic, you can check out 
the following websites or google for more. The  "Standard eye 
response curve" in most of the LED datasheet is the CIE curve.

"The CIE (1931) Photopic Luminosity Function is a symmetrical curve 
fitted to an ensemble of data sets describing the Spectral Response 
Function of the Human Eye to radiation of inadequately controlled 
intensity and color temperature."

http://www.4colorvision.com/files/photopiceffic.htm
http://www.intl-light.com
http://www.imagineeringezine.com/ttaoc/theory-lt.html

The last two links are excellent and also talk
about optic sensors.

Regards,
Xiaofan

-----Original Message-----
From: Peter 
Sent: Tuesday, June 28, 2005 5:56 AM
...
The maximum sensitivity of the human eye coincides with the peak output 
wavelength of the sun.
...
Peter

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