Apparent Brightness / Luminous Intensity The intensity of light as it appears to the human eye. The eye is most sensitive to wavelengths (colors) in the center of the visible spectrum. The graph below shows several curves provided by the CIE Commission Internationale de l'Eclairage Proceedings. This graph can be used to determine a close approximation of the apparent brightness of one wavelength compared to another when the human eye is in either photopic (normal) or scotopic (low light) vision modes.

CIE chart

Some examples of the difference in apparent brightness of a laser under normal (non-low-light) conditions are:
635nm red is about twice as bright as 650nm red.
650nm red is about 3 times brighter than 670nm red.
520nm green is about 7 times brighter than 650nm red.

Many of our customers have had questions regarding the apparent brightness of various wavelengths of the lasers that we sell. The following information should help.

Laser FAQ

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