[Laser] Re: Fresnel lenses and dispersal angle

[Joe Fitzgerald]

KY1K wrote:

> Spherical aberration is the uniformity of the focal length of the lens 
> as the wavelength of the light is varied.
> 


Art, I think you are describing chromatic aberration.

Here is a nice web page on spherical aberration.  It is most definitely 
_not_ our friend!

http://www.glenbrook.k12.il.us/gbssci/phys/Class/refln/u13l3g.html

-Joe KM1P