On Thu, 24 Aug 1995, Guy Cox wrote:
 
> The beam diameter, assuming that your specimen is in a mountant
> of refactive index 1.515, will be an Airy disk at the point of focus,
> since the laser source should approximate to a point.
>
> Thus the radius (centre to 1st minimum) will be
>        0.61 * lambda / NA = 0.61 * 488 / 1.4 = 213nm
> for the 488nm line.
 
 
 
also assuming the BFP of the lens is 100% filled.
 
Regards,
 
******************************************************************************
Stamatis Pagakis
University Laboratory of Physiology            [log in to unmask]
University of Oxford, Parks Rd.                FAX:  +44 (0)1865 272469
Oxford OX1 3PT,   United Kingdom               Tel:  +44 (0)1865 272551