There is a measured   c o n f o c a l  spot in
 
Appl. Phys. Lett, 64, No. 11, 1994, p. 1335-1337 (Hell, et al).
 
The spot is measured for NA=1.4, (Zeiss 100X, oil Planapochromat) 633 nm.
The lateral full-width-at-half-maximum (FWHM) was 200 nm, the axial FWHM
was 520nm. The extent of the PSF scales with the wavelength.
 
The PSF measurement was carried out for an index of refraction of the
specimen matched to the oil immersion system. A mismatched refractive index
of the sample enlarges the spot (especially) in axial direction. This
enlargement depends on the focusing depth. For further reference you can
look up the 'Handbook' or one of the recent issues of 'Bioimaging'.
 
Cheers,
 
Stefan.
 
 
__________________________________
Stefan W. Hell, Dr. rer. nat.
Tel: +358 40 500 2758 (mobile GSM)
 
Centre for Biotechnology
Medical Physics and Chemistry
PO Box 123
FIN- 20521 Turku, Finland
tel: +358 21 633 7070
fax: +358 21 633 8000