10
Fig. 8 Isophote diagram of the intensity distribution
around the illumination-side focus (PSF
ill
).
The intensity at the focus is normalized as 1.
(Born & Wolf, Priniples of Optics, 6th edition 1988,
Pergamon Press)
Let the statements made on PSF so far be further
illustrated by the figure on the left. It shows a sec-
tion through the resulting diffraction pattern sur-
rounding the focus on the illumination side
(PSF
ill
). The lines include areas of equal brightness
(isophote presentation). The center has a normal-
ized intensity of 1. The real relationships result by
rotation of the section about the vertical (Z) axis.
Symmetry exists relative to the focal plane as well
as to the optical axis. Local intensity maxima and
minima are conspicuous. The dashed lines mark
the range covered by the aperture angle of the
microscope objective used.
For the considerations in this chapter, only the
area inside the red line, i.e. the area at half maxi-
mum, is of interest.
min.
max.
min.
max.
0,9
0,7
0,5
0,3
0,2
0,1
0,05
0,03
0,02
0,015
0,01
0,003
0,002
0,001
min.
max.
min.
min.
min.
max.
0,03
0,01
0,003
0,02
0,005
0,01
0,005
0,005
0,002
0,005
0,01
Optical axis
Fo
ca
l plane
337_Zeiss_Grundlagen_e 25.09.2003 16:16 Uhr Seite 13
