BSA Flow Software Installation and User's Guide - CSI

for all the relative refractive indexes between 0,6 and 2 (by steps of 0,01)
The scattering mode may change with the scattering angle.
The sytem was composed of one laser beam, one particle and one detector.
The detectors of the PDA receiver have slightly different scattering angles,
which depend on the collection angle of the receiver optics and the
intersection angle of the beams.
7.7 Catalogue of some common particles
7.7.1 How to read the scattering charts
The following charts have been calculated for a small selection of relative
refractive indices. Each chart has two panels.
Top panel The top panel shows the scattering angles for each incident ray. The incident
rays are shown for the upper half of the particle alone, although the bottom
half is symmetrical, as in Figure 7-63. However, it is difficult to follow the
various rays. Therefore, in these illustrations, only the light rays incident on
the upper half of each sphere are shown.
Reflection: The angles of light cover a range from 180° to 0°, corresponding
to the off-axis distance of the incident beam of 0 to 1.0r (r = radius of the
sphere).
Refraction: Similarly, the angles of scattered light span from 0° to ϕc1, the
critical angle for refracted light.
2nd order refraction: When nrel > 1, the light rays show a characteristic
property: when the off-axis distance of the incident light increases from 0 to
1r, the angle decreases from 180°, passes through minimum (the rainbow
angle) and then increases again till it reaches ϕc2, thus folding back and
forming a range such that for each output angle there are two incident rays -
or even three if 180° is also passed.
When nrel < 1, 2nd order refraction covers the entire range of scattering
angles and gives double contributions in the range 0 to ϕc2 = ϕc1, i.e. in
the range of 1st order refraction.
Bottom panel The bottom panel shows the angular distribution of the relative intensity of
the scattered light (logarithmic scale, 5 decades, 1 decade indicated by each
dotted circle) in each of the three modes: reflection, refraction and 2nd order
refraction. The calculations were based on geometrical optics, and were
made for a particle 50 µm in diameter and a single point receiving aperture.
Upper half: The upper half of the bottom panel shows the situation when
polarization is perpendicular (S, ⊥) to the plane common to the optical axes
of the transmitting and the receiving optics.
7-82 BSA Flow Software: Reference guide