BSA Flow Software Installation and User's Guide - CSI

Scattering angle The scattering angle is measured relative to the direct forward scatter
direction, i.e. positioning the receiver directly opposite to the transmitter
would correspond to a scattering angle of 0 degrees.
Receiver focal length The focal length of the front lens of the receiving optics. Used for
calculation of the fringe spacing in and dimensions of the measurement
volume.
Expander ratio It should be set to 1 if no beam expander is used. The effective receiving
aperture size is multiplied by the expander ratio and the measurable particle
size range is divided by the same factor. Using an expander favours the
measurments of small particles.
Fringe direction The Fringe direction setting describes the direction of fringe motion (in the
beam intersection volume – see 7.3.2.1 Main flow direction and fringes
direction) relative to the receiving optics orientation, i.e. whether the fringes
move in the direction from receiving aperture U1 towards U2 or from U2
towards U1.
The fringe direction setting affects the sign of the phase factors but not
the Doppler frequency. Therefore, the direction of fringe motion affects
the measurement of diameter but not the velocity measurement.
For the ClassicPDA and the FiberPDA the fringe direction can be
positive or negative (see Figure 5-23).
For the DualPDA there are four different possible combinations, because
the fringe direction must also be considered for the V component. The
fringe direction setting can be U+/V+, U+/V-, U-/V+ or U-/V- (see
Figure 5-24).
The user can check the fringe direction by using the phase plot (see
paragraph 5.16). If the fringe direction is incorrect, the phase of most of
the detected particles will be outside the tolerance band (spherical
validation)
Figure 5-23. Fringe direction settings for the FiberPDA (front view).
5-32 BSA Flow Software: Project explorer objects