Self-Assembly of Synthetic and Biological Polymeric Systems of ...

(APD) and its associated optics (pinhole or optical fiber) mounted on the arm of a goniometer.
The detector optics determines the horizontal and vertical dimensions of the scattering
volume, whereas its depth is defined by the incident laser beam width. Band pass filters with
high transmission at the incident laser light wavelength are often used in front of the detector
to suppress undesired contributions of stray light or fluorescence from the sample.
4. The electronic hardware components associated with the detector used for signal
processing. The scattered intensity I (q,t), which is monitored by the optical detector, is
typically digitalized and stored in a computer. These raw data have to be further processed: in
the case of static light scattering, particle form factor models can be used to fit the
experimental data; in a dynamic light scattering experiment, the raw data have to be
converted into the time intensity correlation function g2 (q, τ). This is done during the
measurement using a very fast hardware correlator as, for example, the ALV 5000 from ALV,
Langen, Germany.
5. In a typical light scattering experiment, light from a laser source passes through a
polarizer, which defines the polarization of the incident beam and, then, enters the scattering
medium. The scattered light, then, passes through an analyser, which selects a given
polarization and finally enters a detector. The position of the detector defines the scattering
angle, θ. In addition, the intersection of the incident beam and the beam intercepted by the
detector defines a scattering region of volume V. In modern light scattering experiments the
scattered light spectral distribution is measured by a photomultiplier, which is the main
detector (24).
Figure 2.6. Schematic representation of an usual light scattering experiment (26).
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