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ONFS and ENFS setup for colloid measurements.

The systems are sketched in Figs. 4.10 and 4.11.

**Figure 4.10:** The optical setupt for the measurement of scattering from colloids some microns large with ENFS.
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**Figure 4.11:** The optical setupt for the measurement of scattering from colloids some microns large with ONFS.
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The measurements described in Chapters 7 and 8 cover the wavevector range $\left[q_{min},q_{max}\right]$ about $\left[2\times 10^5\mathrm{m}^{-1},4\times 10^6\mathrm{m}^{-1} \right]$ . By using Eqs. (4.1) and (4.4), we obtain $D\gtrapprox5\mathrm{mm}$ and $z\approx 6\mathrm{mm}$ . A $2\mathrm{cm}$ beam diameter, obtained with lenses with $25\mathrm{mm}$ diameter, as shown in Fig. 4.2, is enough to ensure that the intensity is constant over the length . For the measurements described in Chapters 7 and 8, we used larger lenses with $50\mathrm{mm}$ diameter, with a larger beam diameter, in order to ensure a better uniformity, and was increased acordingly.

Following Eq. (4.3), we obtain the magnification: . We used a 20X microscope objective and numerical aperture of 0.45.

The whole optical system for ENFS is shown in Fig. 4.2.

For ONFS, we insert a beam stop through a hole inside the lens mount. The beam stop and its adjustable mount is shown in Fig. 4.7.

Next: SNFS setup for non Up: The experimental system. Previous: The acquisition and elaboration Contents

2003-01-09

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