The name is absent

Screen Position (mm)

Figure 5.4 : Measured (solid curves) differential fringe patterns produced by the
transmission of the THz beam through the THz SLM in two double-slit Conhgurations,
compared with analytical calculations (dashed curves). The insets show the “on” and
“off” Conhgurations of the 16 pixels, with zero bias on the gray pixels, and the white
pixels modulated with a 3-kHz square signal alternating between 0 and 14V.

Screen Position (mm)

are unbiased. After focusing the transmitted THz wave front with a lens, the THz
detector (with a 1 mm aperture) scans along a line in the focal plane of the lens,
across a 64 mm interval. Figure 5.4 shows the measured differential fringe patterns
(solid curves) at 0.36 THz for the two double-slit configurations. These have the same
slit sizes (b = 4 mm) but different slit separations (α = 8 mm and 12 mm respectively
in Figure 5.4 (a) and (b). As expected, the fringes appear at distances, multiples
of ʌɔ away from the central fringe. Here, Λ is the observation wavelength, f is the
focal length of the focusing lens and α is the slit separation. Analytical calculations
of the double-slit diffraction pattern, assuming a plane wave illumination, best fit the
measured data with а = 9.8 mm and 13.8 mm respectively for the two configurations,
and b = 5 mm (see dashed curves in Figure 5.4). When using metal slits of the same
dimensions as those of the slits formed by the modulator in a direct observation of the
diffraction fringes, similar values for these fit parameters are observed. This indicates
that the differences between the fit parameters and the actual geometrical dimensions

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