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Finite slit: Diffraction


Figure 8: Analysis of diffraction experiment with slit of finite width

Figure 8 shows how we can compute the intensity pattern for a slit of finite width a (no longer infinitesimal compared to the wavelength) by using our result for N slits. The idea is simple. If we made a diffraction grating with N small slits spaced very closely apart at distance d=a/N, and kept adding more little slits, eventually we end up removing all of the grating, leaving just a single slit of width tex2html_wrap_inline1274 . The special term diffraction is generally used to describe interference patterns formed by finite openings. The underlying physical principle, however, remains interference.

Tomas Arias
Thu Sep 13 15:26:14 EDT 2001