Reciprocal Lattice Spacings
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In the formation of TEM diffraction patterns as shown in Figure 2683, the reciprocal lattice spacing Rhkl, measured as the distance from the origin (O, the location of the directly transmitted beam on the screen) to some diffraction spot (A), is related to the real crystal spacing dhkl, by,

          dhkl =λL/Rhkl -------------------------------- [2683]

          L -- The camera length,
          λ-- The wavelength of the incident electron beam,
          λL -- The camera constant.

relationship between the spacing R and the camera length L for diffraction in a TEM

Figure 2683. The relationship between the reciprocal lattice spacing Rhkl and the camera length L for diffraction in a TEM.

By determining the reciprocal space of a crystal, one is able to analyze:
          i) Texture of the material,
          ii) Grain orientation,
          iii) Burgers vector,
          iv) Line directions of dislocations,
          v) Crystallographic nature.