Diffraction of laser radiation by a plasma wave-the near field and far field limiting cases

For the detection of plasma density fluctuations where the wavelength is too large for traditional Bragg scattering, two techniques have been suggested; phase scintillation and far forward scattering. It is shown in this paper that these techniques are not fundamentally different; they correspond respectively to near field and far field detection of electromagnetic radiation diffracted by the density fluctuations.