A CO2laser small‐angle scattering experiment has been set up and used for the investigation of plasma density fluctuations in a magnetized plasma. The local oscillator reference beam for homodyne mixing is produced by diffraction from a thin tungsten wire which lies in the main probe beam near the scattering center. The diffraction wire produces a diffraction pattern covering the scattering plane. An angular adjustment of one single mirror in the outgoing probe beam permits easy alignment of different scattering angles and scattering directions. Rayleigh scattering of ultrasonic waves has been used for testing and calibrating the scattering system. First results from plasma measurements are presented.