AbstractThe influence of the surface roughness of solid conducting spheres on the response of a phase‐Doppler anemometer (PDA) is described by using a ray theory model. A rough particle surface is modeled as an ensemble of distorted spheres. First‐ and second‐order reflection and diffraction are considered for far‐field calculations of the PDA phase difference. The numerical simulations are accompanied and supported by experimental results. Single roughSnspheres are captured inside an electro‐dynamic trap and investigated with a standard phase‐Dop