Effect of the energy resolution on the reflectivity of multilayer

This Letter presents a new method to calculate the reflectance of a multilayer of given design for the polychromatic incidence light. The variation of the reflectance with the energy resolution for this multilayer is given. For a soft X-ray multilayer of given design, the reflectance calculated with the polychromatic incidence light is smaller than that with the homogeneous light. The lower the energy resolution of the incidence light, the smaller the calculated reflectance. Using this method, we can estimate the energy resolution of the incidence light and the interface roughness from the measured reflectance, and also obtain the good fit to the measured data when the energy resolution and roughness are known