Measurements of the thickness distribution of thin films with a slit-beam-profile reflectometer

The thickness distribution of single-layer thin films is measured with a slit-beam-profile reflectometer. A convergent slit beam generated by a cylindrical lens is projected onto a specimen. A CCD chip with a pixel matrix of 512 x 480 is used to detect the intensity distribution of the reflected beam, which is passed through another cylindrical lens. By analyzing the picture taken by the CCD, we can obtain information about the angular reflectance at each reflecting point along the slit line, and the thickness or the refractive index at each point can be evaluated by mathematical fitting to a reflectance formula.