A New Method for Measuring Thin‐Tilm Optical Constants Using Transmission Gratings in the Soft X‐ray Range

In this paper we present an analytical study of a rectangular and translucent diffraction grating composed of a material with known optical constants covered with a vacuum (in situ) deposit of a thin film of a material with unknown optical constants. We show that by choosing gratings of the proper material and dimensions and by measuring the intensity spectra of the coated gratings, we can use the ratios of the observed orders to calculate the optical constants of the thin‐film material. The method’s great advantage is its independence from the absolute intensities of the incoming and transmitted light, i.e., no measurements need be made of the absolute intensities.