Reflectometric method of measurement and apparatus for realizing the method

A method of measuring the reflectometric properties of a sample by employing a 2-channel reflectometer having a measuring channel and a reference channel with each channel having a measuring diaphragm, comprising the steps of calibrating the reflectometer by placing a standard sample in the measuring channel, adjusting the light intensities in the measuring channel and the reference channel into balance through operation of the measuring diaphragm of the reference channel to provide a calibration measurement, placing a sample to be measured in the measuring channel, adjusting the light intensities in the measuring channel and the reference channel to balance by actuation of the measuring diaphragm in the reference channel, and calculating the reflective value of the sample to be measured by use of the set value of the measuring diaphragm of the reference channel from the reflectance value of the standard sample on the basis of the set value of the measuring diaphragm of the reference channel in the calibration measurement.