To acquire the optical parameters of the matters,the variable optical path method and the equipment of the spectrometer dictation with NA are employed.For example,the optical parameters of the deionized water are measured by micron displacement mechanism in the peak of the water absorption.The results of the measurement show that the absorption coefficient is 26.154 cm-1 which accords with those in the existing reference which are 26 cm-1 and 28 cm-1 respectively,and the scattering coefficient is 6 cm-1.The...