According to the extreme large and mutable characteristics of water absorption coefficient in the infrared spectrum

a device for measuring thin thickness of water layer is developed on the basis of the previously presented system for measuring water absorption coefficient in the optical region

in order to change the thickness of water layer from 0.04 mm to 350 mm.Then water absorption coefficient is measured with water layers of different thicknesses between 0.04 mm to 150 mm.After the effect of impurity was removed

measured data is integrated effectively and the absorption coefficient of pure water in spectrum from 900 nm to 2500 nm is obtained.Because the pure water absorption coefficient of each section in the spectrum is measured accurately under optimum detecting range of the instrument

the result is more reliable and agrees well with previous measurements.It can be used as basic data in quantitative remote sensing applications.