  A compact Raman LIDAR system with a spectrograph was used for express ice
thickness measurements. The difference between the Raman spectra of ice and
liquid water is employed to locate the ice-water interface while elastic
scattering was used for air-ice surface detection. This approach yields an
error of only 2 mm for an 80-mm-thick ice sample, indicating that it is
promising express noncontact thickness measurements technique in field
experiments.
