This paper presents optical Fourier transforms having been used to measure wavelengths and orientation of sea waves in the Jasin area of the North Sea, that is located approximately 200 km north-west of Scotland. Input films were obtained from a synthetic aperture radar (SAR) borne on a satellite. The research work was carried out in Blackett Laboratory, Imperial College of Science and Technology, using optical Fourier transform equipment. The Institute of Ooeanographio Science provided us with SAR films as well as a grant partly. Comparing the results obtained from direct measurement on the sea, or using the computer to calculate optical Fourier transforms of the input films of sea waves, with that obtained from our method, it is obvious that this method is quicker and more reliable. Under the guidance of Prof. W. T. "Welford, the researoh work was completed by Canadian academic visitor, Dr. R. A. Lessard and the author jointly. I would be grateful to those who might point out any error which I made in this paper.