چكيده لاتين :
In this paper altitude measurement from water surface using laser beam is
presented. Research data indicate that the reflection of infrared waves from water surface is
about zero and it is less than 2% for visible radiations. Phase-shift and heterodyne
technique was used for the measurement, and the laser beam ( mW p nm 10 , 700 = = l ) was
modulated by a sine wave having a fixed frequency. The optimum design and low-noise
elements made it possible to detect a light power about 20 nW at operating frequency.
