Apparatus for measuring transverse moment of an electromagnetic field associated with an optical beam

摘要

The value of a transverse moment of any order of the electromagnetic field associated with an optical beam (and in particular the spot-size of such a beam) is determined by two successive measurements of the optical power of the beam: one measurement is a direct measurement, the other is effected after spatially modulating the transverse distribution of the electromagnetic field by a factor proportional to the n-th power of the transverse coordinate of the beam, n being the moment order. The moment can be obtained from the ratio between the two measurements. The invention includes also the apparatus for carrying out the method.