Diffraction coupler for measuring laser characteristics

A study is made of the difTraction of laser radiation by widely spaced wire gratings including the cases of a nonperiodic distribution of conductors, with the aim of applying such gratings to measurements of the laser radiation characteristics. A theoretical analysis is carried out in the approximation of single scattering of the incident radiation by components of the gratings without the diffraction interaction between the components of a widely spaced grating. A detailed investigation is made of the Fresnel diffraction which is shown to exhibit a new property: a grating with a certain set of parameters can reproduce the angular distribution of the incident radiation and this simplifies the existing systems for measuring the radiation characteristics and makes it possible to increase the range of the measured quantities. It is shown that a nonequidistant grating possessing these properties introduces fewer distortions into the transmitted beam in the Fresnel diffraction case than a periodic grating. A report is given of a study of the polarization dependence of the scattered field which makes it possible to use the proposed couplers for the determination of the direction of polarization.