Waves with helical wavefronts: wave characterisics within their vortices.

Helical wavefronts can be created by transmission of coherent waves through spiral phase filters (angular wedges), This kind of wavefronts has in the center of a helicoid a singular point (a point dislocation) oiled an optical vortex in optics. According to the number m of transitions of the wavefronts through the plane perpendicular to the direction of propagation in the full angle 360 degrees the vortex is called m-charged. A usual approach supposes for the final step an integer multiple of wavelengths which hts into the whole path difference. This contribution analyses the case when this proposition is not fulfilled and the final step is not an integer multiple of wavelength The wave amplitude in the optical vortex is computed as an integral of phases of all nearest rays around the singular point. As a result it was found that for a linear wedge it is the sine square function with the argument (t(0)/lambda)(n-1), where t(0) is the final jump and n is the refractive index, which describes this situation. For an example of the wedge in form of the sinusoidal function the amplitude is given by the Bessel function of zero order. The charge of the singular point does not have influence on the form of the function.