High precision parallel glass plate test with the use of the optical vortex interferometer

In this paper the new method of parallel glass plat test is presented. In the method an Optical Vortex Interferometer (OVI) is used. The OVI generate the regular net of optical vortices by interference of three plane waves. One wave is deformed after crossing measured parallel glass plate. The deformation of the wave-front is measurable because the deformation of vortex net structure arises from the wave-front deformation. The record of the vortex points' positions before and after parallel glass plate insertion in the optical arrangement is essential. Shown in this paper the analysis vortex points positions change gives high precision information about real shape of the parallel glass plate.