The study on the focusing property of the VLS grating with different types of beams

The VLS grating has the ability of self-focusing and eliminating aberration, and it has been widely used in many fields. The plane VLS grating has two types, one is the one-dimensional VLS grating and another is two-dimensional VLS grating. In some practical applications, we need to know the focusing property of the two-dimensional VLS grating, so it is important to research the focusing property of the two-dimensional VLS grating illuminated by different types of light beams. In this paper, we mainly studied the focusing property of the two-dimensional VLS grating whose grating lines are arc. Light beams diffracted by this kind of the VLS grating can form a focal point in one position or form a horizontal focal line and a vertical focal line respectively in two different positions. We experimentally studied the change of the focusing position under different incident angles using the monochromatic plane wave or spherical wave as incident light, and studied the influence of different wavelengths of the monochromatic plane wave on the focusing position. The difference between the positions of two focal lines which relates with the focusing property of the two-dimensional VLS grating is also discussed in our work.