The invention discloses a concave
axicon capable of producing long distance non-
diffraction beams. The concave
axicon capable of producing long distance non-
diffraction beams is provided with an
axicon, wherein a cone angle of the axicon is gamma, an undersurface
radius of the axicon is a, and an
refractive index of the axicon is n. The axicon is divided into a cylinder part and a
circular cone part along an axis direction, one end in which the cylinder part and the
circular cone part are adjacent is the inside, the other end is the outside, and the outside undersurface of the cylinder part is in a concave spherical
surface shape, wherein a center of the concave spherical
surface shape is the axis of the axicon, and a curvature
radius of the concave spherical
surface shape is R. The long distance non-
diffraction beams can be achieved through a
single element, the problems that a cone angle of a traditional axicon is small and
processing is hard are overcome, the concave axicon capable of producing the long distance non-diffraction beams has the advantages of being easy in element
processing, simple in structure, high in
transfer efficiency, and high in optical damage threshold value, a concise and effective new way is provided for acquiring the long distance non-diffraction beams, and in addition, non-diffraction distance of the non-diffraction beams can be adjusted through adjusting radii of incident beams and a size of the curvature
radius of the undersurface of the concave axicon.