Concave axicon capable of producing long distance non-diffraction beams

Abstract

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.

Description

technical field [0001] The invention relates to the field of optical design, in particular to a concave cone lens capable of producing long-distance non-diffraction light. It can be used for long-distance high-precision collimation, large-scale linear measurement, space optical communication and other tools, and plays an important role in equipment manufacturing and laser communication. Background technique [0002] J. Durnin of the University of Rochester in the United States first proposed a non-diffraction beam in 1987. It propagates in free space without diffraction, that is, the distribution of the transverse light field does not change with the propagation distance during the propagation process; the energy of the light field is concentrated, and the central spot is small and strong. high. These characteristics of the non-diffraction beam make it widely used in the fields of precise measurement and collimation, space optical communication, precision machining and cutt...

AI Technical Summary

Problems solved by technology

Among them, the conversion efficiency of the annular slit-lens method is particularly low, only about 15%; the anti-damage threshold of the holographic method is relatively low, which limits the intensity of the non-diffracting beam; The axicon method has become the most commonly used optical element for obtaining non-diffracting light due to its high damage threshold, high energy utilization rate and simple structure. The non-diffraction distance for generating non-diffraction light can be expressed as That is, when the beam radius a is fixed, the non-diffraction distance is approximately inversely proportional to the base angle γ of the axicon surface and the axicon refractive index n, so to obtain long-distance non-diffraction light, one can choose the base angle of the axicon Very small axicon, but the small base angle of the cone surface is very difficult to process, the minimum can be processed to 0.5° on the market at present, and the price is not cheap

Another solution is to use a material with a lower refractive index to process the axicon, but the range of refractive index of commonly used optical glass materials is not large, and materials with a smaller refractive index are rare and expensive

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