Ultraviolet laser variable power beam expansion lens

Abstract

The invention provides an ultraviolet laser variable power beam expansion lens. The beam expansion lens comprises a first lens, a second lens and a third lens which are arranged in an incident light transmission direction, wherein the first lens L1 is a convexo-plane positive lens; the second lens L2 is a biconcave negative lens; the third lens L3 is a convex positive lens; and the maximum light incidence diameter phi of the ultraviolet laser variable power beam expansion lens is equal to 2 to 8mm and the wavelength lambda is equal to 355nm. The ultraviolet laser variable power beam expansion lens has a very compact integral structure; by using the variable power beam expansion lens, a laser focusing system can obtain a large image space aperture angle, so that the energy density at a focusing point during the laser focusing is greatly improved and the machining efficiency of the laser is improved; and because the beam expansion multiple of the laser beam can be adjusted at any time, the same optical application system can be used for machining for different laser parameters output by different lasers.

Description

technical field [0001] The invention relates to an optical element, in particular to an ultraviolet laser zoom beam expander. Background technique [0002] The optical beam expander occupies a very important position in the laser processing optical system. According to the Lagrange invariant (Lagrange) theorem: [0003] J=nDθ=n'D'θ' [0004] Among them: n and n' represent the refractive index of the optical system in the medium, when the medium is air, n=n'=1, D and D' represent the diameter of the entrance pupil and exit pupil of the optical system; θ and θ' represent The field angle of the incident light and the field angle of the outgoing light can be expressed in radians when the field angle is very small. It can be seen from the above formula that when the outgoing laser beam has a divergence angle, that is, when θ is large, the Beam mirror from D→D', that is, magnification β=D' / D times, can reduce the divergence angle of the laser beam by β times, so as to achieve th...

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Problems solved by technology

[0007] It can be seen that the smaller D is, the larger δ will be, which will greatly reduce the processing accuracy of the system

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