A kind of ultraviolet Zooming expander
[technical field]
The present invention relates to optical lens, relate in particular to a kind of Ultra-Violet Laser beam expanding lens.
[background technology]
The optical beam-expanding mirror occupies considerable status in the Laser Processing optical system, according to Laplace invariant (Lagrange) theorem:
J=nDθ=n′D′θ′
Wherein: n and the refractive index of n ' expression optical system in medium, when medium is air, n=n '=1, the entrance pupil diameter and the exit pupil diameter of D and D ' expression optical system; The field angle of θ and θ ' expression incident light and the field angle of emergent light, when field angle is very little, can represent with radian, by following formula as seen, when the emitting laser bundle has the angle of divergence, when promptly θ is big, by beam expanding lens by D → D ', promptly amplify β=D '/D doubly, all can make the angle of divergence of laser beam dwindle β doubly, thereby reach the purpose of shaping laser beam.
On the other hand, general laser beam bright dipping diameter all very little (about about Φ=1mm) for this reason, directly focus on so thin light beam, and its Rayleigh disk is just very big, according to the Rayleigh disk formula:
Rayleigh disk diameter δ=2.44 λ f/D
As seen, D is more little, and δ is just big more, can reduce the machining precision of system so widely.In view of above two basic demands, the optical system of Laser Processing is generally all wanted the adapted beam expanding lens.
[summary of the invention]
The invention provides this beam expanding lens of a kind of ultraviolet laser variable power beam expansion lens and can regulate laser beam output size in the larger context.
The technical solution used in the present invention is: a kind of ultraviolet Zooming expander, be used for Ultra-Violet Laser and expand bundle, it comprises first lens (L1), second lens (L2) and the 3rd lens (L3) that are arranged in order along the light beam incident direction, the input aperture of this ultraviolet Zooming expander is 1mm, and wavelength is 355mm; Described first lens (L1) and the 3rd lens (L3) all are biconvex lens, and second lens (L2) are biconcave lens, and three lens are positioned on the same optical axis; Described first lens (L1) are d2=3~10.3mm with the spacing of second lens (L2) on optical axis, and described second lens (L1) are d4=149~158.1mm with the spacing of the 3rd lens (L1) on optical axis.
Wherein, described d2=10.3mm, described d4=149mm, the expansion bundle multiple of this ultraviolet Zooming expander is 4.
Wherein, described d2=6.6mm, described d4=155.4mm, the expansion bundle multiple of this ultraviolet Zooming expander is 7.
Wherein, described d2=3mm, described d4=158.1mm, the expansion bundle multiple of this ultraviolet Zooming expander is 10.
Wherein, described first lens (L1) are made of two curved surface S1 and the S2 that the curvature of face is respectively R1 and R2, and R1 is 100.00mm, and R2 is-13.24mm, and the center thickness d1 on optical axis is 3.00mm.
Wherein, described second lens (L2) are made of two curved surface S3 and the S4 that the curvature of face is respectively R3 and R4, and R3 is-10.00mm that R4 is 7.40mm, and the center thickness d3 on optical axis is 2.00mm.
Wherein, described the 3rd lens (L3) are made of two curved surface S5 and the S6 that the curvature of face is respectively R5 and R6, and R5 is 517.32mm, and R6 is-99.22mm, and the center thickness d5 on optical axis is 3.00mm.
Wherein, the material of three lens of described ultraviolet Zooming expander is identical, is Nd/Vd=1.46/67.80.
The laser focusing system that ultraviolet laser variable power beam expansion lens of the present invention can make obtains bigger picture side's aperture angle, the energy density at focus place when greatly improving laser focusing, and the working (machining) efficiency of raising laser; Simultaneously, because the expansion bundle multiple of laser beam can regulate at any time, can use at the different laser parameters of various lasers output with a kind of optical application system; The laser output parameter that also can be used for simultaneously same type is applied to different laser applied optics systems has different requirements to the laser input parameter.
[description of drawings]
The invention will be further described in conjunction with embodiment with reference to the accompanying drawings.
Fig. 1 is a structural representation of the present invention;
Fig. 2 is optical transfer function MTF figure of the present invention;
Fig. 3 is a maximum optical path difference diagrammatic sketch of the present invention.
[specific embodiment]
In the laser processing procedure, require laser very concentrated usually, guarantee the energy density of laser processing procedure focus point, make laser work effectively, and improve the work efficiency of laser at the energy of focus point.Improve the focus energy density of laser, will obtain as far as possible little focus point.According to the diffraction limit theory: the angle of divergence θ of laser and waist diameter d
0The pass be
Wherein for using certain laser instrument, Wavelength of Laser λ is certain, so, the angle of divergence θ of laser and waist diameter d
0Product be constant.Generally less from the laser beam diameter of laser instrument output, before the convergence optical system by certain focal length focuses on, require the expanded light beam diameter to reduce angle of divergence θ, obtain bigger incident beam diameter simultaneously.Suppose to add a laser beam expanding system in laser instrument and focal length are the convergence optical system of f, select suitable expansion bundle multiple β as requested for use, making laser beam enlarge to diameter is D=β d
0, this moment laser angle of divergence θ
Go intoStill satisfy the diffraction limit theoretical relationship
So,
Like this, desirable convergent laser hot spot
So, obtain suitable D value by selecting suitable multiple β for use, just can obtain desirable focal beam spot δ to improve the energy density at job spotlight place.
For adapting to the needs of various lasers beam diameter and angle of divergence shaping, the invention provides a kind of ultraviolet laser variable power beam expansion lens that changes the beam expanding lens multiplying power.
Ultraviolet Zooming expander of the present invention comprises the first lens L1, the second lens L2 and the 3rd lens L3 that is arranged in order along the light beam incident direction, and three lens are positioned on the same optical axis.The input aperture of this Zooming expander is 1mm, and lambda1-wavelength is 355nm.Wherein, described first lens L1 and the 3rd lens L3 are biconvex lens, and the described second lens L2 is a biconcave lens.The first lens L1 is made of two curved surface S1 and the S2 that the curvature of face is respectively R1 and R2, and its center thickness on optical axis is d1, and material is Nd1/Vd1; The second lens L2 is respectively two curved surface S3 of R3 and R4 and S4 by the curvature of face, and to constitute its center thickness on optical axis be d3, and material is Nd2/Vd2; The 3rd lens L3 is made of two curved surface S5 and the S6 that the curvature of face is respectively R5 and R6, and its center thickness on optical axis is d5, and material is Nd3/Vd3.The first lens L1 and the second lens L2 are spaced apart d2, and the second lens L2 and the 3rd lens L3 are spaced apart d4.According to the requirement of using, interval d2 of the lens on optical axis and d4 are regulated.
The concrete data parameters of ultraviolet laser variable power beam expansion lens of the present invention is as follows respectively:
Input aperture: 1mm
Become times scope: 4
x-10
x
Incident beam wavelength: 355mm
Annotate: the implication of negative is the left side that the centre of sphere of curved surface is positioned at curved surface
According to different actual needs, regulate curved surface d2 at interval, d4 realizes becoming doubly and adjusts, and corresponding relation is as follows:
Multiple n
x |
Interval d2 (mm) |
Interval d4 (mm) |
4
x |
10.3 |
149 |
5
x |
9.06 |
152.1 |
6
x |
7.8 |
154.1 |
7
x |
6.6 |
155.4 |
8
x |
5.4 |
156.6 |
9
x |
4.2 |
157.4 |
10
x |
3 |
158.1 |
The optical transfer function MTF of ultraviolet Zooming expander of the present invention schemes as shown in Figure 2, and maximum optical path difference as shown in Figure 3.
More than be the optimum implementation of ultraviolet Zooming expander of the present invention, can accurately draw the corresponding Ultra-Violet Laser light beam that requires to increase multiple according to the above data that provide.
The laser focusing system that ultraviolet laser variable power beam expansion lens of the present invention can make obtains bigger picture side's aperture angle, the energy density at focus place when greatly improving laser focusing, and the working (machining) efficiency of raising laser; Simultaneously, because the expansion bundle multiple of laser beam can regulate at any time, can use at the different laser parameters of various lasers output with a kind of optical application system; The laser output parameter that also can be used for simultaneously same type is applied to different laser applied optics systems has different requirements to the laser input parameter.
Although with reference to the accompanying drawings ultraviolet Zooming expander of the present invention is illustrated; but above-mentioned disclosed content only is in order to understand the present invention better; rather than limit the scope of claim by any way; so all according to the described structure of patent claim of the present invention, feature and principle do etc. change or modify, be included in protection scope of the present invention.