CN101762878A - Laser beam expanding system - Google Patents
Laser beam expanding system Download PDFInfo
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- CN101762878A CN101762878A CN201010102500A CN201010102500A CN101762878A CN 101762878 A CN101762878 A CN 101762878A CN 201010102500 A CN201010102500 A CN 201010102500A CN 201010102500 A CN201010102500 A CN 201010102500A CN 101762878 A CN101762878 A CN 101762878A
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Abstract
The invention relates to a location beam expanding system for ultraviolet laser, comprising a first lens and a second lens arranged in the light beam incidence direction; wherein the first lens is a crescent-shaped negative lens with back side thereof bent towards the incidence direction of light ray, the second lens is a plano-convex positive lens; the beam expanding system composed of the first lens and the second lens can expand diameter of incidence laser beam by 12 times and still eject the laser beam in the form of parallel light. As far as the beam expanding system of the invention is concerned, as the negative lens is short in focal length, thus not affecting aberration much; however, the positive lens is the main part which determines quality of outgoing beam from a beam expander. The beam expanding system enjoys a 12 times of beam expanding magnification, therefore a positive lens is enough to ensure quality of expanded outgoing beam; on the basis, not only shaping requirements are met, but also the best imaging quality is achieved; in addition, contour dimension is guaranteed to be the minimum, the imaging quality of the beam expanding system is very ideally balanced and volume of the whole lens is very small.
Description
[technical field]
The present invention relates to a kind of fixed times beam-expanding system that is applied to Ultra-Violet Laser.
[background technology]
In the laser processing procedure, usually require laser very concentrated at the energy of focus point, guarantee the energy density of laser processing procedure focus point, make laser work effectively, and improve the work efficiency of laser, but how when work, to improve the focus energy density of laser? generally be by obtaining little focus point as far as possible.
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.
Fixed times beam-expanding system of the present invention, mainly be for the shaping that solves UV laser beam and expansion of laser light beam diameter to improve the needs of image quality.Though thisly decide power beam expansion lens design more relatively easily, very convenient effectively to the ability of laser beam reshaping.
[summary of the invention]
The invention provides a kind of the diameter of incoming laser beam can be expanded bundle to 12 times, get very desirable Ultra-Violet Laser beam-expanding system to improve image quality and to expand bundle back picture element balance.
The technical solution adopted in the present invention is a kind of laser beam expanding system, comprising: be positioned at first and second lens that the incident direction of light beam is arranged in regular turn, described first lens are the negative lens of curved month type, its curved surface dorsad the incident direction bending of light; Described second lens are the positive lens of planoconvex; After whole beam-expanding system can expand the diameter of incoming laser beam 12 times of bundles, be still a branch of directional light and penetrate.
Wherein, described first lens and the spacing of second lens on optical axis are 89mm, and its margin tolerance is ± 5%.
Wherein, the largest beam diameter of described incoming laser beam is 2mm.
Wherein, described incident laser is that wavelength is the Ultra-Violet Laser of 355nm.
Wherein, the center thickness of described first lens on optical axis is 1mm, and its margin tolerance is ± 5%.
Wherein, the center thickness of described second lens on optical axis is 2mm, and its margin tolerance is ± 5%.
This laser beam expanding system, by two lens arranging in regular turn with " negative-just " are set, the diameter of incoming laser beam can be expanded 12 times of bundles after, still penetrate with directional light; Because it is 12 times that incoming laser beam expands the bundle multiplying power, so, need bear with a slice positive lens and expand bundle outgoing beam quality, like this, the needs of shaping had both been guaranteed, can also make it reach best image quality, and the physical dimension that guarantees it also is minimum, the picture element of this beam-expanding system also balance to get very desirable whole camera lens volume also very little.
[description of drawings]
The present invention is further described below in conjunction with drawings and Examples.
Fig. 1 is the optical system structure synoptic diagram of laser beam expanding system of the present invention;
Fig. 2 is the disc of confusion figure in the beam-expanding system preferred embodiment of the present invention;
Fig. 3 is the encircled energy figure in the beam-expanding system preferred embodiment of the present invention;
Fig. 4 is the figure of the optical transfer function MTF in the beam-expanding system preferred embodiment of the present invention.
[embodiment]
Along with developing rapidly of Laser Processing, the optical beam-expanding mirror occupies considerable status in the Laser Processing optical system.Owing to be used for the laser beam of Laser Processing the angle of divergence is arranged, so will adjust the irregularity of laser beam with the optics beam expanding lens, can make laser focusing system obtain bigger picture side's aperture angle, the energy density at focus place when improving laser focusing, thereby the elaboration and the efficient of raising laser.
According to Laplace invariant (Lagrange) theorem: energy J=nD θ=n ' D ' θ ', wherein, and 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 the incident light of θ and θ ' expression optical system and the field angle of emergent light when field angle is very little, can be represented with radian.
By following formula as seen, when the emitting laser bundle had the angle of divergence, when promptly θ was big, by D → D ', promptly enlargement factor β=D '/D doubly can make the angle of divergence of laser beam dwindle β doubly, thereby reach the purpose of shaping laser beam by beam expanding lens.
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 for the entrance pupil diameter, and diameter δ is just big more, will reduce the precision of amasthenic lens widely.
In view of above two basic demands, the optical system of Laser Processing is generally all wanted the adapted beam expanding lens.Remove in addition, the beam expanding lens that has can mate use with focus lamp or f-θ camera lens separately, and some also must link together with the optical system that is used and consider the balance of aberration, just can obtain ideal results.
Disclosed by the invention is exactly that a kind of Ultra-Violet Laser is used fixed times beam-expanding system.
As shown in Figure 1, Ultra-Violet Laser disclosed by the invention is used fixed times beam-expanding system, comprise that it is two lens that incident ray direction according to light sorts successively, the difference first lens L1, the second lens L2, these two lens L1, L2 employings " negative-just " combination, wherein the focal length of negative lens is shorter, and is little to aberration effects, and positive lens is the main undertaker of decision beam expanding lens outgoing beam quality.The described first lens L1 is a meniscus lens, and curved surface dorsad the bending of light incident direction; Lens L2 is a plane-convex lens.
Their concrete structure and parameter are: lens L1 is that two curved surface S1, the S2 of R1, R2 constitute by radius-of-curvature respectively, and the center thickness d1 on its optical axis, material are Nd1:Vd1; Lens L2 is that two curved surface S3, the S4 of R3, R4 constitute by radius-of-curvature respectively, and the center thickness d3 on its optical axis, material are Nd1:Vd1; Lens L1 and the spacing of lens L2 on optical axis are d2.
In conjunction with above parameter, we have designed a beam-expanding system, and its concrete data are as follows respectively:
Example:
Φ
Go into=2mm β=12X λ=355nm
Wherein, Φ
Go intoThe maximum light inlet diameter that this beam-expanding system allows, that is: the largest beam of the receivable incoming laser beam of this beam-expanding system directly is 2mm; β is for expanding the bundle multiple, that is: this beam-expanding system is after the diameter expansion of incoming laser beam is restrainted 12 times, to remain a branch of directional light, and the shaping expansion of laser light beam diameter that can solve UV laser beam is to improve the demand of image quality; λ is a wavelength, that is: incident light is the Ultra-Violet Laser of wavelength 355nm.
| Curved surface S | Curvature R (mm) | Face is d (mm) at interval | Material Nd/Vd |
| ??1 | ??4.5 | ?1 | ????1.46/68 |
| ??2 | ??2 | ?89 | |
| ??3 | ??0 | ?2 | ????1.46/68 |
| ??4 | ??-47.5 |
The parameter area that this patent is implemented is as follows:
1)R1-R4????ΔR1-4≤±5％??(R1-R4)
2)d1-d3????Δd1-3≤±5％??(d1-d3)
3)Nd1/Vd1??ΔNd1/ΔVd1≤±5％??(Nd1/Vd1)
By above-mentioned concrete experiment parameter, can probably conclude the process of this beam-expanding system: the largest beam diameter is the incoming laser beam of 2mm, at first light beam is become divergent beams, and then by after the second positive lens L2 shaping by the first negative lens L1, outgoing be parallel beam.The effect that whole beam-expanding system can reach is after the diameter expansion of incoming laser beam is restrainted 12 times, and still penetrates with parallel beam.Wherein the focal length of negative lens is shorter, and is little to aberration effects, and positive lens is the main undertaker of decision beam expanding lens outgoing beam quality.Because the expansion bundle multiple of this beam-expanding system is not big especially, so just can guarantee to expand the beam quality of bundle back laser beam with a slice positive lens.Like this, both guaranteed the needs of shaping, and can also make it reach best image quality, and guaranteed that its physical dimension also was minimum.
Because the irregularity of laser beam, its angle of divergence is not the quantity of being scheduled to, and for the d2 (spacings on optical axis of first lens and second lens) of this this beam-expanding system is adjustable, it is that mechanical adjustment by lens barrel realizes.
By regulating the spacing of first, second lens on optical axis is the size of d2=89mm, just can be easily carry out the shaping of directional light to the laser beam of input, and the picture element of this beam-expanding system also balance to get very desirable whole camera lens volume also very little.
Fig. 2 shows that for the disc of confusion figure in the beam-expanding system preferred embodiment of the present invention image quality is very high; Fig. 3 shows that for the encircled energy figure in the beam-expanding system preferred embodiment of the present invention encircled energy is very high; Fig. 4 shows that for the figure of the optical transfer function MTF in the beam-expanding system preferred embodiment of the present invention the resolution characteristic of this system is very high, reaches perfect condition.
Claims (6)
1. a laser beam expanding system is characterized in that, comprising: be positioned at first and second lens that the incident direction of light beam is arranged in regular turn, described first lens are the negative lens of curved month type, its curved surface dorsad the incident direction bending of light; Described second lens are the positive lens of planoconvex, after this beam-expanding system can expand the diameter of incoming laser beam 12 times of bundles, be still a branch of directional light and penetrate.
2. laser beam expanding system as claimed in claim 1 is characterized in that: described first lens and the spacing of second lens on optical axis are 89mm, and its margin tolerance is ± 5%.
3. laser beam expanding system as claimed in claim 1 is characterized in that: the largest beam diameter of described incoming laser beam is 2mm.
4. laser beam expanding system as claimed in claim 1 is characterized in that: described incident laser is that wavelength is the Ultra-Violet Laser of 355nm.
5. laser beam expanding system as claimed in claim 1 is characterized in that: the center thickness of described first lens on optical axis is 1mm, and its margin tolerance is ± 5%.
6. laser beam expanding system as claimed in claim 1 is characterized in that: the center thickness of described second lens on optical axis is 2mm, and its margin tolerance is ± 5%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201010102500A CN101762878B (en) | 2010-01-25 | 2010-01-25 | Laser beam expanding system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201010102500A CN101762878B (en) | 2010-01-25 | 2010-01-25 | Laser beam expanding system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101762878A true CN101762878A (en) | 2010-06-30 |
| CN101762878B CN101762878B (en) | 2012-10-03 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201010102500A Active CN101762878B (en) | 2010-01-25 | 2010-01-25 | Laser beam expanding system |
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|---|---|
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104142498A (en) * | 2014-08-01 | 2014-11-12 | 北京理工大学 | Novel beam expander of coherent wind lidar |
| CN112756775A (en) * | 2020-10-30 | 2021-05-07 | 苏州创鑫激光科技有限公司 | Laser processing method, optical system and laser processing equipment |
-
2010
- 2010-01-25 CN CN201010102500A patent/CN101762878B/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104142498A (en) * | 2014-08-01 | 2014-11-12 | 北京理工大学 | Novel beam expander of coherent wind lidar |
| CN112756775A (en) * | 2020-10-30 | 2021-05-07 | 苏州创鑫激光科技有限公司 | Laser processing method, optical system and laser processing equipment |
Also Published As
| Publication number | Publication date |
|---|---|
| CN101762878B (en) | 2012-10-03 |
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Owner name: HAN S LASER TECHNOLOGY INDUSTRY GROUP CO., LTD. Free format text: FORMER NAME: DAZU LASER SCI. + TECH. CO., LTD., SHENZHEN |
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Address after: No. 9988 Nanshan District Shennan Road Shenzhen city Guangdong province 518000 Patentee after: HANS LASER TECHNOLOGY INDUSTRY GROUP CO., LTD. Address before: Dazu laser Building No. 9 Nanshan District high tech Park North new road Shenzhen city Guangdong province 518055 Patentee before: Dazu Laser Sci. & Tech. Co., Ltd., Shenzhen |