CN201060306Y - Laser application f Theta lens - Google Patents

Abstract

The utility model discloses a laser application f Theta lens. The system adopts an optical power system in which three lenses with layout of positive-negative-positive are separated. A first lens which is arranged in order is a crescent positive lens binding towards a Y vibrating mirror; a second lens is double-concave-shaped negative lens; a third lens is plane-convex-shaped positive lens. The ratio of optical power of each lens to the optical power of the system meets the following requirements: f1/fw is more than 0 and less than 1.1; f2/fw is more than -0.5 and less than -0.4; f3/fw is more than 0.4 and less than 0.5, wherein, the f1 is the optical power of the first lens; the f2 is the optical power of the second lens; the f3 is the optical power of the third lens; the fw is the optical power of the whole system.

Description

Laser is used f θ camera lens

[technical field]

The utility model relates to a kind of camera lens that is applied to laser marking machine, and particularly a kind of laser is used f θ camera lens.

[technical background]

At present, laser is used the various aspects that have been deep into our modern life.In laser is used, be unable to do without in order to meet the various applied optics systems of various technological requirements.At the machine of laser beam mark in the market, characteristics such as, dirigibility fast with its speed is strong, no material consumption, mark are permanent little by little substitute various inkers, screen printer etc.

Laser galvanometer mark machine is because there has been f θ camera lens just to be achieved.Fig. 1 is a kind of typical f θ mirror optical system of the prior art, and as shown in the figure, light beam through two galvanometers around x axle and the rotation of y axle, focuses on the image planes by f θ mirror in turn at last, forms image by vibration mirror scanning.F θ camera lens is a kind of focus lamp of flattened field, when mark, requires on imaging surface the scanning angle θ of image height η and X galvanometer and Y galvanometer linear, that is: η=f θ.Wherein, f is the focal length of f θ camera lens, and θ is the scanning angle of galvanometer, and its unit is a radian.

Know that by the Gaussian optics imaging theory image height η and lens focus f and galvanometer rotational angle theta are following relationship: η=ftg θ.It does not satisfy η=f θ relational expression.Therefore, laser marking system is infeasible with conventional camera lens, and this is because the rotational angle theta of image height η and galvanometer is not linear variation, and institute carves the figure and material object dissmilarity that come, is the image of a distortion on the contrary.

In order to address this problem, require in the aberration correction when optical design, have a mind to introduce distortion Δ η, make to satisfy shown in the following formula to concern: η=ftg θ-Δ η=f θ.Δ η should satisfy following formula:

Δη＝f·tgθ-f·θ＝f(tgθ-θ)

Following formula shows: distortion just can meet the demands when should be the product of the difference of the tangent of galvanometer corner and radian and lens focus f.That can satisfy this condition just can be called f-θ camera lens.

Another characteristics of optical design require all focus points in the imaging scope exactly, and similar focusing quality should be arranged, and do not allow vignetting, and are all consistent and clear with the picture point that guarantees all " carving ".

[utility model content]

It is good that the technical matters that the utility model institute desire solves provides a kind of image effect of laser marking that can make, on full visual field imaging even, do not have the camera lens of vignetting.

The technical scheme that the utility model adopted is: a kind of laser marking camera lens, comprise three lens, described three lens are arranged in order, wherein first power of lens is for just, second power of lens is for negative, and the 3rd power of lens is being for just, each power of lens f1, f2, the focal power fw ratio of f3 and system meets following requirement:

1.0＜f1/fw＜1.1

-0.5＜f2/fw＜-0.4

0.4＜f3/fw＜0.5

Wherein f1 is first power of lens, and f2 is second power of lens, and f3 is the 3rd power of lens, and fw is the focal power of total system

Further improvement of the utility model is that first lens are under the 20-30mm situation apart from the Y vibrating mirror distance from d0, and first lens are the curved month type positive lens, and bending direction is towards the Y galvanometer; Second lens are the double concave type negative lens; The 3rd lens are the planoconvex positive lens.

The beneficial effect that the utility model can reach is, the focal power system that adopts three lens to be arranged in order " Negative-Positive-Negative " to separate, when being applied in the laser marking system, this f θ camera lens can make the image effect that carves preferable, more clear, and more alike with reality pictures.

[description of drawings]

The utility model will be further described in conjunction with the embodiments with reference to the accompanying drawings.

Fig. 1 is a camera lens synoptic diagram of the prior art.

Fig. 2 is the utility model lens construction figure.

Fig. 3-the 1st, the example one ray trajectory figure that executes of the present utility model.

Fig. 3-the 2nd of the present utility modelly executes example one astigmatism, the curvature of field and distortion.

Fig. 3-the 3rd, the optical path difference figure that executes on example one visual field of the present utility model.

Fig. 3-the 4th, the example one optical transfer function MTF figure that executes of the present utility model.

Fig. 4-the 1st, the utility model execute the ray trajectory figure of example two.

Fig. 4-the 2nd of the present utility modelly executes example two astigmatisms, the curvature of field and distortion.

Fig. 4-the 3rd, the optical path difference figure that executes on example two visual fields of the present utility model.

The optical transfer function MTF figure of Fig. 4-4 the utility model embodiment two.

[embodiment]

F θ camera lens is the photographic lens of a kind of big visual field, middle small-bore, middle long-focus,, selects the photographic lens of " three " type for use from the parameter that it will be born, and should be comparatively suitable.The optical power profile pattern that we adopt " negative-just-just ".The distortion that its entrance pupil produces outside camera lens just in time also is that f θ mirror is needed, and this distortion is easy to reach the requirement of f θ mirror, is the mark of a kind of " not having distortion ".Simultaneously, it is the photographic lens of a big visual field, and is the same with photographic lens, and it is the object lens of " flattened field ".

According to above characteristic analysis, the present invention adopts technical scheme as shown in Figure 2 to be: utilize three lens of the focal power system of " Negative-Positive-Negative " separation to constitute, wherein the focal power of the first lens L1 is for just, the focal power of the second lens L2 is for negative, the focal power of the 3rd lens L3 is for just, each power of lens represents with f1, f2, f3 respectively, meets following requirement with the ratio of the focal power fw of system:

1.0＜f1/fw＜1.1

-0.5＜f2/fw＜-0.4

0.4＜f3/fw＜0.5

The lens L1 that the utility model adopts is 20-30mm apart from the Y vibrating mirror distance from d0, and lens L1 is that curved month type positive lens, lens L2 are that double concave type negative lens, lens L3 are the planoconvex positive lens, and the bending direction of lens L1 is the Y galvanometer towards entrance pupil.

For making understanding those skilled in the art can understand content of the present utility model better, carry out specific description especially exemplified by preferred embodiment of the present utility model.

According to the utility model These characteristics, system's focal length is fw, and it is made of L1, L2, three lens of L3, and L1 is that two curved surface S1, the S2 of R1, R2 constitute by radius-of-curvature respectively, its center thickness d 1, and material is Nd1:Vd1; L2 is that two curved surface S3, the S4 of R3, R4 constitute by radius-of-curvature respectively, its center thickness d 3, and material is Nd3:Vd3; L3 is that two curved surface S5, the S6 of R5, R6 constitute by radius-of-curvature respectively, its center thickness d 5, and material is Nd1:Vd1; Lens L1 and lens L2 are spaced apart d2, and lens L2 and lens L3 are spaced apart d4.

Embodiment 1

Fw=256mm numerical aperture D/fw=1: 16

λ=1064nm field angle 2 ω=50 °

f1/fw＝1.02 f2/fw＝-0.39 f3/fw＝0.45

Curved surface S	Curvature R	Face is d at interval	Material Nd/Vd
				1	-105.99	6	1.8/25.4
2	-83.11	5
				3	-45.3	3	1.47/67
4	-96.41	3
				5	-95.51	8	1.8/25.4

6

-58.67

468

Fig. 3-the 1st originally executes routine ray trajectory figure, Fig. 3-the 2nd originally executes routine astigmatism, the curvature of field and distortion figure, Fig. 3-the 3rd, the visual field of present embodiment is the optical path difference figure on 0,0.3,0.5,0.7,0.85 and 1.0 each visual fields, Fig. 3-the 4th, the optical transfer function MTF that originally executes example schemes.As can be seen, the astigmatism of system and the curvature of field obtain good calibration from the figure, and the optical path difference maximum also is no more than 0.15 λ, and from optical transfer function MTF figure, the mtf value of each visual field is all consistent, illustrate that imaging is even on full visual field, does not have the vignetting existence.Result of use in practice, the utility model have reached above illustrated effect really.

Embodiment 2

Fw=160mm numerical aperture D/f=1: 13.5

λ=1064nm field angle 2 ω=50 °

f1/fw＝1.02 f2/fw＝-0.39 f3/fw＝0.46

Curved surface S	Curvature R	Face is d at interval	Material Nd/Vd
				1	-80.54	7	1.8/25.4
2	-51.05	4
				3	-33.11	3	1.47/67
4	239.9	9
				5	0	11.5	1.8/25.4
6	-56.49	190

Fig. 4-the 1st originally executes routine ray trajectory figure, Fig. 4-the 2nd originally executes routine astigmatism, the curvature of field and distortion figure, Fig. 4-the 3rd, the visual field of present embodiment is the optical path difference figure on 0,0.3,0.5,0.7,0.85 and 1.0 each visual fields, Fig. 4-the 4th, the optical transfer function MTF that originally executes example schemes.As can be seen, the astigmatism of system and the curvature of field obtain good calibration from the figure, and the optical path difference maximum also is no more than 0.15 λ, and from optical transfer function MTF figure, the mtf value of each visual field is all consistent, illustrates that also imaging is even on full visual field, does not have vignetting to exist.Result of use in practice, the utility model produces a desired effect really.

Claims (2)

1. a laser is used f θ camera lens, it is characterized in that: the focal power system that system adopts three lens layouts to become " positive negative-just " to separate, and first lens that are arranged in order are the curved month type positive lens, bending direction is towards the Y galvanometer; Second lens are the double concave type negative lens; The 3rd lens planoconvex positive lens.

2. laser as claimed in claim 1 is used f θ camera lens, and it is characterized in that: the focal power ratio of each power of lens and system meets following requirement:

1.0＜f1/fw＜1.1

-0.5＜f2/fw＜-0.4

0.4＜f3/fw＜0.5

Wherein f1 is first power of lens, and f2 is second power of lens, and f3 is the 3rd power of lens, and fw is the focal power of total system.

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