CN102062931A

CN102062931A - Laser scanning lens

Info

Publication number: CN102062931A
Application number: CN 201010527536
Authority: CN
Inventors: 汪玉树; 高云峰
Original assignee: Shenzhen Hans Laser Technology Co Ltd
Current assignee: Shenzhen Hans Laser Technology Co Ltd; Han s Laser Technology Co Ltd
Priority date: 2010-10-29
Filing date: 2010-10-29
Publication date: 2011-05-18

Abstract

The invention discloses a laser scanning lens comprising a lens group, a diaphragm and a focal plane, wherein the diaphragm is positioned in front of the lens group; the lens group is arranged between the diaphragm and the focal plane and comprises three lenses, wherein the three lenses are respectively the first lens, the second lens and the third lens which are sequentially ranked from the diaphragm, and the first lens, the second lens and the third lens are distributed and designed according to the focal power of positive-negative-positive; the focal length of each lens and the focal length of the whole optical system satisfy the following requirements: f1/f is more than 0.9 and is less than 1.1, f1/f is more than -0.4 and is less than -0.3, and f3/f is more than 0.3 and is less than 0.5; and the laser scanning range is 600mm*600mm. The laser scanning lens has the beneficial effect that the focal point of the laser scanning in an imaging range does not have vignetting, and all 'cut' image points are consistent and clear. In addition, the laser scanning range can reach the diameter range of phi 860mm, i.e. the laser scanning lens can scan the range of 600mm*600mm.

Description

A kind of laser scanning camera lens

[technical field]

The present invention relates to a kind of large-scale F-theta laser scanning camera lens.

[background technology]

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

The F-theta camera lens is the photographic lens of a kind of big visual field, middle small-bore, middle long-focus, the parameter that will bear from it, selecting the photographic lens of " three " type for use, should be comparatively suitable, and laser marking machine is because there has been the F-theta camera lens just to be achieved.

Fig. 1 is a kind of optical system of typical F-Theta camera lens, and light beam through two X galvanometer 1 and Y galvanometers 2 around X-axis and Y-axis rotation, passes through the F-theta lens focus on image planes 4 in turn at last, forms image by vibration mirror scanning.F-theta camera lens 3 is focus lamps of a kind of flattened field, when mark, requires on imaging surface the scanning angle theta of image height h and X galvanometer 1 and Y galvanometer 2 linear, i.e. h=f*Theta (sr).Wherein, f is the focal length of F-theta camera lens 3, and theta is the scanning angle (unit is a radian) of galvanometer.

By the Gaussian optics imaging theory, image height h and lens focus f and galvanometer corner Theta close and are: h=f*tan (theta).It does not satisfy the h=f*theta relational expression.Therefore, laser marking system is infeasible with conventional camera lens, and this is because the corner theta of image height h and galvanometer is not linear variation, and the figure that is carved out is the image of a distortion with in kind dissimilar on the contrary.

In order to address this problem, require in the aberration correction when optical design, have a mind to introduce distortion dh, make to satisfy shown in the following formula to concern: h=(f*tan (theta)-dh)=f*theta.This conclusion is very important.Though dh is what have a mind to introduce, meaning that never distortion just can not consider, random size can, should satisfy following formula:

dh＝f*tan(theta)-f*theta

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 the F-theta optical system.

[summary of the invention]

The objective of the invention is to the F-Theta laser scanning camera lens that pin provides a kind of sweep limit to reach 600mm * 600mm, the laser scanning visual field is big, sweep limit is big to reach, aberration correction is easy.

The embodiment of the invention is to realize like this, the present invention discloses a kind of laser scanning camera lens, comprise lens combination, diaphragm and focal plane, described diaphragm is positioned at the place ahead of lens combination, described lens combination is between diaphragm and focal plane, described lens combination comprises three lens, these three lens by diaphragm begin to arrange in regular turn first, second, the 3rd lens, described first, second, the 3rd lens are with the optical power profile design of " Negative-Positive-Negative ", described first, second, the 3rd lens are meniscus lens, and first, second, the curved surface of the 3rd lens is all towards the bending of diaphragm direction, and the focal length of each lens and the focal length of whole optical system are by following requirement:

0.9＜f1/f＜1.1

-0.4＜f1/f＜-0.3

0.3＜f3/f＜0.5

Wherein, the focal length of whole optical system is f, and the focal length of first, second, third lens is respectively f1, f2, f3; And this laser scanning scope is 600mm*600mm.

Wherein, described first lens are 25-40mm apart from the distance of diaphragm.

Wherein, the focal length of each lens and the focal length of whole optical system are by following requirement: f1/f=1.043, f2/f=-0.3723, f3/f=0.3908.

The invention has the beneficial effects as follows: the focus point of this laser scanning in the imaging scope, there is not vignetting to exist, and all picture points of " carving " are all consistent and clear, and the laser scanning scope can reach Φ 860mm diameter range, can scan 600mm * 600mm scope.

[description of drawings]

The invention will be further described in conjunction with example with reference to the accompanying drawings:

Fig. 1 is the optical system of existing F-Theta camera lens;

Fig. 2 is the structural representation of this laser scanning camera lens;

The optical fiber trace figure of this laser scanning of Fig. 3 camera lens;

Fig. 4 is the energy profile of each field angle of this laser scanning camera lens;

Fig. 5 is the disperse hot spot figure of this laser scanning camera lens;

Fig. 6 is the optical transfer function MTF figure of this laser scanning camera lens.

[embodiment]

The F-theta 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.We adopt the optical power profile pattern of " Negative-Positive-Negative ".The distortion that its entrance pupil produces outside camera lens just in time also is that the F-theta mirror is needed, and this distortion is easy to reach the requirement of F-theta 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 ".

As Fig. 2, the technical solution adopted in the present invention provides a kind of optics F-theta scanning lens that Laser Processing is used that is used for, comprise lens combination and diaphragm (galvanometer) 1, described diaphragm (galvanometer) 1 is positioned at the place ahead of lens combination, lens combination comprises three lens, be respectively first, second, third lens L1, L2, L3, described first, second, third lens L1, L2, L3 adopt the optical power profile of three-chip type " Negative-Positive-Negative " to design, and wherein the material of three lens all is a glass.

Wherein, the first power of lens 1/f1 is a negative lens, and the second power of lens 1/f2 and the 3rd power of lens 1/f3 just are, and wherein the focal distance f ratio of the focal length of each lens and whole optical system is by following requirement:

0.9＜f1/f＜1.1

-0.4＜f1/f＜-0.3

0.3＜f3/f＜0.5

Wherein, the focal length of whole optical system is f, and the focal length of first, second, third lens is respectively f1, f2, f3.

Wherein, the first lens L1 is 25-40mm apart from diaphragm (galvanometer) 1 apart from d0, and the first lens L1 is the curved month type positive lens; The second lens L2 is the curved month type negative lens, and the 3rd lens L3 is the curved month type positive lens, and all curved surface of the first lens L1, the second lens L2 and the 3rd lens L3 is all towards diaphragm (galvanometer) 1 direction bending, and 2 distance is d6 to the 3rd lens L3 to the focal plane.

Their concrete structure and parameter are expressed as: this optics F-theta scanning lens is made of L1, L2, three lens of L3, the first lens L1 is that two curved surface S1, the S2 of R1, R2 constitute by radius-of-curvature respectively, its center thickness d 1, material optical parametric are Nd1/Vd1; The second lens L2 is that two curved surface S3, the S4 of R3, R4 constitute by radius-of-curvature respectively, its center thickness d 3, and the material optical parametric is Nd2/Vd2; The 3rd lens L3 is that two curved surface S5, the S6 of R5, R6 constitute by radius-of-curvature respectively, its center thickness d 5, and the material optical parametric is Nd3/Vd3; The first lens L1 and the second lens L1 are spaced apart d2, and the second lens L1 and the 3rd lens L3 are spaced apart d4, and in conjunction with above parameter, the present invention has designed a set of shots, and its concrete parameter is as follows:

The first lens L1 is that two curved surface S1, the S2 of R1=-1397.98mm, R2=-381.95mm constitute by radius-of-curvature respectively, and the center thickness d1=5.6mm on its optical axis, material are that Nd1/Vd1 is about 1.8/25.4; The second lens L1 is that two curved surface S3, the S4 of R3=-99.43mm, R4=-536.12mm constitute by radius-of-curvature respectively, and the center thickness d3=6.39mm on its optical axis, material are that Nd3/Vd3 is about 1.51/64; The 3rd lens L3 is that two curved surface S5, the S6 of R5=-234.08mm, R6=-110.03 constitute by radius-of-curvature respectively, and the center thickness d5=15.72mm on its optical axis, material are that Nd5/Vd5 is about 1.8/25.4; The first lens L1 and the second lens L2 are spaced apart d2=8.09 on optical axis, the second lens L1 and the 3rd lens L3 are spaced apart d4=4.2mm on optical axis, and the 3rd lens L3 and the distance of imaging surface on optical axis are d6=692.1mm.And be listed as follows:

Wherein, the implication of the negative in the last table is the left side that the centre of sphere of curved surface is positioned at curved surface.

According to last table, it is as follows to draw data:

f＝650mm D/f＝1:43

λ＝1064nm f1/f＝1.043

f2/f＝-0.3723 f3/f＝0.3908

Field angle 2 ω=70 °

Fig. 3 is the ray tracing figure in the last example, and Fig. 4 is the energy profile of each field angle, and Fig. 5 is the disperse hot spot figure of each field angle.Fig. 6 is optical transfer function MTF figure.

Illustrated with each figure by last: the astigmatism of system and the curvature of field obtain good calibration, and the disperse hot spot all in Airy disk, has promptly reached diffraction limit.And from optical transfer function MTF figure, the mtf value of each visual field is all consistent, illustrates that imaging is even on full visual field, does not have vignetting to exist.

As can be seen from Figure 3, the laser scanning scope can reach Φ 860mm diameter range, can scan 600mm * 600mm scope.

Claims

1. laser scanning camera lens, comprise lens combination, diaphragm and focal plane, described diaphragm is positioned at the place ahead of lens combination, described lens combination is between diaphragm and focal plane, described lens combination comprises three lens, these three lens by diaphragm begin to arrange in regular turn first, second, the 3rd lens, it is characterized in that: described first, second, the 3rd lens are with the optical power profile design of " Negative-Positive-Negative ", described first, second, the 3rd lens are meniscus lens, and first, second, the curved surface of the 3rd lens is all towards the bending of diaphragm direction, and the focal length of each lens and the focal length of whole optical system are by following requirement:

0.9＜f1/f＜1.1

-0.4＜f1/f＜-0.3

0.3＜f3/f＜0.5

2. laser scanning camera lens according to claim 1 is characterized in that: described first lens are 25-40mm apart from the distance of diaphragm.

3. laser scanning camera lens according to claim 1: the focal length of each lens and the focal length of whole optical system are by following requirement: f1/f=1.043, f2/f=-0.3723, f3/f=0.3908.