KR101920685B1 - Scan Lens for Laser Micro Processing - Google Patents

Abstract

The present invention relates to a scan lens for laser micro processing and, more specifically, provides a scan lens for laser micro processing, wherein four lenses are arranged in order, and two lenses at a light source side relatively and greatly diffuse and refract a laser beam in an outdoor direction, and two lenses at a phase side relatively and greatly focus and refract a laser beam in a central direction by setting a focal distance of the four lenses. Therefore, a distortion aberration of the lenses can be minimized, and further, an aberration with respect to a laser beam can be easily corrected. Moreover, a lens is easily processed to reduce manufacturing costs, and an irradiation angle of a laser beam irradiated on an object to be processed is close to an orthogonal direction to more accurately process a laser.

Description

 Scan Lens for Laser Micro-machining [

The present invention relates to a scan lens for laser micro-machining. More specifically, four lenses are sequentially arranged, and the two lenses on the light source side diffuse and refract the laser beam relatively outward, and the two lenses on the image plane side focus the laser beam relatively in the center direction By setting the focal length of the single lens, distortion aberration of the lens can be minimized, aberration correction for the laser beam can be easily performed, lens processing can be easily performed, and manufacturing cost can be reduced. And the angle can be brought close to a perpendicular direction to enable more precise laser machining.

In recent years, a precision processing apparatus using a laser has been developed and used. In recent years, a precision processing apparatus using a laser has been developed and used.

The precision machining system using laser is to irradiate a laser beam at a very local place in a non-contact manner to the target to remove the desired target without damaging the surroundings, to perform marking, surface treatment, etc. Recently, .

Such a laser processing apparatus is configured in such a manner that the object to be processed is fixed on the upper surface of the stage, the laser generation unit is disposed on the stage, and the laser beam generated in the laser generation unit is irradiated to the object.

In the initial stage, the irradiation direction of the laser beam is fixed, and the stage where the object to be processed is moved is used to process the entire area of the object. In this case, precision machining was possible but the machining time is long and the expensive There is a problem that a stage is required.

In order to solve these problems, recently, a method of quickly controlling the irradiation direction of a laser beam using a galvanometer and a scan lens has been developed so that a large area can be processed for a workpiece in a short time have.

1, a laser beam generated from a laser generator 10 is reflected by a galvanometer 30 and passes through a diaphragm ST through a scan lens 40, And is irradiated onto the object 20 to be processed. The galvanometer 30 can rapidly adjust the reflection angle of the laser beam so that the laser beam is irradiated to the entire area of the object 20. A scan lens 40 is used to focus the laser beam reflected by the galvanometer 30 onto the object 20. That is, the laser beam reflected by the galvanometer 30 passes through the scan lens 40, is converged on the object 20 to be processed, and the object 20 is processed.

In the initial model of the laser machining apparatus, the galvanometer is not used, but the laser beam is irradiated in a predetermined direction. Therefore, the laser beam is condensed by passing the laser beam through the center of the scan lens. Is used so that the laser beam passes through the outer periphery as well as the center of the scan lens 40. [

As shown in FIG. 1, when the laser beam passes through the center of the scan lens 40, a distortion aberration of the scan lens is minimized, so that the laser beam is incident on the object 20 in a direction perpendicular to the object 20, , The focus region of the laser beam focused on the object 20 is formed to be relatively small as in M1. However, when the laser beam passes through the outer frame of the scan lens 40, the distortion aberration of the scan lens increases, and as shown in Fig. 1, the laser beam is inclined at an angle of? And is incident and condensed. In this case, the focus region of the laser beam focused on the object 20 is formed not only relatively large as in M2 but also in a distorted shape to some extent.

Therefore, in recent years, research and development have been actively conducted on the scan lens 40 that can minimize such a distortion aberration. For example, as shown in FIG. 1, if the scan lens 40 is composed of two lenses of the first and second lenses 41 and 42, the structure is simplified, but the distortion aberration is increased, In order to reduce the distortion aberration, the size of the scan lens 40 must be increased so that the laser beam can pass through the center portion of the scan lens 40 as much as possible. As the size of the scan lens 40 is increased, the overall size of the apparatus is increased and the manufacturing cost of the lens is rapidly increased. Thus, there are limitations in increasing the size of the scan lens 40.

Due to these various problems, it is very difficult to develop an optimized scan lens for a laser processing apparatus, and the research process is also very slow.

Korean Patent No. 10-0364404

SUMMARY OF THE INVENTION The present invention has been made in order to solve the problems of the prior art, and it is an object of the present invention to provide an optical pickup apparatus, in which four lenses are arranged sequentially and two lenses on a light source side diffuse and refract a laser beam relatively outwardly, By setting the focal lengths of the four lenses so that the laser beam is relatively concentrated and refracted in the center direction, it is possible to minimize the distortion aberration of the lens as well as to correct the aberration of the laser beam. It is possible to reduce the cost and make the irradiation angle of the laser beam irradiated on the object close to the direction perpendicular to the direction of the laser beam, thereby enabling more precise laser processing.

The present invention relates to a scan lens for fine processing for collecting and irradiating a laser beam incident from a light source at various incidence angles to a processing point of an object to be processed, comprising: a first lens arranged in order from the light source side along the image plane side; Wherein the first lens and the second lens have a negative refracting power, the third lens and the fourth lens are formed to have a positive refracting power, and the second lens, the third lens and the fourth lens, The focal lengths of the first to fourth lenses are f1, f2, f3, and f4, and the total focal length of the first to fourth lenses is f, the following conditional expression 1 is satisfied And a scan lens for fine processing the laser.

<Conditional Expression 1>

-1.6 < f1 / f < -1.3

-3.2 < f2 / f < -2.7

0.9 < f3 / f < 1.2

1.8 < f4 / f < 2

When the integrated focal length of the first lens and the second lens is f12 and the integrated focal length of the third lens and the fourth lens is f34, The following conditional expression (2) can be satisfied.

<Conditional expression 2>

-1.1 < f12 / f < -0.96

0.68 < f34 / f < 0.75

At this time, a diaphragm for limiting the light amount of the laser beam may be disposed at a position spaced apart from the first lens in the direction of the light source, and the diaphragm may be arranged to have a distance of 25 to 30 mm from the first lens .

According to the present invention, the four lenses are sequentially arranged, and the two lenses on the light source side diffuse and refract the laser beam relatively outward in the outward direction, and the two lenses on the image plane side focus the laser beam relatively in the center direction By setting the focal lengths of the four lenses, not only distortion aberration of the lens can be minimized, aberration correction for the laser beam can be easily performed, lens processing is also easy, and manufacturing cost can be reduced. It is possible to make the irradiation angle close to the perpendicular direction so that more accurate laser processing can be performed.

FIG. 1 is a schematic view showing a configuration of a conventional laser processing apparatus and a scan lens according to the related art,
FIG. 2 is a view schematically showing the construction of a scan lens for laser micro-machining according to an embodiment of the present invention;
3 is a schematic view illustrating a detailed arrangement structure of a scan lens for laser micro-machining according to an embodiment of the present invention,
FIG. 4 is a view showing a shape of a focus region when a scan lens for laser micro-machining according to an embodiment of the present invention is used.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to designate the same or similar components throughout the drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

FIG. 2 is a view schematically showing a configuration of a scan lens for laser micro-machining according to an embodiment of the present invention. FIG. 3 is a schematic view illustrating a detailed arrangement structure of a scan lens for laser micromachining according to an embodiment of the present invention. FIG. 4 is a view showing a shape of a focus region when a scan lens for laser micro-machining according to an embodiment of the present invention is used.

A scan lens for laser micro-machining according to an embodiment of the present invention is a lens for collecting and irradiating a laser beam incident at various incidence angles from a light source onto a processing point of a workpiece 20, A first lens 100, a second lens 200, a third lens 300, and a fourth lens 400 arranged in this order.

A diaphragm 600 capable of limiting the light amount of the laser beam is disposed at a position spaced apart from the light source side of the first lens 100. A lens 600 is provided at a position spaced apart from the image forming side of the fourth lens 400 A protective glass 500 is disposed.

The first lens 100 and the second lens 200 have a negative refractive power and the third lens 300 and the fourth lens 400 are formed to have a positive refractive power. do.

Since the first lens 100 and the second lens 200 have a negative refracting power, the first lens 100 and the second lens 200 refract and diffuse the incident laser beam toward the outer periphery of the lens, Since the laser beam 400 has a positive refracting power, it functions to refract the incident laser beam toward the center direction.

Accordingly, when the laser beams L2, L3, L4, and L5 are incident on the scan lens at an incident angle oblique to the scan lens, the laser beam is incident on the first lens 100 and the second lens 200, Passes through the third lens 300 and the fourth lens 400, and is refracted so as to be collected in the center direction. Of course, the laser beam L1 incident along the optical axis of the scan lens is not refracted but travels in parallel with the optical axis.

The laser beam having passed through the first lens 100 to the fourth lens 400 with such a refraction path is then irradiated at an irradiation angle very close to the direction perpendicular to the object 20 as shown in Fig.

At this time, the first lens 100, the second lens 200, the third lens 300, and the fourth lens 400 are formed to satisfy the following conditional expression (1).

<Conditional Expression 1>

-1.6 < f1 / f < -1.3

-3.2 < f2 / f < -2.7

0.9 < f3 / f < 1.2

1.8 < f4 / f < 2

Here, f1 is the focal length of the first lens 100, f2 is the focal length of the second lens 200, f3 is the focal length of the third lens 300, and f4 is the focal length of the fourth lens 400 , and f denotes the entire focal length of the entire first to fourth lenses 100 to 400. [

Since the first lens 100 and the second lens 200 have a negative refracting power as described above, the first lens 100 and the second lens 200 refract in the direction of diffusing the incident laser beam. The first lens 100 and the second lens 200 ) Is formed to be out of the range of the above conditional expression (1), the diffraction refraction of the laser beam is excessively generated or the diffraction refraction occurs too small.

For example, if the range of f2 / f is set to a value smaller than the range, the curvature of the second lens 200 becomes gentle and the angle of the incident laser beam becomes relatively small, The diffraction refraction degree of the laser beam 200 is reduced and the refraction paths of the laser beams of various incident angles are superimposed on each other, thereby making it difficult to correct the lens aberration at the outer periphery of the lens. Further, in this case, since the laser beam passing through the lens outer periphery and the laser beam passing through the lens center are located very close to each other without being separated, aberration correction for them is also difficult.

Therefore, it is possible to largely diffuse and refract the laser beam of various incident angles in the outward direction by forming the f2 / f range to be relatively large and the diffraction refraction degree of the laser beam passing through the second lens 200 to be large The aberration correction for the laser beam becomes easy.

However, if the range of f2 / f is largely increased to a certain range or more, the curvature of the second lens 200 becomes abrupt, so that it is difficult to process the lens, and the incidence angle of the laser beam incident on the lens increases, .

In the embodiment of the present invention, the range of f2 / f is set as above in accordance with this principle, and the range of f1 / f is also set for the first lens having negative refracting power on the same principle.

The third lens 300 and the fourth lens 400 have a positive refracting power and refract the laser beam diffused and refracted by the first lens 100 and the second lens 200 in the center direction The refraction performance of the third lens 300 and the fourth lens 400 is relatively high in response to the degree of diffusion refraction relatively set by the first lens 100 and the second lens 200, .

This makes it possible to bring the angle of incidence of the laser beam irradiated on the object 20 close to the perpendicular direction, thereby reducing the area of the machining spot and enabling more precise machining.

In addition, the first lens 100, the second lens 200, the third lens 300, and the fourth lens 400 according to an embodiment of the present invention are formed to satisfy the following conditional expression (2).

<Conditional expression 2>

-1.1 < f12 / f < -0.96

0.68 < f34 / f < 0.75

Here, f12 denotes an integrated focal length of the first lens 100 and the second lens 200, and f34 denotes an integrated focal length of the entire third lens 300 and the fourth lens 400 do.

As described above, the first lens 100 and the second lens 200 are formed to diffuse and refract the incident laser beam in the outward direction, and the third lens 300 and the fourth lens 400 form a laser beam The first lens 100 having negative refracting power and the second lens having the negative refracting power as in the <Conditional Expression 2> can be used as the first lens 100 and the second lens 100, respectively, as shown in <Conditional Expression 1> The setting range for the integrated focal length f12 of the second lens 200 and the setting range for the integrated focal length f34 of the third lens 300 and the fourth lens 400 are also very important have.

The combined focal length f12 of the first lens 100 and the second lens 200 and the combined focal length f12 of the third lens 300 and the fourth lens 400, The integrated focal length f34 is set so that the degree of diffusing refraction is set relatively large through the first lens 100 and the second lens 200 and the third lens 300 and the fourth lens 400 So that the aberration can be easily corrected and the degree of refraction of the laser beams corresponding to the laser beam can be increased. It is possible to form the irradiation angle to be close to the perpendicular direction.

According to the setting range described above, the first lens 100 to the fourth lens 400 are constructed as shown in Table 1 below as an embodiment.

division Radius thickness Street d1 27 The first lens R1 (light source side) -493 2.5 R2 (image plane side) 128 d2 30.5 The second lens R1 (light source side) -30 13 R2 (image plane side) -39 d3 0.2 Third lens R1 (light source side) -363 21 R2 (image plane side) -72 d4 0.5 The fourth lens R1 (light source side) 190 15 R2 (image plane side) -481 d5 One

L2, L3, L4, and L5 so as to have five incidence angles through the scan lens having the above-described configuration, the laser beams L1, L2, L3, L4, The shape of the focus area appearing on the surface of the object to be processed 20 is shown in Fig.

The five incident angles of the laser beams are 0 °, 6.870 °, 11.45 °, 16.03 ° and 22.9 °. In this case, the paths through which the laser beams L1, L2, L3, L4, M2, M3, M4, and M5 are formed in the outer region of the object 20 as the incident angle is increased. It was confirmed that the shapes of the respective focus areas M1, M2, M3, M4, and M5 appear as shown in FIG.

On the other hand, a diaphragm 600 capable of limiting the light amount of the laser beam is disposed at a position spaced apart from the first lens 100 in the light source side direction so that the diaphragm has a distance of 25 to 30 mm from the first lens So that the angle of incidence of the laser beam can be limited within a range that minimizes the distortion aberration of the scan lens.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

100: first lens
200: second lens
300: third lens
400: fourth lens
500: Protection glass
600: aperture

Claims (3)

1. A scan lens for fine processing for converging a laser beam incident from a light source at various incidence angles on a processing point of a workpiece,
A first lens, a second lens, a third lens, and a fourth lens arranged in order from the light source side along the image plane side,
Wherein the first lens and the second lens have a negative refracting power, the third lens and the fourth lens are formed to have a positive refracting power,
Wherein f1, f2, f3, and f4 are the focal lengths of the first to fourth lenses, and f is a total focal length of the first to fourth lenses, respectively, the following conditional expression For laser micro-machining.
<Conditional expression>
-1.6 < f1 / f < -1.3
-3.2 < f2 / f < -2.7
0.9 < f3 / f < 1.2
1.8 < f4 / f < 2
The method according to claim 1,
Wherein an integrated focal distance of the first lens and the second lens is f12, and an integrated focal distance of the third lens and the fourth lens is f34, the following conditional expression is satisfied: Scan lens for fine processing.
<Conditional expression>
-1.1 < f12 / f < -0.96
0.68 < f34 / f < 0.75
The method according to claim 1,
A diaphragm capable of limiting the light amount of the laser beam is disposed at a position spaced apart from the first lens in the light source side direction,
Wherein the diaphragm is disposed so as to have a separation distance of 25 to 30 mm from the first lens.

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