JP2002107660A - Optical equipment and laser processing machine - Google Patents

Abstract

(57) Abstract: Provided is an optical device that can convert the cross-sectional shape of a light beam from a circular shape to an elongated shape without causing anisotropy in a projection magnification, and can give a direction difference to a focused NA. SOLUTION: A conical light beam L1 emitted from an end face of an optical fiber 2 is converted into a parallel light beam L2 by a collimator 10, and then reflected by three reflecting surfaces M11 to M13 provided on a first optical element M1. Luminous flux L21
~ L23. The partial light beams L21 to L23 reflected by the reflecting surfaces M11 to M13 respectively enter the corresponding reflecting surfaces M21 to M23 of the second optical element M2, are reflected by the reflecting surfaces M21 to M23, and are aligned in the x-axis direction. Let me do. These partial light beams L21 to L23 are condensed by the condensing optical system 11, and an optical fiber end face image is formed on the work W.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical device for converting a light beam cross-sectional shape and a laser beam machine equipped with the optical device.

[0002]

2. Description of the Related Art In many laser processing machines, a laser oscillator is installed at a place away from a processing place in consideration of safety and functionality, and a laser beam is guided from the laser oscillator to a processing head by an optical fiber. ing. If the optical fiber for guiding the laser beam becomes longer than a certain length, the NA (numerical aperture) of the light beam emitted from the optical fiber becomes the NA of the incident light beam.
And spread to about the critical angle of the optical fiber. The critical angle of the optical fiber is, for example, 0.2 in NA for quartz fiber.
The degree is normal.

[0003] As described above, a light beam that spreads in a conical shape over the entire critical angle is emitted from the optical fiber. The processing head is provided with a condensing optical system, and the laser light emitted from the optical fiber is condensed by the condensing optical system, and an emission surface image of the optical fiber is formed on a processed portion of the work. This condensed light beam is also condensed in a conical shape, and the converged NA is determined by the projection magnification of the exit plane image formed in the processing section. For example, NA = 0.
When the same magnification is projected by the two optical fibers, the focused NA becomes 0.2. When the workpiece is irradiated with such conical laser light, the processed part is melted in a rotationally symmetric manner with respect to the laser light irradiation center, and the area larger than the exit plane image is melted due to the conical light flux. Will be done.

[0004]

In the case where a steel plate or the like is cut along a straight line, there is a demand for making the melting width of the cut portion as narrow and sharp as possible. But,
As described above, the luminous flux applied to the workpiece has a conical shape that narrows downward, so that the fusion width is larger than the diameter of the projected image, and the tendency increases as the plate thickness increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical device capable of converting the cross-sectional shape of a light beam from a circular shape to an elongated shape without causing anisotropy in the projection magnification, and giving anisotropy to the converging NA. An object of the present invention is to provide a laser beam machine provided with the optical device.

[0006]

An embodiment of the present invention will be described with reference to FIGS. (1) Explaining in association with FIG. 2, the optical device 4 according to the first aspect of the present invention maintains the isotropy of the projection magnification and converts the light beam L2 having the isotropic incidence NA into the anisotropic focusing NA. The above object is achieved by converting the light beams into light beams L21, L22, and L23 having the following. (2) The optical device 4 according to the second aspect of the present invention includes a collimator 10 that converts a light beam L1 emitted from a light source having a finite size into a parallel light beam L2, and a parallel light beam such that the light beam cross section is divided into a plurality. The first optical element M1 having a plurality of reflection surfaces M11 to M13 that divide L2 into a plurality of partial light beams L21 to L23, and the traveling directions of the plurality of partial light beams L21 to L23 are aligned in the same direction (y-axis negative direction). At the same time, a plurality of reflecting surfaces M21 to L21 which arrange the partial light beams L21 to L23 in a line in a direction (x-axis direction) orthogonal to the traveling direction.
A second optical element M2 having M23, and a plurality of partial light beams L21 to L arranged in a line by the second optical element M2.
The above-mentioned object is achieved by providing a light-collecting optical system 11 having an anisotropic NA for converging light from the light source 23 to form an image of the light source. (3) In connection with FIG. 3 and FIG.
The present invention provides the optical device 4 according to claim 1, wherein
Are arranged at a predetermined interval x1 in the traveling direction (x-axis direction) of the parallel light beam L2 and are displaced stepwise in a direction (z-axis direction) perpendicular to the traveling direction. Different portions of the light beam L2 are divided into partial light beams L21 and L2.
3 includes a plurality of first reflection surfaces M11 to M13 parallel to each other that reflect in a direction different from the traveling direction (y-axis negative direction), and the second optical element M2 includes partial light beams L21 to L23.
Are provided corresponding to each of the plurality of first reflecting surfaces M11 to M13 at the position where the light is received, and the received partial light fluxes L21 to L2.
3 is provided with a plurality of parallel second reflecting surfaces M21 to M23 that reflect the light to the condensing optical system 11, respectively. (4) Explaining in association with FIG. 1, a laser processing machine according to a fourth aspect of the present invention includes the optical device 4 according to any one of the first to third aspects, and transmits laser light from the laser light source 1 to the optical device. Irradiation is performed on the workpiece W via the reference numeral 4.

[0007] In the section of the means for solving the above-mentioned problems, which explains the configuration of the present invention, the drawings of the embodiments of the present invention are used to make the present invention easy to understand. However, the present invention is not limited to the embodiment.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a view showing one embodiment of a laser beam machine according to the present invention, and is a view schematically showing a schematic configuration of an optical system of the laser beam machine. 1 is a laser oscillator, the laser processing machine such as a CO ₂ laser or a YAG laser is generally used. The laser light generated by the laser oscillator 1 is guided to the processing head 3 of the processing machine by the optical fiber 2 and is irradiated on the work W via the optical device 4 provided in the processing head 3.

FIG. 2 is a schematic view of the optical device 4, and FIG.
Is a front view, (b) is a plan view, and (c) is a left side view as seen from the optical fiber 2 direction. The optical device 4
Collimator 10, first optical element M1, second optical element M
2 and a condensing optical system 11. The laser light emitted from the optical fiber 2 is a conical light beam L1.
The light beam L1 is converted by the collimator 10 into a parallel light beam L2 having a circular cross-sectional shape.
In the present embodiment, the optical device 4 has the same magnification, and an exit end face image of the optical fiber 2 is formed on the work W.

FIGS. 3A and 3B show the details of the first optical element M1. FIG. 3A is a perspective view, and FIG. 3B is a view as seen from the y-axis negative direction (the collimator 10 direction). The first optical element M1 has three reflecting surfaces M11,
M12 and M13 are formed. Each reflection surface M11, M
The normal lines 12 and M13 form an angle of 45 degrees with the x-axis (negative direction) and the y-axis (negative direction), respectively. Also,
The reflecting surfaces M12 and M13 are respectively x1, x2 in the x direction and y1, y1 in the y direction with respect to the reflecting surface M11.
It is formed shifted only.

The hatched portion in FIG. 3B indicates the first optical element M
2 shows a cross section of a parallel light beam L2 incident on the light beam L1.
In the parallel light beam L2 incident on the first optical element M1, the partial light beam indicated by L21 is reflected by the reflecting surface M11, the partial light beam indicated by L22 is reflected by the reflecting surface M12, and the partial light beam indicated by L23 is reflected by the reflecting surface M13. Is done. As shown in FIG. 3A, the partial luminous flux L reflected by each of the reflection surfaces M11 to M13
As indicated by J1 to J3, the optical paths of the optical elements 21 to 23 are bent by 90 degrees in the positive y-axis direction, and enter the second optical element M2 shown in FIG.

As described above, with respect to the reflecting surface M11,
Since the reflecting surface M12 is formed so as to be shifted by x1 in the x direction and the reflecting surface M13 is formed so as to be shifted by 2 · x1 in the x direction, the optical paths J2 and J3 after reflection are shifted by x with respect to the optical path J2 after reflection.
In the direction by x1 and 2 · x1 respectively. Since the reflection surfaces M11 to M13 are parallel to each other, the divided partial light beams L21, L22, and L23 are also parallel to each other. As described above, the parallel light beam L2 is divided into three partial light beams L21, L22, and L23 by the first optical element M1 having the three reflection surfaces M11 to M13, and is incident on the second optical element M2.

FIGS. 4A and 4B are diagrams showing details of the second optical element M2. FIG. 4A is a perspective view of the second optical element M2, and FIG. 4B is a plan view of the second optical element M2 viewed from the z direction. is there. In the second optical element M2, three reflecting surfaces M21, M22, M23 having a positional relationship parallel to each other are formed. The normal line of each reflection surface M21, M22, M23 forms an angle of 45 degrees with respect to the y-axis (positive direction) and the z-axis (negative direction), respectively. Further, each of the reflection surfaces M22 and M23 is a reflection surface M21.
X1, x2 in the x direction and y in the y direction, respectively.
It is formed shifted by 1,2 · y1.

Therefore, the reflecting surface M1 of the first optical element M1
The partial light beam L21 that is reflected and split by 1 and travels in the negative y-axis direction is reflected by the reflection surface M21 in the negative z-axis direction. Similarly, the partial light beams L22 and L23 are also reflected in the negative direction of the z-axis by the reflecting surfaces M22 and M23, respectively. The hatched portions in FIG. 4 show the light beam cross sections of the partial light beams L21, L22, L23 reflected by the reflecting surfaces M21, M22, M23. Reflection surface M21 of second optical element M2
To M23 are arranged in a line in the x-axis direction.
The partial light beams L21 to L23 reflected by 21 to M23 are also arranged in a line in the x-axis direction as shown in FIG. 4B.

That is, the cross section of the parallel light beam L2 emitted from the collimator 10 is circular as shown in FIG. 3B, but after the parallel light beam L2 is divided into three by the first optical element M1, the second By being rearranged by the optical element M2,
The light is converted into a light flux having an elongated cross section as shown in FIG. 4B (a combination of the partial light fluxes L21 to L23). In this case, the processing direction by the laser beam is as shown in FIG.
Are in the x-axis direction, and the partial luminous fluxes L21 to L22
Are arranged in a line in the processing direction. Thereafter, the respective partial light beams L21, L emitted from the second optical element M2 in the negative z-axis direction
Reference numerals 22 and L23 denote the condensing optical system 1 as shown in FIG.
The light is condensed on the processed portion of the workpiece W by the light source 1, and an emission end face image of the optical fiber 1 is formed. Condensing optical system 1
As 1, various types such as a refraction type, a reflection type, and a combination of a refraction type and a reflection type are possible.

Next, the focusing NA of the laser beam focused on the workpiece W will be described. Here, a case will be described in which the parallel light beam L2 is divided into N parts so that the sectional division widths are equal. The N-divided partial light beams L21 to L23 are arranged in a line in the processing direction (x direction), and the direction in which the NA becomes maximum is the x direction, which is referred to as NAx. On the other hand, NA becomes minimum in the y direction, and this is described as NAy. These N
The values of Ax and NAy are slightly different depending on the specific system of the light condensing optical system 11, but the rough guide is given by the following equations (1) and (2).
Given by NA0 is the emission NA from the optical fiber 1, and M is the projection magnification of the exit end face image of the optical fiber 1 formed on the work W.

NAx = NA0 × N / M (1) NAy = NA0 × (1 / N) / M (2)

For example, in the case of the same size in the above-described example of three divisions, NAx in the processing direction is three times as large as the conventional one, and NAy in the direction perpendicular to the processing direction is one third of the conventional one. 5A and 5B are diagrams showing a relationship between NA and a processing cross section, wherein FIG. 5A is a cross sectional view in a cutting width direction, and FIG. 5B is a cross sectional view along a cutting direction. In FIG. 5, the dashed line indicates the luminous flux of NA0, and the solid line indicates the luminous flux of NA.
The luminous flux of x, NAy is shown. As shown in FIG. 5 (a), in this embodiment, the NAy is reduced to approximately 1/3 of NA0, so that the melting width in the cutting width direction (y direction) can be made smaller than before and the cutting edge can be made smaller. Can be sharpened vertically.

Conventionally, an anamorphic optical system combining a cylindrical lens and the like is used.
It is known that the use of an optical system can provide anisotropy to the converging NA. However, when such an optical system is used, the optical fiber core image projected on the workpiece will differ. Anisotropy occurs. FIGS. 6A and 6B are diagrams conceptually showing an example of an optical system using the cylindrical lenses 51 and 52, and FIG. 6A shows the optical system from the scanning direction (x-axis direction) of the laser beam. (B) is a cross-sectional view as viewed from the direction A in FIG.
(C) is a diagram showing the shape of the beam spot on the workpiece W, and (d) is a diagram showing the beam spot shape in the case of the present embodiment.

When such an optical system is used, the converging NAx
Can be made smaller than NA0 while keeping the same as NA0. By the way, since the projection magnification of the optical system is almost inversely proportional to the converging NA, the projection magnification in the NAy direction becomes maximum and the projection magnification in the NAx direction becomes minimum. As a result, the shape of the beam spot on the workpiece W is as shown in FIG.
As shown in (c), the shape becomes an oval shape that is the longest in the cutting width direction (y direction), and there is a disadvantage that the effect of reducing the converging NA is reduced or negated.

However, in the present embodiment, since the conversion of the light beam cross-sectional shape is performed by the optical elements M1 and M2 having a plane reflecting surface, the anisotropy in the projection magnification of the optical fiber exit end image onto the workpiece W is small. Does not occur. That is, even if the converging NA is converted to have anisotropy, the beam spot shape on the work W becomes a circle as shown in FIG. Therefore, it is possible to prevent the melting width from expanding as described above.

In the above-described embodiment, the laser processing machine has been described. However, the optical device 4 can be used as an optical device for converting a light beam cross section other than the laser processing machine. Further, when the above-described optical device 4 is used in the reverse optical path, it is possible to convert a light beam having an elongated cross section into a conical light beam. In addition, the reflection surface M1 of the optical elements M1 and M2
Each of 1 to M13 and M21 to M23 may be configured by a reflecting mirror or may be configured by using a total reflection prism.

<< Explanation of Optical Elements M1 and M2 >> FIG. 7 is a view showing a specific example in which a prism is used for the optical elements M1 and M2. The prisms P11, P12 and P13 constitute the optical element M1. P21, P22 and P23 constitute the optical element M2. FIG. 8 is an exploded perspective view of the optical elements M1 and M2. FIG. 8A is related to the optical element M1, and FIG. 8B is related to the optical element M2.

Each prism P11 constituting the optical element M1
To P13 each have a shape as shown in FIG. The reflection surface M11 of the prism P11 forms an angle of 45 degrees with each of the end surfaces S11 and S14 orthogonal to each other. Similarly, the reflection surface M12 of the prism P12 forms an angle of 45 degrees with the end surfaces S12 and S15 orthogonal to each other, and the reflection surface M13 of the prism P13 forms an angle of 45 degrees with respect to the end surfaces S13 and S16 orthogonal to each other. Make an angle. Such prisms P11 to P13 are connected to end surfaces S11, S12, S13, which are incident surfaces of the parallel light flux L2.
Are bonded together so that they are on the same plane.
Form one.

On the other hand, the prism P constituting the optical element M2
21, P22 and P23 have shapes as shown in FIG. The reflection surface M21 of the prism P21 forms an angle of 45 degrees with each of the end surfaces S21 and S24 orthogonal to each other. Similarly, the reflection surface M2 of the prism P22
2 has an angle of 45 degrees with respect to the end faces S22 and S25 that are orthogonal to each other, and the reflection surface M23 of the prism P23 has an angle of 45 degrees with respect to the end faces S23 and S26 that are orthogonal to each other. Then, each end face S24, S25, S26 of each prism P21 to P23 is connected to the end face S of the optical element M1.
14 to S16, the optical element M2
Is formed.

The optical elements M1 and M2 have end faces S11 to S1.
3 are arranged so as to be orthogonal to the x-axis, and the end faces S21 to S23 are orthogonal to the z-axis. The parallel light beam L2 is perpendicularly incident on the end faces S11 to S13 as shown in FIG.
The reflected light 13 is divided into three light beams L21 to L23. The partial light beams L21 to L23 are incident on different prisms P21 to P23, respectively, and are reflected by the reflection surfaces M21 to M23.
The partial light beam L21 is reflected from the end surface S21, the partial light beam L22 is emitted from the end surface S22, and the partial light beam L23 is emitted from the end surface L23. Emitted partial light beam L
21 to L23 enter the condensing optical system 11 shown in FIG.

<< Explanation of Condensing Optical System 11 >> Next, the condensing optical system 11 will be described. 9A and 9B are diagrams illustrating an example of the light collecting optical system 11, wherein FIG. 9A is a cross-sectional view of the light collecting optical system 11 viewed from the negative direction of the y-axis, and FIG. FIG. The condenser optical system 11 includes lenses 111 to 11
6 and a dustproof window glass 117. For example, a YAG laser having a wavelength of 1064 nm is used, and the optical fiber 2 has a core diameter of 0.8 mm and an NA of 0.2.
And the focal length of the collimator 10 and the condensing optical system 11 is f = 80 mm.

At this time, the diameter of the parallel light beam L2 emitted from the collimator 10 becomes φ32.7 mm, and the work W
The upper optical fiber core image is a circular spot of φ0.8 mm. The distance from the dust-proof window glass 117 to the work W, that is, the working distance of the condensing optical system 11 was set to 100 mm. Also, the lens 11
Quartz glass was used as the material of the glass windows 1-116 and the dustproof window glass 117. In FIG. 9, L201 denotes a light beam on the optical axis, L201
Reference numerals 202 and L203 denote peripheral light beams.

In the above embodiment, the optical elements M1,
M2 using a reflecting mirror and using a prism have been described. When prisms are used for the optical elements M1 and M2, the prisms P11 to P13, P21 to P23
Are bonded by bonding or the like, and the optical element M1 and the optical element M2 are integrated. Therefore, there is an advantage that the entire optical elements M1 and M2 can be reduced in size. Further, since the optical elements M1 and M2 are integrated, the optical element M
1 and M2 do not shift from each other, and a decrease in accuracy can be prevented. On the other hand, when the reflecting mirrors are used for the optical elements M1 and M2, the attenuation of the light quantity of the laser beam can be suppressed to a very low level, and the thermal load is small even when a high energy laser is used as compared with the case where a prism is used. There is an advantage.

In the correspondence between the embodiment described above and the elements in the claims, the reflecting surfaces M11 to M13 are the first
The reflecting surfaces, the reflecting surfaces M21 to M23 form the second reflecting surface, the laser oscillator 1 forms the laser light source, and the work W forms the workpiece.

[0030]

As described above, according to the first aspect of the present invention, it is possible to obtain a light beam having an isotropic focusing NA with an isotropic projection magnification. According to the second and third aspects of the present invention, even if the incident NA of the light beam incident on the collimator is isotropic, the first optical element converts the parallel light beam emitted from the collimator into a plurality of partial light beams. And a plurality of partial luminous fluxes arranged in a line by the second optical element are condensed by a condensing optical system to form a condensing NA having an elongated cross section and a narrow cross section width. Can obtain a small luminous flux. According to the fourth aspect of the present invention, the laser beam emitted from the optical element has an elongated cross-sectional shape, and the melt width of the processed portion can be reduced by setting the longitudinal direction of the cross section as the processing direction. Further, since the light converging NA in the direction in which the cross-section width is small can be reduced, it is possible to perform processing so that the cut cross-section becomes sharp.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a laser processing machine according to the present invention, and is a view schematically showing a schematic configuration of an optical system of the processing machine.

FIGS. 2A and 2B are schematic diagrams of an optical device 4, wherein FIG.
(B) is a plan view, and (c) is a left side view as seen from the optical fiber 2 direction.

FIG. 3 is a diagram showing details of a first optical element M1,
(A) is a perspective view, (b) is the figure seen from the x-axis negative direction.

FIG. 4 is a diagram showing details of a second optical element M2;
(A) is a perspective view, (b) is a plan view.

FIG. 5 is a diagram showing a relationship between NA and a processing cross section,
(A) is a sectional view in the cutting width direction, and (b) is a sectional view along the cutting direction.

6A and 6B are diagrams illustrating an example of an anamorphic optical system. FIG. 6A is a cross-sectional view of the optical system as viewed from an x-axis direction.
(B) is a cross-sectional view as viewed from the direction A in (a), and (c)
FIG. 4 shows a beam spot shape, and FIG. 4D shows a beam spot shape in the case of the present embodiment.

FIG. 7 is a diagram showing optical elements M1 and M2 using a prism.

8 is an exploded perspective view of the optical elements M1 and M2 shown in FIG. 7, where (a) relates to the optical element M1 and (b) relates to the optical element M2.

FIG. 9 is a diagram illustrating an example of a light collecting optical system 11;
Is a cross-sectional view of the condensing optical system 11 as viewed from the y-axis negative direction.
(B) is sectional drawing seen from B direction of (a).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser oscillator 2 Optical fiber 3 Processing head part 4 Optical device 10 Collimator 11 Condensing optical system L2 Parallel light flux L21-L23 Partial light flux M1, M2 Optical element M11-M13, M21-M23 Reflection surface W Work

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G02B 13/14 G02B 27/00 E

Claims (4)

[Claims] 1. An optical device, wherein a light beam having an isotropic incident NA is converted into a light beam having an anisotropic convergent NA while maintaining isotropic projection magnification. 2. A collimator for converting a light beam emitted from a light source having a finite size into a parallel light beam, and a plurality of reflections for dividing the parallel light beam into a plurality of partial light beams so that a light beam cross section is divided into a plurality of light beams. A first optical element having a surface, and a second reflecting surface having a plurality of reflecting surfaces for aligning the traveling directions of the plurality of partial light beams in the same direction and arranging the partial light beams in a line in a direction orthogonal to the traveling direction. An optical element; and an anisotropy N for condensing the plurality of partial light beams arranged in a line by the second optical element to form an image of the light source.
An optical device comprising: a condensing optical system having A. 3. The optical device according to claim 2, wherein the first optical elements are arranged at predetermined intervals in a traveling direction of the parallel light beam and are shifted stepwise in a direction orthogonal to the traveling direction. And a plurality of parallel first reflecting surfaces that reflect different portions of the parallel light beam as the partial light beams in a direction different from the traveling direction, wherein the second optical element receives the partial light beams And a plurality of parallel second reflecting surfaces that are provided at positions corresponding to the plurality of first reflecting surfaces, respectively, and reflect the received partial light beams to the condensing optical system, respectively. apparatus. 4. A laser processing machine comprising the optical device according to claim 1, wherein a laser beam from a laser light source is irradiated onto a workpiece through the optical device.