JPH0150517B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention divides the output of one laser beam from a laser oscillator into 2 ⁿ (n: integer) beams with equal output,
The present invention relates to an improvement of a laser processing apparatus that focuses each divided laser beam using each condenser lens and irradiates a workpiece to process it.

A conventional laser processing apparatus of this type is shown in FIG. 1a. FIG. 1a is an explanatory diagram showing an embodiment for obtaining each divided laser beam in a conventional laser processing apparatus. In the figure,
1 is a laser oscillator, L1 is one laser beam output from laser oscillator 1, 2a, 2b, 2c
is a partially transmitting mirror provided at an angle of approximately 45 degrees with respect to the laser beam L1; L2, L3, and L4 are laser beams that partially pass through each partially transmitting mirror 2a, 2b, and 2c; and 3 is a total reflecting mirror. 4a, 4b, 4c, 4
d is each divided laser beam La, which is deflected by each partially transmitting mirror 2a, 2b, 2c and total reflecting mirror 3;
This is a condensing lens that focuses Lb, Lc, and Ld and processes a workpiece (not shown) using each focused energy.

FIG. 1b is a table showing an example of numerical specifications of each part in the laser processing apparatus shown in FIG. 1a. Now, if the laser beams transmitted through each of the partially transmitting mirrors 2a, 2b, and 2c are respectively L2, L3, and L4, and the output of the laser beam L1 output from the laser oscillator 1 is W, each divided laser beam La, Lb,
In order to achieve the purpose of dividing the output into four equal outputs, in which the outputs of Lc and Ld are each 1/4W, each laser beam L
2, L3, L4 output and each partially transmitting mirror 2
The reflectance or transmittance of a, 2b, 2c, and the total reflection mirror 3 may be set to values as shown in the specification numerical example shown in the table of FIG. 1b.

Conventional laser processing equipment is configured as described above, so when one laser beam is divided into 2 ⁿ laser beams, 2 ⁿ -1 partially transmitting mirrors with different reflectances (or transmittances) are used. and for this,
Not only did the number of types of parts increase, but there were also drawbacks such as the inability to obtain optical elements with a reflectance that met the requirements due to coatings, etc., and the division accuracy not being improved. Furthermore, since the angle of incidence of the laser beam incident on each partially transmitting mirror is large, when splitting a laser beam whose polarization components are not constant, there is a drawback that the splitting ratio is not constant due to the selective transmittance of the polarized light wave. In order to avoid this problem, there is a drawback that a linearly polarized laser beam must be used.

This invention was made in order to eliminate the drawbacks of the conventional ones as described ^above .
3...) In a laser processing device that divides the output into equal outputs, focuses each divided laser beam using each condenser lens, and irradiates the workpiece to process the workpiece, at least one total reflection mirror; It has a configuration in which ⁿ -1 semi-transmissive mirrors are used, and the incident angle of the laser beam incident on all of these semi-transmissive mirrors is within about 15 degrees. The purpose is to provide highly accurate laser processing equipment.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is an explanatory diagram showing an embodiment for obtaining a four-split laser beam in a laser processing apparatus which is an embodiment of the present invention. As shown in the figure,
Reference numeral 5a denotes a first semi-transmissive mirror disposed so as to have an incident angle θ ₁ with respect to one laser beam L ₁ output from the laser oscillator 1, and 1 of the incident energy of the laser beam L ₁ . It consists of an optical element that reflects 1/2 and transmits the remaining 1/2. First semi-transparent mirror 5
The laser beam that has passed through a is reflected by a first total reflection mirror 3a that is disposed at the same angle as the first semi-transmission mirror 5a, and is reflected by the first semi-transmission mirror 5a. is deflected in a direction approximately parallel to the path of. Thus, the laser beams reflected by the first semi-transmissive mirror 5a and the first total reflection mirror 3a are reflected by the two second mirrors disposed so as to form reflective surfaces in a direction perpendicular to the laser beam L1. The light is incident on the semi-transmissive mirror 5b at an incident angle θ ₂ =2θ ₁ . Assuming that the second semi-transmissive mirror 5b also has the same optical function as the first semi-transmissive mirror 5a,
As shown in FIG. 2, the reflected laser beam and the transmitted laser beam by the two second semi-transmissive mirrors 5b are reflected by the four second total reflective mirrors 3b and each condenser lens 4.
By a, 4b, 4c, and 4d, it is possible to finally obtain a four-split laser beam divided into equal outputs.

FIG. 3 is an explanatory diagram showing an embodiment for obtaining an eight-divided laser beam in a laser processing apparatus which is another embodiment of the present invention. Similarly to the structure shown in FIG. 2, the structure shown in FIG. 3 is similar to the structure shown in FIG. First total reflection mirror 3a, two second semi-transmission mirrors 5
b. By arranging the four third semi-transmissive mirrors 5c and the eight second total reflection mirrors 3b as shown in FIG. 3, it is easy to obtain an eight-divided laser beam. Since it is easy to understand, detailed explanation will be omitted.

As explained above, what is important here is the incident angle θ of all the laser beams to the semi-transmissive mirror in the laser beam splitting process, and the incident angle θ of the single laser beam L1 output from the laser oscillator 1. When dividing elements whose polarization characteristics are not determined, as shown in Figure 4, when the incident angle θ exceeds approximately 15°, a coating with a thickness of 1/4 wavelength applied to a semi-transmissive mirror is used. The difference in the splitting output W of the P-wave and S-wave due to Incident angle θ of the incident laser beam incident on the semi-transmissive mirror
The smaller the value, the better the beam splitting. However, due to physical constraints, the incident angle θ=0
However, according to the applicant's experimental results, if the upper limit of the incident angle θ is within about 15°, then it is possible to divide it into 1/8 as shown in Figure 3. However, it turned out that there was no practical problem because the division accuracy could be kept within ±10%. Here, the laser processing equipment used in the above experiment is CO ₂
It is a laser (wavelength: 10.6 μm) processing equipment, the polarization characteristics are random polarization, and the semi-transparent mirror is made of ZnSe.
Seven 50% beam splitters and one total reflection mirror made of Si and coated with Ag were used.

FIG. 5 shows the four
FIG. 3 is a schematic diagram showing a beam transmission situation of a divided laser beam to a final condensing lens. Although the semi-transmitting mirror and the total reflecting mirror are not shown in the figure, one laser beam L1 output from the laser oscillator 1 spreads with a certain divergence angle, so each focused beam The condensing spot diameter d in the lenses 4a to 4d is
Laser output wavelength λ, condensing lens focal length f,
It is determined by d∞λf/D as a function of the laser beam diameter D incident on the condenser lens. Therefore, even if the divided output of the laser beam is equally distributed, the difference in the laser beam diameter D incident on each of the condensing lenses 4a to 4d causes the condensing spot diameter d to change and the output density to change. However, there was an inconvenience that there was a difference in machining performance when multiple simultaneous machining was performed with equal output distribution. In order to eliminate this inconvenience, as shown in FIG.
4d, a beam expander 6 or the like is provided as a means for correcting the laser beam diameter D at at least one location, thereby adjusting the laser beam diameter D incident on each of the condensing lenses 4a to 4d. It is advantageous to provide a correction.

In addition, for measurement of each divided laser beam, laser beam path after division, maintenance of each condensing lens 4a to 4d, etc., the laser beam transmission path where each divided laser beam leads to each condensing lens 4a to 4d is required. It is advantageous to provide therein means, such as a beam shutter (not shown), which can independently cut off each respective split laser beam.

Furthermore, when the processing laser beam is an invisible laser beam such as a CO ₂ laser, in order to facilitate the alignment of optical elements and optical axis alignment,
As a means for arranging a visible light laser beam such as a He--Ne laser on the same optical axis as the processing laser beam, it is advantageous to provide, for example, a He--Ne laser weighing device.

As described above, according to the laser processing apparatus of the present invention, ^{at least one total reflection mirror and 2 n -} The configuration uses one semi-transmissive mirror and keeps the incident angle of the laser beam incident on all of these semi-transmissive mirrors within about 15 degrees, so it is extremely simple.
It can be constructed at low cost and has extremely high division accuracy.
Moreover, the excellent effect of providing a laser processing device that is easy to maintain is achieved.

[Brief explanation of drawings]

FIG. 1a is an explanatory diagram showing an embodiment for obtaining each divided laser beam in a conventional laser processing device, and FIG. 1b is a table showing example numerical specifications of each part in the laser processing device shown in FIG. 1a. 2 is an explanatory diagram showing an embodiment for obtaining a four-split laser beam in a laser processing apparatus which is an embodiment of the present invention, and FIG. 3 is an explanatory diagram showing an embodiment of the laser processing apparatus which is another embodiment of the invention. , an explanatory diagram showing an embodiment for obtaining an eight-divided laser beam, FIG.
In each laser processing device shown in FIGS. 2 and 3,
Characteristic diagram showing the relationship between the incident angle θ of the laser beam on the semi-transmissive mirror and the divided output W (or reflectance %), fifth
The figure is a schematic diagram showing the beam transmission situation of the four-split laser beam to the final condensing lens in the laser processing device shown in Fig. 2, and Fig. 6 shows the beam transmission situation improved from the beam transmission situation shown in Fig. 5. FIG. In the figure, 1...laser oscillator, L1 to L4
...Laser beam, La~Ld...Divided laser beam, 2a~2c...Partially transmitting mirror, 3, 3a, 3b
... Total reflection mirror, 4a to 4d ... Condensing lens, 5a
~5c...Semi-transparent mirror, 6...Beam expander. In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. One laser beam output from a laser oscillator is divided into 2 ⁿ (n=1, 2, 3...) beams with equal output, and each divided laser beam is divided by each condenser lens. In laser processing equipment that focuses and processes the workpiece by irradiating it, at least one total reflection mirror and 2 ⁿ -1 semi-transmission mirrors are used, and the laser beam incident on all of these semi-transmission mirrors is The angle of incidence is approximately
A laser processing device characterized in that the angle is within 15°. 2. The laser processing apparatus according to claim 1, further comprising means for correcting a laser beam diameter at at least one location in a laser beam transmission path from the laser oscillator to each of the condensing lenses. . 3. A means for independently cutting off each of the divided laser beams is provided in a laser beam transmission path in which each of the divided laser beams reaches each of the condensing lenses. The laser processing device described. 4. The laser according to claim 1, wherein when the laser beam is an invisible laser beam, the invisible laser beam is provided with means for co-locating a visible laser beam on the same optical axis. Processing equipment.