JPS59129485A - Laser oscillation device - Google Patents

Abstract

PURPOSE:To obtain an oscillation device enabling a cutting with high accuracy by setting up at least one linearly polarized light select-element arranged at a Brewster's angle on a laser optical axis in a laser oscillator and turning the select-element around the optical axis while maintaining the Brewster's angle. CONSTITUTION:A cylindrical mechanism vessel 5 having a rotary function is disposed on an axis of resonance constituted by a total reflection mirror 21 and a transmission mirror 22 as an output coupling mirror positioned at both ends of a laser oscillator 3. A polarized light select element 40 turning around a laser optical axis while maintaining a Brewster's angle to the optical axis is set up in the vessel 5, and the element 40 is turned by a motor 6. Laser beams 1 from the oscillator 3 are irradiated to a workpiece 12 through an external optical mirror 7 and a condenser lens 2 while controlling a rotation-angle input to the motor 6 by a control system 11 while X and Y tables 8, 9 on an XY driving base 10 are moved, and the quantity of the movement is fed back to the control system 11.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a laser oscillation device that effectively uses laser energy and is suitable for laser cutting and the like.

2B-2P Conventional Structure and Problems The waves of the C02 and YACi laser beams are a type of electromagnetic wave, and the laser beams travel while vibrating in a direction perpendicular to the direction of travel.

The direction of vibration perpendicular to the direction of travel of the laser beam is called the polarization direction, and the polarization direction can be used for circularly polarized laser beams that rotate in the same direction with the same amplitude over time, or for circularly polarized laser beams whose polarization direction is only in a certain direction over time. There is a linearly polarized laser beam that has a fixed component of . Whether the laser beam is circularly polarized or linearly polarized can be selected depending on the configuration of the laser oscillator and the configuration of an external optical system that modulates the polarization direction of the laser beam after it exits the laser oscillator.

Conventionally, when laser processing (cutting) is performed using a linearly polarized laser beam, it has been found that the cutting effect is significantly different depending on the direction of movement of the cutting aligned with the direction of the linearly polarized light.

FIG. 1 is a diagram schematically showing how the cutting situation differs depending on the direction of movement of the cutting. 31'' The laser beam 1 is vertically polarized in the Ox direction. 2 is a condenser lens that focuses the laser beam 1 on the surface of the workpiece 120 for cutting. When the workpiece 12 is moved in the Ox direction and cut, the absorption of the laser beam is high, so the laser energy is efficiently converted into cutting energy, and the cutting speed is high. , is also narrow during cutting.On the other hand,
When cutting the workpiece 12 by moving it in the oY direction, the absorption of the laser beam is low, and the absorption of the laser beam mainly occurs at the cutting plane perpendicular to the cutting direction OY, so the kerf width Wc of the workpiece 12 is wide. , the cutting speed is slow. an Ox direction in which the direction of linearly polarized light of the laser beam and the cutting direction are the same;
Alternatively, FIG. 2 shows a row in which the cutting speed V and the cutting kerf width Wc change depending on the thickness of the iron plate in the perpendicular OY direction. As shown in Figure 2, when cutting in the Ox direction, which is the same as the linear polarization direction, the cutting speed is approximately twice that of cutting in the OY direction, which is perpendicular to the linear polarization direction, and the kerf l] is approximately %.
become.

Next, the light is circularly polarized in a direction perpendicular to the direction of travel of the conventional laser.
A method has been used in which a laser beam with isotropic cutting ability is generated using an external optical system outside the laser resonator.

FIG. 3 shows an example of the configuration of an external optical system for circularly polarizing light. The laser resonator 3 is constructed so that the laser beam 1 emitted from the laser resonator 3 becomes a laser beam 1 tilted at an angle of 46° with respect to the vertical component of the traveling direction. Reflector, phase retarder-4
By configuring the beam to have an incident angle of 45°, the light can be easily circularly polarized, and the workpiece 12 can be isotropically cut by the condenser lens 2. Figure 4 is the third
It is a diagram in which the polarization characteristics of the cross section at each location of the laser beam 1 shown in the figure were investigated. a shows the linear polarization characteristic in the A-A' cross section tilted at 45 degrees before circular polarization. However, the laser output is 10%. b is phase retarder-4
circularly polarizes the light through the condenser lens 2: s-
B' section shows circular polarization characteristics.

FIG. 2 shows the cutting efficiency 5 and the effect of circularly polarized light in the configuration shown in FIG. 3 in terms of cutting speed v' and cutting kerf width Wc'. In the case of circularly polarized light, it is true that it is possible to cut isotropically compared to linearly polarized light, but since the laser energy usage is %, when comparing the cutting speed V of IM line polarized light in the OX direction and the cutting speed of circularly polarized light V', it is about 25%. Since the circularly polarized light cutting speed becomes slower and the kerf width becomes wider, about 25% to 30%, the cutting efficiency and precision are not necessarily good. However, in the case of circularly polarized light, isotropic cutting becomes possible.

As stated above, when laser cutting is performed using linearly polarized light, which has a fixed component in only a certain direction, laser energy can be used efficiently if the cutting is performed in the same direction as the linearly polarized light. In the opposite direction, the polarization direction is fixed, resulting in poor efficiency and accuracy, making it unsuitable for isotropic cutting. Therefore, a method of circularly polarizing light that allows isotropic cutting has been adopted. However, as shown in Figure 4, circularly polarized light is
In addition, it is necessary to construct a resonator that polarizes the straight line 6 with an inclination of 46°, and the deterioration of the phase retarder 4 decreases. This had the disadvantage of deteriorating the circular polarization characteristics.

OBJECTS OF THE INVENTION The present invention eliminates the above-mentioned drawbacks and provides a laser oscillation device that can perform high-speed cutting, high efficiency, narrow kerf width, and highly accurate laser cutting.

SUMMARY OF THE INVENTION The present invention achieves the above object by providing at least one linearly polarized light selection element disposed at a bleeder angle on the laser optical axis inside a laser oscillator, and in which the linearly polarized light selection element is breech-selected. The object of the present invention is to provide a laser oscillation device provided with means for rotating the laser around the optical axis while maintaining the star angle.

Description of examples FIG. 6 shows a typical embodiment of the invention.

In this example, as shown in FIG. 1, by linearly polarizing the light, it is possible to obtain a highly efficient and narrow kerf width for the same cutting direction, and total internal reflection within the laser oscillator 3. A laser optical 'fill (Jl; Class 1 1 (1) l-) that resonates and amplifies with a mirror 21 and a transmitting mirror (output coupling mirror) 22 is provided with a linear polarization selection element 4o arranged at a Brewster's angle. The selection element 40 is fixed in a cylindrical mechanical container 5 with one rotational geometry.

FIG. 6 is an enlarged view showing how the polarization selection element 40 is rotated by the driving motor 6. The laser optical axis 1 and the Priest angle θ are set in the cylindrical mechanism container 5 disposed in the co-book device 3. The polarization selection element 4o is configured so that it can be rotated around the laser optical axis 1 while the polarization selection element 4o is
0 is two bearings 61 and a rotating transmission belt 62
By adding , the drive motor 6 can freely rotate around the laser optical axis 1 .

Therefore, the selection element 4o is capable of linearly polarizing light inside the resonator and changing the direction of linear polarization.

In implementation-〇, two selection elements 4o are used, but this is because the selection element 4o refracts the laser beam that is resonantly amplified and is used to correct the deviation of the optical axis, so it is not necessary to use two selection elements. You can use one sheet instead of one, or conversely, you can use multiple sheets. At least in this embodiment, it is sufficient that the laser beam is configured to coincide with the laser resonance axis and that the loss of light can be minimized.

By providing the ability to rotate the linearly polarizing element 40, linearly polarized light can be set in any direction.

Therefore, when performing laser cutting using a laser beam,
By introducing the light to a processing point on the workpiece 12 using the external optical mirror 7, focusing it through the condensing lens 2, and irradiating it using the XY drive stage 1o, it is possible to process and cut an arbitrary shape.

The laser oscillator of this embodiment includes a motor 8o that operates the X-axis table 8 so that when freely cutting the workpiece 12, the tangential direction of the processed shape is always in the direction of linearly polarized light by using the XY drive base 1o. The motor 90 that operates the Y-axis table 9 is operated. For example, the control system 11 automatically determines the tangential direction from the rotation amounts of the X-axis and Y-axis drive motors 80 and 90 and automatically provides the necessary rotation angle input of the single-stroke motor 6 to the selection element 4o. I'll do it at Alternatively, the tangential direction of the processing point may be determined from the cut shape of the workpiece to be processed, and the necessary rotation angle may be inputted to match the tangential direction of the processing shape with the polarization direction. Electric front leg system 1
As a specific example of Embodiment 1, the process of cutting a figure P will be explained using FIG. The solid line is the cut part and the dotted line is the uncut part).

The polarization direction of the laser beam is divided by the OY direction, and the X-axis table 8 and Y-axis table 9 in FIG. 5 are moved to adjust the beam to the state shown in FIG. 7A.

In steps A22B, E and G, the intra-cavity polarization selection element 4o shown in FIGS. 5 and 6 is oriented in a fixed direction.

On the other hand, in steps C and 2, the selection element 4o is rotated so that the direction of polarization and the direction of cutting coincide with each other.

FIG. 8 shows the selection element drive motor 6 shown in FIGS. 5 and 6.
This is an example of a flowchart for commanding the rotation angle to be given to. 61 is a block for inputting processing figures, which can be input using paper tape, magnetic tape, cards, etc. 10.

Strengthen. A block 52 reads out the processing point, and a block 53 calculates the amount of translational movement so that the processing point comes to the focused spot of the laser. Block 54 indicates the amount of translational movement. In block 55, it is determined whether the cutting point is on a straight line or a curved line. If it is on a straight line, the rotation angle of the rotary table is calculated in block 66, and the rotation angle to be given to the rotary motor is specified in block 58.

When it is determined in block 65 that the cutting point is curved, the rotation angle on the figure tangent is calculated in block 57, and the rotation angle to be given to the rotary motor is specified in block 68.

FIG. 9 is a diagram showing how the polarization direction of the laser beam changes by rotating the mechanical container 6 equipped with the linear polarization selection element 4o shown in FIG.
- Linear polarization characteristics at A' are shown. By controlling the linear polarization selection element 40, the polarization direction can be controlled to any angle from β to β'. The operation of the drive motor 6 only needs to transmit a rotation of at least 0° to 18 CI', and may be not only a continuous operation but also a step operation.

Effects of the Invention The present invention provides a laser oscillation device that is equipped with a linear polarization element in the laser oscillator and can change the direction of linear polarization by adding a rotation function, and requires no parts or maintenance procedures for circular polarization. In addition, the laser cutting speed can be increased to increase cutting efficiency, and the scarf width can be narrowed to produce a highly accurate laser beam.

[Brief explanation of drawings]

Figure 1 is a diagram schematically showing the relationship between cutting direction and polarization direction, Figure 2 is a diagram showing the relationship between cutting speed, cutting kerf width, and plate thickness, and Figure 3 is circularly polarized light. 4 is a diagram showing the polarization characteristics of the beam cross section at each location of the laser oscillation device shown in FIG. , b is B-B
'The circular polarization characteristics of each cross section are shown. FIG. 6 is a configuration diagram of a laser oscillation device as an embodiment of the present invention, FIG. 6 is a sectional view of the main part of the embodiment shown in FIG. 6, and FIG. 7 is a cutting process of the laser oscillation device of the present invention. FIG. 8 is a block diagram for calculating the amount of rotation of the laser oscillation device of the present invention, and FIG. 9 shows custom polarization in the A-A' cross section of the laser oscillation device of the present invention shown in FIG. It is a diagram. 1-... Laser beam, 2... Condensing lens, 3... Laser oscillator, 4-...-7 Aze retarder, 4°... Linear polarization selection element, 5...-
... Mechanism container, 6... Drive motor, 7... External reflector, 8-... X-axis table, 80... X-axis motor, 9... Y-axis table, 90... ...Y-axis motor, 1o...xY drive stand, 11...
Control system, 12...-Workpiece, 21...
Total reflection mirror, 22-... Output transmission window, 51...
Bearing, 52...Transmission belt. Name of agent: Patent attorney Toshio Nakao and 1 other person - Senkan 37

Claims (2)

[Claims] (1) At least one linear polarization selection element is provided inside a laser oscillator that performs resonance and amplification between a total reflection mirror and an output coupling mirror, and the linear polarization selection element is arranged at a Priester angle on the laser optical axis. 1. A laser excavation device, characterized in that the linearly polarized light selection element is rotated around the laser optical axis without being maintained at the Brewster's angle. (2) The laser oscillation device according to claim 1, further comprising means for controlling the rotation of the linear polarization selection element so that the linear polarization direction coincides with the processing direction.