JPH0444373A - Linear deflection laser oscillator - Google Patents

Abstract

PURPOSE:To make it possible to cut a profile by constituting a ridgeline angle of a rear mirror so that it may be controlled to make rotation to a desired polarization angle where said rear mirror is a right angle roof type reflecting mirror. CONSTITUTION:An oscillator comprises a rear mirror, which is a right angle roof type reflecting mirror 10 and an output coupling mirror 4. In the roof reflecting mirror 10, light enters each reflected plane at an incident angle of 45 degree. In this case, a linear polarization light parallel to a ridgelin 10a provides the maximum reflectance. Since laser oscillation is a kind of positive feedback phenomenon, laser light is oscillated under this linear polarization condition. When it is arranged to make the roof reflecting mirror 10 rotatable around an axis which crosses the ridgeline 10a, it is possible to rotate the direc tion E of the field vector. When profile cutting processing is carried out, if the angle of the ridgeline 10a of the roof reflecting mirror 10 is rotated under control so that the direction E of the field vector of a laser beam 13 may con form to the direction of a processing passage, it will be possible to cut and process at the maximum absorption rate all the time.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a linearly polarized laser oscillator that emits eight linearly polarized beams with electric field vectors polarized in a desired direction. This invention relates to a linearly polarized laser oscillator used as an output laser oscillator.

[Conventional technology]

The importance of polarization properties in laser cutting is well known. For example, profile cutting typically uses a circularly polarized beam.

FIG. 4 is a diagram showing the structure of a conventional laser oscillator provided with an external circular polarization unit. In order to create a circularly polarized beam, in the conventional technique, as shown in FIG. 4, linearly polarized light is first oscillated within a resonator, and then this is converted into circularly polarized light using an external optical system. In FIG. 4, parts for laser excitation such as a discharge tube are omitted because they are well known, and only the optical system is shown.

In FIG. 4, the laser resonators are rear mirror 1, folding mirror 2.
3. The output coupling mirror consists of 4.

This is also based on a well-known principle, and the laser light inside the resonator is linearly polarized light whose electric field vector is orthogonal to the plane determined by the three optical axes 7a, 7b, and 7C. Moreover, in FIG. 4, this plane has been rotated by π/4 around the straight line 7a. Therefore, the output beam 8 from the resonator is π/4 with respect to the earth's surface.
It is linearly polarized light tilted by .

This output beam 8 is transmitted through a set of two π/2 face retarders 5
and 6. According to well-known principles, the beam 9 emitted from the retarder is circularly polarized.

In fact, it is well known that when cutting metal or the like with a laser beam, it is desirable to use a linearly polarized beam whose electric field vector matches the cutting direction. This is possible in the case of straight-line cutting, but in general profile cutting it is necessary to always control the rotation of the electric field vector direction in the direction of cutting. Since the direction of polarization cannot be changed arbitrarily, circularly polarized laser light has been used for profile cutting.

[Problem to be solved by the invention]

The conventional technology has the following problems. First, in an oscillator that generates a linearly polarized laser beam with an electric field vector tilted at 45 degrees to the ground surface, the plane formed by the folded optical axis is also tilted to the ground surface, and the structure of the resonator is It gets complicated.

Second, since profile cutting is not possible with linearly polarized light, a polarization unit is required to generate circularly polarized light.

The present invention has been made in view of these points, and an object of the present invention is to provide a linearly polarized laser oscillator that can rotate and control the polarization angle of linearly polarized light to a desired angle.

Another object of the present invention is to provide a linearly polarized laser oscillator that has a multistage folding structure and can rotate and control the polarization angle of linearly polarized light to a desired angle.

Furthermore, another object of the present invention is to change the polarization angle of linearly polarized light by
An object of the present invention is to provide a linearly polarized laser oscillator that enables profile cutting with a linearly polarized laser beam by matching the direction of a processing path.

[Means for resolving the problem] In order to solve the above problem, the present invention provides a linearly polarized laser oscillator comprising an output coupling mirror and a rear mirror, wherein the rear mirror is a right-angle roof reflector, and the rear mirror is a right-angle roof reflector. Provided is a linearly polarized laser oscillator characterized in that the angle of the ridge line can be rotationally controlled to a desired polarization angle.

Further, in a multi-folding type linearly polarized laser oscillator comprising an output coupling, a rear mirror, and a folding mirror, the rear mirror is a right-angle roof reflector, all the folding mirrors are zero-shift reflectors, and the ridgeline of the rear mirror is angle,
A linearly polarized laser oscillator is provided, which is characterized in that it is configured such that its rotation can be controlled to a desired angle.

[Effect]

In the present invention, the rear mirror of the laser oscillator is constructed of a right-angle roof reflector, and its ridgeline is rotated around the optical axis to control rotation of the electric field vector direction. This makes it possible to perform processing in which the cutting direction of profile cutting matches the direction of the electric field vector.

Furthermore, in a laser oscillator with a multi-stage folding structure, all folding mirrors are constructed of zero-shift reflecting mirrors, and the ridge line of the roof reflecting mirror is rotated around the optical axis to control the rotation of the electric field vector direction. This makes it possible to perform processing in which the cutting direction of profile cutting matches the direction of the electric field vector.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a diagram showing an embodiment of a linearly polarized laser oscillator according to the present invention. In the resonator used here, the rear mirror is a right-angle roof reflector 10, and the output coupling mirror is 4. In the roof reflecting mirror 10, light is incident on each of the opposite slopes at an incident angle of 45 degrees. In this case, linearly polarized light whose electric field vector is parallel to the ridgeline 10a has the maximum reflectance. Laser oscillation is a type of positive feedback phenomenon, so it oscillates in a levered linearly polarized state.

As shown in the figure, if the roof reflector 10 is made rotatable around an axis perpendicular to the ridgeline 10-1, the direction E of the electric field vector can be rotated.

In FIG. 1, a pulse motor 16 and a reduction gear 14, 15 are shown.
The rotation of the roof reflector IO is controlled.

In FIG. 1, the ridge line 10a is located perpendicular to the earth's surface, so the laser beam is also polarized in this direction. Fourth
In the device shown in the figure, the electric field direction is inclined at 45 degrees with respect to the ground surface. On this side, there is a ridgeline 10a of the roof reflector 10.
It is sufficient to maintain the angle of inclination. That is, there is no need to create a structure in which the optical axis is tilted by 45 degrees.

When actually performing profile cutting, if the angle of the ridgeline 10a of the roof reflector 10 is controlled to rotate so that the direction E of the electric field vector of the laser beam 13 matches the direction of the processing path, it will always be possible to Cutting can be performed with maximum absorption rate.

FIG. 2 is a schematic block diagram of a numerical control device for controlling the angle of the roof reflector so that it coincides with the advancing direction of the processing path. The numerical control device 20 has a microprocessor configuration, and FIG. 2 shows only functional blocks of software processing.

The interpolation means 21 performs interpolation on the X and Y axes, and generates an interpolation pulse X.
Output P and YP. This interpolation pulse controls the movement of the table that fixes the workpiece.

The interpolation means 21 can calculate the direction of the machining path on the XY plane from the interpolation pulses of the X and Y axes. For example, Y
Let this angle be θ with respect to the axis.

The interpolation means 21 outputs this angle θ to the rotation control means 22.

The rotation control means 22 outputs a rotation command to the axis control circuit 23 from this angle θ. That is, if the previous angle is 01 and the current angle is 02, Δθ=θ2−01 is given to the axis control circuit 23. The axis control circuit 23 outputs this command to the servo amplifier 24, which rotates the servo motor 17 and rotates the roof reflector 10 via gears 18 and 19.

FIG. 3 is a diagram showing another embodiment of the linearly polarized laser oscillator. The resonator used here is a folding type resonator using folding mirrors 11 and 12 in addition to the roof reflecting mirror 10 and the output coupling mirror 4.

In this case, the number of folding stages may be greater.

The rotation of the ridgeline 10a of the roof reflecting mirror 10 can be controlled as in FIG. 1, but the pulse motor for rotation control is omitted in FIG. In this case, special mention should be made of the folding mirrors 11 and 12, which must be zero-shift mirrors.

If so, of all the mirror surfaces that make up the resonator, including the roof reflector 10, the output coupling mirror 4, and the folding mirrors 11 and 12, only the roof reflector 10 has polarization selectivity. The laser beam 13 guided by the laser beam 13 becomes linearly polarized light whose electric field vector E coincides with the direction of the ridge line 10a. In other words, if the vertical axis is the y-axis, then with respect to the y-axis,
θ is tilted.

In this case as well, it is sufficient to tilt only the roof reflector 10 in order to tilt the polarization angle by 45 degrees with respect to the ground surface. That is, as shown in FIG. 3, the optical axis 7a.

There is no longer a need for the planes created by 7b and 7C to be inclined at 45 degrees with respect to the ground surface. As a result, the configuration of the entire device becomes simple.

In the above explanation, the rotation of the roof reflector is controlled by a pulse motor or a servo motor, but it can also be configured to be set at any angle by hand or the like. That is, if the cutting direction required by the cutting process is always constant and the angle needs to be changed only when the workpiece etc. changes, the rotation mechanism becomes simple.

〔Effect of the invention〕

As explained above, in the present invention, by controlling the rotation of the angle of the roof reflector, the direction of the electric field vector of linearly polarized light can be rotationally controlled. It can be applied to cutting.

In addition, by controlling the rotation angle of the roof reflector so that the direction of the processing path and the direction of the electric field vector match,
Profile cutting can be performed using linearly polarized light.

Further, a laser oscillator with a multi-stage folding structure can also have a structure in which the rotation of the roof reflecting mirror is controlled.

Furthermore, by fixing the rotation angle of the roof reflector to a desired angle, it is also possible to obtain a laser beam with a fixed linearly polarized direction.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an embodiment of the linearly polarized laser oscillator of the present invention, and Fig. 2 is a schematic block diagram of a numerical control device for controlling the angle of the roof reflector so that it coincides with the advancing direction of the processing path. , FIG. 3 is a diagram showing another embodiment of a linearly polarized laser oscillator, and FIG. 4 is a diagram showing the structure of a conventional laser oscillator provided with an external circularly polarized light unit. 1 Rear mirror 2.3 Folding mirror 4 Output coupling mirror 5.6 Phase retarder? a, 7b, 7c Optical axis 8 Outgoing beam 9 Outgoing beam 10 Roof reflecting mirror 11 Turning mirror 12 Turning mirror 13 Laser beam 14 Gear 15 Gear 16 Pulse motor 17 Servo motor 18 Gear 19 Gear 20 Numerical control device Interpolation means Rotation control means Axis control circuit servo amplifier

Claims (7)

[Claims] (1) In a linearly polarized laser oscillator comprising an output coupling mirror and a rear mirror, the rear mirror is a right-angle roof reflector, and the angle of the ridgeline of the rear mirror can be rotationally controlled to a desired angle. Characteristic linear polarization laser oscillator. (2) In a multifold folding type linearly polarized laser oscillator comprising an output coupling, a rear mirror, and a folding mirror, the rear mirror is a right-angle roof reflector, all of the folding mirrors are zero-shift reflectors, and the ridgeline of the rear mirror 1. A linearly polarized laser oscillator characterized in that the angle of the linearly polarized laser oscillator is configured such that the rotation can be controlled to a desired angle. (3) Claim 1, wherein the rotational control of the angle of the ridge line is performed by a pulse motor or a servo motor.
Or the linearly polarized laser oscillator according to 2. (4) The linearly polarized laser oscillator according to claim 1 or 2, wherein the angle of the ridge line is configured such that the traveling direction of the processing path during laser processing and the direction of the electric field vector of the laser beam coincide. . (5) The linearly polarized laser oscillator according to claim 4, wherein the direction of movement of the processing path is calculated from interpolation pulses of a servo motor that controls the XY table. (6) The linearly polarized laser oscillator according to claim 1 or 2, wherein the angle of the ridge line is fixed at a desired angle. (7) The linearly polarized laser oscillator according to claim 6, wherein the angle of the ridge line is fixed at 45 degrees with respect to the ground surface.