JP2001281582A - Laser oscillation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser oscillation device with which a fixed beam diameter can always be obtained in a machining position. SOLUTION: The device is provided with a concave mirror 2a and convex mirror 2b with which a laser beam 4 made incident satisfies prescribed reflecting conditions after being reflected twice or more, mirror driving devices 3a, 3b capable of changing and holding the distance and each angle between the concave mirror 2a and the convex mirror 2b in the sate where reflecting conditions are satisfied, a reflecting mirror 9 provided with a plurality of minute through- holes 9a which are provided on laser beam routes and detects the diameters of the laser beams, a photosensor 10 to detect the light intensity of the laser beam made incident on each through-hole 9a, an output part 11 to calculate the diameter of the laser beam by the output and to output it as the diameter signal of the laser beam, and a controller 6 to control the mirror driving devices 3a, 3b to obtain the preset value of the detected diameter of the laser beam.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser oscillating apparatus which always provides a stable and high quality processing by controlling a beam diameter at a processing position to be constant in a laser processing apparatus.

[0002]

2. Description of the Related Art In a laser processing apparatus, a laser beam taken out of a laser oscillator is transmitted to a processing position via several reflection mirrors, and is condensed by a converging lens provided in a processing head. Focused on diameter. The condensed laser beam is irradiated on the workpiece to perform laser processing.

[0003] The processing quality of laser processing largely depends on the diameter of the focused spot of the laser beam, and it is essential to keep the diameter of the focused spot constant for stable laser processing.

Since the diameter of the focused spot is determined by the diameter of the beam incident on the focusing lens, that is, the beam diameter at the processing position, if the beam diameter at the processing position changes, the diameter of the focused spot also changes, and the processing quality increases. Will decrease. Therefore, in order to perform stable laser processing, it is necessary to always keep the beam diameter at the processing position constant.

[0005] Since the laser beam extracted from the laser oscillator has a constant divergence angle, if the optical path length changes, the beam diameter at the processing position changes. In an optical path length variable type laser processing device, the optical path length from the laser oscillator to the laser processing head changes depending on the processing position, and accordingly, the beam diameter at the processing position changes, and the processing performance changes. There's a problem. Therefore, a method of inserting a combination of concave and convex lenses and a combination of concave and convex mirrors for beam collimation into the laser beam path so that the beam diameter at the processing position is constant even if the optical path length changes has been used as a conventional method. I have.

[0006]

However, in practice, it is extremely difficult to completely keep the beam diameter constant even if the beam is collimated, and a change in the processing quality due to the processing position can be completely suppressed. Absent.

As one method for solving this problem, a laser processing apparatus of a fixed optical path length type, which does not change the optical path length even when the processing position changes, has been used. However, this type of laser processing equipment has many problems in terms of cost and reliability due to its complicated structure. For the variable optical path length type, a method of completely keeping the beam diameter at the processing position constant is required. Was desired.

As a common problem of the variable optical path length type and the fixed optical path length type, there is a problem of the temporal change of the diameter of the laser beam itself extracted from the laser oscillator. Of the mirrors that make up the resonance system of the laser oscillator, the air side of the output mirror that extracts the laser beam is constantly exposed to dirt and dust in the atmosphere, so that dirt gradually adheres to it and the resulting heat Due to the lens effect, the divergence angle of the laser beam changes over time, and the beam diameter at the processing position decreases.

As a technique for solving these problems, for example, a sensor provided in the middle of a laser beam path between a laser oscillator and a condensing lens for condensing a laser beam as disclosed in Japanese Patent Application Laid-Open No. 1-271087. There is also proposed an idea of detecting the diameter of a laser beam by using the method, and moving a collimator provided between the sensor and the laser oscillator by a driving device so as to always control the diameter of the laser beam to be constant. However, the idea itself does not go beyond the category of known facts, but rather, a concrete method for realizing it was required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a laser beam diameter is detected by a sensor provided in a laser beam path between a laser oscillator and a condenser lens for condensing a laser beam. Provided is a laser oscillation device capable of moving a collimator provided between the sensor and a laser oscillator by a driving device and controlling the diameter of the laser beam to be always constant without deteriorating the laser beam quality. The purpose is to:

[0011]

According to a first aspect of the present invention, there is provided a laser oscillating device, wherein an incident laser beam is reflected at least two times and then emitted in a direction parallel to the incident direction in the same direction as the incident direction. And at least a pair of reflecting optical systems arranged so as to face each other so as to satisfy the reflecting condition, and a mirror that changes the distance and each angle between the pair of reflecting optical systems in a state where the reflecting condition is satisfied. A laser beam having a driving device and a reflecting mirror provided on a laser beam path and having an optical sensor located on the back of the reflecting mirror and detecting light incident on the reflecting mirror, and detecting a laser beam diameter A diameter detection device; and a control device for controlling the mirror driving device such that the laser beam diameter detected by the laser beam diameter detection device has a preset value.

According to the laser oscillation device of the first aspect,
Since the laser beam diameter is constantly monitored, the beam diameter at the processing position can be constantly controlled based on the laser beam diameter, and the occurrence of aberration in the collimation section having a reflective optical system can always be minimized. Irrespective of disturbance factors such as a change in length or a change in the beam diameter of the laser oscillator over time, a constant beam diameter can always be obtained at the processing position without significantly lowering the laser beam quality by the optical sensor. And high-quality laser processing can be provided over a long period of time.

According to a second aspect of the present invention, in the first aspect, the reflecting mirror is provided with a plurality of fine through holes.
A plurality of optical sensors detect the light intensity of the laser light incident on each through-hole, and the laser diameter detecting device has an output section for calculating a laser beam diameter from the output of each optical sensor and outputting it as a laser beam diameter signal. It is.

According to the laser oscillation device of the second aspect,
This has the same effect as the first aspect.

According to a third aspect of the present invention, in the first aspect, the reflecting mirror is provided with a plurality of fine through holes.
The optical sensor is for detecting the light intensity of the laser beam incident on each through hole, and the laser beam diameter detecting device is a scanning device for scanning the optical sensor across each of the through holes, and the optical sensor And an output unit for calculating a laser beam diameter from the output of (1) and outputting it as a laser beam diameter signal.

According to the laser oscillation device of the third aspect,
This has the same effect as the first aspect.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a laser oscillation device according to a first embodiment of the present invention.

First, the configuration of the present apparatus will be described. The laser beam 4 extracted from the laser oscillator 1 is applied to a beam collimation unit, that is, a convex mirror 2a having a convex spherical surface and a concave mirror 2b having a concave spherical surface as an example of a pair of reflective optical systems. After being reflected twice at an incident angle of 10 degrees or less, the light is emitted in the same direction as the incident direction at a position shifted in parallel to the incident direction, and then is passed through the laser beam diameter detecting device 5 and is at the processing position. Condensing lens 7
Incident on. After being condensed by the condenser lens 7, the workpiece 8
And is processed.

The distance between the convex mirror 2a and the concave mirror 2b and the respective angles are determined by the driving device 3 provided so as to be able to hold the respective mirrors.
a, 3b, and can be adjusted.
a and 3b are controlled by the control device 6.

When changing the distance between the convex mirror 2a and the concave mirror 2b, the control device 6 performs a predetermined calculation in accordance with the change, and the convex mirror 2a, the incident position, the exit position and the direction of the laser beam 4 are kept constant. The angle of the concave mirror 2b is changed. At this time, the positions of the reflecting mirrors 2a and 2b are set so that the incident angle is always 10 degrees or less.

FIG. 2 shows the relationship between the angle of incidence θ of the laser beam 4 on the spherical mirror (2a, 2b) and the roundness of the laser beam after reflection. Basically, the spherical mirror is least affected by aberration when the incident angle is 0 degree, that is, when the incident direction and the reflection direction are completely opposite to each other, and the roundness of the reflected laser beam 4 is 100% of the best state. Become. However, it is practically impossible to use at an incident angle of 0 degree, and it is necessary to provide a certain incident angle within a range where the influence of aberration can be minimized. As is clear from FIG. 2, when the incident angle is 10 degrees or less, there is almost no influence of aberration, and the roundness of the laser beam is maintained at about 100%. From this, it can be seen that in the configuration of the present invention, it is possible to prevent a decrease in the roundness of the laser beam due to reflection by the convex mirror 2a and the concave mirror 2b, that is, a decrease in the quality of the laser beam.

The laser beam diameter detecting device 5 includes a reflecting mirror 9 having a plurality of fine through holes 9a, and a light intensity of a laser beam incident on each through hole 9a located on the back of the reflecting mirror 9. An optical sensor 10 to be detected and an output unit 11 for calculating a laser beam diameter from an output of the optical sensor 10 and outputting the calculated laser beam diameter signal are provided. The control device 6, which has received the laser beam diameter signal, adjusts the laser beam diameter at the processing position to a predetermined value in accordance with information such as the beam characteristics of the laser oscillator and the optical path length at the processing position given in advance. By controlling the driving devices 3a and 3b, the distance between the convex mirror 2a and the concave mirror 2b and the angle of each spherical mirror 2a and 2b are adjusted.

According to the configuration of the present invention, in the laser processing apparatus of the variable optical path length type, the convex mirror 2a to the concave mirror 2b of the beam collimation unit are changed according to the change in the optical path length at the processing position.
By adjusting the distance, the beam diameter at the processing position is always constant, and by adopting the configuration of the present invention, the influence of deviation and aberration of the laser beam path is minimized, so that high quality is always achieved. A laser beam will be obtained.

In addition, since a method of detecting the beam diameter without interfering with the laser beam itself can be adopted, the divergence angle of the laser beam can be changed over time without deteriorating the quality of the laser beam. Thus, the beam diameter at the processing position can always be kept constant.

FIG. 3 shows a change in processing quality over time between the first embodiment of the present invention and a conventional example. Conventional Example 1 shows a case in which the sensing of the laser beam diameter itself is not performed, and it can be seen that the processing quality decreases as the divergence angle of the laser beam extracted from the laser oscillator changes over time. Conventional example 2 is a case in which a laser beam diameter is sensed by inserting a sensor in a laser beam path as shown in Japanese Patent Application Laid-Open No. 1-271087, and there is no decrease in processing quality over time. However, the quality of the laser beam is degraded due to the sensing itself. In the first embodiment of the present invention,
High processing quality can be maintained without change over time.

FIG. 4 is a block diagram of a laser oscillation device according to a second embodiment of the present invention. The laser beam diameter detecting device 5 includes a reflecting mirror 9 having a plurality of fine through holes 9a, an optical sensor 10 for detecting the light intensity of the laser light incident on each of the through holes 9a, and an optical sensor 10 for each. Scanning device 1 for scanning over through hole 9a
2 and an output unit 11 for calculating a laser beam diameter from the output of the optical sensor 10 and outputting the calculated laser beam diameter signal. The control device 6 that has received the laser beam diameter signal
Is the beam characteristic of the laser oscillator given in advance,
In order to adjust the laser beam diameter at the processing position to a predetermined value in accordance with information such as the optical path length at the processing position, the driving device 3a,
3b, and adjusts the distance between the convex mirror 2a and the concave mirror 2b and the angle of each spherical mirror (2a, 2b).

A feature of the second embodiment of the present invention is that the reliability of the laser beam diameter detecting device can be improved and economy can be expected because one optical sensor can be constituted.

The other parts common to the first embodiment are the same as those of the first embodiment, and the same reference numerals are used in the drawings.

The optical system, the convex mirror and the concave mirror are not limited to these, but may be any pair or more.

[0031]

According to the first aspect of the present invention, the laser beam diameter can be constantly monitored, and based on the laser beam diameter, the beam diameter at the processing position can always be controlled to be constant. Since the occurrence of aberrations in the laser section can always be minimized, the laser sensor greatly reduces the laser beam quality regardless of disturbance factors such as changes in the optical path length and changes in the beam diameter of the laser oscillator over time. Without this, a constant beam diameter can always be obtained at the processing position, and high-quality laser processing can be provided for a long period of time.

According to the laser oscillation device of the second aspect,
This has the same effect as the first aspect.

According to the laser oscillation device of the third aspect,
This has the same effect as the first aspect.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a laser oscillation device according to a first embodiment of the present invention, which relates to claims 1 and 2;

FIG. 2 is a diagram showing the relationship between the angle of incidence of a laser beam on a spherical mirror and the roundness of the laser beam after reflection.

FIG. 3 is a diagram showing a change in processing quality over time between the first embodiment of the present invention and a conventional example.

FIG. 4 is a configuration diagram of a laser oscillation device according to a second embodiment of the present invention and according to claims 1 and 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser oscillator 2a Convex mirror 2b Concave mirror 3a Convex mirror drive device 3b Concave mirror drive device 4 Laser beam 5 Laser beam diameter detection device 6 Controller 7 Condenser lens 8 Workpiece 9 Reflector mirror provided with a plurality of fine through holes 10 Light Sensor 11 Output unit 12 Scanning device

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroyuki Hayashikawa 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (reference) 2H045 AB02 AB13 BA15 CB03 CB24 DA31 4E068 CA07 CB05 CC01 CD12 5F072 HH02 HH03 JJ05 KK05 MM08 MM09 YY06

Claims (3)

[Claims] 1. An incident laser beam is reflected at least two times and then opposed to each other at a position translated in parallel with the incident direction so as to satisfy a reflection condition of being emitted in the same direction as the incident direction. At least one pair of reflecting optical systems arranged in a mirror, a mirror driving device for changing the distance and each angle between the pair of reflecting optical systems in a state where the reflection condition is satisfied, and a reflecting mirror provided on a laser beam path A laser beam diameter detecting device that has a light sensor positioned on the back of the reflecting mirror and detects light incident on the reflecting mirror, and a laser beam diameter detecting device that detects a laser beam diameter, which is detected by the laser beam diameter detecting device. A control device for controlling the mirror driving device so that the laser beam diameter becomes a preset value. 2. A reflecting mirror provided with a plurality of fine through holes, a plurality of optical sensors detecting the light intensity of laser light incident on each of the through holes, and a laser diameter detecting device outputting the output of each of the optical sensors. 2. The laser oscillation device according to claim 1, further comprising an output unit for calculating a laser beam diameter and outputting the calculated laser beam diameter signal. 3. The reflecting mirror is provided with a plurality of fine through holes, the optical sensor detects the light intensity of the laser beam incident on each of the through holes, and the laser beam diameter detecting device is the optical sensor. 2. The laser oscillation device according to claim 1, further comprising: a scanning device for scanning a laser beam across each of the through holes; and an output unit for calculating a laser beam diameter from an output of the optical sensor and outputting the calculated laser beam diameter as a laser beam diameter signal.