JPH06339786A - Energy splitting device for laser beam processing - Google Patents

Abstract

PURPOSE:To reduce the energy loss, eliminate the influence of a temp. rise and facilitate the adjustment of energy splitting. CONSTITUTION:A splitting optical system has a mirror system 14 which splits the laser beam of an almost circular section past a collimating lens 11 to plural laser beams by splitting the section of the laser beam and is provided with an operating part 20a of an adjusting means for finely moving this mirror system 14 in a direction perpendicular to the optical axis of the laser beam past the collimating lens 11 outside the device. Plural apertures 13 are so disposed as to exist at almost the centroid of the sectional shape of the plural laser beams split in section from the circular section.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention can send laser light to a plurality of laser processing machines when the laser light output from a laser oscillator is supplied to a laser processing machine for welding, cutting, drilling and the like. The present invention relates to an energy splitting device for laser processing.

[0002]

2. Description of the Related Art Generally, in a laser beam machine, a laser beam output from a laser oscillator is made incident on an optical fiber by a coupling lens, and the laser beam is guided from the other end of the optical fiber to a processing condenser lens. In this case, a single laser oscillator can only send laser light to a single processing point, but as shown in Japanese Patent Publication No. 3-9834, in a transmission path by an optical fiber, By installing the repeater 1 and arranging a semi-transmissive beam splitter for dividing the laser light in the repeater 1, as shown in FIG. 7, the laser light output from the laser oscillator 2 is processed into a plurality of beams. Can be sent to the optical system 3, 3.

[0003]

Here, as shown in FIG. 8, the repeater 1 has a collimating lens 11 for collimating the laser light emitted from the incident optical fiber 10,
It is composed of a condenser lens 12 for making parallel laser light enter the emitting optical fiber.

By the way, in order to make a laser beam incident on an optical fiber, the following conditions must be satisfied.
That is, when the spot diameter of the laser light is d, the core diameter of the optical fiber is df, the incident angle of the laser light is θ, and the numerical aperture (mmerical aperture) peculiar to the optical fiber is NA, d ≦ df (1) θ = 2sin ^-1 NA (2) Further, the light emitted from the optical fiber is emitted from the optical fiber 10 with the focal length of the collimating lens 11 being f1, the focal length of the condensing lens 12 being f2 in the optical system shown in FIG. When the angle is θ1, the converging angle of the condensing lens 12 is θ2, the beam diameter of the laser light made parallel by the collimating lens 11 is D, the core diameter of the optical fiber 10 is d1, and the condensing diameter is d2, then f1θ1 = F2θ2 = D (3) d2 / d1 = f2 / f1 (4) ∴d1θ1 = d2θ2 (5) θ1 = 2sin ⁻¹ NA (6) is satisfied.

At this time, as disclosed in the above publication, it is preferable to reduce the diameter of the outgoing optical fiber 18 in order to increase the energy density of the laser light. It is very difficult to make laser light enter the emitting optical fiber 18 having a small diameter. Because the laser light emitted from the incident optical fiber 10 is
As shown in the expression (6), since the angle is expanded to the angle determined by the numerical aperture NA peculiar to the optical fiber, when the collimating lens 11 collimates the parallel light and the condensing lens 12 condenses it, the condensing diameter d2 is In order to make the light incident on the emission optical fiber 18 having a small diameter, the above (3), (4) and (5)
As is clear from the equation, it is necessary to use a condenser lens 12 having a small focal length f2 and therefore a large condenser angle θ2. At this time, the condenser angle θ2 is the numerical aperture of the emission optical fiber 18. If NA is exceeded, the formula (2) may not be satisfied. That is, only a part of the laser light can be used, and in order to avoid this, it is necessary to use an optical fiber having a large numerical aperture NA and a large diameter.

In addition, when the laser light emitted from the optical fiber is incident on the optical fiber having the same numerical aperture NA again by using the lens system, the incident optical fiber 10 is used as the incident optical fiber 10 to satisfy the expression (2). It must have a diameter equal to or larger than the diameter of the fiber 18, but it is difficult to re-enter the optical fiber of the same diameter completely because the lens has aberrations. Light has a very high energy density, so if it is not properly incident on the optical fiber, the end face of the optical fiber may be damaged and damaged. In fact, the optical fiber with a small diameter is output side (that is, laser processing side). Cannot be used for.

The present applicant has proposed Japanese Patent Application No. 4-262205 as a solution to the above problem. As shown in FIG. 6, this has a focal length shorter than that of the incident side laser beam side collimating lens 11 by cutting a part of the laser beam using an aperture 13 to reduce the diameter of the laser beam. The condensing lens 12 can condense the laser light to enter the optical fiber. As a result, the laser light can be divided and transmitted without damaging the emitting optical fiber 18. However, the diameter of the laser beam divided by the beam splitter 14, that is, the cross-sectional area is substantially the same as that before the division. That is, if it is attempted to condense the spot diameter of the laser light on the end face of the emitting optical fiber 18 to about 0.8 to 0.9 times the core diameter of the optical fiber, the aperture 13 makes the collimator lens parallel to each other. The diameter of the generated laser light must be 0.8 to 0.9 times, and the area is 0.64 to 0.81 times. That is, 19 to 36% is cut by the aperture 13. The cut laser light becomes a loss. When an energy splitting device is used, one portion is processed by a fraction of the laser oscillator, so it is desirable that the loss be as low as possible, and if the laser output becomes large, the temperature of the aperture becomes extremely high. It also becomes higher, and adversely affects optical lenses and mirrors.

In the above example, the beam splitter 14
However, it is difficult to manufacture the beam splitter 14 according to the designed division ratio, and there is some variation. However, since the position of the beam splitter 14 is fixed, when variations in processing pose a problem, the energy is reduced so that the beam splitter 14 is adjusted to the smallest energy after being divided so that the energy becomes approximately the same. I was doing.

The present invention has been made in view of the above circumstances, and an object thereof is an energy splitting device for laser processing, which has a small loss, is not affected by a temperature rise, and can be easily adjusted in energy splitting. To provide.

[0010]

In order to solve the above-mentioned problems, according to a first aspect of the present invention, an incident optical fiber for guiding a laser beam outputted from a laser oscillator and an incident optical fiber emitted from the incident optical fiber are provided. A collimator lens that collimates the laser light, a splitting optical system that splits the laser light, multiple apertures that narrow the split laser light, and a core diameter that has a shorter focal length than the collimator lens and is the same as the above-mentioned optical fiber for incidence. In the energy splitting device for laser processing, comprising: a plurality of condensing lenses for condensing laser light on a plurality of emitting optical fibers having:
It has a mirror system that divides the cross section of the laser beam having a substantially circular cross section that has passed through the collimator lens into a plurality of laser beams, and that mirror system is with respect to the optical axis of the laser beam that has passed through the collimator lens. An operation unit for adjusting means for finely moving in a vertical direction is provided outside the device, and the plurality of apertures have a circular cross section at a substantial center of gravity of a cross sectional shape of a plurality of laser beams obtained by dividing the cross section. It is configured to be arranged.

According to a second aspect of the present invention, the operating portion of the adjusting means is interlocked with driving means driven by an electric signal.

[0012]

According to the first aspect of the present invention, since the circular aperture is arranged at the substantially center of gravity of the sectional shape obtained by dividing the substantially circular laser beam by the mirror system, the laser energy cut by the aperture. Is kept low, and even if the mirror system does not have a predetermined division ratio due to manufacturing variations, the mirror system should be placed in the direction perpendicular to the optical axis of the laser beam that has passed through the collimator lens. Since the operating portion of the adjusting means for finely moving is provided outside the apparatus, it is possible to easily and easily adjust to the predetermined division ratio by operating the operating portion.

According to the second aspect of the invention, the division ratio by the mirror system can be automatically adjusted by driving the driving means by the electric signal and operating the operating portion of the adjusting means.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS. In FIG. 1, a connector 16 for an incident optical fiber 10 that guides laser light from a laser oscillator is provided at one end of a repeater 1, and an outgoing end for guiding the laser light to a processing optical system is provided at the other end. Connector 17 for optical fiber 18
Two are provided. Then, in the repeater 1, a collimator lens 11 for making the laser light emitted from the optical fiber 10 parallel light, and a mirror for dividing the cross section of the laser light having the parallel beam diameter D1 emitted from the collimator lens 11. The system 14 and the total reflection mirrors 15 and 15 for converting the directions of the laser beams divided and reflected by the mirror system 14 to make the directions of the two laser beams divided by the mirror system 14 the same, and more than the above D1. The apertures 13 and 13 each having a small aperture diameter D2 and arranged at a substantially center of gravity position 0 of the sectional shape of the laser light having the divided cross section, and the two optical fibers 18 for emitting the two laser lights having passed through the apertures 13 and 13, respectively. , 18 and two condenser lenses 12 and 12 to be incident on them are housed.

More specifically, as shown in FIG. 5, the mirror system 14 includes two reflecting surfaces 1 oblique to the laser optical axis.
It is a pentahedral mirror having 4a and 14b, and as shown in FIG. 2, a central portion 1 of a transparent substantially U-shaped support member 19.
The other surface that intersects with the two reflecting surfaces 14a and 14b is fixed to the inner surface of 9a, and the total reflection mirror 15 is provided on the inclined surfaces of the triangular pillar-shaped supporting portions 19d and 19e provided further outward from the facing portions 19b and 19c. , 15 are fixed.

The mirror system 14 is constituted by the following division ratio adjusting means. That is, the support member 19 is fixed on the flat slide member 20,
The slide member 20 has a disc-shaped operation unit 20 at one end.
The other end of the operating shaft 20b having a is screwed. As shown in FIG. 1, the operating portion 20a is disposed so as to be exposed from the outer frame 1a of the repeater 1, and as shown in FIG. 3, the adjusting scale of the operating portion 20a is provided on the outer frame 1a. When a person manually rotates the operation unit 20a from the outside of the outer frame 1a based on the adjustment scale, the slide member 20 moves in the axial direction of the operation shaft 20b, that is, with respect to the optical axis of the laser light passing through the collimator lens 11. It is finely moved in the vertical direction.
Then, the two reflecting surfaces 14a, 14 of the mirror system 14 are
The two laser beams reflected by b are transmitted through the facing portions 19b, 19c of the transparent support member 19 at a predetermined division ratio, and then are reflected by the total reflection mirrors 15, 15 so that their directions are the same. It is sent to 13, 13.

The aperture 13 is formed of a metal that has heat resistance and heat dissipation and reflects the laser light (for example, brass, aluminum, or metal plated with gold).

Then, the condenser lens 1 in this one
The focal lengths f2 of 2 and 12 satisfy the following condition: f1θ1 = D1 (7) f2θ2 = D2 (8) d2 / d1 = f2 / f1 (9) d2 ≦ df (10) θ2 = 2sin ⁻¹ NA (11) Is set to be smaller than the focal length f1 of the collimator lens 11. Condensing lens 12
Since the beam diameter of the incoming laser light is narrowed by the aperture 13, it is advantageous to increase the focal length f2 and to reduce the converging angle θ2. As the optical fiber 18, the numerical aperture N
A having a small A and a small diameter can be used.

As shown in FIG. 4, the cross section of the laser beam divided into two by the mirror system 14 has a semicircular shape which is a half of a circle having a diameter of D1, and the approximate center of gravity of the cross sectional area of the semicircle. Position 0
Aperture 13 so that the center of circular opening diameter D2 comes to
Are arranged. The above-mentioned approximate center of gravity position 0 is a position where the area of the overlapped portion becomes maximum when a circle having a diameter D2 is overlapped with a semicircle having a diameter D1. ing. Thereby, the laser energy that does not pass through the aperture 13, that is, the loss can be suppressed low.

In such an energy splitting device for laser processing, a circular aperture 13 is provided at a position of substantially center of gravity 0 of a sectional shape obtained by splitting a substantially circular laser beam by a mirror system 14.
Since the laser energy cut by the aperture 13 is kept low, the mirror system 1
4 does not have a predetermined division ratio due to manufacturing variations, the adjustment means for finely moving the mirror system 14 in the direction perpendicular to the optical axis of the laser light passing through the collimator lens 11. Since the operation unit 20a is provided outside the apparatus, it is possible to easily adjust the division ratio to a predetermined value by operating the operation unit 20a, and it is possible to perform stable laser processing.

In this embodiment, the operating portion 20a of the adjusting means for adjusting the division ratio of the mirror system 14 is manually operated by a person, but the driving means such as a motor is driven by an electric signal. Then, the operation unit 20a of the adjusting means may be operated, and in that case, the adjustment can be made automatically.

[0022]

According to the first aspect of the present invention, since the circular aperture is arranged at the substantially center of gravity of the sectional shape obtained by dividing the substantially circular laser light by the mirror system, the laser energy cut by the aperture. Is kept low, and even if the mirror system does not have a predetermined division ratio due to manufacturing variations, the mirror system should be placed in the direction perpendicular to the optical axis of the laser beam that has passed through the collimator lens. Since the operating portion of the adjusting means for finely moving is provided outside the apparatus, it is possible to easily and easily adjust to the predetermined division ratio by operating the operating portion.

According to the second aspect of the present invention, the division ratio by the mirror system can be automatically adjusted by driving the driving means by the electric signal and operating the operating portion of the adjusting means.

[Brief description of drawings]

FIG. 1 is an optical system diagram showing an embodiment of the present invention.

FIG. 2 is a perspective view of adjusting means for adjusting the division ratio of the mirror system of the above.

FIG. 3 is a front view showing an operating section of the adjusting means of the above.

FIG. 4 is an explanatory diagram showing a setting relationship between a laser beam cross section divided by the mirror system and an aperture of an aperture.

FIG. 5 is an explanatory diagram of a mirror system of the above.

FIG. 6 is a schematic view of a conventional example.

FIG. 7 is a schematic view of another conventional example.

FIG. 8 is an optical path diagram for explaining conditions of the above optical system.

[Explanation of symbols]

 10 Input Optical Fiber 11 Collimating Lens 13 Aperture 14 Mirror System 18 Output Optical Fiber 20a Operation Unit of Adjustment Means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiromi Nishimura Inventor Hiromi Nishimura 1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.

Claims (2)

[Claims] 1. An incident optical fiber for guiding a laser beam output from a laser oscillator, a collimator lens for collimating the laser beam emitted from the incident optical fiber, and a splitting optical system for splitting the laser beam. A plurality of apertures for squeezing the divided laser light, and a plurality of light condensing light for condensing the laser light on a plurality of emission optical fibers having a focal length shorter than that of a collimator lens and having the same core diameter as the incident optical fiber. In the energy splitting device for laser processing including a lens, the splitting optical system has a mirror system that splits a cross section of the laser beam having a substantially circular cross section that has passed through the collimating lens into a plurality of laser beams. In addition, an operating unit of adjusting means for finely moving the mirror system in the direction perpendicular to the optical axis of the laser light passing through the collimator lens is provided outside the device. Moni, wherein the plurality of apertures, laser processing energy divided apparatus characterized by comprising been arranged to come to substantially the center of gravity of the plurality of laser beam cross-sectional shape of a circular cross-section is divided to the cross-section. 2. The energy splitting device for laser processing according to claim 1, wherein the operating portion of the adjusting means is interlocked with driving means driven by an electric signal.