JP3458668B2 - Laser processing equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing apparatus, and more particularly to a multimode laser beam or TEM00.
The present invention relates to a laser processing apparatus that performs hole processing, cutting, and the like using a single laser beam such as a mode.

[0002]

2. Description of the Related Art A conventional laser processing apparatus will be described below.

FIG. 17 is a conceptual diagram of a conventional laser processing apparatus. In FIG. 17, reference numeral 81 is a concave total reflection mirror, 82 is a concave partial reflection mirror arranged to face the total reflection mirror 81, 83 is a partial reflection film applied to the partial reflection mirror 82, and 84 is a partial reflection mirror. A non-reflective film 82 is applied to the reference numeral 82, and a laser medium 85 is a gas medium excited by discharge or the like in the case of a gas laser such as a carbon dioxide gas laser, and a flash lamp or the like in the case of a solid laser such as YAG. It is a solid medium that is excited.

Next, 86 is an aperture for controlling the diameter of the laser beam, 87 is a box covering the periphery, 88 is a mirror 81,
A laser beam generated inside the stable resonator constituted by 82, 89 a laser beam taken out from the partial reflection mirror 82, 90 a condenser lens, and 91 a non-reflection applied to the condenser lens 90. A film, 92 is a focused beam focused by the focusing optical system 90, and 93 is a workpiece.

The operation of the above arrangement will be described below. First, since the mirrors 81 and 82 compose a stable resonator, the generated laser beam 88 is amplified by the laser medium 85 while reciprocating through the mirrors 81 and 82 while passing through the aperture 86. Part of the laser beam 88 is extracted to the outside through the mirror 82 provided with the partially reflective film 83 and the non-reflective film 84.

Here, the aperture 86 controls the mode order while adjusting the diameter of the laser beam 88 generated in the resonator to obtain the laser beam 89 of a predetermined mode.

Then, the laser beam 89 taken out to the outside becomes a focused beam 92 by passing through a condenser lens 90, and performs processing such as cutting, drilling and welding of a workpiece such as an iron plate.

Among laser beams oscillated from a laser oscillator using a stable resonator, a laser beam of the lowest order mode, that is, a TEM00 mode is often used for cutting during processing.

The intensity distribution on the wavefront of the TEM00 mode laser beam has a Gaussian distribution, and the phase distribution of the optical wavefront of the laser beam is almost in phase. When the laser beam is condensed by a condenser lens or the like. It has a good light collecting property.

In order to generate such a TEM00 mode laser beam, the expansion of the laser beam diameter may be limited by the aperture 86 installed in the stable resonator.

On the other hand, if the diameter of the aperture 86 is increased, a high laser output can be obtained, but a multimode laser beam will be generated.

[0012]

As described above, when the mode is selected by the aperture 86, the TE having a good light collecting property is obtained.
If an M00 mode laser beam is to be obtained, a large output laser beam cannot be obtained, and there is a problem that the processing time increases.

On the other hand, when processing is performed with a multimode laser beam by increasing the aperture diameter in order to obtain a large output laser beam, the condensing property is poor because the laser beam is multimode, As a result, there arises a problem that the processing time increases.

Therefore, there is a great demand for the realization of a laser processing apparatus capable of improving the converging property of a laser beam having various modes while securing the output level itself of the laser beam.

The present invention has been made in order to solve the above-mentioned problems, and condenses a laser beam having a large output while reducing the condensing diameter of the laser beam on the surface of the workpiece. It is an object of the present invention to realize a laser processing device that can be manufactured.

[0016]

In order to solve this problem, the present invention is a laser processing apparatus for processing a workpiece by focusing a laser beam on the workpiece via a focusing optical system. Then, the phase shift means is used to change the phase of the light wavefront of the laser beam used for processing in accordance with the declination around the optical axis.

With this configuration, it is possible to realize a laser processing apparatus capable of converging a laser beam having a large output while reducing the converging diameter of the laser beam on the surface of the workpiece.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention according to claim 1 is a laser oscillator that oscillates a laser beam, a focusing optical system that focuses the laser beam on a workpiece, and an optical wavefront of the laser beam. And a phase shift means for shifting the phase of
The phase shift means is a laser processing device that shifts a phase in accordance with a deviation angle around the optical axis with respect to a polar coordinate system on a plane perpendicular to the optical axis of the focusing optical system.

With such a structure, the phase of the laser beam can be shifted, the diameter of the laser beam of various modes condensed on the workpiece can be reduced, and the peak value of the intensity distribution can be increased.

For example, the laser beam may be a multi-mode laser beam, and may be a TEM00 mode, TEM10 mode, TEM01 mode or TE.
It is also applicable to the M11 mode.

Here, as described in claim 2, the phase shift means may be a phase shift member for continuously shifting the phase in accordance with the declination.

More specifically, as described in claim 3,
The condensing optical system has a condensing lens and a phase shift member integrally provided with the condensing lens so that the optical axes thereof coincide with each other.
The phase shift member may have a structure in which the thickness in the optical axis direction continuously increases in response to an increase in the declination angle. The thickness may be continuously increased in proportion to the increase in the deflection angle.

With such a structure, even a multimode laser beam can be applied, and in particular, TEM01.
It is also applicable to the mode or the TEM11 mode.

Alternatively, as described in claim 5, the phase shift means may be a phase shift member which intermittently shifts the phase according to the declination.

More specifically, as described in claim 6,
The condensing optical system has a condensing lens and a phase shift member integrally provided by making the optical axis of the condensing lens coincident with each other, and the phase shift member has a thickness in the optical axis direction. The configuration may be increased intermittently in response to an increase in declination,
As described in claim 7, the phase shift member has a plurality of regions that are evenly divided in terms of declination, and the thickness of the region in the optical axis direction intermittently corresponds to an increase in declination. The configuration may be increased equally.

With such a structure, a multi-mode laser beam can be applied, and in particular, a TEM.
It is also applicable to the 01 mode or the TEM 11 mode.

On the other hand, as described in claim 8, the phase shift means may have a configuration in which two phase shift means are arranged in the optical axis.

With this structure, a multi-mode laser beam can be applied, and in particular, a TEM.
It is also applicable to 00 mode or TEM10 mode.

Further, as described in claim 9, it is preferable that one of the phase shift means increases the phase shift amount according to the declination angle and the other one decreases the phase shift amount according to the declination angle. Is.

Here, as described in claim 10, both of the phase shift means may be phase shift members that continuously shift the phase in accordance with the declination.

More specifically, as described in claim 11, one of the phase shift members is integrally provided with the condensing lens of the condensing optical system so that the optical axis thereof coincides with each other. The thickness continuously increases in response to an increase in the deflection angle, and the other phase shift member is integrally provided with the output mirror of the resonator of the laser oscillator in alignment with the optical axis, The thickness in the optical axis direction may be continuously reduced in response to an increase in the declination angle. As described in claim 12, one of the phase shift members has a deviated thickness in the optical axis direction. Alternatively, the thickness may be continuously increased in proportion to the increase of the angle, and the other may be such that the thickness in the optical axis direction is continuously decreased in proportion to the increase of the deviation angle.

Alternatively, as described in claim 13, both of the phase shift means may be phase shift members which intermittently shift the phase corresponding to the declination.

More specifically, as described in claim 14, one of the phase shift members is integrally provided with the condensing lens of the condensing optical system so that the optical axis thereof coincides with each other. The thickness increases intermittently in response to an increase in the deflection angle, and the other phase shift member is integrally provided with the optical axis of the output mirror of the resonator of the laser oscillator in alignment with each other. The thickness in the optical axis direction may intermittently decrease in response to an increase in the declination, and one of the two phase shift members arranged in the optical axis as described in claim 15. , Having a plurality of regions equally divided in terms of declination, the thickness of the region in the direction of the optical axis intermittently increases equally in response to an increase in declination, and the other uniformly It has a plurality of divided areas, and the thickness of the area in the optical axis direction is intermittently equalized in response to an increase in declination. It may be configured to decrease.

Further, in the structure in which one phase shift member is provided, the structure may be such that the phase shift member and the condenser lens are formed by using the same optical material. Further, in the configuration in which two phase shift members are provided, the phase shift member and the condenser lens, and / or the phase shift member and the output mirror of the resonator of the laser oscillator have the same optical structure. The structure may be formed using a material.

In the above, as described in claim 18,
The laser beam may be a multimode laser beam, and the laser beam may be T
It may be a single mode laser beam of EM00 mode, TEM10 mode, TEM01 mode or TEM11 mode.

Hereinafter, each embodiment of the present invention will be described in more detail with reference to the drawings.

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a conceptual diagram showing a cross section of a laser processing apparatus according to this embodiment. In FIG. 1, reference numeral 1 is a concave total reflection mirror, 2 is a concave partial reflection mirror arranged to face the total reflection mirror 1, 3 is a partial reflection film applied to the partial reflection mirror 2, and 4 is a partial reflection mirror. The non-reflective film 5 applied to 2 is a laser medium, for example, carbon dioxide gas (CO
₂ ) In the case of a gas laser such as a laser, it is a gas medium excited by discharge or the like, and in the case of a solid laser such as YAG, it is a solid medium excited by a flash lamp or the like. A CO ₂ laser laser medium was typically used.

Further, 6 is an aperture for controlling the diameter of the laser beam, and 7 is a box body which covers the circumference, and the above constitutes a laser oscillator.

Next, 8 is composed of mirrors 1 and 2.
CO generated inside the stable resonator ₂Laser beam, 9
Is preferably a mask taken out from the partial reflection mirror 2.
Multi mode CO₂Laser beam, 10 is a condenser lens,
10a is the front surface of the condenser lens, 10b is the rear surface of the condenser lens, 1
1 is a laser beam incident on the front surface 10a of the condenser lens.
The laser beam phase to a polar coordinate system in a plane perpendicular to the optical axis.
However, the phase is continuously shifted according to the declination around the optical axis.
Is a phase shift member, and 12 is a phase shifter with the condenser lens 10.
It is a non-reflective film applied to the shift member 11. Collect these
The lens 10, the phase shift member 11 and the antireflection film 12 are
Laser optics with the function of shifting the phase of the laser beam
Make up.

Numeral 13 is a focused beam condensed by the condensing optical system, and numeral 14 is a workpiece. In addition, in the present embodiment, the phase shift member is typically configured to shift the phase by the same angle as the declination angle.

The condenser lens 10 may be made of a material such as ZnSe having a non-reflective film that allows a CO ₂ laser to pass therethrough, and the phase shift member 11 may be made of the same material, for example, by vapor deposition. , ICB (ion cluster beam) coating and the like, which can be easily and inexpensively manufactured.

Based on the above configuration, the operation will be described with reference to a more detailed configuration. First, mirrors 1 and 2
, Which constitute a stable resonator, the generated laser beam 8 passes through the aperture 6 and the mirrors 1, 2
While being reciprocated, the laser medium 5 amplifies the laser beam and a part of the CO ₂ laser beam 8 is partially reflected.
It is taken out to the outside via.

Here, the aperture 6 controls the mode order of the CO ₂ laser beam 8 generated in the resonator,
In this embodiment, in order to obtain a large output laser beam, its aperture diameter is set so as to obtain a multimode laser beam.

Specifically, the energy ratio of each mode is T
EM00: TEM10: TEM01 = 1.0: 1.5:
It was set to 2.5.

Then, the multi-mode CO ₂ laser beam 9 extracted to the outside becomes a focused beam 13 by passing through the focusing optical system, is focused on the surface of the workpiece 14, and is a workpiece such as an iron plate. Processing, that is, cutting, drilling,
Welding etc. will be performed efficiently.

Here, the amplitude distribution on the wavefront of each mode generally included in the multimode laser beam is given by the following (Equation 1).

[0048]

[Equation 1]

Since the different modes are incoherent, the intensity distribution on the wavefront of the multimode laser is an addition value of the intensity distribution of each mode multiplied by the energy of the mode.

FIG. 2A shows the intensity distribution of the CO ₂ laser beam 9 on the wavefront in the pupil of the focusing optical system, where the horizontal axis represents the distance from the optical axis and the vertical axis represents the intensity. is there.
The unit of the horizontal axis is mm, the vertical axis standardizes the peak value of the intensity distribution to 1.0, and the focal length of the condenser lens 10 is 12
It was set to 7 mm.

In the case of the present embodiment, the phase shift member 11
Is provided on the front surface 10a of the condenser lens with its optical axis aligned, and the thickness d of the phase shift member 11 is given by the following (Formula 2) with respect to a polar coordinate system in a plane perpendicular to the optical axis. As described above, the thickness d is continuously changed in proportion to the magnitude of the deviation angle. However, since it is difficult to form the shape of the portion on the optical axis or the changing surface near the optical axis, that portion may have a constant thickness within the range that does not affect the phase shift function.

[0052]

[Equation 2]

Specifically, the phase shift amount of the phase shift member 11 is shown in FIG. 2 (b), the vertical axis shows the phase, and the horizontal axis shows the deviation angle with respect to the in-plane polar coordinate system perpendicular to the optical axis. And
In the present embodiment, the phase shift amount and the declination angle are equal.

FIG. 2C shows a perspective view of the condenser lens 10 and the phase shift member 11 of the present embodiment having such a function as seen obliquely from the front with respect to the plane perpendicular to the optical axis.
For the reason of fabrication, the shape near the optical axis is, for example, a depth in which the thickness of the bottom side matches the thinnest thickness of the phase shift member 11 while aligning the center of the minute cylindrical hole with the optical axis. Although it is preferable in practice to form it up to this point, it is omitted in the drawings and is shown only for the sake of illustration.

Therefore, when the CO ₂ laser beam 9 is focused using the above focusing optical system, the intensity distribution of the focused beam 13 after passing through the focusing optical system is the same as the result shown in FIG. became.

In FIG. 3, the condenser lens 10 for comparison with the case where the phase shift member 11 of this embodiment is used.
With the same focal length and no phase shift member
₂ shows the intensity distribution of the laser beam 9 on the converging surface.

Here, regarding the amplitude distribution on the converging surface, for each mode, considering the amplitude of the secondary wave emitted from a minute portion of the wavefront on the pupil at each point on the converging surface, these 2
By superimposing the influence of the next wave on the entire wavefront, the calculation formula can be obtained as in the following (Equation 3).

[0058]

[Equation 3]

However, in (Equation 3), wps = 0 when there is no phase shift member 11, and when there is the phase shift member 11, generally, from (Equation 2), w
Although ps = 2π (n−1) d / λ, the phase shift amount shown in FIG. 2B is obtained in this embodiment.

The intensity distribution of the multimode laser beam on the converging surface is obtained by adding the intensity distribution of each mode and the mode energy.

In FIG. 3, the horizontal axis represents the distance from the optical axis, and the vertical axis represents the intensity. However, the horizontal axis can be formed by connecting points having an intensity 1 / e ² times the peak value of the intensity of the image plane intensity distribution condensed by an optical system having the same focal length as the condenser lens 10 and having no phase shift function. The radius of the circle was standardized to 1. Further, the vertical axis standardizes the peak value of the image plane intensity distribution condensed by an optical system having the same focal length as the condenser lens 10 and having no phase shift function to 1.

The intensity distribution in the present embodiment is shown by a solid line a, and the intensity distribution when an optical system having the same focal length as the condensing optical system 10 and having no phase shift member is used is shown by a dotted line b.

Here, the processing threshold value (Th
Reshold) is different depending on the material, so here, the point where the strength becomes 0.135 times the peak value of the intensity distribution of the dotted line b is assumed to be the processing threshold and is represented by the dotted line c.

That is, in FIG. 3, the width of the intensity distribution inside the dotted line c corresponds to the converging diameter in the actual processing.

As can be understood with reference to FIG. 3, when the light is condensed using the condensing optical system having the phase shift function, the condensed diameter at the time of processing is reduced by about 31%. Furthermore, since the peak value of the intensity distribution is high, the energy density is also high.

Therefore, in processing such as punching and cutting, by using the optical system having this phase shift function, the processing speed is significantly faster than that of the ordinary condensing optical system, and the processing characteristics themselves are also improved. It will be.

Here, the phase shift amount of the phase shift member 11 in the present embodiment is typically described as a case where the deviation angle with respect to the polar coordinate system in the plane perpendicular to the optical axis is equal to the phase shift amount. Similarly, if a phase shift amount that continuously changes corresponding to this declination is given, the light-converging diameter at the time of processing becomes smaller and the energy density also becomes larger.

The same effect may be obtained even when the laser beam is not a multi-mode laser beam but a predetermined single mode, in particular, TEM01 mode and TEM.
A good effect is recognized for the 11 mode.

As described above, according to the present embodiment, the phase of the multimode laser beam or the specific single mode laser beam used for processing corresponds to the polar angle deviation with respect to the plane perpendicular to the optical axis. , For example, by using an optical system that shifts and focuses light by the same angle, it is possible to reduce the focused diameter of the focused beam on the workpiece and increase the peak value of the intensity distribution. We were able to increase the processing speed and improve the processing characteristics.

In this embodiment, the laser beam has an energy ratio of each mode of TEM00: TEM1.
Although the multi-mode laser beam of 0: TEM01 = 1.0: 1.5: 2.5 has been described, the energy ratio that can be combined with the phase shift member is not limited to this.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 is a conceptual diagram showing a cross section of the laser processing apparatus according to the present embodiment. In FIG. 4, reference numeral 21 is a concave total reflection mirror, 22 is a concave partial reflection mirror arranged to face the total reflection mirror 21, 23 is a partial reflection film applied to the partial reflection mirror 22, and 24 is a partial reflection mirror. 22 is a non-reflective film, and 25 is a typical CO ₂
A laser medium, 26 is an aperture for controlling the diameter of the laser beam, 27 is a box that covers the circumference, and the above constitutes a laser oscillator.

28 is a CO ₂ laser beam generated inside the stable resonator constituted by the mirrors 21 and 22, and 29 is C extracted from the partial reflection mirror 2 to the outside.
An O ₂ laser beam, 30 is a condenser lens, 30a is a front surface of the condenser lens, 30b is a rear surface of the condenser lens, and 31 is a phase shift member.

Reference numeral 32 is a non-reflective film formed on the condenser lens 30 and the phase shift member 31.
The phase shift member 31 and the antireflection film 32 constitute a condensing optical system having a function of shifting the phase of the laser beam.

Reference numeral 33 is a focused beam focused by the focusing optical system, and 34 is a workpiece. In the above configuration, the difference between the configuration of the present embodiment and the first embodiment lies in the phase shift member 31.

This phase shift member 31 is added to the front surface 30a of the condenser lens, and the phase of the laser beam incident thereon is substantially continuous with respect to the deviation angle of the polar coordinate system in the plane perpendicular to the optical axis. The thickness d
Is changed stepwise with a predetermined regularity as shown in the following (Equation 4).

[0077]

[Equation 4]

For example, in the present embodiment, as shown in FIG. 5A, the phase in the range of 0 radian to π / 6 radian is 0 radian, from π / 6 radian to π / 3 radian. , Π / 6 radians, π / 3 radians to π / 2 radians, π / 3 radians, π / 2 radians to 2π / 3 radians, π / 2 radians, 2π / 3 radians to 5π /
Phase up to 6 radians is 2π / 3 radians, 5π
The phase in the range from / 6 radians to π radians is 5π /
Phases in the range from 6 radians, π radians to 7π / 6 radians are π radians, 7π / 6 radians to 4π / 3
Phases up to radians are 7π / 6 radians, 4π /
Phase in the range from 3 radians to 3π / 2 radians is 4
π / 3 radian, phase in the range of 3π / 2 radian to 5π / 3 radian is 3π / 2 radian, phase in the range of 5π / 3 radian to 11π / 6 radian is 5π /
The phase in the range from 3 radians and 11π / 6 radians to 2π radians is shifted by 11π / 6 radians.

FIG. 5 (b) is a perspective view of the condenser lens 30 and the phase shift member 31 of the present embodiment that realizes such a phase shift function, as seen from the oblique front side of the plane perpendicular to the optical axis. Is shown. As for the shape in the vicinity of the optical axis, a minute cylindrical hole or the like may be formed for the reason of fabrication or the like, as in the first embodiment.

The operation of the above configuration will be described below. First, since the mirrors 21 and 22 form a stable resonator, the CO ₂ laser beam 28 is reflected by the mirror 2.
It is similar to the first embodiment that a part of the CO ₂ laser beam 28 is extracted to the outside through the partial reflection mirror 22 while being amplified by the laser medium 25 while going back and forth between 1 and 22.

Here, the aperture 26 controls the mode order of the CO ₂ laser beam 28 generated in the resonator, and its aperture diameter is a multimode laser beam in order to obtain a large output laser beam. To set. Also in the present embodiment, as an example, the energy ratio of each mode is TEM00: TEM10: TEM01 = 1.
It was set to 0: 1.5: 2.5.

Then, the CO ₂ laser beam 29 taken out to the outside becomes a focused beam 33 by passing through the focusing optical system, is focused on the surface of the workpiece 34, and is processed into a workpiece such as an iron plate. That is, cutting, drilling, welding and the like are performed as in the first embodiment.

When the laser beam 29 is condensed by using the above condensing optical system, its intensity distribution becomes as shown in FIG.

FIG. 6 shows a case in which the focal length is the same as that of the condensing optical system of the present embodiment but does not have a phase shift function, that is, an ordinary condensing optical system, when the condensing optical system of the present embodiment is used. The intensity distribution on the converging surface of the laser beam 29 in the case of using the optical optical system is shown in the same manner as in the first embodiment, and the intensity distribution in the present embodiment is shown by the solid line a, this condensing optical system. The intensity distribution when a normal focusing optical system having the same focal length and no phase shift function is used is shown by a dotted line b. The processing threshold is set in the same manner as in the first embodiment and is shown by a dotted line c.

As is clear from FIG. 6, when the light is condensed by using the condensing optical system equipped with the phase shift function, the condensed diameter at the time of processing is reduced by about 31%. Furthermore, since the peak value of the intensity distribution is high, the energy density is also high.

Therefore, also in the present embodiment, when the condensing optical system having this phase shift function is used in machining such as punching and cutting, the machining speed is significantly higher than that in the case of using the ordinary condensing optical system. It will be faster and the processing characteristics will be improved.

In the present embodiment, in the polar coordinate system in which the phase shift member 31 is in a plane perpendicular to the traveling direction of the multimode laser beam, the polar coordinate deviation angle is 0 radian to 0 radian.
The area up to 2π radians was divided into areas of π / 6 radians, but the point is that the thickness of the laser beam is intermittently changed correspondingly to the declination angle and focused on the workpiece. It is only necessary to be able to realize the function of increasing the peak value of the intensity distribution and decreasing the condensing diameter, and the size of the separated area and the difference in the phase shift amount between adjacent areas are not limited. It is also possible to adopt a configuration in which the regions have different sizes or the thickness is continuously changed within the regions.

Also in this embodiment, the energy ratio between modes is not limited, and a good effect can be exhibited even for a single mode laser beam, especially for TEM01 and TEM11 modes.

As described above, according to this embodiment, the phase of the multimode laser beam or the specific single mode laser beam used for processing corresponds to the deviation angle of the polar coordinate system with respect to the plane perpendicular to the optical axis. Then, for example, by using an optical system that intermittently shifts the light beam by the same angle to focus the light beam, it is possible to reduce the focus diameter of the focused beam on the workpiece and increase the peak value of the intensity distribution. As a result, the processing speed was increased and the processing characteristics were also improved.

In the above embodiments, the phase shift member is integrated with the condenser lens, but it goes without saying that it may be provided as a separate body in the optical axis.

(Third Embodiment) Hereinafter, a third embodiment of the present invention will be described with reference to the drawings.

FIG. 7 is a conceptual diagram showing a cross section of the laser processing apparatus according to the present embodiment. In FIG. 7, 41 is a concave total reflection mirror, 42 is a concave partial reflection mirror that is arranged to face the total reflection mirror 41, 42a is a partial reflection mirror front surface, 42b is a partial reflection mirror rear surface, and 43 is a partial reflection mirror. The partial reflection film 44 applied to the front surface 42a corresponds to the deviation angle around the optical axis of the laser beam phase incident on the rear surface 42b of the partial reflection mirror with respect to the polar coordinate system in the plane perpendicular to the optical axis. Phase shift member for continuously shifting the phase by 45, 45 is a non-reflective film applied to the phase shift member 44, 46 is a laser medium, for example, in the case of a gas laser such as a carbon dioxide (CO ₂ ) laser, discharge or the like. in a gas medium is excited, also in the case of the solid-state laser such as YAG, is a solid medium which is excited by flash lamp or the like, in the present embodiment, CO ₂ lasers Leh Using a medium typically.

Further, 47 is an aperture for controlling the laser beam diameter, and 48 is a box body that covers the periphery thereof, and the above constitutes a laser oscillator.

Next, 49 is a CO ₂ laser beam generated inside the stable resonator composed of the mirrors 41 and 42, and 50 is a CO ₂ laser, preferably a TEM00 mode CO ₂ laser which is taken out from the partial reflection mirror 42. Beam, 51
Is a condenser lens, 51a is the front surface of the condenser lens, 51b is the rear surface of the condenser lens, 52 is the phase of the laser beam added to the front surface 51a of the condenser lens, and the phase is perpendicular to the optical axis with respect to the polar coordinate system. A phase shift member that continuously shifts the phase according to the declination around the optical axis, and 53 is a non-reflection film provided on the condenser lens 51 and the phase shift member 53. The condenser lens 51, the phase shift member 52, and the antireflection film 53 constitute a condenser optical system having a function of shifting the phase of the laser beam.

Numeral 54 is a focused beam condensed by the condensing optical system, and numeral 55 is a workpiece. Here, in the present embodiment, the phase shift member 52 is typically configured to increase the phase by the same angle as the declination angle, and the other phase shift member 44 is phased by the same angle as the declination angle. Is configured to reduce.

The materials of the partial reflection mirror 42 and the condenser lens 51 are, for example, C such as ZnSe coated with a non-reflection film.
A material that allows the O ₂ laser to pass therethrough may be used, and the phase shift members 44 and 52 may be made of the same material, and may be easily and inexpensively manufactured by a method such as vapor deposition or ICB (ion cluster beam) coating. It is a thing.

The radii of curvature of the concave mirrors 41 and 42 are both 4000 mm, and the concave mirrors 41 and 42 are
The mirror spacing is 4000 mm, and the distance from the rear surface 42 of the partial reflection mirror to the pupil plane of the condenser lens is 5435 mm.
And

The focal length of the condenser lens 51 is 12
It was set to 7 mm. Based on the above configuration, the operation will be described with reference to a more detailed configuration.

First, the mirrors 41 and 42 are stable resonators.
Generated CO ₂Laser beam 49
Moves the mirrors 41 and 42 while passing through the aperture 47.
As it is amplified by the laser medium 46 during the round trip,
And CO₂Part of the laser beam 49 is a partial reflection mirror
It is taken out through 42.

Further, the aperture 47 controls the mode order of the CO ₂ laser beam 49 generated in the resonator. In the present embodiment, the aperture diameter is T.
It is set so as to obtain a laser beam in the EM00 mode.

Here, in general, T on the wavefront of the laser beam is
The amplitude distribution of the EM00 mode is given by the following (Equation 5).

[0102]

[Equation 5]

When the resonator as shown in this embodiment is used, the radius of curvature of the wavefront of the CO ₂ laser beam 49 on the front surface of the partial reflection mirror is 4000 mm and the beam spot diameter is 3.673736 mm.

The TEM00 mode CO ₂ laser beam 50 extracted to the outside is supplied to the phase shift member 4
While being phase-modulated by 4, 52, a focused beam 54 is formed by passing through the condensing optical system, and is focused on the surface of the workpiece 55, that is, processing of a workpiece such as an iron plate, that is, cutting, punching, Welding etc. will be performed efficiently.

In the case of the present embodiment, the phase shift member 44 is integrally provided on the rear surface 42b of the partial reflection mirror with its optical axis aligned, and the thickness d of the phase shift member 44 is perpendicular to the optical axis. For the polar coordinate system in the plane, the following (Equation 6)
The thickness d is continuously changed in proportion to the magnitude of the declination. However, since the shape of the portion on the optical axis and the changing surface near the optical axis is difficult to manufacture, that portion may have a constant thickness within a range that does not affect the phase shift function.

[0106]

[Equation 6]

Specifically, the phase shift amount of the phase shift member 44 is shown in FIG. 8A, the vertical axis indicates the phase, and the horizontal axis indicates the polar coordinate system in the plane perpendicular to the optical axis. It is a declination angle, and the amount of phase shift decreases in proportion to the declination angle.

FIG. 8B is a perspective view of the partially reflecting mirror 42 and the phase shift member 44 of this embodiment having such a function, as seen obliquely from the rear with respect to the plane perpendicular to the optical axis. The shape near the optical axis has a
Further, for example, it is practically preferable to form a minute cylindrical hole so that the thickness of the bottom side matches the thinnest thickness of the phase shift member 44 while aligning the center with the optical axis, but it is omitted in the drawing. The outline is only shown.

FIG. 9A shows the intensity distribution of the CO ₂ laser beam 50 which has been phase-shifted by the phase shift member 44 and propagated from the partial reflection mirror 42 in the optical axis direction by 5430 mm. However, this intensity distribution shows the intensity distribution on the wavefront when it is assumed that the phase shift member 44 is not provided in the laser oscillator according to the present embodiment.
That is, the wavefront referred to here is the wavefront when the laser beam output from the laser oscillator according to the present embodiment is propagated from the partial reflection mirror 5430 mm as in the conventional case without performing the phase shift. That is.

In FIG. 9A, the horizontal axis represents the distance from the optical axis and the vertical axis represents the intensity. The unit of the horizontal axis is mm, and the vertical axis is the peak value of the intensity distribution normalized to 1.0.

Further, FIG. 9B shows the phase shift member 44.
3 shows the wavefront aberration of the CO ₂ laser beam 50 that has been phase-shifted by and has propagated from the partial reflection mirror 42 in the optical axis direction by 5430 mm. However, this wavefront aberration is calculated by using the wavefront on the assumption that the phase shift member 44 is not provided in the laser oscillator according to the present embodiment as a reference spherical surface. In other words, the reference sphere here is
This is a wavefront when the laser beam output from the laser oscillator according to the present embodiment is propagated from the partial reflection mirror 42 by 5430 mm as in the conventional case without phase shifting.

Although the partial reflection mirror 42 actually has a finite thickness in this embodiment, the intensity distribution shown in FIG. 9A and the wavefront aberration shown in FIG. 9B are calculated. In doing so, the thickness of the partial reflection mirror was treated as 0 mm.

Here, in the present embodiment, when the thickness of the partial reflection mirror is treated as 0 mm, the amplitude distribution of the laser beam on the partial reflection mirror and the optical axis of the laser beam propagated by an arbitrary distance are plotted. The relationship of the amplitude distribution on an arbitrary spherical surface having a center of curvature or a plane perpendicular to the optical axis is given by the following (Equation 7).

[0114]

[Equation 7]

This (Equation 7) is an arbitrary surface (an arbitrary spherical surface having a center of curvature on the optical axis or an arbitrary plane perpendicular to the optical axis).
Calculates the amplitude of the observation surface (any observation spherical surface having the center of curvature on the optical axis or any observation plane perpendicular to the optical axis) from the above amplitude, and any surface (here, a partial reflection mirror surface) The secondary wave emitted from the minute portion of is superposed at each point on the observation surface. Here, when the observation surface is assumed to have no phase shift member 44 in the laser oscillator of the present embodiment, It corresponds to the wavefront where the laser beam propagated 5435 mm from the partially reflecting mirror. However, when there is no phase shift member 44 in (Equation 7), w
When ps = 0 and the phase shift member 44 is present,
The value of wps is generally obtained from (Equation 6), but in the case of the present embodiment, it is the phase shift amount shown in FIG.

On the other hand, the phase shift member 52 is provided on the front surface 51a of the condenser lens so that the optical axis thereof coincides with the thickness d of the phase shift member 52 with respect to the polar coordinate system in a plane perpendicular to the optical axis. It is continuously changed as given by the following (Equation 8), and the thickness d is continuously changed in proportion to the magnitude of the declination. However, since the shape of the portion on the optical axis and the changing surface near the optical axis is difficult to manufacture, that portion may have a constant thickness within a range that does not affect the phase shift function.

[0117]

[Equation 8]

Specifically, the phase shift amount of the phase shift member 52 is shown in FIG. 10 (a), the vertical axis represents the phase,
The horizontal axis is the declination angle with respect to the in-plane polar coordinate system perpendicular to the optical axis, and in this embodiment, the phase shift amount and the declination angle are equal.

As can be seen by comparing (Equation 6) and (Equation 8), and FIG. 8A and FIG. 10A, the phase shift member 44
And the phase shift change amount with respect to the declination of the phase shift member 52 has the same absolute value and opposite signs. That is,
For the laser beam 50 that has been phase-shifted by the phase-shifting member 44 and has propagated to the focusing optical system, the phase-shifting member 52
Is configured to restore the amount of the phase shifted by the phase shift member 44.

FIG. 10B shows a perspective view of the condenser lens 51 and the phase shift member 52 of the present embodiment having such a function as seen obliquely from the front with respect to the plane perpendicular to the optical axis. The shape near the optical axis has a
For example, it is practically preferable to form the minute cylindrical hole to a depth such that the thickness of the bottom side matches the thinnest thickness of the phase shift member 52 while aligning the center with the optical axis, but it is omitted in the drawing. Only an outline is shown.

When the CO ₂ laser beam 50 is condensed using the laser oscillator and the condensing optical system as described above, the intensity distribution of the focused beam 54 after passing through the condensing optical system is shown in FIG. The results are shown.

FIG. 11 shows the phase shift of the present embodiment.
For comparison with the case where the tongue members 44 and 52 are used.
When the conditions and conditions are the same and there is no phase shift member
CO ₂Best focus position of each laser beam 50
Shows the intensity distribution at.

Here, the amplitude distribution of the laser beam at the best focus position is obtained by using the above-mentioned (Equation 7) in the case of a single mode laser beam. In this case,
The observation surface is in the best focus position (a plane perpendicular to the optical axis),
An arbitrary surface corresponds to the wavefront on the focusing optical system pupil. However,
When there is no phase shift member 52 in (Equation 7), wps
= 0 and the phase shift member 52 is present, wp
The value of s is generally obtained from (Equation 8), but in the case of the present embodiment, it is as shown in FIG. Also,
The condenser lens 51 is a thin lens with no aberration.

In FIG. 11, the horizontal axis is the distance from the optical axis,
The vertical axis represents intensity. However, the vertical axis standardizes the peak value of the intensity distribution at the best focus position of the CO ₂ laser beam 50 in the case where the conditions are the same as those of the present embodiment and the phase shift member is not provided, to 1.

The intensity distribution at the best focus position in this embodiment is represented by a solid line a, and the intensity of the CO ₂ laser beam 50 at the best focus position under the same conditions as this embodiment and without the phase shift member. The distribution is shown by the dotted line b.

Here, the processing threshold value (Th
Reshold) is different depending on the material, so here, the point where the strength becomes 0.135 times the peak value of the intensity distribution of the dotted line b is assumed to be the processing threshold and is represented by the dotted line c.

That is, in FIG. 11, the width of the intensity distribution inside the dotted line c corresponds to the converging diameter in the actual processing.

As can be understood with reference to FIG. 11, when the laser oscillator and the condensing optical system having the phase shift function as in this embodiment are used, compared with the normal case not having the phase shift function. , The condensing diameter when processing is about 23%
Get smaller. Furthermore, since the peak value of the intensity distribution is high, the energy density is also high.

Therefore, in processing such as punching and cutting, by using the laser oscillator and the condensing optical system having the phase shift function, the machining speed can be greatly increased as compared with the ordinary laser oscillator and the condensing optical system. Therefore, the processing characteristics themselves will be improved.

In addition, the laser beam is not the TEM00 mode laser beam, but the same effect may be obtained even for other single mode or multimode laser beams. In particular, the TEM10 mode or a multimode including many of these modes may be obtained. A good effect is recognized for the mode laser beam.

As described above, according to the present embodiment, the phase shift member whose optical axis thickness continuously increases in proportion to the increase of the deviation angle is provided with the optical axis aligned with the condensing optical system. By integrally providing a phase shift member whose optical axis thickness decreases continuously in proportion to the increase of the angle of deviation so that the optical axis and the rear surface of the partial reflection mirror of the laser oscillator coincide with each other, The focused diameter of the focused beam on the work piece can be reduced and the peak value of the intensity distribution can be increased. As a result, the processing speed can be increased and the processing characteristics can be improved.

(Embodiment 4) Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings.

FIG. 12 shows the laser processing in this embodiment.
It is a conceptual diagram which shows the cross section of an engineering device. In FIG. 12, 6
1 is a concave total reflection mirror, 62 is a total reflection mirror 61
62a is a partial reflection mirror with a concave surface facing each other
The front surface of the reflection mirror, 62b is the rear surface of the partial reflection mirror, and 63 is
Partial reflection film provided on the front surface 62a of the partial reflection mirror, 64
Is a phase shifter added to the rear surface 62b of the partial reflection mirror
Material, 65 is a non-reflective film applied to the phase shift member 64, 6
6 is a laser medium, for example, carbon dioxide gas (CO ₂)laser
In the case of gas lasers such as
In the case of solid-state lasers such as YAG,
This is a solid medium that is excited by a lamp
In the form of CO₂The laser medium of the laser is typically used
It was

Further, 67 is an aperture for controlling the laser beam diameter, and 68 is a box body that covers the periphery thereof, and the above constitutes a laser oscillator.

Next, 69 is a CO ₂ laser beam generated inside the stable resonator constituted by the mirrors 61 and 62, and 70 is a CO ₂ laser, preferably a TEM00 mode CO ₂ laser which is taken out from the partial reflection mirror 62. Beam, 71
Is a condenser lens, 71a is a condenser lens front surface, 71b is a condenser lens rear surface, 72 is a phase shift member added to the condenser lens front surface 71a, and 73 is a condenser lens 71 and a phase shift member 72. It is a reflective film. The condenser lens 71, the phase shift member 72, and the antireflection film 73 configure a condenser optical system having a function of shifting the phase of the laser beam.

Further, 74 is a focused beam condensed by the condensing optical system, and 75 is a workpiece. Here, the radiuses of curvature of the concave mirrors 61 and 62 were both 4000 mm, and the mirror spacing between the concave mirrors 61 and 62 was 4000 mm.

The distance from the rear surface 62b of the partial reflection mirror to the pupil surface of the condenser lens is 5435 mm.

The focal length of the condenser lens 71 is 127.
mm. The materials of the partial reflection mirror 62 and the condenser lens 71 are, for example, C such as ZnSe coated with a non-reflection film.
A material that allows the O ₂ laser to pass therethrough may be used, and the phase shift members 64 and 72 may be made of the same material, and can be easily and inexpensively manufactured by a method such as vapor deposition or ICB (ion cluster beam) coating. It is a thing.

In the above structure, the difference between the structure of the present embodiment and the third embodiment is that the phase shift member 6
4 and 72.

The phase shift member 64 is the partial reflection mirror 6
2 and the thickness d of the laser beam incident thereon is such that the phase can be regarded as a substantially continuous change with respect to the deviation angle of the polar coordinate system in the plane perpendicular to the optical axis. It is changed stepwise with a predetermined regularity as shown in the following (Equation 9).

[0141]

[Equation 9]

For example, in the present embodiment, FIG.
As shown in, the phase in the range of 0 radians to π / 6 radians is 11π / 6 radians, and the phase in the range of π / 6 radians to π / 3 radians is 5π / 3 radians and π / 3 radians. To π / 2 radians, the phase is 3π / 2 radians, and the phase from π / 2 radians to 2π / 3 radians is 4π / 3 radians, 2π / 3.
Phase in the range from radians to 5π / 6 radians is 7π
/ 6 radians, phases in the range of 5π / 6 radians to π radians are π radians, phases in the range of π radians to 7π / 6 radians are 5π / 6 radians, and phases of 7π / 6 radians to 4π / 3 radians. The phase of 2π /
3 radians, phases in the range of 4π / 3 radians to 3π / 2 radians are π / 2 radians, phases in the range of 3π / 2 radians to 5π / 3 radians are π / 3 radians, 5π / 3 radians to 11π / Phases in the range up to 6 radians are π / 6 radians, 11π / 6 radians to 2
The phase in the range up to π radian is shifted by 0 radian.

FIG. 13B is a perspective view of the partial reflection mirror 62 and the phase shift member 64 of the present embodiment that realizes such a phase shift function, as seen from the diagonally rear side of the plane perpendicular to the optical axis. Is shown. Regarding the shape in the vicinity of the optical axis, a minute cylindrical hole or the like may be formed for reasons such as fabrication.

On the other hand, the phase shift member 72 is added to the condenser lens 71, and the phase of the laser beam incident thereon is substantially continuous with respect to the deviation angle of the polar coordinate system in the plane perpendicular to the optical axis. The thickness d is
It is changed stepwise with a predetermined regularity as shown in the following (Equation 10).

[0145]

[Equation 10]

For example, in the present embodiment, FIG.
As shown in, the phase in the range of 0 radian to π / 6 radian is 0 radian, π / 6 radian to π / 3.
Phases in the range up to radians are π / 6 radians, phases in the range from π / 3 radians to π / 2 radians are π / 3 radians, and phases in the range from π / 2 radians to 2π / 3 radians are π / 2. Radians, 2π / 3 radians to 5π
Phases up to / 6 radians are 2π / 3 radians, 5
The phase in the range from π / 6 radians to π radians is 5π
/ 6 radians, π radians to 7π / 6 radians in the range of π radians, 7π / 6 radians to 4π /
Phases up to 3 radians are 7π / 6 radians, 4π
Phases in the range from / 3 radians to 3π / 2 radians are in the range of 4π / 3 radians, phases in the range from 3π / 2 radians to 5π / 3 radians are in the range of 3π / 2 radians, 5π / 3 radians to 11π / 6 radians The phase of the range is 5π
The phase in the range from / 3 radians and 11π / 6 radians to 2π radians is shifted by 11π / 6 radians.

FIG. 14B is a perspective view of the condenser lens 71 and the phase shift member 72 of the present embodiment that realizes such a phase shift function, as seen from the front side in the oblique direction of the plane perpendicular to the optical axis. It is shown. As for the shape in the vicinity of the optical axis, a minute cylindrical light or the like may be formed for the reason of fabrication or the like, as in the third embodiment.

(Equation 9) and (Equation 10), and FIG. 13 (a)
As can be seen by comparing FIG. 14A with each other, the amounts of change in the phase shift with respect to the angle of deviation of the phase shift member 64 and the phase shift member 72 have the same absolute value and opposite signs. That is, with respect to the laser beam 70 that has been phase-shifted by the phase-shifting member 64 and has propagated to the focusing optical system, the phase-shifting member 72 restores the amount of phase-shifted by the phase-shifting member 64.

Based on the above configuration, the detailed configuration will be touched.
The operation will be described as it is performed. First, the mirror 61,
Since 62 is a stable resonator, the generated C
O ₂The laser beam 69 does not pass through the aperture 67.
The laser medium 66 while reciprocating from the mirrors 61 and 62
More amplified and CO₂Part of laser beam 69
Are taken out through the partial reflection mirror 62.
Is the same as in the third embodiment.

Here, the aperture 67 controls the mode order of the CO ₂ laser beam 69 generated in the resonator, but in the present embodiment, the aperture diameter is the TEM00 mode laser as in the third embodiment. Set to get the beam.

When the resonator as shown in this embodiment is used, the radius of curvature of the wavefront of the CO ₂ laser beam 49 on the front surface of the partial reflection mirror is 4000 mm, and the beam spot is 3.673736 mm.

The TEM00 mode CO ₂ laser beam 70 extracted to the outside is supplied to the phase shift member 6
4 and 72 are phase-modulated and pass through the condensing optical system to become a focused beam 74, which is the workpiece 7
It is possible to efficiently perform processing of a workpiece such as an iron plate that is focused on the surface of 5, such as cutting, drilling, and welding.

FIG. 15A shows the intensity distribution of the CO ₂ laser beam 70 which is phase-shifted by the phase-shifting member 64 and propagated from the partial reflection mirror 62 in the optical axis direction by 5430 mm. However, this intensity distribution shows the intensity distribution on the wavefront when it is assumed that the phase shift member 64 is not provided in the laser oscillator according to the present embodiment. That is, the wavefront referred to here is a wavefront in the case where the laser beam output from the laser oscillator is propagated from the partial reflection mirror by 5430 mm in the conventional manner without phase shifting.

In FIG. 15A, the horizontal axis represents the distance from the optical axis, and the vertical axis represents the intensity. The unit of the horizontal axis is mm, and the vertical axis is the peak value of the intensity distribution normalized to 1.0.

Further, FIG. 15B shows the phase shift member 6
4 shows the wavefront aberration of the CO ₂ laser beam 60 phase-shifted by 4 and propagated from the partial reflection mirror 62 in the optical axis direction by 5430 mm. However, this wavefront aberration is calculated by using the wavefront on the assumption that the phase shift member 64 is not provided in the laser oscillator according to the present embodiment as a reference spherical surface. In other words, the reference sphere here is
It is a wavefront in the case where the laser beam output from the laser oscillator is propagated from the partial reflection mirror 62 by 5430 mm in the conventional manner without phase shifting.

In the present embodiment, the partial reflection mirror 62 actually has a finite thickness, but in calculating the intensity distribution shown in FIG. 15A and the wavefront aberration shown in FIG. 15B. Was treated as if the thickness of the partial reflection mirror was 0 mm.

Here, in the present embodiment, when the thickness of the partial reflection mirror is treated as 0 mm, the amplitude distribution of the laser beam on the partial reflection mirror and the curvature on the optical axis of the laser beam propagated by an arbitrary distance. The relationship of the amplitude distribution on an arbitrary spherical surface having a center or a plane perpendicular to the optical axis is given by the above (Equation 7), an arbitrary surface is a partial reflection mirror surface, and an observation surface is a phase shift member. This corresponds to the wavefront of the laser beam propagated from the partial reflection mirror by 5435 mm when it is assumed that 64 is not present. However, when there is no phase shift member 64 in (Equation 7), wps = 0, and when there is the phase shift member 64, wps is generally represented by the above (Equation 9). Specifically, FIG.
The phase shift amount shown in (a) is obtained.

When the CO ₂ laser beam 70 is focused using the laser oscillator and the focusing optical system as described above, the intensity distribution of the focused beam 74 after passing through the focusing optical system is shown in FIG.
The result is shown in 6.

FIG. 16 shows the phase shift of the present embodiment.
For comparison with the case of using the support members 64 and 72
When the conditions and conditions are the same and there is no phase shift member
CO ₂Best focus position of each laser beam 70
Shows the intensity distribution at.

Here, the amplitude distribution of the laser beam at the best focus position can be obtained from the above (Equation 7) in the case of a single mode laser beam. In this case, (Equation 7)
At, the observation surface corresponds to the best focus position (a plane perpendicular to the optical axis), and any surface corresponds to the wavefront on the focusing optical system pupil.
However, when there is no phase shift member 72 in (Equation 7),
When wps = 0 and the phase shift member 72 is present, wps is generally represented by the above-mentioned (Equation 10), but specifically, it is the phase shift amount shown in FIG. Further, the condenser lens 71 is a thin lens with no aberration.

In FIG. 16, the horizontal axis is the distance from the optical axis,
The vertical axis represents intensity. However, on the vertical axis, the peak value of the intensity distribution at the best focus position of the CO ₂ laser beam 70 under the same conditions as in the present embodiment and without the phase shift member was normalized to 1.

The intensity distribution in the present embodiment is indicated by a solid line a, and the intensity distribution at the best focus position of the CO ₂ laser beam 70 under the same conditions as in the present embodiment and without the phase shift member is indicated by a dotted line b. Indicated.

Here, the processing threshold value (Th
Reshold) is different depending on the material, so here, the point where the strength becomes 0.135 times the peak value of the intensity distribution of the dotted line b is assumed to be the processing threshold and is represented by the dotted line c.

That is, in FIG. 16, the width of the intensity distribution inside the dotted line c corresponds to the focused diameter in the actual processing.

As can be understood with reference to FIG. 16, when the laser oscillator and the condensing optical system having the phase shift function as in this embodiment are used, compared with the normal case not having the phase shift function. , The condensing diameter when processing is about 23%
Get smaller. Furthermore, since the peak value of the intensity distribution is high, the energy density is also high.

Therefore, in processing such as punching and cutting, by using the laser oscillator and the condensing optical system having the phase shift function, the machining speed can be greatly increased as compared with the ordinary laser oscillator and the condensing optical system. Therefore, the processing characteristics themselves will be improved.

In the present embodiment, in the polar coordinate system in which the phase shift members 64 and 72 are in a plane perpendicular to the traveling direction of the laser beam, the polar coordinate deviation angle is 0 radian to 2π.
The area up to radians was divided into regions of π / 6 radians. The point is that the thickness of the laser beam changes intermittently corresponding to the declination, and It is only necessary to be able to realize the function of decreasing the focused diameter while increasing the peak value of the intensity distribution, and the size of the divided areas and the difference in the amount of phase shift between adjacent areas are not limited, The size of the areas is different,
It is also possible to adopt a configuration in which the thickness continuously changes within the region.

In addition, the laser beam is not the TEM00 mode laser beam, and the same effect may be obtained even for other single mode or multimode laser beams. In particular, the TEM10 mode or a multimode including many of these modes may be obtained. A good effect is recognized for the mode laser beam.

As described above, according to the present embodiment, the phase shift member whose thickness of the optical axis intermittently increases in proportion to the increase of the declination is aligned with the optical axis of the condensing optical system. By integrally providing a phase shift member whose optical axis thickness decreases intermittently in proportion to an increase in declination with the rear surface of the partial reflection mirror of the laser oscillator aligned with the optical axis, The focused diameter of the focused beam on the work piece can be reduced and the peak value of the intensity distribution can be increased. As a result, the processing speed can be increased and the processing characteristics can be improved.

In the third and fourth embodiments,
Although the phase shift member is integrated with the partial reflection mirror and the condenser lens, it goes without saying that the phase shift member may be provided separately in the optical axis.

Further, in the above-mentioned embodiments, the CO ₂ laser beam is used as a laser beam as a typical description, but other lasers such as a YAG laser and a ruby laser may be used depending on the application of processing. It is also possible to use.

[0172]

As described above, the laser processing apparatus having the phase shift means of the present invention reduces the focused diameter of the laser beam on the workpiece as compared with the case where the phase of the laser beam is not shifted. In addition, the peak value of the intensity distribution can be increased, the focused beam diameter can be reduced, and the processing intensity can be increased to sharply focus light.

Therefore, with an extremely simple structure, the processing speed can be improved as compared with the conventional one, and in addition, finer processing can be performed with high quality.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a laser processing apparatus according to a first embodiment of the present invention.

FIG. 2A is a diagram showing an intensity distribution immediately before entering the focusing optical system; FIG. 2B is a diagram showing a phase shift amount of the focusing optical system; and FIG. 2C is a surface perpendicular to the optical axis of the focusing optical system. Perspective configuration diagram for

FIG. 3 is a diagram comparing the intensity distribution on the converging surface of the same laser beam with the intensity distribution on the converging surface without phase shift.

FIG. 4 is a configuration diagram of a laser processing apparatus according to a second embodiment of the present invention.

FIG. 5A is a diagram showing a phase shift amount of the same phase shift member, and FIG. 5B is a perspective configuration diagram of a plane perpendicular to the optical axis of the same focusing optical system.

FIG. 6 is a diagram comparing the intensity distribution of the same laser beam on the converging surface with the intensity distribution on the converging surface without phase shift.

FIG. 7 is a configuration diagram of a laser processing apparatus according to a third embodiment of the present invention.

8A is a diagram showing a phase shift amount of the phase shift member 44, and FIG. 8B is a perspective configuration diagram of the partial reflection mirror and the phase shift member 44 with respect to a plane perpendicular to the optical axis.

FIG. 9A is a diagram showing an intensity distribution immediately before entering the same focusing optical system, and FIG. 9B is a diagram showing wavefront aberration just before entering the same focusing optical system.

FIG. 10A is a diagram showing a phase shift amount of the same phase shift member 52, and FIG. 10B is a perspective configuration view of a plane perpendicular to the optical axis of the same focusing optical system.

FIG. 11 is a diagram comparing the intensity distribution at the best focus position of the same laser beam with the intensity distribution at the best focus position without phase shift.

FIG. 12 is a configuration diagram of a laser processing device according to a fourth embodiment of the present invention.

13A is a diagram showing the amount of phase shift of the same phase shift member 64, and FIG. 13B is a perspective configuration diagram of the partial reflection mirror and the phase shift member 64 with respect to a plane perpendicular to the optical axis.

FIG. 14A is a diagram showing a phase shift amount of the same phase shift member 72, and FIG. 14B is a perspective configuration diagram of a plane perpendicular to the optical axis of the same focusing optical system.

FIG. 15A is a diagram showing an intensity distribution immediately before entering the same focusing optical system, and FIG. 15B is a diagram showing wavefront aberration just before entering the same focusing optical system.

FIG. 16 is a diagram comparing the intensity distribution at the best focus position of the same laser beam with the intensity distribution at the best focus position without phase shift.

FIG. 17 is a block diagram of a conventional laser processing apparatus.

[Explanation of symbols]

1 Total reflection mirror 2 partial reflection mirror 3 Partial reflection film 4 Anti-reflection film 5 Laser medium 6 apertures 7 boxes 8 laser beam 9 laser beam 10 Condensing lens 10a front of condenser lens 10b Rear surface of condenser lens 11 Phase shift member 12 Anti-reflection film 13 Focused beam 14 Workpiece 21 total reflection mirror 22 Partial reflection mirror 23 Partial reflection film 24 Anti-reflection film 25 laser medium 26 Aperture 27 boxes 28 laser beam 29 laser beam 30 condenser lens 30a front of condenser lens 30b Condenser lens rear surface 31 Phase shift member 32 Anti-reflection film 33 Focused beam 34 Workpiece 41 total reflection mirror 42 partial reflection mirror 42a Front of partial reflection mirror 42b Partial reflection mirror rear surface 43 Partial reflective film 44 Phase shift member 45 Anti-reflection film 46 Laser medium 47 Aperture 48 boxes 49 laser beam 50 laser beam 51 Condensing lens 51a front of condenser lens 51b Condenser lens rear surface 52 Phase shift member 53 Anti-reflection film 54 Focused beam 55 Workpiece 61 total reflection mirror 62 partial reflection mirror 62a front of partial reflection mirror 62b Partial reflection mirror rear surface 63 Partial reflective film 64 Phase shift member 65 Anti-reflection film 66 laser medium 67 Aperture 68 Box 69 laser beam 70 laser beam 71 Condensing lens 71a front of condenser lens 71b Rear surface of condenser lens 72 Phase shift member 73 Anti-reflection film 74 Focused beam 75 Workpiece 81 total reflection mirror 82 Partial reflection mirror 83 Partial reflective film 84 Anti-reflection film 85 Laser medium 86 aperture 87 boxes 88 laser beam 89 laser beam 90 condenser lens 91 Anti-reflection film 92 Focused beam 93 Workpiece

Claims (19)

(57) [Claims] 1. A laser oscillator for oscillating a laser beam, a condensing optical system for condensing the laser beam on a workpiece, and a phase shift means for shifting the phase of the light wavefront of the laser beam. Then, the laser processing device in which the phase shift means shifts the phase corresponding to a deviation angle around the optical axis with respect to a polar coordinate system on a plane perpendicular to the optical axis of the condensing optical system. 2. The laser processing apparatus according to claim 1, wherein the phase shift means is a phase shift member that continuously shifts the phase in accordance with the deviation angle. 3. A condensing optical system includes a condensing lens and a phase shift member integrally provided with the condensing lens so that the optical axes thereof coincide with each other, and the phase shift member is arranged in the optical axis direction. The laser processing apparatus according to claim 2, wherein the thickness continuously increases in accordance with the increase in the deflection angle. 4. The phase shift member has a thickness in the optical axis direction,
The laser processing apparatus according to claim 3, wherein the laser beam continuously increases in proportion to the increase of the deviation angle. 5. The laser processing apparatus according to claim 1, wherein the phase shift means is a phase shift member that intermittently shifts the phase in accordance with the declination angle. 6. The condensing optical system includes a condensing lens and a phase shift member integrally provided with the condensing lens so that the optical axes thereof coincide with each other, and the phase shift member has an optical axis. 6. The laser processing apparatus according to claim 5, wherein the thickness in the direction increases intermittently in response to an increase in declination. 7. The phase shift member has a plurality of regions that are evenly divided in terms of declination, and the thickness of the regions in the direction of the optical axis increases intermittently and equally as the declination increases. The laser processing apparatus according to claim 6. 8. The laser processing apparatus according to claim 1, wherein two phase shift means are arranged in the optical axis. 9. The laser processing apparatus according to claim 8, wherein one of the phase shift means increases the phase shift amount in accordance with the declination angle and the other decreases the phase shift amount in accordance with the declination angle. 10. The laser processing apparatus according to claim 9, wherein both of the phase shift means are phase shift members that continuously shift the phase in accordance with the deviation angle. 11. One of the phase shift members is integrally provided with a condensing lens of a condensing optical system so that its optical axis coincides with each other, and the thickness in the optical axis direction is continuous corresponding to an increase in declination. The phase shift member on the other side is integrally provided with the output mirror of the resonator of the laser oscillator so that the optical axis thereof coincides, and the thickness in the optical axis direction increases the declination angle. 11. The laser processing apparatus according to claim 10, which correspondingly continuously decreases. 12. One of the phase shift members has a thickness in the optical axis direction that continuously increases in proportion to an increase in declination, and the other has
The laser processing apparatus according to claim 11, wherein the thickness in the optical axis direction continuously decreases in proportion to the increase in the deflection angle. 13. The laser processing apparatus according to claim 9, wherein both of the phase shift means are phase shift members that intermittently shift the phase in accordance with the deviation angle. 14. One of the phase shift members is integrally provided with a condensing lens of a condensing optical system with its optical axis aligned, and the thickness in the optical axis direction is intermittent in response to an increase in declination. The phase shift member on the other side is integrally provided with the output mirror of the resonator of the laser oscillator so that the optical axis thereof coincides, and the thickness in the optical axis direction increases the declination angle. 14. The laser processing apparatus according to claim 13, which is correspondingly intermittently reduced. 15. One of the two phase shift members arranged in the optical axis has a plurality of regions that are evenly divided in terms of declination, and the thickness of the regions in the optical axis direction is the declination angle. The number of regions increases equally in an intermittent manner corresponding to the increase, and the other has a plurality of regions that are evenly divided with respect to the declination, and the thickness of the region in the optical axis direction intermittently corresponds to the increase of the declination. 15. The laser processing apparatus according to claim 14, wherein the laser processing is reduced equally. 16. The phase shift member and the condenser lens are formed by using the same optical material.
Or the laser processing apparatus according to 7. 17. A phase shift member, a condenser lens, and / or
Alternatively, the phase shift member and the output mirror of the resonator of the laser oscillator are formed by using the same optical material.
The laser processing apparatus according to 12, 14, or 15. 18. The laser processing apparatus according to claim 1, wherein the laser beam is a multimode laser beam. 19. The laser beam is a TEM00 mode,
TEM10 mode, TEM01 mode or TEM11
A mode single mode laser beam.
7. The laser processing device according to any one of 7.