JPH02172286A - Laser apparatus - Google Patents

Abstract

PURPOSE:To change the convergent beam intensity in a specified spot, and enable high quality working by installing an aperture member to make the diameter of a convergent light beam constant in the vicinity of the focus of a convergent light optical system to converge a laser beam with phase difference. CONSTITUTION:By operating movable mechanism, phase difference between laser beams 80, 81 is made 0 deg., and a laser beam 8 is converged by a condenser lens 15; an object 16 to be worked is put at the focus position; the laser beam is converged to a spot of a specified diameter on the surface of the object 16 to be worked. When a filter 17 having a hole whose diameter is nearly equal to the diameter of the convergent light spot is arranged on the surface of the object 16 to be worked, the laser beam 8 is projected on the object 16 to be worked without being eliminated by the filter 17. When the phase difference between the laser beams 80, 81 is made 180 deg., the intensity distribution on the surface of the object 16 to be worked extends to a wide range. When the filter 17 is arranged, the beam of a specified diameter passes the filter 17, and the object 16 to be worked is irradiated with a part of laser power. Thereby, the intensity of the convergent beam can be changed in a specified spot, and high quality working of the object to be worked is enabled.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a laser device and a method for controlling the intensity of a laser beam reflected from a total reflection mirror with a phase adjustment function while keeping the beam diameter constant. , relates to devices that can be controlled.

[Conventional technology]

FIG. 7 is a cross-sectional configuration diagram schematically showing a conventional laser device disclosed in, for example, Japanese Patent Application No. 182354/1982, in which C11 is a collimating mirror made of a concave mirror, (2)
is a partially reflective coating Kl, (31 is a laser medium; for example, a gas laser such as a CO2 laser is a gas medium excited by an electric discharge, and for a solid-state laser such as a YAG laser, it is a gas medium excited by a flash lamp, etc. It is a glass medium. (4) is a wind mirror (5) is a non-reflective coating applied on the surface of the wind mirror (4), (6) is a box that covers the surrounding area, +71. (70)
, (71) is the laser beam inside the cavity, (8)
, (80), (81) are laser beams taken out from the laser resonator, and (9) is the laser resonator.

This movable mirror a is a total reflection mirror provided on the optical path of the laser beams (80) and (81) taken out from the wind mirror (4), and has a movable mirror Ql).

For example, the central part of the total reflection mirror α value is hollowed out using an electric discharge machine and is configured to be movable in the axial direction.

03 is a fixed part fixed to the total reflection mirror t11, C14
is a movable mechanism that linearly moves i′ along the fixed part lI3.
Both constitute an rI[s movement mechanism a2, and a movable mirror q9 is attached to the movable mechanism a4.

09 is a condensing lens, 1e is a workpiece, rIs is a telescopic element, for example, a piezo element attached to the moving part I of the rig movement mechanism (13), and α9 is a power source that excites the telescopic element 0 barrel.

819(a) and 819('b) are explanatory diagrams each showing the operation of the conventional laser device shown in FIG.
Figure fa) shows that when the phase difference between the movable mirror αυ and the laser beam reflected by the other parts is 0°, Figure 8 (1)
) is the case where the phase difference is 1800°.

Next, the operation will be explained.

Collimating mirror (1) and convex wind mirror f4
Partially reflective coating model (2) of Part 1 constitutes a so-called unstable resonator, and model (2) of partially reflective coating (2) constitutes a so-called unstable resonator.
) The laser beam (7) partially reflected and expanded is amplified by the laser medium (3) and collimated into a parallel beam by the collimating mirror (1).

A part of the central laser beam (70) passes through the partially reflective coating (2) to the outside of the laser beam (80).
), and most of the laser beam (71) in the peripheral area passes through the anti-reflection coating pattern (5) and is emitted to the outside as a laser beam (8I). Since both laser beams are extracted through different coatings on the surface of the wind mirror (4), a phase difference occurs between the two laser beams.

In order to cancel this phase difference, two laser beams (81
) leads the laser beam (80) in phase by δ, then let the wavelength of the laser beam be λ.

δ! The propagation distance of the laser beam (81) increases by =λ□2π
The movable mirror aO may be protruded by moving the movable mechanism α center of the linear motion mechanism σ2 so that the propagation distance is greater than the propagation distance of 80). Total reflection mirror I14 and movable mirror α0
If the angle of incidence on is 45°, its protrusion ta is! d=sin45°. Conversely, if the laser beam (80) leads the laser beam (8I) in phase by δ.

It is sufficient to move the movable mirror a9 backward by the amount d mentioned above.

Therefore, for example, when the elastic element Ql is moved periodically, the movable mechanism I is also moved periodically.

The phase of the laser beam (80) changes periodically.

The laser beam (8) that has undergone a phase change in this way is focused by a condensing lens 09, and as a result, when performing laser processing on the mouth e of the workpiece, it is possible to realize laser processing in which the intensity changes periodically. .

[Problem to be solved by the invention]

Since the conventional laser device is configured as described above, 2
For example, in FIG. 7, the movable mechanism 114) is operated.

When the phase difference between the laser beams (80) and (81) is zero, the laser beam (81) becomes the 819th (a)
), the light is focused within a fixed spot. But 1
For example, in Fig. 7, the laser beams (80) and (81)
When the phase difference between the two is set to 180', there is a problem in that the laser beam (8) spreads beyond the diameter of the condensed spot, as shown in FIG. 8 (bl).

This invention was made in order to alleviate the above-mentioned problems, and aims to provide a laser device that can perform high-quality processing of a workpiece by changing the intensity of a focused beam within a fixed spot. purpose.

[Means to solve the problem]

The laser device according to the present invention includes a laser device + tIC that modulates intensity using the phase difference between two laser beams, and an aperture member that keeps the diameter of the focused beam constant near the focal point of the focusing optical system. It is something.

[Effect]

The aperture member in this invention keeps the diameter of the focused beam constant, which changes with respect to changes in the two-phase difference.

[Real ellipse example]

Hereinafter, one practical example of this invention will be explained with reference to the drawings.

In FIG. 1, (1) to 18) are exactly the same as the conventional device described above.

αη is the condenser lens a! This is a filter installed near the focal point of j, and is an aperture member that makes the diameter of the 9% light beam constant.

Fig. 2 is a distribution diagram showing the intensity distribution of the laser beam according to an embodiment of the present invention, and Fig. 2 fa) shows the intensity distribution of the laser beam reflected by the movable mirror [+11 and other parts]. Intensity distribution near the focal point before entering the filter surface when the phase difference between laser beams is 0°.

FIG. 2(1)l shows the intensity distribution near the focal point before entering the filter 09 when the phase difference is 180°. In addition, on the horizontal axis, one point P in the horizontal plane is the beam irradiation center position.

In a laser device configured as described above.

The entire operation is the same as that of the conventional device until the laser beam (8) passes through the laser beam lens 9, but after passing through the condensing lens a5, the laser beam (8) irradiates the workpiece (IQ). In Fig. 1, when the phase difference between the laser beams (80) and (81) is set to 09 by operating the frame 04, the laser beam (8) is transferred to the condenser lens α. Then, the intensity distribution on the surface of the workpiece aS is within a certain spot diameter as shown in Figure 2 (al) ζ. Therefore, as shown in FIG. 3, for example, a filter surface with a hole approximately the same diameter as the focal spot diameter is placed near the surface of the workpiece (1e).

The laser beam (8) is not filtered out by the filter aη, so most of the laser power is irradiated onto the workpiece (Ill).

Next, in FIG. 1, the movable mechanism j1 is operated.

For example, if the phase difference between the laser beam (aO) and (S) is 1
When the angle is 80°, the intensity distribution on the surface of the workpiece ae covers a wide range as shown in FIG. 2(b). Therefore, as shown in FIG. 3 (bl), when the filter αη is placed, the beam with a constant spot diameter will pass through the filter aη, and therefore only a portion of the laser power 9 For example, in this case, 5% The other laser beams are removed by the filter αη.

Figure 3 (a), (b) Each state's condition, workpiece il
l:@ Comparing the emitted beam intensity, Figure 3 fa)
is, for example, 20 times more specific. Therefore, if, for example, the workpiece tl[i is processed at the strength of Fig. 3 ia), but not i-1'' at the strength of Fig. 3 1b), then the elastic element configuration of Fig. 1 is Laser beam (80
).

(81) When the movable mechanism I is operated so as to periodically change the phase difference between 06 and 180 degrees.

Pulse processing can be performed.

When pulsing a laser, the upper limit frequency is usually determined by the characteristics of the laser medium; for example, in the case of a gas laser such as Ha002, the upper limit is several KHz.

However, in this method, pulsing is completely unrelated to the characteristics of the laser medium, and the frequency can be increased to 10 KHz, I or more.

In the above actual situation series, a total reflection mirror n1 for adjusting one phase and a movable mirror tlll are provided outside the resonator, but as shown in FIG. may be provided within the resonator as one of the resonator mirrors. In addition, 1′! Q is a mirror that changes the beam optical path.

Further, in the above actual situation series, a laser resonator having one optical path within the resonator is shown as an example, but the present invention is not limited to this.For example, a stable resonator as shown in FIG. Similar effects can be obtained by using Note that (700) is the laser beam inside the resonator.Furthermore, in the above embodiment, one condensing lens is used, but a plurality of condensing lenses may be used.2For example, as shown in FIG. The same effect can be obtained by using two condensing lenses and inserting a filter between them as shown in (1:++). Figure 6 (a) shows the position between the laser beams. This is a case where the phase difference is 0°, and the laser beam !8) is not deleted even if a filter surface is inserted at the focal position of the condenser lens 12D (the workpiece 118 is irradiated.
Figure (b) shows a case where the phase difference is 1800, and the portion of the laser beam (8) other than the focused spot diameter is removed by the filter a71, so that the workpiece l1ls is irradiated with a focused beam with weak intensity. Ru.

〔Effect of the invention〕

As described above, according to the present invention, a condensing optical system that condenses a laser beam giving two phase differences in a laser device that controls the intensity of the beam by using the phase difference between the two laser beams. Since a member 11 for making the diameter of the condensed beam constant is provided near the focal point, the beam intensity can be changed while the beam diameter remains constant, which has the effect of allowing high-quality processing to be performed.

Moreover, it has the effect of making it possible to raise the frequency even higher.

[Brief explanation of the drawing]

No. 11 is a cross-sectional configuration diagram showing a laser device according to an embodiment of the present invention, and FIG. 2 is a distribution diagram showing the intensity distribution of a laser beam according to an embodiment of the present invention.
31'1la) fb) Figures 4 and 5 each illustrate the operation of a laser device according to an embodiment of the present invention.
6(a) and 6(b) are partial cross-sectional configuration diagrams showing a part of the laser device according to another embodiment of the present invention, respectively; Figure 7 shows the cross-sectional structure of a conventional laser device, and
Figures (a) and (fb) are explanatory layers each explaining the operation of a conventional laser device. In the figure, +71 (70) (71) (700)・
81 (8i1X81) is a laser beam, (9) is a laser with mW, ill is a total reflection mirror, lIt+ is a movable mirror, α2 is a linear movement/motion mechanism, I is a possible @ tower beak, sho is a condensing lens, qn is It's a filter. In the figure, the symbol @-sasa indicates the same or equivalent part.

Claims (1)

[Claims] A laser resonator, a total reflection mirror provided inside or outside the laser resonator and having a movable part in which a part of the reflection surface can be moved in the axial direction, and condensing the laser beam reflected from the total reflection mirror. a condensing optical system that controls the amount of movement of the movable part to change the phase between the laser beam reflected by the movable part and other parts to change the intensity of the condensed beam, A laser device characterized in that an aperture member is provided near the focal point of the condensing optical system to make the diameter of the condensed beam constant.