JPS63108318A - Laser working device - Google Patents

Abstract

PURPOSE:To minimize optical loss and to uniform the distribution of light intensity by passing the central light of a light beam without deflecting it and exchanging outer light and inner light in the ring area of the light beam by using a light beam converting optical member. CONSTITUTION:The light beam converting optical member consists of two truncated cone-like optical members 4A, 4B the same in shape. The projection side plane 43 of the member 4A and the incident side plane 44 of the member 4B are arranged in parallel. Thereby, the central beam made incident upon the incident side plane 41 of the member 4A is passed without being deflected and projected from the projection side plane 46 of the member 48. On the other hand, the light beam in the ring area is made incident upon the conical face 42 of the member 4A, refracted, replaced in the vicinity of an optical axis Ax, and then made incident upon the plane 44 of the member 4B. The incident beams are refracted and projected from the conical face 45 in parallel with the optical axis Ax. Consequently, the optical loss can be minimized and the intensity distribution of light beam can be uniformed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a processing device using a laser beam.

[Conventional technology]

The light intensity distribution of the laser beam emitted from the laser light source has a Gaussian distribution in which the light intensity is strong at the center and weak at the periphery, as shown in FIG. 3 (1) at -S. Therefore, is it possible to process using a light beam with such intensity as a light source? i
When M is used for cutting semiconductor fuses, welding, etc., there is a problem in that it is difficult to perform processing with higher precision.

For this reason, several proposals have been made to obtain a uniform light intensity distribution from a light beam having such a Gaussian distribution.

For example, (a) Japanese Patent Publication No. 51-37264 discloses an extension of the technology for converting the intensity of light as disclosed in US Pat. No. 3,547,526. This problem can be solved by integrating two conical or polygonal pyramidal prisms that have approximately the same apex angle by joining them at their bases, or by making the base members and apex sides of the lenses face each other. It was an attempt to solve it. Also (mouth) JP-A-61-
Japanese Patent No. 83501 discloses a technique in which the center portions of both sides of a single biconvex lens are made flat, and only the light flux incident on the peripheral portion of the lens is focused to solve the above problem.

[Problem to be solved by the invention] However, the above (
In the case of (a), although it is effective in making the light quantity distribution uniform, the light ffi loss tends to increase because the high-intensity central light beam is dispersed to the periphery.

On the other hand, (b) above has the advantage that the light intensity distribution becomes almost trapezoidal in shape through the condensing lens, and uniform light intensity can be obtained, but the positions where uniform light intensity can be obtained are limited. - Because of this, there was a problem that the degree of freedom in designing was reduced and restrictions were increased.

It is an object of the present invention to solve these problems, minimize light loss, and provide a highly efficient and high-performance laser processing device.

[Means for solving problems]

The laser processing device according to the present invention is equipped with a light flux conversion optical member for converting light intensity, and the light flux conversion optical member allows the central portion of the light beam to pass through without being deflected, and converts the light beam into an annular region. It has a pair of annular refracting surfaces that refract outward and inward rays interchangeably.

[Effect]

The light flux converting optical member 4 allows the light flux in the center region of the laser beam to pass through without being deflected, thereby minimizing the loss of light quantity, and by exchanging the inner and outer light rays of the annular region, the intensity distribution of the light flux is made uniform. can be converted into

[Example 1] The optical arrangement of Example 1 according to the present invention will be explained.

The first TyJ is a schematic optical path diagram in an embodiment of the present invention. The diameter of the light beam having a Gaussian distribution light intensity emitted from the laser light source 1 is expanded by a first afocal optical system 20 configured by a positive lens 2 and a positive lens 3.

The light beam enters the light beam converting optical member 4 with a wide diameter. The light flux converting optical member 4 converts the light into a uniform intensity distribution as will be explained later. Then, the light flux passes through the aperture 6 and is converted into an optical path by the reflection ja7, and the diameter of the light flux expanded by the first afocal optical system is transferred to the second afocal optical system consisting of a positive lens 8 and a positive lens S. reduced by 30. The light beam whose diameter has been reduced by the second afocal optical system 30 is then transmitted to the aperture 10.
and is irradiated onto the object plane 13 by the objective lens 11.12.

Note that the aperture 10 is located at a position conjugate with the aperture 6 with respect to the second afocal system. Further, the object plane 13 is the objective lens 11
．． It is located at a position conjugate with the aperture lO with respect to 12. Therefore,
On the object plane 13 is an aperture of a diaphragm lO (generally a rectangular aperture)
is projected and irradiates the workpiece placed on the object plane 13 with a beam of light, making it possible to perform precise micromachining.

Furthermore, a second afocal system 3 consisting of a positive lens 8.3
By setting the zero magnification to a different value, the diameter of the light beam at the aperture 10 can be changed. By changing the diameter of the diaphragm 10 in accordance with the change in the diameter of the light beam, it is possible to obtain a light beam with a desired diameter at the object plane 13 without losing energy.

Next, the light flux conversion by the light flux conversion optical member 4 of Example 1 according to the present invention will be explained. The light flux conversion optical member 4 is composed of a first truncated cone optical member 4A and a second truncated cone optical member 4B. Then, the first truncated cone optical member 4A and the second
The truncated conical optical members 4B are arranged with their bottom surfaces facing each other. As shown in FIG. 2, the light intensity distribution before the light beam enters the first truncated cone optical member 4A has a Gaussian distribution as shown in FIG. 3(I). The entrance side plane 41 of the first truncated cone optical member 4A is parallel to the output side plane 43 (bottom of the truncated cone), and the center portion is transparent. Therefore, the light incident on this transparent portion (center area of the light beam) is not refracted and deflected (progresses straight. ) is refracted toward the center, as shown in FIG.

Then, the light beams in the annular region that are symmetrical with respect to the optical axis, which are incident on the conical surface 42, intersect in the vicinity of the optical axis between the first truncated cone optical member 4A and the second truncated cone optical member 4B. Then, beyond the point where the light beams intersect, the outer light ray and the inner light ray switch places and enter the second truncated cone optical section.

The second truncated cone optical member 4B has the same shape as the first truncated cone optical member 4A, and the incident side plane 44 (bottom of the truncated cone) is parallel to the output side plane 4B, and the center portion is transparent. Therefore, the light beam in the center region that has entered the incident side plane 41 of the first truncated cone optical member 4A enters the incident side plane 44, is transmitted as it is, and exits from the output side plane 46. The light beam in the annular region which is incident on the conical surface 42 of the optical member 4A and where the inner light beam and the outer light beam are exchanged is incident on the incident side plane 44 of the second truncated cone optical member 4B and is refracted, forming a cone. After being further refracted by the surface 45, it exits as a beam parallel to the optical axis Ax (.

Therefore, looking at the intensity distribution, as shown in FIGS. 3(1) and (U), the outward rays of light incident on the conical surface of the annular region light flux are a
The strength of! +11 is converted into intensity fax at the position G inside the annular region light beam. Also, the inner position it! of the annular region light beam incident on the conical surface! Intensity 1b of the inner ray at B
t is the intensity ITht at the peripheral part of the annular region luminous flux IIH
is converted to Similarly, the intensity of the outward ray d is 141 (
-1-1) to Iat<-1,), the position is transformed from the peripheral part of the annular region light flux to the inside F of the annular region, and the intensity of the inner ray C is changed from I c+ (-, 1b+) to ! . (-1
), the position is transformed from the inside C of the annular region light beam to the outside of the periphery, respectively. In this way, the light beam having the Gaussian distribution shown in FIG. are exchanged, and due to wave optical effects such as diffraction and interference, as shown in Figure 3 (II),
It can be converted into a luminous flux with a certain degree of uniform intensity and no loss of light quantity.

Incidentally, in order to adjust the luminous flux, a transparent parallel plane plate 5 with a variable inclination angle may be installed between the first truncated cone optical member 4A and the second truncated cone optical member 4B. The plane plate 5 has a variable inclination angle with respect to the optical axis, and has a function of correcting a relative deviation of the optical axis between the two truncated conical optical members 4A and 4B. Then, the inclination angle is adjusted in advance so that the intensity distribution of the light beam is in the best condition.

[Example 2] Cross-sectional views of a light flux conversion optical member 40 used in Example 2 of the present invention are shown in FIGS. 5 and 6, respectively.

The light flux conversion optical member 40 used in Example 2 is composed of two members 40A and 40B of the same shape,
Each of them has a ring-shaped positive refractive cadric surface on one side of its periphery, and has an entrance side plane 401 and an exit side plane 403.
are parallel to each other. These two members 4QA, 40B having the same shape are arranged facing each other on their respective planes 403 and 404. Therefore, optically, as in the first embodiment, the light beam incident on the center portion 401 of the first optical member 40A is transmitted and travels straight. The light beam incident on the toric surface 402 at the peripheral portion of the first optical member 40A is focused at the focal point F (focal length f) of the toric surface, and the inner ray and the outer ray are exchanged from the focusing position. Here, toric surface 40
The principal ray of the annular region light beam (the shaded area in FIG. 5) entering the optical system 2 is always parallel to the optical axis Ax of the optical system.

Then, each light beam enters the second optical member 40B having a toric surface onto the incident side plane 404. The light beam that entered the incident side plane 401 of the optical member 40A exits from the exit side plane 406 of the optical member 40B without being refracted, and the light beam that entered the toric surface 402 of the optical member 40A exits the optical member 40A. It exits from the toric surface 405 of 40B. Here, the focal length of the optical member 40B is also f. Even when such a light flux conversion optical member 40 is used, the light flux having a Gaussian distribution intensity can be transmitted through the light flux conversion optical member 40 having a pair of toric surfaces as shown in FIG.
It is possible to obtain a luminous flux converted into a uniform intensity as shown in I).

Therefore, similar effects can be expected even if the light flux converting optical member 40 having a toric surface used in the second embodiment is used in place of the light flux changing optical member 4 used in the first embodiment.

In addition, in Example 2, an example was explained in which the bottom surfaces of the light flux conversion optical member 40 having two toric surfaces are arranged opposite to each other. A similar effect can be expected even when used with the sides facing each other.

〔Effect of the invention〕

As described above, according to the present invention, by passing through the center of the light intensity distribution and exchanging the outer rays and inner rays in the peripheral area, the light intensity can be made uniform to some extent, and the loss of light amount can be minimized. As a result, highly efficient laser processing equipment can be obtained. Furthermore, the light flux that has passed through the light flux conversion optical member is collimated in the same way as before entering, so uniformity is maintained at any position on the optical axis, allowing for greater freedom in design. It is possible to easily design and have a simple configuration without reducing the performance.

[Explanation of symbols of main parts]

Claims (3)

[Claims] (1) In a laser processing device equipped with a light flux conversion optical member for converting the light intensity distribution, the light flux conversion optical member allows the light beam in the central region of the light flux to pass through without being deflected, and in the annular region of the light flux. 1. A laser processing device comprising: a pair of annular refracting surfaces that refract an external beam and an internal beam so as to exchange them; (2) The light flux converting optical member has two optical members in the form of a truncated cone or a truncated polygonal pyramid having the same shape and arranged with their bottom surfaces facing each other. The laser processing device according to item 1. (3) The laser processing apparatus according to claim 1, wherein the light flux conversion optical member includes a parallel plane member disposed between the two optical members in the form of a truncated cone or a truncated polygonal pyramid. .