JPH09189881A - Optical system in laser device - Google Patents

Abstract

(57) Abstract: To provide an optical system in a laser device capable of forming a linear laser beam capable of uniformly heating a processed surface. A collimated laser beam having a circular cross section is made incident on a cylindrical lens to be compressed into a flat elliptical shape, and the elliptical laser beam is divided by a prism to form a linear shape with a narrowed central portion. A laser beam 1 is formed and the processed surface 2a is irradiated with this laser beam 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system in a laser device, and is particularly useful when applied to heat treatment and welding with a linear laser beam.

[0002]

2. Description of the Related Art Conventionally, a linear laser beam has been used for heat treatment and welding of a workpiece such as a steel plate. In the heat treatment and welding in this case, as shown in FIG. 5, a linear laser beam 1 is applied to the processing surface 2a of the workpiece 2, and the laser beam 1 is directed in a direction perpendicular to the linear shape of the laser beam 1. This is done by moving. That is, as a result of the irradiation of the laser beam 1, the width of the laser beam 1 is set to one side on the processed surface 2a, and a portion corresponding to an area obtained by multiplying the width by the moving distance of the laser beam 1 is heated. The desired heat treatment and welding is possible on the part.

Therefore, a laser device for performing this kind of heat treatment requires an optical system for shaping a laser beam having a circular cross section into a linear laser beam 1.

FIG. 6 is an explanatory view conceptually showing an optical system according to the prior art. FIG. 2A shows X, which are orthogonal to each other.
Of the Y-axis, the aspect on the X-axis and the figure (b) show the aspect on the Y-axis, respectively.

In FIG. 6, 3 is a collimator lens, 4 is a cylindrical lens, 5 is a condenser lens, and these collimator lens 3, cylindrical lens 4 and condenser lens 5 are from the laser light incident side (left side in the figure). The optical axes are arranged in parallel in order. Of these, the cylindrical lens 4 is a lens having a shape obtained by cutting a part of a cylinder along a plane parallel to its axis, and compresses the incident circular laser light only in the X-axis direction to form a flat elliptical shape. This elliptical shape is shown in FIG.

In such an optical system, the laser light emitted from the laser is collimated by the collimator lens 3,
The light enters the cylindrical lens 4 as parallel rays, is compressed into a flat elliptical shape by the cylindrical lens 4, is further condensed by the condensing lens 5, and becomes a linear laser beam 1 which is applied to the processing surface 2a.

[0007]

However, the linear laser beam 1 formed by the optical system according to the prior art as described above is used.
6C is a condensing elliptical laser beam as shown in FIG. 6C, its intensity distribution has a convex characteristic with a peak at the center as shown in FIG. 6D. have.

Therefore, the central portion of the processed surface 2a is intensively heated, and in the case of welding, this portion is first melted and a good quality welded portion cannot be obtained, and in the case of heating, uniform heating is performed. It becomes a factor that causes various problems such as impossible.

The present invention has been made in view of the above-mentioned prior art, and an object of the present invention is to provide an optical system in a laser device capable of forming a linear laser beam capable of uniformly heating a processed surface.

[0010]

The structure of the present invention for achieving the above object is as follows.

1) A cylindrical lens for flattening the shape of the incident laser light, a prism for shifting the shape of the incident laser light to a position on the opposite side to the optical axis and dividing it into two, and the incident laser light The cylindrical lens, the prism, and the condenser lens are arranged side by side so as to form a linear beam which is a linear laser beam with a condenser lens for condensing.

2) In 1), the cylindrical lens, the condenser lens and the prism are arranged in this order in order from the incident side, and the collimated laser light is made incident on the cylindrical lens.

3) In 1), the prism, the condenser lens, and the cylindrical lens are arranged in this order in order from the incident side, and the collimated laser light is incident on the prism.

4) In 1), the cylindrical lens, the prism, and the condenser lens are arranged side by side in this order from the incident side, and the collimated laser light is incident on the cylindrical lens.

5) In 1), the prism, the cylindrical lens, and the condenser lens are arranged in this order in order from the incident side, and the collimated laser light is incident on the cylindrical lens.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is an explanatory view conceptually showing the optical system of this embodiment. FIG. 11A shows a mode on the X axis of X and Y axes orthogonal to each other, and FIG. 16B shows a mode on the Y axis.

As shown in FIG. 1, the optical system according to this embodiment is obtained by adding a prism 6 to the optical system according to the prior art shown in FIG. The prism 6 moves the shape of the incident laser light to a position on the opposite side to the optical axis L and divides it into two. That is, as shown in FIG. 2A, the circular beam incident on the prism 6 has a shape in which two divided semicircles are in contact with each other at one point on the optical axis L (hereinafter, this shape is a divided semicircular shape). That is). Therefore, when the split semicircular laser beam is further incident on the cylindrical lens 4, the split semicircular shape is compressed in the X-axis direction (hereinafter, this shape is referred to as a split elliptical shape). This split elliptical shape is a beam having a narrowed central portion.

In this embodiment, the cylindrical lens 4, the condenser lens 5 and the prism 6 are arranged in parallel on the same optical axis in order from the incident side (the left side in the figure) on which the collimated laser light is incident. Configured.

Therefore, the collimated circular laser light is compressed in the X-axis direction by the cylindrical lens 4 to become an elliptical shape, and is made incident upon the condenser lens 5 to be condensed and become a nearly linear beam. . Then, the elliptical beam is incident on the prism 6 to be split into a linear split elliptical shape as shown in FIG. 3, and the laser beam 1 of this shape is applied to the processing surface 2a.

Thus, as shown in FIG. 4, the light intensity distribution on the irradiation surface of the laser beam 1 has a characteristic that the central portion is relatively lowered, and the temperature rise of the processed surface 2a, which is the integrated value of the irradiation energy, is caused by the laser. It becomes almost a straight line in the width direction of the beam 1. Therefore, the processed surface 2a is heated uniformly.

In the above embodiment, the cylindrical lens 4,
Although the condenser lens 5 and the prism 6 are arranged in this order from the incident side, there is no particular limitation in this order. Therefore, although there are a total of six possible side-by-side arrangements including the above-described modes, the structure in which the laser light is first condensed by the condenser lens 5 and then the laser light is compressed, divided, etc. It is not common as a structure. Therefore, as another mode, the cylindrical lens 4, the prism 6, and the condenser lens 5 are sequentially arranged from the incident side.
The optical system having the prism 6, the cylindrical lens 4 and the condenser lens 5 arranged in parallel, and the optical system having the prism 6, the condenser lens 5 and the cylindrical lens 4 arranged in parallel are practically useful. Conceivable.

[0023]

As described above in detail with the embodiments, according to the present invention, since a laser beam having a substantially uniform light intensity in the width direction can be formed, this laser beam is irradiated. The processed surface can be heated uniformly, and good heating and heat treatment can be performed by this heating.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram conceptually showing an optical system according to an embodiment of the present invention.

FIG. 2 shows the shape of a laser beam split by a prism 6 (a).
FIG. 3 is an explanatory view conceptually showing the shape (b) of laser light obtained by further compressing this shape with the cylindrical lens 4.

FIG. 3 is an explanatory view conceptually showing the shape of a laser beam 1 with which a processed surface 2a is irradiated.

FIG. 4 is a characteristic diagram showing a light intensity distribution in the above embodiment.

FIG. 5 is an explanatory view conceptually showing an aspect of heat treatment using a linear laser beam.

FIG. 6 is an explanatory view conceptually showing an optical system according to a conventional technique and the shape of laser light compressed by this cylindrical lens, and a characteristic view showing a light intensity distribution of the emitted light.

[Explanation of symbols]

 1 Laser Beam 2 Workpiece 2a Processed Surface 4 Cylindrical Lens 5 Condenser Lens 6 Prism

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoichi Hamada 1-1-1, Wadasaki-cho, Hyogo-ku, Kobe-shi, Hyogo Mitsubishi Heavy Industries, Ltd. Kobe Shipyard (72) Inventor Takashi Akabane, Hyogo-ku, Kobe-shi, Hyogo 1-1-1 Tasakicho Mitsubishi Heavy Industries, Ltd. Inside Kobe Shipyard (72) Inventor Katsura Otaki 3 2-3 Marunouchi Marunouchi, Chiyoda-ku, Tokyo Inside Nikon Corporation

Claims (5)

[Claims] 1. A cylindrical lens for flattening the shape of incident laser light, a prism for shifting the shape of the incident laser light to a position on the opposite side to the optical axis, and dividing the incident laser light into two parts. An optical system in a laser device characterized in that the cylindrical lens, the prism, and the condenser lens are arranged in parallel so as to form a linear beam that is a linear laser beam with a condenser lens for condensing. system. 2. A cylindrical lens, a condenser lens, and a prism are arranged in this order from the incident side, and collimated laser light is made incident on the cylindrical lens. [1] The optical system in the laser device. 3. A prism, a condenser lens, and a cylindrical lens are arranged in this order in order from the incident side, and collimated laser light is incident on the prism. ] The optical system in the laser apparatus described in. 4. A cylindrical lens, a prism, and a condenser lens are arranged in this order in order from the incident side, and collimated laser light is made incident on the cylindrical lens. [1] The optical system in the laser device. 5. A prism, a cylindrical lens, and a condenser lens are arranged in this order in order from the incident side, and collimated laser light is made incident on the cylindrical lens. [1] The optical system in the laser device.