JPH021811A - Light beam homogenizer and formation thereof - Google Patents

Abstract

PURPOSE:To convert a distributed intensity beam which has an intensity distribution in its cross section into a beam which has a uniform intensity distribution in cross section by arranging light converting elements which converge parallel light on one point opposite each other while aligning their optical axes so that their focus are at the same position and then arranging a scattering body at the focus position. CONSTITUTION:The incidence-side convex lens 1 and emission-side convex lens 5 are arranged opposite each other having their focuses at the same position and the scattering body 4 is arranged at the focus position. The intensity distributed beam 2 which is made incident on the incidence-side convex lens 1 is converged on the focus position and scattered by the scattering body 4 arranged there. The scatterrd light becomes parallel light through the emission side convex lens 5 to obtain the uniform beam 6. Therefore, the light beam having the intensity distribution in its cross section like excimer laser light can be converted into the light beam which has the uniform intensity distribution in the cross section. The scattering body is formed in a transparent body or a light converging transparent body by projecting laser light on the focus position in the light converging transparent body and working the focus position by heat or optochemical reaction.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a method for converting a light beam (hereinafter referred to as an intensity distribution beam) having an intensity distribution in a cross section, such as an excimer laser beam, into a light beam with a uniform intensity distribution in a cross section. The present invention relates to a light beam homogenizer that converts into a certain light beam (hereinafter referred to as a uniform beam) and a method of forming the same.

[Conventional technology]

Conventional optical beam homogenizers are described in the document “Solid-3tate Technology”.
TechnoIogy ) J 1980, August issue.

It is described on pages 115-120. Figure 5(a) shows
FIG. 2 is a configuration diagram of a conventional light beam homogenizer using a prism described in the above-mentioned document. In the light beam homogenizer shown in FIG. 5(a), the intensity distribution beam 2 is
The beam is made incident on a prism 13 divided into two parts, and the beams emitted from each prism 13 are superimposed to be converted into a uniform beam 6.

[Problem to be solved by the invention]

Conventional light beam homogenizers using prisms, lenses, or mirrors divide the intensity distribution beam 2 in the cross-sectional direction and overlap them to make the intensity distribution uniform in the cross-sectional direction, as described in the above-mentioned literature. I'm getting beam 6. However, as shown in FIG. 5(b), there is a limit to the uniformity of the intensity distribution in the cross section depending on the number of divisions when dividing the intensity distribution beam in the cross-sectional direction of the sakaki. For this reason, when a semiconductor process such as CVD or annealing is performed using the uniform beam, processing unevenness occurs due to non-uniformity in the cross section of the uniform beam.

An object of the present invention is to solve the conventional drawbacks and provide a light beam homogenizer and a method for forming the same, which converts an intensity distributed beam having an intensity distribution in a cross section into a uniform beam having an even intensity distribution in a cross section. There is a particular thing.

[Means to solve the problem]

In the optical homogenizer according to the present invention, at least two condensing elements for condensing parallel light to one point are arranged facing each other so that their optical axes are aligned and their focal points are at the same position, and It has a structure in which scatterers are arranged.

Furthermore, another light beam homogenizer according to the present invention has a structure in which a scatterer is placed at a focal position inside a light-converging transparent body that focuses incident parallel light onto a single point inside the homogenizer.

In addition, the method for forming a light beam homogenizer according to the present invention is to irradiate a transparent body or a light-concentrating transparent body with a laser beam, so that a focal position within the transparent body or a light-concentrating transparent body is different from that of the surroundings in terms of refractive index, tissue density, etc. The structure includes a process of forming regions with different physical and chemical properties.

[Action/Principle]

The light beam homogenizer according to the present invention includes a condenser element and a scatterer, and the scatterer is installed at the focal point of the condenser element. In such a light beam homogenizer, the intensity distribution beam is focused at the focal point of the condensing element, so it is easily affected by scatterers, and the intensity distribution beam is scattered and has a uniform intensity distribution, making it difficult to obtain a uniform beam. I can do it.

Furthermore, the scatterer of the light beam homogenizer of the present invention can be formed by processing using laser light. That is, by irradiating the focal position inside the transparent body or the light-concentrating transparent body with a laser beam, the focal position can be processed by heat or photochemical reaction, and a scatterer can be formed inside the light-concentrating transparent body.

〔Example〕

Next, the present invention will be explained using the drawings.

FIG. 1 shows a first embodiment of a light beam homogenizer according to the present invention. The intensity distribution beam 2 that has entered the entrance side convex lens 1 is focused at a focal point position 3. The focused light is placed at the focal point 3 and is affected by the scatterer 4, where it is scattered.

This light is made into parallel light by the exit side convex lens 5 to obtain a uniform beam 6, thereby converting the intensity distribution beam 2 into a uniform beam 6.
Convert to In this embodiment, a single convex lens is used as the condensing element, but the condensing element may also be formed by bonding or combining several lenses, for example, like a camera lens. Furthermore, several sets of the configuration shown in FIG. 1 may be arranged in series.

Note that a glass bulb with an uneven back surface was used as the scatterer.

FIG. 2(a) shows a second embodiment of a light beam homogenizer according to the present invention. The intensity distribution beam 2 that has entered the incident side concave mirror 7 is focused at a focal point position 3. The focused light is affected by the scatterer 4 placed at the focal point position 3 and is scattered. The intensity distribution beam 2 is converted into a uniform beam 6 by converting this light into parallel light by the exit side concave mirror 8 to obtain a uniform beam 6.

In this embodiment, the exit side concave mirror 8 is provided with a hole, but each concave mirror may be arranged as shown in FIG. 2(b) without providing a hole on the exit side concave mirror. In this case, the shadow of the concave mirror on the incident side is not formed in the uniform beam, resulting in a beam with better uniformity. Furthermore, although a concave mirror is used as the condensing element, the condensing element may also be a combination of a plane mirror and a convex lens.

In this case, by carefully arranging the plane mirror and convex lens,
The degree of freedom in arranging each light condensing element is increased. The same scatterer as in the first example was used.

FIG. 3 shows an embodiment of a light beam homogenizer according to the present invention, which is provided with a scatterer at a focal point in a part of a light-condensing transparent body. The convex lens 9 is elongated in the optical axis direction so as to include the focal point 3 therein. The intensity distribution beam 2 that has entered the entrance-side convex lens surface 10 is focused at a focal point 3 inside the convex lens 9 . The focused light is affected by the scatterer 4 provided at the focal point position 3 and is scattered. This light is transferred to the exit side convex lens surface 11
The intensity distribution beam 2 is converted into a uniform beam 6 by collimating the beams 2 and 3 to obtain a uniform beam 6.

In this embodiment, a convex lens is used as a transparent medium having a light condensing function at the end, but it may also be configured such that the end is made flat or concave and a plano-convex lens, a convex lens, etc. is bonded to this part. Alternatively, the shape of the end portion may be arbitrary, and the composition of the end portion may be changed by ion exchange, impurity diffusion, etc., and the refractive index of the end portion may be changed to produce a light condensing effect. The refractive index may change not only at the ends but also throughout the transparent body, that is, a refractive index distribution may be formed within the transparent body to provide a light condensing function.

Next, a method of forming a scatterer of a light beam homogenizer having a scatterer at a focal point inside a light-condensing transparent body according to the present invention shown in FIG. 3 will be described. FIG. 4(a) shows a convex lens 9 having an internal focal point before forming a scatterer.

When a laser beam 12 is incident on this convex lens 9 from the entrance side convex lens surface 10 as shown in FIG. 4(b), the laser beam 1
2 is condensed at focal point position 3. Since the laser beam is focused, the power density of the laser beam at the focal point position 3 increases. Because the power density of the laser beam has increased, the focal position 3
is processed by heat or photochemical reaction to form a scatterer. As a result, a scatterer 4 can be formed at the focal position 3 by irradiating the laser beam 12, as shown in FIG. 4(C).

In addition, the scatterer is made by irradiating the transparent body with laser light through a condensing optical system before the transparent body is made into a convex lens, that is, before the end has a condensing function, that is, before the end has a condensing function. After that, the ends of the transparent body may be processed to have light condensing properties to form a light condensing transparent body.

In the example, a glass sphere with an uneven surface was used as the scatterer, but other materials such as a glass sphere containing many bubbles,
Any material that scatters light may be used, such as a glass plate or a sphere or plate made of an aggregate of fine particles such as opal (which is an aggregate of fine quartz particles).

〔Effect of the invention〕

As described above, according to the present invention, an intensity distribution beam having an intensity distribution within a cross section can be converted into a uniform beam having an even intensity distribution within a cross section.

Furthermore, in the light beam homogenizer according to the present invention, which is equipped with a scatterer at the focal point inside the light-concentrating transparent body, by integrating the light-condensing element and the scatterer, the light beam can be focused even when subjected to external mechanical vibrations. Since the positional relationship between the optical element and the scatterer is immovable, the optical axis is unlikely to shift.

Further, the method for forming the scatterer of the light beam homogenizer according to the present invention is a simple and accurate method for accurately detecting and processing the focal position using laser light.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a light beam homogenizer which is a first embodiment of the present invention, and FIGS. 2(a) and (b) are block diagrams of a light beam homogenizer which is a second embodiment of the present invention. FIG. 3 is a configuration diagram of an embodiment of a light beam homogenizer including a scatterer at a focal position inside a light-condensing transparent body according to the present invention. Also, FIG. 4(a). (b) and (c) are conceptual diagrams showing a method of forming a scatterer of a light beam homogenizer according to the present invention;
(b) shows the state before the scatterer is formed, (b) shows the state during formation, and (c) shows the state after the scatterer is formed. Furthermore, FIG. 5(a) is a block diagram of a conventional optical beam homogenizer, and FIG. 5(b) is an intensity distribution in a cross section of a uniform beam in the conventional optical beam homogenizer. 1... Incidence side convex lens, 2... Intensity distribution beam, 3
... Focal point position, 4... Scatterer, 5... Outgoing side convex lens, 6... Uniform beam, 7... Incoming side concave mirror, 8
... Output side concave mirror, 9... Convex lens, 10... Incident side convex lens surface, 11... Output side convex lens surface, 12.
... Laser light, 13... Prism.

Claims (3)

[Claims] (1) At least two condensing elements that condense parallel light to one point are arranged so that their focal points are at the same position, and a scatterer is placed at the focal point of the condensing elements (hereinafter referred to as the focal position). A light beam homogenizer characterized by: (2) A light beam homogenizer, characterized in that a scatterer is provided at the internal focus position of a light-condensing transparent body that focuses incident parallel light onto a single point inside the light beam homogenizer. (3) Irradiating a transparent body or a light-concentrating transparent body with a laser beam through a condensing optical system or directly without passing through a condensing optical system to physically target the focal position within the transparent body or light-concentrating transparent body. Target/
A method for forming a light beam homogenizer, comprising the step of forming a region having different chemical properties from surrounding areas.