JPH04313701A - Polyhedral convex type prism and laser beam projecting device - Google Patents

Abstract

PURPOSE:To obtain an inexpensive polyhedral convex type prism which can equalize the intensity distribution of light in a light focusing surface, and the laser beam projecting device which uses its lens. CONSTITUTION:In the convex type prism having opposed light incoming/outgoing faces, on one light incoming/outgoing face, a first convex edge face 11A consisting of a band-like center plane 12 being vertical to an optical axis, and plural sets of band-like inclined planes 14, 16 which are symmetrical to the center plane and whose inclination becomes large successively on both its sides is formed, and on the other light incoming/outgoing face, a second convex edge face 11B consisting of a band-like center plane 12 which extends out in the direction intersecting or thogonally with the band-like plane of a first convex edge face 11A, and is vertical to the optical axis, and plural sets of band-like inclined planes which are symmetrical to the center plane and whose inclination becomes large successively on both its sides is formed. The face angle of the inclined plane for forming a first and a second convex edge faces 11A, 11B is set so that parallel rays which are made incident on one light incoming/outgoing face are emitted from the other light incoming/outgoing face, and subjected to face focusing on the optical axis in a rectangular shape matched with a superposed area in the optical axis direction of two band-like center planes 12, 12.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to pattern CVD or etching using laser light such as an excimer laser.
The present invention relates to a multifaceted convex prism that is effective in uniformizing the intensity of irradiated laser light, and a laser beam projection device using this multifaceted convex prism.

0002

2. Description of the Related Art Laser CVD is a method of forming a circuit pattern on a substrate using the energy of laser light. As shown in FIG. 8, a mask 2 in which a transparent part 2a corresponding to a circuit pattern is formed is placed in front of the laser beam 1, and a reaction cell 6 is passed through a projection lens 4 placed in front of the mask 2. The circuit pattern formed on the mask 2 is projected onto the substrate 8 inside the cell.The material gas inside the cell 6 is photolyzed by laser light, and the generated radicals are recombined on the substrate 8 to form a film. It is said that it is formed. The excimer laser is well known as the laser beam used, but the intensity distribution of the light is not uniform and there are differences in the energy distribution of the laser beam irradiated onto the substrate, so it is difficult to form a film on the substrate. There was a problem that the thickness was not constant. Further, the laser beam enters through the window 6a of the reaction cell and is irradiated onto the substrate 8, but a photodecomposition reaction of the material gas occurs also in the vicinity of this window 6a, and radicals are recombined to form the window 6a.
There was a problem in that a film was formed on the inside of a, and this film deteriorated the transmission efficiency of laser light. For this reason, conventionally, as shown in FIG. 9, a fly's eye lens 3 is placed in front of the mask 2 to diffuse the laser beam, thereby making the energy distribution of the irradiated laser beam uniform.

0003

However, fly's eye lenses are difficult and expensive to manufacture. Furthermore, it is not possible to focus all of the light diffused by the fly's eye lens, and a high output laser device is required in consideration of loss. Therefore, there was a problem that the product cost increased. The present invention was made in view of the problems of the prior art described above, and its purpose is to provide an inexpensive multifaceted convex prism that can uniformize the intensity distribution of light on a light focusing surface without using a fly's eye lens. The object of the present invention is to provide a new laser beam projection device using this lens.

0004

[Means for Solving the Problems] In order to achieve the above object, in a multifaceted convex prism according to claim 1, in a convex prism having opposing light input/output surfaces, one light input/output surface has a , a band-shaped central plane extending perpendicular to the optical axis, and a plurality of sets of band-shaped inclined planes extending parallel to the central plane on both sides of the central plane, symmetrical with respect to the central plane, and having gradually increasing inclinations. A first convex ridge surface is formed, and the other light input/output surface has a first convex ridge surface extending in a direction perpendicular to the extending direction of each plane forming the first convex ridge surface and perpendicular to the optical axis. a second convexity consisting of a strip-shaped central plane extending to the central plane; and a plurality of sets of strip-shaped inclined planes extending parallel to the central plane on both sides of the central plane, symmetrical with respect to the central plane and gradually increasing inclination; A ridge surface is formed, and the parallel light incident on one light input/output surface is emitted from the other light input/output surface, forming a rectangular shape on the optical axis that matches the overlapping region of the two band-shaped central planes in the optical axis direction. The surface angles of the inclined planes forming the first and second convex ridge surfaces are set so that the surfaces converge.

According to a second aspect of the present invention, in the polygonal convex prism according to the first aspect, the first convex ridge surface and the second convex ridge surface are made to have the same shape, so that the emitted light has a substantially square shape on the optical axis. It is designed to focus on a plane. Further, in claim 3, the first
a convex ridge prism in which the convex ridge surface is formed on the front side and the back side is a plane perpendicular to the optical axis; and the second convex ridge surface is formed on the front side, and the back side is a plane perpendicular to the optical axis. The second
The polygonal convex prism according to claim 1 is constructed by integrating the convex ridge prisms with their back sides facing each other.

According to a fourth aspect of the present invention, in the polygonal convex prism according to the third aspect, the first convex ridge prism and the second convex ridge prism are made to have the same shape, so that the emitted light has a square optical axis. It is designed to focus approximately on a surface at the top. Furthermore, in the polygonal convex prism according to claim 5, in a convex lens having opposing light input/output surfaces, one light input/output surface is formed with a plane perpendicular to the optical axis, and the other light input/output surface is formed with a plane perpendicular to the optical axis. forms a convex ridge surface consisting of a circular central plane perpendicular to the optical axis and a plurality of ring-shaped tapered surfaces concentric with the central plane and gradually increasing inclination around this central plane; A taper forming the convex ridge surface such that parallel light incident on the light input/output surface of the light exit surface exits from the other light input/output surface and is focused on the optical axis into a circular shape that matches the circular central plane. This allows you to set the surface angle of the surface.

Further, in the laser beam projection device according to claim 6, the polygonal convex prism according to any one of the aforementioned aspects 1 to 5 is disposed on the optical path of the laser beam, and the output from the polygonal convex prism is A mask on which a pattern to be projected is formed is placed on the convergence plane of the emitted light, and an enlargement-side telecentric projection lens for reducing and projecting the pattern to be projected is placed in front of the mask.

According to a seventh aspect of the present invention, in the laser beam projection apparatus according to the sixth aspect, each focal point is a confocal lens, a vertically diffusing cylindrical concave lens that diffuses the emitted light in the vertical direction, and a lateral concave lens that diffuses the emitted light in the horizontal direction. Laser light is guided to a polygonal convex prism through a beam expander optical system consisting of a diffusing cylindrical concave lens and a collimator lens that makes the emitted light parallel.

[0009]

[Operation] According to claims 1 to 5, when the light beam enters the polygonal convex prism, it is dispersed into a luminous flux for each ridge surface constituting the light incident surface, and when it exits from the polygonal convex prism, it is a dispersed luminous flux. Each of the light beams is dispersed into light beams for each ridge surface constituting the light exit surface, and all the dispersed light beams are converged on a convergence surface on the optical axis. In the first to fourth aspects of the present invention, the belt-shaped central plane of the first convex ridge surface and the belt-shaped central plane of the second convex ridge surface are surface-focused into a rectangular shape that overlaps in the optical axis direction. Further, in a fifth aspect of the present invention, the surface is focused into a circular shape that matches the circular central plane.

According to a sixth aspect of the present invention, the laser beam is dispersed into a plurality of light beams by a polygonal convex prism, and is focused on a converging surface on which a mask is arranged. The light beam that passes through the mask on the focusing surface is dispersed and enters the telecentric projection lens on the magnification side, exits from this projection lens in a dispersed state, and is focused on a predetermined position (image forming plane) on the optical axis. . Further, in a seventh aspect of the present invention, the laser beam is diffused by the beam expander optical system and then enters the polygonal convex prism.

[0011]

Embodiments Next, embodiments of the present invention will be described based on the drawings. 1 and 2 show a first embodiment of the polygonal convex prism according to the present invention. FIG. 1 is a perspective view of the polygonal convex prism, and FIG. 2 shows the convergence of light emitted from the polygonal convex prism. FIG. 2 is an explanatory diagram illustrating the situation.

In these figures, a polygonal convex prism 1
0 has a square shape as a whole, and has a pair of opposing light input/output surfaces 11.
A, 11B. And one light input/output surface is
A tanzaku-shaped (band-shaped) first plane 12 perpendicular to the optical axis L
a, and a first plane 12 adjacent to both sides of this first plane
a pair of symmetrical second planes 14a, 14 inclined with respect to a;
a, adjacent to the outside of the second planes 14a, 14a, and the first plane
The convex ridge surface 11A is made up of a total of five planes, including a pair of symmetric third planes 16a, 16a in a tanzag shape that are more inclined than the second plane with respect to the plane 12a. In addition, the other light input/output surface has a slightly different surface angle between the convex ridge surface 11A and the inclined plane, and the convex ridge surface 11A is aligned with the optical axis L.
The convex ridge surface 11B is similar to a shape rotated by 90 degrees. That is, like the convex ridge surface 11A, the convex ridge surface 11B also has second planes 14b, 14b, and third planes 16b, 16b, which have increasing inclinations on both sides of the tanzaku-shaped first plane 12b.
6b has a symmetrical shape.

The inclined planes 14a, 14a, 16a, 16a forming the first convex ridge surface 11A and the inclined planes 14b, 14b, 16b, 1 forming the second convex ridge surface 11B.
6b directs the light incident parallel to the optical axis L to a predetermined position on the optical axis in front of the lens.
A and the central plane 12b on the second convex ridge surface 11B side overlap in the direction of the optical axis L, and the surface angle is set to converge the light into a square A. That is, the first convex ridge surface 11A is parallel to the optical axis L.
The light flux that has entered the lens 10 from the 5 planes (12a, 14a, 14a
, 16a, 16), and is dispersed into five light beams having a tanzaku cross section. Then, when each light beam exits from the second convex ridge surface 11B, the five planes (12b, 14b, 14b, 16b, 16b
), that is, a total of 25 light fluxes, and all of these 25 light fluxes are distributed on the first convex ridge surface 1.
The wavelength of the laser beam, the refractive index of the prism material (laser beam Considering the thickness of the prism (the laser beam passage distance within the prism), the eight inclined planes (14a , 14a, 16a, 16a, 14a
, 14b, 16b, 16b) are set. This squarely focused light beam is dispersed into 25 light beams each having a square cross section by passing through the polygonal convex prism 10, and then all of the dispersed light beams are again focused into one beam. Therefore, the light on the focusing surface has no unevenness in intensity, that is, the light has a smoothed intensity distribution. In the embodiment described above, the light emitted from the polygonal convex prism 10 is focused into a square surface, but it is possible to change the number of strip planes, the width of the strip, and the angle of inclination of the inclined plane with respect to the central plane. Accordingly, a light beam having an arbitrary aspect ratio can be formed regardless of the cross-sectional shape of the light beam incident on the lens.

FIG. 3 shows a second embodiment of the polygonal convex prism according to the present invention, in which two polygonal convex prisms 22
A and 22B are brought into close contact with each other and integrated as a polygonal convex prism 20. Multifaceted convex prism 22A (22B
), the front side is the convex ridge surface 11A (11B) of the first embodiment.
), that is, the first plane 12a (12b),
Slanted second planes 14a, 14a (14b, 14b)
and the inclined third planes 16a, 16a (16b, 16
b) A convex ridge surface 11C (11D) composed of
The back side is a plane 11E perpendicular to the optical axis L. Then, the first planes 12a and 12b are overlapped perpendicularly to the optical axis direction, and the back sides are brought into close contact with each other. In this second embodiment, since the polygonal convex prism 22A (22B) only needs to be processed into a convex ridge on one side, the processing is that much easier, and the polygonal convex prism 10 shown in the first embodiment is
It is easier to manufacture than However, since there is loss due to reflection of the light from the front and back surfaces when passing through the contact surface, there is a drawback that the intensity of the light is lower than that of the polygonal convex prism 10.

In the polygonal convex prism 10 (20) in the first and second embodiments, in order to surface-focus the emitted light onto the optical axis L, the light incident surface side and the light exit surface side of the prism are inclined. Although the surface angles of the planes were slightly different, even if the light input/output surfaces 11A, 11B (11C, 11D) have exactly the same shape, the emitted light can be substantially focused on the optical axis.

FIGS. 4 and 5 show a third embodiment of the polygonal convex prism according to the present invention. FIG. 4 is a perspective view of the polygonal convex prism, and FIG. 5 shows the convergence of light emitted from the polygonal lens. FIG. This polygonal convex prism 30 has a truncated cone shape as a whole, and one light input/output surface is a plane 11F perpendicular to the optical axis L, and the other light input/output surface is a circular central plane 32 perpendicular to the optical axis L. And this circular central plane 3
2, and the outer one is a circular central plane 32
A ring-shaped tapered surface 34, 3 that is greatly inclined with respect to
The convex ridge surface 11G is composed of 6 and 38. The surface angles of the tapered surfaces 34, 36, and 38 are such that the light emitted from the tapered surfaces 34, 36, and 38 is aligned with the central plane 3 on the optical axis L.
It is set so that the surface converges on the same circle B as 2.

That is, light that enters the polygonal convex prism 30 from the plane 31 side parallel to the optical axis L travels straight through the prism, but when exiting from the prism 30, it passes through the central plane 32, the tapered surface 34, 36 and 38, and all of these dispersed lights are focused into a circle B, which is a cross section of the light that has passed through both the plane 11F and the central plane 32. Since the tapered surfaces 34, 36, and 38 are synonymous with a structure in which an infinite number of planes are continuously formed in the circumferential direction, the light beam focused in the circle B is transmitted through the polygonal convex prism 30. This is light that is dispersed into an infinite number of light beams and then refocused into one light beam. Therefore, the light on the converging surface has even more uniform intensity than that obtained in the first embodiment, that is, the light has a smoother intensity distribution.

Further, since the tapered surfaces can be formed by grinding and polishing the corner portions of the cylindrical prism material while it is rotated around the axis, it is better to process the tapered surfaces 34, 36, and 38 in accordance with the first method. It is easier to manufacture the multifaceted convex prism 30 of this example than the case of machining the inclined plane in the example. In FIG. 5, the polygonal convex prism 30 is arranged so that light is incident on the plane 11F side, but it may be arranged so that the convex ridge surface 11G side is the light incident side.

FIG. 6 shows an embodiment of a laser beam projection apparatus according to the present invention, which uses the polygonal convex prism shown in the first embodiment. Reference numeral 40 denotes a beam expander optical system, which has a confocal f and includes a vertical diffusion cylindrical lens 42 that diffuses light in the vertical direction, a horizontal diffusion cylindrical lens 44 that diffuses the light in the horizontal direction, and converts the light into parallel light. It is composed of a collimator lens 46. A polygonal convex prism 10 is disposed in front of the beam expander optical system 40, and a mask 50 on which a circuit pattern 52 is formed by a transparent portion is disposed at the focusing surface of the polygonal convex prism 10. An enlargement-side telecentric projection lens 60 is arranged in front of the circuit pattern 50 to project the circuit pattern 52 forward in a reduced size.

The excimer laser beam having a horizontally long rectangular beam cross section is expanded in the vertical and horizontal directions by passing through the beam expander optical system 40 to become a square parallel beam L1, which passes through the polygonal convex prism 10. As a result, the light beam is dispersed into 25 light beams and focused onto the mask 50 in a square shape. And the mask circuit pattern 52
The dispersed light beam L2 that has passed through is projected onto a predetermined position in front (image forming plane position) by the projection lens 60, and the circuit pattern is projected in a reduced size. This projected position is the position where all the light beams emitted from the projection lens are focused and the energy of the laser beam is maximized. Further, the laser beam on this image forming plane is transmitted to the polygonal convex prism 10 at 25
Since the laser beam is dispersed into individual beams and then focused, the intensity distribution of the irradiated laser beam is homogeneous on the projection plane (imaging plane).

In the laser beam projector shown in FIG. 6, the beam expander optical system 40 expands the beam of the laser beam into a square shape, but the polygonal convex prism 10 is used to cross the beam of the laser beam. If it is formed to a size that matches the surface shape, the expander optical system 4
Laser light can be made to directly enter the convex polygonal prism 10 without using zero.

FIG. 7 is a sectional view showing the optical path inside the reaction cell when the apparatus shown in FIG. 6 is used for pattern CVD. In this figure, reference numeral 70 denotes a reaction cell placed in front of the projection lens 60, and the opening of the reaction cell 70 is provided with a sealed window 72 made of synthetic quartz glass. A reaction gas (material gas) is sealed in the reaction cell 70, and a substrate 74 is placed at the projection position by the projection lens 60. Reference numerals 71a and 71b are an inlet and an outlet for reactant gas.

The laser beam emitted from the projection lens 60 is focused on the substrate 74 and projects the circuit pattern 52 formed on the mask onto the substrate surface, and the reactive gas is photolyzed by the laser beam, and the generated radicals are Recombine substrate 7
Form a film on 4. In particular, the laser beam when passing through the window 72 is dispersed into 25 beams, and since the beams hardly overlap with each other, the window 72 inside the cell 70
The energy density of the laser beam at a position near point 2 is low, and the energy density is not sufficient to photolyze the reaction gas. Therefore, highly efficient laser CVD can be achieved without the problem of the reaction occurring near the window of the reaction cell, causing the window to become cloudy and reducing the transmittance of laser light, which is the case in the prior art. Furthermore, since the energy of the laser beam focused on the substrate is smoothed, a film with a uniform thickness can be formed, and products with high processing precision can be supplied at low cost.

[0024] In the above embodiment, the present invention was applied to pattern C.
Although the embodiment applied to VD has been described, it can be applied to various technologies such as those described below. In other words, at the 1990 Spring and Fall 1990 Japan Society of Applied Physics conferences, researchers reported on a technology that omitted resist formation in the lithography process when manufacturing semiconductors and directly etched Si using an ArF excimer laser without a resist. The present invention can also be applied to Si resist etching using this laser. In addition, at the same conference, an ultra-high molecular weight PMMA resist with resistance to NF3 gas and fluorine was used to irradiate ArF excimer laser, and exposure and development were performed simultaneously, simplifying the lithography process in the semiconductor circuit manufacturing process. Although proposed, the present invention can also be applied to dry development of this lithography resist. Similarly, at the Japan Society of Applied Physics held in the spring and fall of 1990, a report was made on circuit pattern etching of crystalline SiC using a KrF excimer laser, and the present invention can also be applied to this SiC circuit pattern etching. Similarly, at the Japan Society of Applied Physics Conference in the spring of 1990, there was a report on surface modification of polymeric materials (e.g. Teflon) using excimer laser light, but the present invention focuses on surface modification of polymeric materials by excimer laser irradiation. It can also be used for

[0025]

Effects of the Invention As is clear from the above description, according to the polygonal convex prism according to the present invention, when the light beam enters the polygonal convex prism, it is dispersed into a luminous flux for each ridge surface that constitutes the light incidence surface. Furthermore, when the light is emitted from the multifaceted convex prism, each of the dispersed lights is dispersed into a light beam for each ridge surface that constitutes the light exit surface, and all the dispersed light beams are converged on the converging surface on the optical axis. , light with a smooth intensity distribution and high energy density can be obtained at the focusing surface.

Further, according to the laser beam projection device according to the present invention, the laser beam is dispersed into a plurality of light beams by the polygonal convex prism, focused on the mask on which the pattern to be projected is formed, and further transmitted through the mask. The light flux enters the magnifying telecentric projection lens in a dispersed state, and exits from the projection lens in a dispersed state to a predetermined position on the optical axis (imaging plane).
Since the light is focused on the surface and the projected pattern is projected thereon, a projected pattern without unevenness in light intensity can be obtained. Furthermore, by expanding the laser beam into a predetermined shape using a beam expander optical system, the convex polygonal lens can be made into an appropriate size that is easy to process, making the device less expensive. . If a reaction cell is placed in front of the projection lens and the laser beam is incident through the window, the laser beam will pass through the window while being dispersed into many beams, so the energy of the laser beam near the window will be reduced. This eliminates the conventional problems associated with reactant gases reacting near the window. In addition, since the energy density of the laser beam is highest near the substrate located at the position corresponding to the imaging plane, multiphoton absorption decomposition occurs, and material gases that do not have absorption at the wavelength of the irradiated laser are also photodecomposed. Can be done.

Generally, the output pattern of a laser is a Gaussian distribution, and therefore the energy density is highest at the center of the laser beam, making it difficult to perform clean laser processing. If a lens) is used for pattern transfer, the energy density becomes homogeneous, so even if it is used for thermal processing with a CO2 laser or YAG laser, a clean processed surface can be obtained. Furthermore, when the polygonal convex prism according to the fifth aspect of the present invention is used for pattern transfer, since the convergence surface is circular, the light that has entered the pupil of the projection lens can be effectively used.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment of a multifaceted convex prism according to the present invention.

[Figure 2] An explanatory diagram illustrating how light emitted from a polygonal convex prism is focused.

FIG. 3 is a perspective view of a second embodiment of a polygonal convex prism according to the present invention.

FIG. 4 is a perspective view of a third embodiment of a polygonal convex prism according to the present invention.

[Figure 5] An explanatory diagram illustrating how light emitted from a polygonal convex prism is focused.

FIG. 6 is a diagram showing an embodiment of a laser beam projection device according to the present invention.

[Fig. 7] A cross-sectional view illustrating how the laser light emitted from the projection lens is focused within the reaction cell.

[Figure 8] Diagram showing the overall structure of a conventional laser beam projection device

[
FIG. 9 is a diagram showing the overall structure of a conventional improved laser beam projection device

[Explanation of symbols]

10, 20, 30 Multifaceted convex prism 11A, 11B
, 11C, 11D Convex ridge surfaces 12a, 12b which are light input/output surfaces Central planes 14a, 14b, 16a, 16b Inclined plane 32
Circular central plane 34, 36, 38 Tapered surface 40 Beam expander optical system 42 Vertical diffusing cylindrical lens 44 Laterally diffusing cylindrical lens 46 Collimator lens 50 Mask 52 Circuit pattern 60 as a pattern to be projected Telecentric projection lens f Confocal

Claims (7)

[Claims] Claim 1: In a convex prism having opposing light input/output surfaces, one light input/output surface has a strip-shaped central plane perpendicular to the optical axis, and a strip-shaped central plane perpendicular to the optical axis; A first convex ridge surface is formed by a plurality of sets of band-shaped inclined planes whose inclinations become larger in sequence, and the other light input/output surface has an extension of each plane forming the first convex ridge surface. It consists of a strip-shaped central plane that extends in a direction perpendicular to the exit direction and is perpendicular to the optical axis, and a plurality of sets of strip-shaped inclined planes on both sides of this central plane, which are symmetrical with respect to the central plane and have gradually increasing inclinations. Second
A convex ridge surface is formed, and the parallel light incident on one light input/output surface is emitted from the other light input/output surface, and the optical axis is aligned in a rectangular shape that aligns with the overlapping region in the optical axis direction of the two strip-shaped central planes. A multifaceted convex prism, characterized in that the surface angles of the inclined planes forming the first and second convex ridge surfaces are set so that the surfaces converge at the top. 2. The first convex ridge surface and the second convex ridge surface have the same shape, and the emitted light is substantially focused on the optical axis in a square shape. Multifaceted convex prism. 3. The polygonal convex prism includes a first convex ridge prism in which the first convex ridge surface is formed on the front side and a back side is a plane perpendicular to the optical axis; 2. The second convex ridge prism having a convex ridge surface formed on the front side and a back side having a plane perpendicular to the optical axis is integrated with the back sides facing each other. Multifaceted convex prism. 4. The first convex ridge prism and the second convex ridge prism have the same shape, and the emitted light is substantially focused on the optical axis in a square shape. The polyhedral convex prism described. 5. In a convex prism having opposing light input and output surfaces, one light input and output surface has a plane perpendicular to the optical axis, and the other light input and output surface has a plane perpendicular to the optical axis. A convex ridge surface consisting of a vertical circular central plane and a plurality of ring-shaped tapered surfaces that are concentric with the central plane and gradually increase in slope is formed around this central plane. The surface angle of the tapered surface forming the convex ridge surface is set so that the incident parallel light exits from the other light input/output surface and is focused on the optical axis into a circular shape that matches the circular central plane. A multifaceted convex prism. 6. The polygonal convex prism according to any one of claims 1 to 5 is arranged on the optical path of the laser beam, and a projected pattern is formed on the converging surface of the light emitted from the polygonal convex prism. A laser beam projection device characterized in that a mask is disposed, and an enlargement side telecentric projection lens for projecting a reduced projection pattern in front of the mask is disposed. 7. Each focal point is confocal, and it consists of a vertically diffusing cylindrical concave lens that diffuses the emitted light in the vertical direction, a horizontally diffusing cylindrical concave lens that diffuses the emitted light in the horizontal direction, and a collimator lens that makes the emitted light parallel. 7. The laser beam projection apparatus according to claim 6, wherein the laser beam is guided to the polygonal convex prism via a beam expander optical system.