KR20160021017A - Illumination apparatus, optical tester and optical microscope - Google Patents

Abstract

Provided is an illumination device capable of changing the ray angle distribution of illumination light while suppressing loss of light quantity. A light source 2 for emitting light and a plurality of reflection elements 4 that enter the light incident surface, multiply reflect the light therefrom and then exit from the light emission surface, and a plurality of different types of light beams And the optical element 3 of the first embodiment is freely arranged to replace any one of the plurality of optical elements 3 in the optical path between the light source 2 and the multiple reflective elements 4. [

Description

TECHNICAL FIELD [0001] The present invention relates to an illuminating device, an optical inspection device, and an optical microscope,

The present invention relates to a lighting device, an optical inspection device, and an optical microscope.

For example, an optical inspection apparatus is generally used for inspection of semiconductor wafers. In the optical inspection apparatus, an illumination light is irradiated to a semiconductor wafer to be inspected, an image obtained by the light reflected by the surface of the semiconductor wafer is picked up, and the presence or absence of defects is inspected from this image . Also in the optical microscope, illumination light is irradiated to an observation target, and an image that can be obtained by the transmitted light or reflected light is captured.

In such an optical inspection apparatus or optical microscope, imaging is performed by a digital camera using an imaging element such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal-Oxide Semiconductor). However, in the case of using a digital camera, since the imaging element is sensitive to a change in luminance, the influence is noticeable if there is a mura in the illumination light. Therefore, in an optical inspection apparatus or an illumination apparatus (illumination optical system) used in an optical microscope, it is required to irradiate uniform illumination light free from unevenness.

As the optical inspection apparatus, as a method for raising the detection sensitivity of a defect to a semiconductor wafer, parameters such as a light amount of an illuminating light irradiated on a surface of a semiconductor wafer, a ray angle distribution, a wavelength, and a polarization direction are adjusted . Since there are various circuit patterns on a semiconductor wafer, parameters optimal for each wafer exist. Among them, there is a circuit pattern in which the detection sensitivity is increased by changing the ray angle distribution incident on the semiconductor wafer.

As an illumination device for an optical inspection apparatus, an ultra-high pressure mercury (UV) lamp is used as a light source, the light emitted from the light source is reflected by a reflector, and is condensed toward a downstream optical system. However, the light amount distribution of illumination light to be irradiated on the semiconductor wafer reflects the light ray angle of the light incident on the above-mentioned optical system, and becomes nonuniform. In other words, as shown in Fig. 17, the light amount distribution at the pupil plane of this illumination light is the lowest at the central portion due to the shadow of the valve of the ultra-high pressure mercury lamp, and the light amount is the highest at the position subtracting the shadow , And the intensity of the light beam gradually decreases from there to the outer peripheral portion. On the other hand, Fig. 17 is a graph showing the distribution of the sectional light quantity through the center of the moving surface of the illumination light.

Here, it has been proposed to use a DMD (Digital Micromirror Device) device in which a plurality of fine mirrors whose tilt is changed by on / off of a driving voltage, to change the ray angle distribution of illumination light by each mirror 1). However, when the DMD device is used, since the reflectance of the mirror is low, the light amount is entirely lowered.

The light amount of the illumination light is a parameter required for inspecting all the semiconductor patterns. For this reason, it is essential to secure a sufficient amount of light after inspection of the semiconductor wafer. Therefore, when a DMD device is used, it is difficult to secure a sufficient amount of light to raise the detection sensitivity.

On the other hand, it has been proposed to use an optical element having a different transmittance in the direction of a concentric circle to change the ray angle distribution of illumination light (see Patent Document 2). However, even when such an optical element is used, the detection sensitivity may be lowered due to loss of light quantity.

Prior art literature

[Patent Literature]

Patent Document 1: Japanese Laid-Open Patent Application No. 2005/026843

Patent Document 2: Japanese Unexamined Patent Publication No. 2007-33790

One aspect of the present invention has been proposed in view of such conventional circumstances, and it is an object of the present invention to provide a lighting apparatus capable of changing the light ray angle distribution of illuminating light while suppressing the loss of light amount, And an object of the present invention is to provide an optical inspection apparatus and an optical microscope capable of further improving the detection sensitivity by including such a lighting device.

In order to achieve the above object, the present invention provides the following means.

[1] An illumination device according to a first aspect of the present invention includes: a light source that emits light; a multiple reflection element that enters the light from the light incident surface, multiply reflects the light inside and then exits from the light emission surface; And a plurality of other optical elements of a kind changing a light ray angular distribution of light so that any one of the plurality of optical elements can be freely replaced in an optical path between the light source and the multiple reflective elements .

[2] The illuminating device according to [1] above may be provided with a changing mechanism for changing the arrangement of the plurality of optical elements.

[3] In the illuminating device according to the above [1] or [2], the plurality of optical elements may include any one of a concave lens, a convex lens, a conical lens, a mirror, a prism, and a cylindrical lens .

[4] In the illuminating device according to any one of [1] to [3], the plurality of optical elements may be configured to change one of the spot diameter, shape, and number of the light.

[5] An optical inspection apparatus according to a second aspect of the present invention is characterized by including the illuminating device according to any one of [1] to [4].

[6] An optical microscope according to a third aspect of the present invention is characterized by including the illuminating device according to any one of [1] to [4].

As described above, according to one aspect of the present invention, there is provided an illumination device capable of changing the light angle distribution of the illumination light while suppressing the loss of the light amount, particularly, changing the light angle distribution of the illumination light into another one, It is possible to provide an optical inspection apparatus and an optical microscope capable of further improving the detection sensitivity.

1 is a schematic diagram showing a schematic configuration of an illumination apparatus and an optical inspection apparatus according to a first embodiment of the present invention.
2 is a plan view showing a configuration example of an optical element included in the illumination apparatus shown in Fig.
Fig. 3 is a graph showing the in-plane light amount distribution of the hibernation of illumination light when the optical element shown in Fig. 2 is used.
4 is a plan view showing a configuration example of an optical element included in the illumination apparatus shown in Fig.
Fig. 5 is a graph showing the in-plane light amount distribution of the hibernation of illumination light when the optical element shown in Fig. 4 is used.
6 is a plan view showing a configuration example of an optical element included in the illumination apparatus shown in Fig.
Fig. 7 is a graph showing the in-plane light amount distribution of the hibernation of illumination light when the optical element shown in Fig. 6 is used.
8 is a plan view showing a configuration example of an optical element included in the illuminating device shown in Fig.
Fig. 9 is a graph showing the in-plane light amount distribution of the hibernation of illumination light when the optical element shown in Fig. 8 is used.
10 is a plan view showing a configuration example of an optical element included in the illuminating device shown in Fig.
11 is a graph showing the in-plane light amount distribution of the hibernation of illumination light when the optical element shown in Fig. 10 is used.
12 is a plan view showing a configuration example of an optical element included in the illumination device shown in Fig.
13 is a graph showing the in-plane light amount distribution of the hibernation of illumination light when the optical element shown in Fig. 12 is used.
14 is a plan view showing a configuration example of an optical element included in the illuminating device shown in Fig.
Fig. 15 is a graph showing the in-plane light amount distribution of the hibernation of illumination light when the optical element shown in Fig. 14 is used.
16 is a side view showing a configuration example of a light diffusion device included in the illumination device shown in Fig.
17 is a graph showing the distribution of the sectional light quantity through the center of the moving surface of the illumination light.

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

In the following description, in order to make each component easy to see, the scale of dimensions is shown differently by the constituent elements in the figure.

First Embodiment

First, as a first embodiment of the present invention, for example, an illumination apparatus 1 and an optical inspection apparatus 100 shown in Fig. 1 will be described. 1 is a schematic diagram showing a schematic configuration of an illumination apparatus 1 and an optical inspection apparatus 100. Fig.

As shown in FIG. 1, the optical inspection apparatus 100 is for examining the presence or absence of defects in, for example, a semiconductor wafer (hereinafter, simply referred to as a wafer) W to be inspected. Specifically, the optical inspection apparatus 100 includes a light source 2, an optical element 3, a multiple reflection element 4, a light diffusion element 5, a relay optical system 6, an optical path changing element 7 ), A condensing optical system 8, an imaging optical system 9, and an image capturing apparatus 10 are schematically shown.

Among them, the light source 2, the optical element 3, the multiple reflection element 4, the light diffusing element 5, the relay optical system 6, the optical path changing element 7 and the condensing optical system 8, Are sequentially arranged on the first optical axis AX1. On the other hand, the optical path changing element 7, the imaging optical system 9 and the imaging device 10 are arranged on a second optical axis AX2 orthogonal to the first optical axis AX1, Respectively.

The illumination apparatus 1 includes a light source 2, an optical element 3, a multiple reflection element 4, a light diffusing element 5, a relay optical system 6 and a condensing optical system 8, Thereby constituting an illumination optical system for irradiating the illumination light L with respect to the wafer W.

The light source 2 is an ultrahigh-pressure mercury (UV) lamp. A reflector 11 is disposed around the light source 2. The reflector 11 has an inner reflecting surface 11a formed such that its cross-sectional shape draws an ellipse and reflects the light La emitted from the light source 2 by the inner reflecting surface 11a, And the light Lb is condensed toward the light incident surface 4a of the multiple reflection element 4. [

On the other hand, for the light source 2, for example, an LED lamp or the like can be used in addition to the above-described ultra high-pressure mercury lamp. A point light source having a small light emitting point such as LPP (Laser Produced Plasma) or LDLS (Laser Driven Light Source) may be used as the light source 2 in order to improve the detection sensitivity. In other words, the kind of the light source 2 is not particularly limited, and it is possible to appropriately select and use an optimum light source in accordance with the object to be inspected.

The optical element 3 changes the angle of light ray distribution of the light Lb from the light source 2 to the multiple reflective elements 4. [ In the lighting apparatus 1 of the present embodiment, for example, at least two of the plurality of optical elements 3A to 3G of the kind shown in Figs. 2, 4, 6, 8, 10, 12, It is possible to arbitrarily replace one optical element 3 selected therefrom among the optical paths between the light source 2 and the multiple reflection elements 4.

Specifically, the optical element 3A shown in Fig. 2 includes a pair of collimator lens groups 31 and 32. In Fig. The pair of collimator lens groups 31 and 32 is a combination of a concave lens and a convex lens, and the lens is arranged in the optical axis direction (on the first optical axis AX1). Concretely, among the pair of collimator lenses 31 and 32, the collimator lens group 31 on the front end side is constituted by a plurality of (two in this embodiment) concave lenses 31a and 31b. On the other hand, the collimator lens group 32 on the rear end side is constituted by a plurality of (two in this embodiment) convex lenses 32a and 32b. On the other hand, the combination of the concave lens and the convex lens constituting the pair of collimator lens groups 31 and 32 can be appropriately changed.

In the optical element 3A, the light Lb emitted from the light source 2 is made into a collimated light flux FL by the collimator lens group 31 at the front end side, and the collimated light flux FL is collimated by the collimator lens The light Lc condensed toward the light incident surface 4a of the multiple reflection element 4 is emitted.

3 shows the in-plane light amount distribution on the moving surface of the illuminating light L when the optical element 3A is used. As shown in Fig. 3, the spot of the illumination light L when the optical element 3A is used has a substantially circular shape.

On the other hand, the optical element 3B shown in Fig. 4 includes, in addition to the configuration of the optical element 3A, a pair of concave lens 33 and convex lens 34 ) Arranged in the direction of the optical axis (on the first optical axis AX1).

In the optical element 3B, the light Lb emitted from the light source 2 is made into a parallel light flux FL1 by the collimator lens group 31 at the front end side, and this parallel light flux FL1 is transmitted through the concave lens 33, And is converged by the convex lens 34 to become the parallel luminous flux FL2 which is diameter expanded than the parallel luminous flux FL1. Thereafter, the collimated light flux FL2 is condensed by the collimator lens group 32 on the downstream side, so that the condensed light Lc is emitted toward the light incident surface 4a of the multiple reflection element 4 .

5 shows the in-plane light amount distribution on the aspherical surface of the illumination light L when the optical element 3B is used. As shown in Fig. 5, the spot of the illumination light L in the case of using the optical element 3B has a substantially circular shape which is diameter expanded as compared with the case shown in Fig.

On the other hand, the optical element 3C shown in Fig. 6 has, in addition to the constitution of the optical element 3A, a pair of convex lenses 35 and a concave lens (not shown) between the pair of collimator lens groups 31 and 32 36 are arranged in the direction of the optical axis (on the first optical axis AX1).

In the optical element 3C, the light Lb emitted from the light source 2 is made into a parallel light flux FL1 by the collimator lens group 31 at the front end side, and the parallel light flux FL1 is transmitted through the convex lens 35, And is then diffused by the concave lens 36 to become a collimated light flux FL2 which is deeper than the collimated light flux FL1. Thereafter, the parallel light flux FL2 is condensed by the collimator lens group 32 at the rear end side, so that the condensed light Lc is emitted toward the light incident surface 4a of the multiple reflection element 4 .

The in-plane light amount distribution on the aspherical surface of the illumination light L when the optical element 3C is used is shown in Fig. As shown in Fig. 7, the spot of the illumination light L when the optical element 3C is used has a substantially circular shape which is smaller in diameter than the case shown in Fig.

On the other hand, the optical element 3D shown in Fig. 8 includes, in addition to the configuration of the optical element 3A, a pair of conical lenses 37 and 38 between the pair of collimator lens groups 31 and 32, (On the first optical axis AX1). In addition, the pair of conical lenses 37 and 38 are arranged so as to face each other on the surface opposite to the surface on which the ceiling portions are formed. The arrangement of the two conical lenses 37 and 38 is not limited to the above-described arrangement. For example, the arrangement of the two conical lenses 37 and 38 may be such that the surfaces on which the ceiling portions are formed are opposed to each other, Or may be arranged in a state of being oriented in the direction of the arrow.

In the optical element 3D, the light Lb emitted from the light source 2 is converted into a parallel light flux FL1 by the collimator lens group 31 at the front end side, The parallel light flux FL2 becomes a reversed parallel light flux path between the inner peripheral side and the outer peripheral side of the parallel light flux FL1 while passing between the conical lenses 37, In other words, of the light beams constituting the parallel light flux FL1, the optical path of the light beam passing through the inner peripheral side of the conical lens 37 is replaced with the outer peripheral side (refer to the two-point chain line in Fig. On the other hand, the optical path of the light ray passing through the outer peripheral side of the conical lens 37 is changed to the inner peripheral side (see the broken line in Fig. 8). Thereafter, the parallel light flux FL2 is condensed by the collimator lens group 32 on the rear end side, so that light Lc condensed toward the light incident surface 4a of the multiple reflection element 4 is emitted .

The in-plane light amount distribution on the aspherical surface of the illuminating light L when this optical element 3D is used is shown in Fig. As shown in Fig. 9, the spot of the illumination light L when the optical element 3D is used has a substantially circular shape. The in-plane light quantity distribution shown in Fig. 9 has a light ray angular distribution in which the light intensity is reversed in the internal and external states.

On the other hand, the optical element 3E shown in Fig. 10 has a configuration in which an optical path division element 39 is arranged between a pair of collimator lens groups 31 and 32 in addition to the configuration of the optical element 3A. The optical path separation element 39 is formed by combining three triangular prism mirrors 40a, 40b and 40c.

In the optical element 3E, the light Lb emitted from the light source 2 is made into a parallel light flux FL1 by the collimator lens group 31 at the front end side, and this parallel light flux FL1 is reflected by the optical path separation element 39 To be separated into two parallel light fluxes FL21 and FL22. Thereafter, the two collimated light fluxes FL21 and FL22 are condensed by the collimator lens group 32 at the rear end side, so that the light Lc (Lc) converged toward the light incidence surface 4a of the multiple reflection element 4 ).

FIG. 11 shows the light amount distribution on the surface of the illuminating light L when this optical element 3E is used. As shown in Fig. 11, the spot of the illumination light L when the optical element 3E is used has a shape divided into two symmetrically with the center axis thereof interposed therebetween.

On the other hand, in addition to the configuration of the optical element 3A, the optical element 3F shown in Fig. 12 has two optical path division elements 39A and 39B disposed between a pair of collimator lens groups 31 and 32 Lt; / RTI > The two optical path division elements 39A and 39B have basically the same configuration as the optical path division element 39 described above. The optical path separation element 39A at the front stage and the optical path separation element 39B at the rear stage are arranged such that the longitudinal directions of the mutual delta mirrors 40a, 40b and 40c are perpendicular to the first optical axis AX1 And are disposed orthogonally.

In the optical element 3E, the light Lb emitted from the light source 2 is made into a parallel light flux FL1 by the collimator lens group 31 at the front end side, and this parallel light flux FL1 passes through the optical path division element Passes through the parallel light fluxes 39A, and is separated into two parallel light fluxes FL21 and FL22. The two parallel light fluxes FL21 and FL22 pass through the rear end optical path separation element 39B and are separated into two parallel light fluxes FL31 and L32 and two parallel light fluxes FL33 and FL34 respectively. Thereafter, the four parallel light fluxes FL31, FL32, FL33, and FL34 are condensed by the collimator lens group 32 on the rear end side so as to be condensed toward the light incident surface 4a of the multiple reflection element 4 And the emitted light Lc is emitted.

FIG. 13 shows the light amount distribution on the antinode of the illumination light L when this optical element 3F is used. As shown in Fig. 13, the spot of the illumination light L when the optical element 3F is used has a shape divided into four parts symmetrically with the center axis thereof interposed therebetween.

On the other hand, the optical element 3G shown in Fig. 14 includes, in addition to the configuration of the optical element 3A, a pair of cylindrical lenses 41 and 42 between a pair of collimator lens groups 31 and 32, (On the first optical axis AX1). One of the two cylindrical lenses 39 (in this embodiment, the cylindrical lens 41 at the front end) is a negative lens, and the other lens (the rear end cylindrical lens 42 in this embodiment) is a positive lens. The cylindrical lens 41 at the front end and the cylindrical lens 42 at the other end are disposed so as to coincide with each other in the longitudinal direction within a plane perpendicular to the first optical axis AX1.

In the optical element 3G, the light Lb emitted from the light source 2 is made into a collimated light flux FL1 by the collimator lens group 31 at the front end side, 41) and then converged by the rear-end cylindrical lens 42 so that the collimated light flux FL2 in the one direction (the longitudinal direction of the cylindrical lenses 41, 42) is larger than the parallel light flux FL1 ). Thereafter, the parallel light flux FL2 is condensed by the collimator lens group 32 on the rear end side, so that the light Lc condensed toward the light incident surface 4a of the multiple reflection element 4 is emitted .

15 shows the in-plane light amount distribution on the moving surface of the illuminating light L when the optical element 3G is used. As shown in Fig. 15, the spot of the illumination light L when the optical element 3G is used has a substantially elliptical shape enlarged in one direction as compared with the case shown in Fig.

The illuminating device 1 of the present embodiment can change the diameter, shape, and number of spots of the illumination light L irradiated to the surface of the wafer W by replacing the above-described plurality of optical elements 3A to 3G It is possible to change any one of them.

The optical element 3 includes any one of a concave lens, a convex lens, a conical lens, a mirror, a prism, and a cylindrical lens in addition to the configuration of the optical elements 3A to 3G described above. Shape, or number of spots of the illumination light L irradiated on the surface of the illumination light L may be changed.

The illuminating device 1 is provided with a changing mechanism 50 for changing the arrangement of the plurality of optical elements 3A to 3G mentioned above. The changing mechanism 50 is a detachable type in which the above-described plurality of optical elements 3A to 3G are freely detachably arranged in the optical path between the light source 2 and the multiple reflecting elements 4, The optical elements 3A to 3G are allowed to move freely in the optical path between the light source 2 and the multiple reflection elements 4 by rotating the turret (not shown) And a turret type in which the material is changed and arranged.

As shown in Fig. 1, the multiple reflective element 4 is made of a rod integrator, and has a light incident surface 4a at one end in the long direction and a light exit surface 4b at the other end in the long direction. The multiple reflective elements 4 are arranged such that the light Lc having passed through the optical element 3 is incident on the light incidence surface 4a and multiply reflected thereon and then the light Ld is emitted from the light exit surface 4b do.

The light diffusing element 5 diffuses the light Ld emitted from the light exit surface 4b of the multiple reflection element 4. Specifically, as shown in Fig. 16, for example, the light diffusion element 5 has a structure in which a minute uneven pattern 5b is formed on one side of the base material 5a. The light diffusing element 5 is arranged so that the surface on which the concavo-convex pattern 5b is formed faces toward the side opposite to the multiple reflective elements 4. [ Thus, the light diffusing device 5 emits the light Le diffused by the concavo-convex pattern 5b. Accordingly, the light diffusion element 5 can be arranged so that the surface on which the concavo-convex pattern 5b is formed faces the multiple reflective elements 4. [

1, the relay optical system 6 includes a first relay lens 12 and a second relay lens 13. The relay optical system 6 includes a first relay lens 12 and a second relay lens 13, .

The optical path changing element 7 is made of a dichroic mirror and transmits light Lf directed toward the wafer W while returning light Lg reflected from the wafer W to be described later. To the image pickup device 10.

The condensing optical system 8 includes a condenser lens 14 and an objective lens 15 and irradiates the condensed light (illumination light L) onto the surface of the wafer W. [ The light Lg reflected by the surface of the wafer W passes through the objective lens 15 and the condenser lens 14 and is incident on the optical path changing element 7 and is reflected toward the imaging optical system 9 do.

The imaging optical system 9 includes a condenser lens 16 and an imaging lens 17. The imaging optical system 9 focuses the light Lh reflected by the optical path changing element 7 on the imaging device 10 in accordance with the size of the imaging surface of the imaging device 10 10).

The imaging apparatus 10 is constituted by a digital camera using, for example, an imaging element such as a CCD or CMOS. The image pickup device 10 picks up an image that can be obtained by the light Lg reflected from the surface of the wafer W. [ The optical inspection apparatus 100 can check the presence or absence of defects on the wafer W from this image.

In the illumination device 1 of the present embodiment, the optical angle distribution of the illumination light L incident on the wafer W can be changed by the above-described optical element 3 while suppressing the loss of light quantity. In the illumination device 1, it is possible to change the light ray angle distribution of the illumination light L to another by replacing the plurality of optical elements 3A to 3G.

This allows the illumination device 1 to change either the diameter, the shape or the number of the spots of the illumination light L irradiated on the surface of the wafer W in accordance with circuit patterns of various colors of the wafer W . As a result, it is possible to obtain the illumination light L optimal for raising the detection sensitivity of the circuit pattern.

As described above, in the optical inspection apparatus 100 of the present embodiment, by providing the above-described illuminating device 1, in order to further improve the detection sensitivity while suppressing the loss of light quantity, Inspection with resolution can be performed.

Furthermore, the present invention is not necessarily limited to the objects of the above-described embodiments, and various modifications can be added within the scope of the present invention.

For example, in the above embodiment, the case where the inspection of the wafer W is carried out in the optical inspection apparatus 100 provided with the illumination apparatus 1 is exemplified. However, in the optical inspection apparatus 100 provided with the illumination apparatus 1, And the subject to be inspected is not particularly limited.

In addition to the optical inspection apparatus 100, the illumination apparatus 1 can be applied to an optical microscope that irradiates illumination light L to an observation target and captures an image that can be obtained by the transmitted light or the reflected light Do. In the optical microscope having such a lighting device 1, it is possible to further improve the detection sensitivity while suppressing the loss of the light amount, and thus observation with high resolution becomes possible.

1: Lighting device 2: Light source
3, 3A to 3G: Optical element 4: Multiple reflection element
5: light diffusion element 6: relay optical system
7: optical path conversion element 8: condensing optical system
9: imaging optical system 10: imaging device
11: Reflector 12: First relay lens
13: second relay lens 14: condenser lens
15: objective lens 16: condensing lens
17: imaging lens 31, 32: collimator lens group
33: concave lens 34: convex lens
35: convex lens 36: concave lens
37, 38: conical lens 39, 39A, 39B: optical path separation element
41, 42: cylindrical lens 50: changing mechanism
100: Optical inspection apparatus W: Semiconductor wafer
L: Lighting light

Claims (6)

A light source for emitting light;
A multiple reflection element which makes the light incident on the light incident surface, multiply reflects the light inside and then exits from the light emission surface; And
And a plurality of other optical elements of a kind which change the light ray angle distribution of the light,
Wherein any one of the plurality of optical elements is freely replaced and placed in an optical path between the light source and the multiple reflective elements. The method according to claim 1,
And a changing mechanism for changing the arrangement of the plurality of optical elements. 3. The method according to claim 1 or 2,
Wherein the plurality of optical elements include any one of a concave lens, a convex lens, a conical lens, a mirror, a prism, and a cylindrical lens. 4. The method according to any one of claims 1 to 3,
Wherein the plurality of optical elements change any one of the spot diameter, shape, and number of the light. 5. The method according to any one of claims 1 to 4,
And an illumination device. 5. The method according to any one of claims 1 to 4,
And an illumination device.

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