JP5484929B2 - Antireflection optical element and laser light source device - Google Patents

Description

  The present invention relates to an antireflection optical element and a laser light source device.

A method of realizing an antireflection function by laminating a thin film dielectric layer has been widely known, but recently, as an alternative to such an antireflection method, a so-called “subwavelength structure”, that is, a period rather than a wavelength. The one which realizes antireflection by a short fine periodic structure is being proposed.

In the sub-wavelength structure, the “apparent refractive index of the fine periodic structure viewed from the incident light (hereinafter referred to as“ effective refractive index ”) changes according to the shape of the irregularities.
Therefore, when “one-dimensional fine periodic structure is formed with a triangular cross section” on the surface of the substrate made of an optical material, the spatial period of the fine periodic structure is continuous from the top to the bottom of the triangular shape forming the unit of the concavo-convex structure. Therefore, the effective refractive index can be changed continuously in the height direction of the triangle, and the “discontinuous step-like change in effective refractive index” does not occur in the portion of the fine periodic structure. Therefore, reflection due to the discontinuous effective refractive index change is prevented, and a good antireflection function can be realized.

  Patent Documents 1 and 2 are known as proposals for such an antireflection function.

  Recently, the oscillation wavelength of a laser light source used for laser processing or the like has been shortened, and accordingly, the concave / convex period of the fine periodic structure needs to be shortened. The laser light source used for the laser processing has a large output, and when an antireflection optical element is used in the optical path of the laser beam, if the antireflection function is not sufficient, the laser beam component reflected by the antireflection optical element becomes a laser light source. Return and adversely affect laser oscillation.

  In addition, it is preferable that a laser beam used for laser processing irradiates a workpiece with “more” of its light energy. For this reason, it is necessary to increase the transmission efficiency of the laser beam. There is “diffraction” as an element that hinders the improvement of the above. When the period of the fine periodic structure is equal to or greater than the wavelength of the laser beam, a considerable part of the incident laser beam is deviated from the “original beam traveling direction” due to diffraction, and energy utilization efficiency is reduced.

For this reason, it is necessary to further reduce the period in the fine periodic structure. For this purpose, it is necessary to reduce the space between the tops of the triangular cross-sections constituting the fine periodic structure, but in this case, the “vertical angle” in the triangular cross-section is reduced, and the triangular shape is “thin” Become. Such a thin periodic structure with a thin triangular shape as a cross-sectional shape has low mechanical strength, requires careful handling, and tends to reduce the production yield of antireflection optical elements. .
When the period becomes small, it becomes difficult to form a fine periodic structure.

  In the case of laser processing, a large amount of heat is generated during processing, and thus the antireflection optical element needs to have high heat resistance.

  The antireflection optical element described in Patent Document 1 has a fine periodic structure formed of “thermoplastic resin” and is not suitable for “laser processing” in terms of “heat resistance” because the material is resin.

  The antireflection optical element described in Patent Document 2 has a function as a “diffraction grating” as well as an antireflection function, and is not suitable for “laser processing” in terms of “energy use efficiency”.

  The present invention is a novel anti-reflection optical element suitable as an anti-reflection optical element in laser processing, that is, it has high anti-reflection function, excellent heat resistance, excellent mechanical strength, and can be produced easily and at low cost. An object is to realize an antireflection optical element.

The antireflection optical element according to claim 1 is formed by forming a one-dimensional fine periodic structure with a triangular cross section on the surface of a substrate made of an inorganic optical material, and having an antireflection effect within a predetermined wavelength region. Is.
That is, “inorganic optical material” is used as the material.
As the inorganic optical material, for example, quartz glass, general optical glass, or Tempax glass, which satisfies the transmittance characteristics in a desired wavelength region, can be appropriately used, and it is chemically stable and heat resistant. The nature is also high.
When the fine periodic structure is “one-dimensional”, it means that fine irregularities are arranged in one direction and there is no change in shape in a direction perpendicular to the one direction.
“Within a predetermined wavelength region” is “the range of the wavelength of the laser light from the laser light source in the application (which depends on the light source)” in which the antireflection optical element is used.

  The “fine periodic structure” has a first uneven structure and a second uneven structure.

  The “first concavo-convex structure” is formed by arranging “structural units having a mountain-shaped triangular cross section” having a height: H 1 and a width: D 1 with a period: P 1.

  The “mountain triangle” is a triangular shape having a bottom width of D1 and a height of H1, and the width monotonously decreases toward the top in the height direction. Each of the two hypotenuses forming the top in the height direction is generally a straight line, but is not limited thereto, and may be a curved line. The cross-sectional shape of the triangular triangle having the first concavo-convex structure is constant in the direction orthogonal to the cross-section.

  Therefore, the structural unit having the triangular cross section is a prism shape, and this is arranged in units of one structural unit, that is, one prism at a period: P.

  Period: P is larger than bottom width: D. Therefore, in the first concavo-convex structure, in the portion where the cross-sectional chevron triangles constituting the structural unit are adjacent, the bottoms of the cross-sectional chevron triangles are spaced apart from each other, and the bottoms do not contact each other.

Further, the width D of the structural unit in the first concavo-convex structure is
0 <P−D ≦ D / 2
Satisfied. Furthermore, the period P is shorter than the shortest wavelength in the wavelength region.

In the “second uneven structure”, the height of the unevenness: H2 is between adjacent structural units in the first uneven structure.
0.4H1 ≦ H2 ≦ 0.8H1
Is formed by an array of structural units having a triangular cross section satisfying
Each of the two oblique sides forming the top in the height direction of the structural unit forming the second concavo-convex structure is generally a straight line, but is not limited thereto and may be a curve. The cross-sectional shape of the triangular triangle having the first concavo-convex structure is constant in the direction orthogonal to the cross-section.

  Since the combination of the first concavo-convex structure and the second concavo-convex structure constitutes a “one-dimensional fine periodic structure” with a triangular cross section, the arrangement of the structural units in the first and second concavo-convex structures is a mountain shape. The apex of the triangular cross-sectional shape is aligned in one direction, and the ridge lines at the apex are parallel to each other in the direction perpendicular to the cross section.

  As described above, in the first concavo-convex structure, “the cross-sectional chevron triangles forming the structural unit are adjacent to each other and the bottoms of the cross-sectional chevron triangles are spaced apart from each other, and the bottoms do not contact each other”. If there is not, the adjacent portions of the bottom of the first concavo-convex structure become “flat surfaces”, and the discontinuous change of the effective refractive index occurs in this portion, causing the antireflection function to deteriorate. It becomes.

  In the antireflection optical element of the present invention, the second concavo-convex structure is formed between the first concavo-convex structures so that the “flat surface” portion does not occur.

One or more “cross section chevron triangles” as structural units constituting the second concavo-convex structure are formed between adjacent structural units (cross section chevron triangles) in the first concavo-convex structure.
Therefore, in the case of forming one structural unit of the second concavo-convex structure between adjacent structural units (cross-sectional triangles) in the first concavo-convex structure, the arrangement period is P and the width of the bottom thereof Is “PD”. Of course, it is also possible to further reduce the width of the bottom and form “two or more between adjacent structural units (cross-sectional triangles) in the first concavo-convex structure”.

  The first and second concavo-convex structures form “wedge-shaped concave portions without flat portions”, and are “periodic structures that do not generate diffracted light” for the shortest wavelength in the predetermined wavelength region.

  That is, since the first and second concavo-convex structures form “wedge-shaped concave portions having no flat portion”, the bottom portions of the cross-sectional chevron triangles are in contact with each other in the entire first and second concavo-convex structures, and “flat surfaces”. Does not form.

  Further, as described above, the first and second uneven structures are “periodic structures that do not generate diffracted light” with respect to the shortest wavelength in a predetermined wavelength region. That is, throughout the first and second concavo-convex structures, there is no period equal to or greater than “the shortest wavelength in a predetermined wavelength region”, and the period P is also the same for the light with the shortest wavelength. The size is such that substantially no diffraction occurs.

As described above, the width of the structural unit of the first concavo-convex structure: D is equal to the period: P,
0 <P−D ≦ D / 2
Therefore, the width of the bottom of the triangular triangle shape constituting the first concavo-convex structure can be sufficiently secured, and the top of the structural unit of the first concavo-convex structure is not “too sharp and thinned”. Therefore, it is possible to secure the mechanical strength in the first uneven structure portion.
On the contrary, when “P−D ≧ D / 2” is satisfied, when the period P, which should be a size that does not substantially cause diffraction even for light having the shortest wavelength, is realized, the first uneven structure The top of the triangular triangle is “pointed”, making it difficult to ensure the mechanical strength at the first uneven structure.

  The prism shape of the cross-sectional angle triangle that forms the structural unit of the second concavo-convex structure, even if the top part is “pointed to some extent”, the top part exceeds the top part of the prism that forms the first concavo-convex structure. Therefore, the first uneven structure effectively protects against the action of mechanical force from the outside.

  However, when the height of the structural unit in the second concavo-convex structure: H2 is smaller than 0.4H1 with respect to the height of the structural unit in the first concavo-convex structure: H1, the “antireflection of the second concavo-convex structure” "Contribution to function" becomes smaller. Further, when H2 is larger than 0.8H1, the top of the structural unit of the second concavo-convex structure becomes “close to the top of the first concavo-convex structure”, and “because of the first concavo-convex structure according to the action of mechanical force from the outside” “Protective function” may deteriorate.

  The above description will be described with reference to “two antireflection optical elements” illustrated in FIG.

FIGS. 1A and 1B show two examples of a fine periodic structure formed as a surface shape of a substrate made of “inorganic optical material”. In these figures, the left-right direction is the periodic direction in the fine periodic structure.
What is shown is a cross-sectional shape of a fine periodic structure, as shown in the figure, a one-dimensional periodic structure with a triangular cross-section, and the cross-sectional shape is the same in a direction orthogonal to the drawing.

  In the example shown in FIG. 1A, the first concavo-convex structure has a height: H1, a width: D, and the structural units 1-1, 1-2, 1-3,. > D). Further, in the second concavo-convex structure, the structural units 2-1, 2-2, 2-3,. Do it.

  In the example of FIG. 1A, the individual structural units 2-1, 2-2, 2-3,... Of the second concavo-convex structure are the adjacent structural units 1-1, 1 and 1 of the first concavo-convex structure. -1, 1-3,... That is, in the periodic direction, the structural units of the first concavo-convex structure and the structural units of the second concavo-convex structure are alternately arranged one by one.

In the example shown in FIG. 1 (b), the first concavo-convex structure has a height: H1, a width: D, and structural units 1-1, 1-2, 1-3,. (> D).
On the other hand, the second concavo-convex structure is formed by arranging the structural units 2-11, 2-12, 2-21, 2-22,. Two structural units (2-11, 2-12, etc.) are arranged between adjacent structural units of the concavo-convex structure.

And H1, H2, D, and P in FIG.
0 <P−D ≦ D / 2 (Therefore, naturally, P> D.)
0.4H1 ≦ H2 ≦ 0.8H1
And the period: P is shorter than the “shortest wavelength in the wavelength region”, and the first and second concavo-convex structures are sandwiched between wedge-shaped concave portions (for example, structural units 1-1 and 2-1) having no flat portion. A periodic structure that does not generate diffracted light with respect to the shortest wavelength.

  The antireflection optical element of claim 1 can increase the antireflection function in the “short wavelength region” by reducing the period: P while satisfying the above conditions, and by increasing the height: H1. The antireflection function in the “long wavelength region” can be increased.

  The antireflection optical element according to claim 1, wherein the inorganic optical material is “quartz glass”, the height of the structural unit of the first concavo-convex structure: H1 and the period: P is 100 nm to 200 nm, and the second concavo-convex structure The structural unit is formed as “one between adjacent structural units of the first concavo-convex structure”, and has a transmittance of 97% or more for light having a wavelength of 266 nm (claim 2).

  The laser light source device of the present invention is a “laser light source device for a laser processing device”, and includes a YAG laser light source, a wavelength conversion element, a casing, and a cover plate.

The “YAG laser light source” emits a laser beam.
The “wavelength conversion element” is an element that converts the wavelength of the laser beam from the YAG laser light source into a “wavelength suitable for processing”. As the wavelength conversion element, a known appropriate element can be used. The “wavelength suitable for processing” is “the wavelength of the fourth harmonic: 266 nm” among the wavelengths obtained by converting the wavelength of the laser beam from the YAG laser light source. At this wavelength, the reflectivity is low for many metals, and the processing laser light can be effectively absorbed by the object to be processed.

  The “casing” is for housing the YAG laser light source and the wavelength conversion element.

  The “cover plate” closes the laser beam emission hole opened in the casing and transmits the “laser beam wavelength-converted by the wavelength conversion element”.

  The antireflection optical element according to claim 1 or 2 is used as the cover plate.

As described above, according to the present invention, a novel antireflection optical element can be realized.
Since the antireflection optical element of the present invention is composed of the “inorganic optical material” as described above, it has excellent heat resistance. As described above, the first and second concavo-convex structures provide “discontinuous effective refractive index”. Since there is no step change, ”a high antireflection function can be realized, and the first and second concavo-convex structures as described above have excellent mechanical strength, and there is no energy loss of the transmitted beam due to diffraction.

It is a figure which illustrates a fine periodic structure illustratively. It is a figure for demonstrating the transcription | transfer pattern of the metal mold | die for forming a fine periodic structure. It is a figure for demonstrating the fine periodic structure of the comparative example with respect to the Example of an antireflection optical element. It is a figure for demonstrating a laser light source device. It is a figure which shows the spectral transmittance characteristic of a comparative example. It is a figure which shows the spectral transmittance characteristic of the antireflection optical element containing an Example.

Hereinafter, embodiments will be described.
First, formation of a fine periodic structure will be described.
As described above, the period of the fine periodic structure is in the sub-wavelength region, and the wavelength to be antireflection is as small as 100 nm, but can be formed as follows.
That is, the shape transfer by the mold and the etching are combined.

A case where a fine periodic structure of the type shown in FIG.
As an inorganic optical material for forming a fine periodic structure, a “quartz glass” made of parallel plates is assumed.
The first manufacturing step is the production of a mold.
As the mold material, for example, a silicon substrate having a diameter of 100 mm is used, and a large number of transfer patterns are formed on one surface thereof. The size of one transfer pattern is, for example, “5 mm × 5 mm”, and about 200 transfer patterns are formed on one silicon substrate.

The transfer pattern is formed using a “FIBSEM apparatus” to obtain a line-and-space pattern having a cross-sectional shape as shown in FIG. 2 in which the irregularities of the fine periodic structure shown in FIG.
The portions indicated by reference numerals M1-1, M1-2, and M1-3 in the transfer pattern shown in FIG. 2 correspond to the top portions 1-1, 1-2, 1-3, etc. of the first concavo-convex structure in the desired fine periodic structure. The portions denoted by reference numerals M2-1, M2-2, and M2-3 are portions corresponding to the top portions 2-1, 2-2, 2-3, etc. of the second concavo-convex structure in the desired fine periodic structure. It is.

The surface of the mold manufactured as described above is “cleaned by caro cleaning using a mixed solution of sulfuric acid and hydrogen peroxide solution”, and further irradiated with excimer light (excimer laser light) while flowing oxygen gas (O ₂ ). Then, an “excimer treatment” for removing organic substances on the surface by oxidation is performed, and further a mold release treatment is performed with a fluorine-based mold release treatment agent.

  On the other hand, a “silane coupling process” is performed on one side of a parallel plate-like quartz glass (hereinafter referred to as “material substrate”) having the same size and shape as the silicon substrate. As a coupling treatment material, KBM503 (trade name, manufactured by Shin-Etsu Silicone Co., Ltd.) is dissolved in water, the material substrate is surface-treated, and then cured by heating.

  Thereafter, the substrate is washed with an organic solvent, leaving only “a single molecular layer of the coupling treatment material” on the surface of the material substrate.

  The material substrate that has been subjected to the above processing is set in a resin discharge device, and 0.3 mg is applied to one chip (one chip is one unit of an antireflection optical element) on the region where the transfer pattern is transferred. A curable resin (GRANDIC RC 8790, manufactured by Dainippon Ink Co., Ltd.) is applied by an inkjet method toward the center of the region.

  The mold is also set in the resin discharge device, and 0.3 mg of the ultraviolet curable resin is applied in the same manner for each transfer pattern.

Subsequently, the material substrate is placed on the mold so that the "transfer site coated with the UV curable resin" is aligned with each other, and the two are brought into close contact with each other by a pressure of 1 MPa by an automatic pressurizer, The ultraviolet curable resin is cured by irradiation with ultraviolet light at an energy density of 20000 mJ / cm ² .

  Next, the mold and the material substrate integrated with each other by the ultraviolet curable resin are set on a release jig, and the material substrate is separated from the mold. At this time, since the surface of the material substrate has been subjected to silane coupling treatment, it is firmly bonded to the ultraviolet curable resin, and the surface of the mold is subjected to release treatment with a fluorine-based release treatment agent. UV cured resin does not remain on the mold surface.

  Thus, a layer of “ultraviolet curable resin to which the transfer pattern on the mold surface is transferred” is integrated with the surface of the material substrate. The mold can be washed and used repeatedly.

Subsequently, the same quartz glass as the material substrate is used as a dummy substrate, set in the chamber, and the inside of the chamber is evacuated to 4.0 × 10 ⁻⁴ Torr or less. Thereafter, the upper electrode power of the RIE apparatus is set to 1250 watts, the power of the lower electrode (RF) is set to 50 watts, CHF ₃ is supplied at 17 Sccm, and etching is performed for 5 minutes.

Next, the dummy substrate is taken out from the chamber, and instead, the material substrate integrated with the ultraviolet curable resin to which the transfer pattern is transferred is set in the chamber, and the inside of the chamber is 4.0 × 10 ⁻⁴ Torr or less. Exhaust.

Thereafter, the upper electrode power of the RIE apparatus is set to 1250 watts, the power of the lower electrode (RF) is set to 300 watts, CHF ₃ is supplied at 17 Sccm, dry etching is performed for 120 seconds, and the transferred pattern is transferred onto the ultraviolet curable resin. Is transferred to the surface of the material substrate. Dry etching “over-etches” until the UV curable resin is completely removed.

  In this way, “a large number of antireflection optical elements having the fine periodic structure of the type shown in FIG. 1A as a line-and-space pattern” is obtained. Hereinafter, an antireflection optical element is obtained by separating each element for each chip.

By the manufacturing method as described above, the following five types of fine periodic structures of the type shown in FIG. 1A were formed by using parallel plate-like quartz glass as a substrate material.
In each example, the period of the first uneven structure: P was 200 nm, the height of the structural unit: H1 was 300 nm, and the width: D was 140 nm.
The height of the structural unit of the second concavo-convex structure: H2 was changed as in the following five examples.
Example 1 (Structure A) H2 = 60 nm
Example 2 (Structure B) H2 = 120 nm
Example 3 (Structure C) H2 = 180 nm
Example 4 (Structure D) H2 = 240 nm
Example 5 (Structure E) H2 = 300 nm.

Since the period: P = 200 nm and the width: D = 140 nm,
PD = 60 nm, D / 2 = 70
These are the satisfactory conditions for an anti-reflection optical element:
0 <P−D ≦ D / 2
Satisfied.

Meanwhile, conditions:
0.4H1 ≦ H2 ≦ 0.8H1
The structures: BD are satisfied.
On the other hand, two “antireflection optical elements” having a fine periodic structure as shown in FIG.
As shown in FIG. 3, in the fine periodic structure of the comparative example, the height of the second concavo-convex structure of the fine periodic structure of the type shown in FIG. The “part” is a flat surface. In addition, the inorganic optical material as a material is quartz glass like the thing of the said Example.

  As shown in FIG. 3, it is assumed that the arrangement period of the triangular cross section is P0, the height is H0, and the width is D0.

First comparative example (Structure 1)
H0 = 300nm
D0 = 105nm
P0 = 150 nm.

Second comparative example (Structure 2)
H0 = 300nm
D0 = 140 nm
P0 = 200 nm.
Spectral transmittance was examined for the structures A to E and structures 1 and 2.
First, spectral transmittances for the structures 1 and 2 are shown in FIG.
Structure 1 exhibits extremely good transmittance characteristics of 99% or more in a wide wavelength region of wavelength: 220 nm or more. This is because the period of the fine periodic structure is as extremely small as P = 150 nm. Incidentally, for the wavelength: 266 nm, it is 0.996 (= 99.6%).

  The structure 2 exhibits good transmittance characteristics for light with a wavelength of 300 nm or more, which is not inferior to that of the structure 1, but the transmittance is lowered for light with a wavelength of 300 nm or less. The reflectance of quartz glass, which is an inorganic optical material, is 0.04 with respect to the wavelength: 266 nm, and the transmittance is 96%.

  In the case of the structure 2, the transmittance with respect to the wavelength: 266 nm does not reach 97%, and there are few merits of forming a fine periodic structure.

FIG. 6 shows the spectral transmittance characteristics of the structures A to E mentioned as examples.
All of the structures A to E show good transmittance characteristics in the wavelength region of 300 nm or more, but when viewed in the wavelength range of 250 to 300 nm, the structures B to E are excellent, and the value at the wavelength of 266 nm. Is 0.977 in the structure B, 0.986 in the structure C, 0.989 in the structure D, and 0.99 in the structure E, which are extremely excellent.

  Accordingly, the structure 1 in the comparative example and the structures B to E in the example are superior in terms of spectral transmittance characteristics.

  Next, the mechanical strength of these structures 1, 2, and A to E was examined as follows. Since the fine periodic structure is extremely fine, it is difficult to examine the strength by applying a physical external force, so that ultrasonic waves with a frequency of 46 KHz are obtained by an ultrasonic cleaner (VS-700 manufactured by ASONE). After 10 minutes exposure, the state of the fine periodic structure was evaluated by a method of examining with a microscope.

  As a result, in structure 2 and structures A to D, no change was observed in the fine periodic structure, but in structure 1 and structure E, “defects” on the order of several μm were recognized.

  In terms of the difficulty of manufacturing each structure, the structure 1 is difficult to manufacture because the period P of the fine periodic structure is as small as 150 nm. Other structures are easy to make.

The above results can be summarized as follows.
The transmittance characteristics, the mechanical strength, and the production difficulty are indicated by “very good”, “good”, and “bad”.

Structure Transmission characteristics Mechanical strength Production difficulty
1 Very good Defect Defect
2 Good Good Good
A Defect Good Good Good
B Good Good Good
C Good Good Good
D Good Good Good
E Very good, bad, bad.

  Based on this result, it can be seen that the structures B to D shown in the examples are suitable from the viewpoint of transmittance characteristics, mechanical strength, and manufacturability.

That is, the structures B to D are antireflection optical elements in which a one-dimensional fine periodic structure having a triangular cross section is formed on the surface of a substrate made of an inorganic optical material and has an antireflection effect within a predetermined wavelength region. The fine periodic structure includes a first concavo-convex structure in which structural units having a height: H1, a width: D, and a mountain-shaped triangular cross section are arranged with a period: P1 (> D1), and the first concavo-convex structure. Between structural units, the height of irregularities: H2
0.4H1 ≦ H2 ≦ 0.8H1
The second concavo-convex structure is formed by the structural unit having a triangular triangular cross section, and the width of the structural unit in the first concavo-convex structure: D is a period: P
0 <P−D ≦ D / 2
And the period P is shorter than the shortest wavelength in the wavelength region, and the first and second concavo-convex structures form a wedge-shaped concave portion without a flat portion, and generate diffracted light for the shortest wavelength. It has a periodic structure that does not.

  Further, the inorganic optical material is quartz glass, the height of the structural unit of the first concavo-convex structure: H1 and the period: P1 is 100 nm to 200 nm, and the structural unit of the second concavo-convex structure is the first concavo-convex structure. One is formed between adjacent structural units, and the transmittance for light with a wavelength of 266 nm is 97% or more.

  FIG. 4 is a diagram showing an embodiment of the laser light source device.

  This laser light source device is for a laser processing apparatus, a YAG laser light source 41, a wavelength conversion element 43 that converts the wavelength of a laser beam from the YAG laser light source 41 into a wavelength suitable for processing, a YAG laser light source 41, and a wavelength conversion element 43. And a cover plate 47 that closes the laser beam emission hole 45A opened in the casing 45 and transmits the laser beam (wavelength: 266 nm) wavelength-converted by the wavelength conversion element 43.

As the cover plate 47, an antireflection optical element having any one of the structures B to D described above is used.
Since the antireflection optical element having the structures B to D is excellent in mechanical strength, it can be provided “exposed” on the outer wall of the casing 43 as shown in FIG. 4, and the light source device can be easily handled.
Further, since the reflectivity is extremely low, there is substantially no return light reflected by the cover plate 47 and returning to the YAG laser light source 41, and a decrease in oscillation efficiency due to the return light can be prevented. Further, by sealing the inside of the casing, the adhesion of dust and the like to the YAG laser light source 41 and the wavelength conversion element 43 is reduced, and the generation failure of the element is reduced.

1-1, 1-2, 1-3 Structural units forming the first concavo-convex structure
2-2, 2-2, 2-3 Structural unit forming the second uneven structure

WO2005 / 010572 Publication JP 2006-185562 A

Claims (3)

An anti-reflection optical element having a one-dimensional fine periodic structure with a triangular cross section on the surface of a substrate made of an inorganic optical material and having an anti-reflection effect within a predetermined wavelength region,
The fine periodic structure includes a first concavo-convex structure formed by arranging structural units having a height: H1, a width: D, and a cross-sectional angle triangle with a period: P (> D), and an adjacent structure in the first concavo-convex structure. Between units, the height of the unevenness: H2
0.4H1 ≦ H2 ≦ 0.8H1
The second concavo-convex structure is formed by the structural unit having a triangular triangular cross-section satisfying
The width of the structural unit in the first concavo-convex structure : D is the period: P ,
0 <P−D ≦ D / 2
And the period P is shorter than the shortest wavelength in the wavelength region,
The antireflection optical element, wherein the first and second concavo-convex structures have a periodic structure that forms a wedge-shaped concave portion without a flat portion and does not generate diffracted light with respect to the shortest wavelength. The antireflection optical element according to claim 1,
The inorganic optical material is quartz glass,
The height of the structural unit of the first concavo-convex structure: H1 and the period: P is 100 nm to 200 nm,
One structural unit of the second uneven structure is formed between adjacent structural units of the first uneven structure,
An antireflection optical element having a transmittance of 97% or more for light having a wavelength of 266 nm. A laser light source device for a laser processing device,
A YAG laser light source;
A wavelength conversion element that converts the wavelength of the laser beam from the YAG laser light source into a wavelength suitable for processing;
A casing for housing the YAG laser light source and the wavelength conversion element;
A cover plate for closing the laser beam emission hole opened in the casing and transmitting the laser beam wavelength-converted by the wavelength conversion element;
A laser light source device using the antireflection optical element according to claim 1 or 2 as the cover plate.

Images