JP2023015179A - Reformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily manufacture an LEO stable in quality.

SOLUTION: A reformer for reforming an irradiating place of a light beam by causing multiphoton absorption by irradiating a transparent substrate with the light beam, has: a light source for generating the light beam; an anisotropic condensation element having a condensation capacity for condensing the light beam only in a direction of one axis of two axes crossing in an advance direction of the light beam, and acting on the light beam from the light source; an isotropic condensation element having a condensation capacity for condensing a light beam of a parallel light flux to one point, and acting on the light beam passed through the anisotropic condensation element to form a linear beam having a focus linearly expanding in the direction crossing with the advance direction of the light beam; and a reflection element for reflecting the light beam passed through the anisotropic condensation element to guide it the isotropic condensation element, and moving the focus of the linear beam to a direction crossing with the focus expanding direction by changing a reflection angle.

SELECTED DRAWING: Figure 10

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to a reformer.

Unlike visible light, X-rays are difficult to use with direct incidence optics. For this reason, an oblique-incidence optical system is used that utilizes the fact that metal has a refractive index of less than 1 with respect to X-rays and is based on total internal reflection of a metal surface. Since the critical angle of total reflection in this case is as small as about 1 degree, in order to increase the effective area of the reflecting surface, a method is known in which a large number of metallic cylindrical reflecting mirrors with different diameters are arranged coaxially. ing.
Also, by observing X-rays other than visible light, it is possible to observe stars that are hotter than the sun. Since X-rays are absorbed by the atmosphere, it is impossible to observe them on the ground, and in order to observe them outside the atmosphere, it is necessary to install an X-ray focusing mirror on a spacecraft. However, the method of arranging a large number of metal cylindrical reflecting mirrors coaxially as described above increases the weight of the entire X-ray reflecting device (weight of 1 ton or more per 1 m2), so it cannot be used in space. In some cases, it interferes with transportation from the ground, so weight reduction is required.

Patent Literature 1 proposes an X-ray optical system base material that utilizes a silicon wafer wall surface formed by anisotropic etching as an X-ray reflecting mirror as an X-ray optical system base material that is lightweight and can be manufactured relatively easily. This method has the advantage that the mirror is more than an order of magnitude lighter than conventional mirrors because fine holes are made in a thin wafer, and that a large number of mirrors can be produced with a single etching. However, the holes that can be formed by anisotropic etching are limited to linear slit-shaped holes. Light performance is limited. Also, in order to approximate the ideal curved surface, the X-ray optical system is made small and arranged along the ideal curved surface, so a large number of X-ray optical systems are required, and the labor and cost required for manufacturing are large.

A lobster eye optical element (LEO) is known as an optical element having a mirror surface when viewed from any direction on the celestial sphere. LEO has the advantage of a wider observation range than the Wolter type optical system described in Patent Document 1.

Patent Document 2 discloses a configuration example of a lobster eye optical element (LEO). In addition, LEO, which has conventionally been used to observe an astronomical object, i.e., an object existing at infinity (x = ∞), can be replaced with a non-astronomical object, i.e., a finite distance LEO comparable to the lens radius R It is described as being applied to the imaging of objects present in (xR).

Japanese Patent No. 4025779 Japanese translation of PCT publication No. 2009-503506

According to the conventional manufacturing method of LEO, the LEO is manufactured through the following steps.
Step 1. A solid core material and a hollow clad material are provided.
Step 2. A core material is inserted into the clad material and integrated to create multiple assemblies.
Step 3. A plurality of assemblies are stretched and bundled to form a laminate.
Step 4. After slicing the laminate obtained in step 3 thinly in a direction orthogonal to the axial direction, it is bent to have a predetermined curvature.
Note that the following steps may be performed instead of the steps 3 and 4 above.
Step 3'. A laminate obtained by bundling a plurality of assemblies obtained in step 2 is bent so as to have a predetermined curvature.
Step 4'. The laminate after step 3' is thinly sliced in a direction orthogonal to the axial direction.

However, in such a manufacturing method, there is a problem that the quality is not stable because the element is mechanically deformed in the process of bundling the assembly and the process of bending the laminate after slicing. If there is a quality problem, the imaged image deviates from the ideal cross shape.
Accordingly, an object of the present invention is to produce LEO with stable quality and in a simple manner.

In order to solve the above problems, one aspect of the method for manufacturing a microhole optical element according to the present invention includes a transparent substrate and a plurality of aligned holes penetrating the transparent substrate, each of the holes extending in the depth direction. A plurality of linear first slit holes extending halfway in the thickness direction from the surface of the transparent substrate such that extension lines extend toward a common intersection point located outside the transparent substrate and intersect a common spherical surface centered on the intersection point. and linear second slit holes extending in a direction intersecting the first slit holes and reaching the rear surface of the transparent substrate, wherein the plurality of first slit holes are formed. For each formation location where the first slit hole extends, a linear beam whose focus linearly spreads in the direction in which the first slit hole extends is irradiated to the transparent substrate to cause multiphoton absorption, thereby modifying the location. 1. A modification step, and for each formation location where the plurality of second slit holes are formed, irradiate the transparent substrate with a linear beam whose focal point linearly spreads in the direction in which the second slit holes are formed, to irradiate the transparent substrate with multiple beams. A second modifying step of modifying the location by causing photon absorption, and removing the location modified in the first modifying step and the second modifying step to remove the first slit hole and the The method includes a removing step of forming a second slit hole and a reflecting layer forming step of forming a reflecting layer on the inner wall of each of the first slit hole and the second slit hole.

According to such a method for manufacturing a micro-hole optical element, slit holes with smooth wall surfaces are efficiently formed by linear beams, so that a so-called Schmidt-type LEO can be easily manufactured with stable quality.

In such a method for manufacturing a micro-hole optical element, the first modifying step and the second modifying step are performed by irradiating a beam from one side of the front and back surfaces of the transparent substrate to form the first slit hole and the above-mentioned slit hole. It is preferable to modify both the second slit holes. By modifying both the first slit hole portion and the second slit hole portion from one side of the transparent substrate, the step of turning over the transparent substrate can be omitted, thereby reducing the number of steps.

Further, in the method for manufacturing a microporous optical element in which both the first slit hole and the second slit hole are modified from one side of the transparent substrate, the first modification step and the second modification step are performed. Preferably, in the modifying step, of the first slit hole and the second slit hole, the slit positioned on the front side in the traveling direction of the beam is modified first. According to this manufacturing method, since disturbance of the beam due to the modified portion is avoided, the accuracy of the modified portion is improved.

Further, in the method for manufacturing a micro-hole optical element, the direction in which the focal point of the linear beam spreads and the direction in which the second slit hole extends are changed between the first modifying step and the second modifying step. Alternatively, between the first modifying step and the second modifying step, the direction in which the focal point of the linear beam spreads and the above A beam rotation step of rotating the linear beam so as to match the direction in which the second slit hole extends may be provided.

Having a substrate rotation step avoids moving the precision optics. Also, providing a beam rotation step avoids moving the transparent substrate, which is preferable when a large and heavy transparent substrate is used.

Further, in the method for manufacturing a micro-hole optical element, the linear beam is an anisotropic condensing element having a condensing ability to converge the light beam only in one of two axes that intersect with the traveling direction of the light beam. and an isotropic light condensing element having a light condensing ability for condensing a parallel light beam to one point. By combining such elements, a linear beam with a narrow and long linear focal point can be obtained.

Further, in the method for manufacturing a micro-hole optical element, at least one of the first modifying step and the second modifying step includes irradiating the transparent substrate with the linear beam and the irradiation position of the linear beam. It is also preferable that the step of reforming each of the plurality of formation locations extending in parallel with each other by repeating the change of . According to this manufacturing method, it is possible to modify the formation locations of the plurality of slit holes with one or a small number of linear beams.
Further, in the manufacturing method in which the irradiation of the linear beam and the change of the irradiation position of the linear beam are repeated in this manner, the change of the irradiation position of the linear beam is performed by the reflection of the reflecting element that reflects the linear beam. More preferably, it is done by changing the angle of the plane. According to this manufacturing method, the movement of the linear beam with respect to each of the plurality of slit holes is easily realized by the reflecting element.

Further, in the method for manufacturing a micro-hole optical element, at least one of the first modifying step and the second modifying step includes modifying the formation location in the partial region on the transparent substrate, and It is also preferable to repeat the above movement of the partial area to improve the formation location of the slit hole extending longer than the spread of the focal point in the linear beam. According to such a manufacturing method, it is possible to form a slit hole longer than the spread of the focal point of the linear beam.

Further, in the manufacturing method in which the modification and the movement of the partial region are repeated, the movement of the partial region includes movement in a direction in which the focus of the linear beam spreads and movement in a direction intersecting with the direction. It is further preferable to perform modification over the range in which the partial regions are two-dimensionally arranged. According to such a manufacturing method, it is possible to easily deal with large-area transparent substrates.

Further, as the movement of the partial areas, the partial areas may be moved by a distance such that the partial areas are adjacent to each other or partially overlapped with each other, or the partial areas may be moved by a distance such that there is an interval between the partial areas. good too. When the regions are adjacent to each other or partially overlap, the continuity of the slit holes can be easily maintained. can be avoided.

In order to solve the above-mentioned problems, one aspect of a modification apparatus according to the present invention is a modification apparatus that modifies a portion irradiated with a light beam by irradiating a transparent substrate with a light beam to cause multiphoton absorption. having a light source that generates a light beam and a light collecting ability to collect the light beam only in one of two axes that intersect with the traveling direction of the light beam, and the light beam from the light source It has an acting anisotropic light condensing element and a light condensing ability of condensing a parallel light beam to one point, and by acting on the light beam that has passed through the anisotropic light condensing element, a direction that intersects the traveling direction of the light beam. The isotropic light condensing element that forms a linear beam whose focal point linearly spreads toward the center, and the light beam that has passed through the anisotropic light condensing element is reflected and guided to the isotropic light condensing element. a reflective element that moves the focal point of the focal point in a direction intersecting the direction in which the focal point spreads.

According to such a modification apparatus, the combination of the anisotropic condensing element and the isotropic condensing element forms a linear beam with a narrow and long line whose focal point is widened, and the reflective element irradiates the linear beam. Locations are easily changed.

In such a modifying apparatus, the transparent substrate is held and moved along the direction of travel of the light beam irradiated to the transparent substrate, so that the portion to be modified by the light beam is moved in the direction of travel. It is preferred to have a substrate holder extending along. By moving the transparent substrate by the substrate holding table, the modified portion can be easily extended forward and backward in the traveling direction of the light beam.

According to the present invention, LEO can be produced easily with stable quality.

1 is a diagram conceptually showing a micro-hole optical element; FIG. FIG. 4 is an enlarged perspective view schematically showing the structure of a slit hole; FIG. 4 is a cross-sectional view showing the structure of a slit hole for one stage; It is a figure which shows the direction of each slit hole in a microhole optical element. FIG. 4 is an explanatory diagram of a light condensing action in LEO; It is a figure which shows the ideal condensing image in LEO. It is a figure which shows the condensing form of the light which injected into the microhole optical element from a different direction. It is a figure which shows a property modification process. It is a figure which shows an etching process, a grinding|polishing process, and a reflective layer formation process. It is a front view of a laser modification apparatus. FIG. 4 is a view of the laser modification device viewed in the −Y direction; It is the figure which looked at the laser modification apparatus in the -X direction. It is a figure which shows the luminous flux change in the direction in XY plane. It is a figure which shows the luminous flux change in a Z direction. It is a figure which shows the detail of the modification process performed with a laser modification apparatus. Fig. 2 shows an optical device incorporating a microhole optical element; It is an assembly drawing of the optical system portion of the optical device. FIG. 4 is a cross-sectional view showing a method of fixing a microhole optical element to a frame; FIG. 4 is a front view showing a method of fixing the microhole optical element to the frame; It is a figure which shows the laser modification apparatus of 2nd Embodiment. FIG. 10 is a diagram showing a first example of a modification process for a large transparent substrate; FIG. 10 is a diagram showing a second example of a modification process for a large transparent substrate; FIG. 10 is a diagram showing a third example of a modification process for a large transparent substrate;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram conceptually showing a micro-hole optical element. FIG. 1 shows a front view (A) and a side view (B).

The microhole optical element 1 is a so-called Schmidt-type lobster-eye optical element (LEO), and has a rectangular outer shape with a side of 40 mm and a thickness of 1 mm, for example. It has a structure in which an upper slit hole 3a and a lower slit hole 3b having a depth of 0.5 mm, for example, are formed. The transparent substrate 2 is made of, for example, glass or transparent resin, and in particular, if it is made of fused quartz glass, the slit holes 3a and 3b can be easily processed in the manufacturing method described later.

In FIG. 1, the density of the slit holes 3a and 3b is drawn more coarsely than it actually is, and the actual slit width of each of the slit holes 3a and 3b is, for example, 20 μm or more and 200 μm. The width of the portion of the glass or resin that contacts is, for example, 6 .mu.m or more and 30 .mu.m or less.
FIG. 2 is an enlarged perspective view schematically showing the structure of the slit holes 3a and 3b.

The upper (upper in FIG. 2) slit hole 3a and the lower (lower in FIG. 2) slit hole 3b extend, for example, in directions perpendicular to each other. In addition, a through hole is substantially formed in the micro-hole optical element 1 by passing through the two stages of the slit holes 3a and 3b. Light such as X-rays and vacuum ultraviolet rays is incident on the fine hole optical element 1 from the upper side, and light is emitted from the lower side.
FIG. 3 is a sectional view showing the structure of the slit holes 3a and 3b for one stage.

The light L is incident on the slit holes 3a and 3b from the upper side of the figure, and the light L is emitted to the lower side of the figure. The ratio h1/h2 between the length h1 of the slit holes 3a and 3b in the traveling direction of the light L and the width h2 of the hole where the light L is emitted from the slit holes 3a and 3b is a large value such as 20 or more and 50 or less. It's becoming

A metallic reflective layer 4 is formed on the inner wall of each of the slit holes 3a and 3b. The reflective layer 4 is, for example, a single layer film or a multilayer film made of a heavy metal such as hafnium oxide. The light L incident on each of the slit holes 3a and 3b is reflected by the reflective layer 4 0 to 2 times depending on the incident angle of the light L on the slit holes 3a and 3b.

Examples of materials for the reflective layer 4 include, in addition to hafnium oxide, oxides such as tantalum oxide, titanium oxide, lanthanum oxide, and zinc oxide; nitrides such as titanium nitride, tantalum nitride, and hafnium nitride; , rubidium, copper, tungsten, molybdenum, platinum, iridium and gold. The reflective layer 4 of a single layer film is formed with a film thickness of, for example, several hundred to several thousand angstroms.

Moreover, the reflective layer 4 may be a multilayer film composed of a thin film of heavy metal and a thin film of light metal, and in this case, the outermost layer is composed of a thin film of heavy metal. Aluminum oxide, for example, is used as the light metal thin film, but silicon oxide may also be used. Furthermore, the reflective layer 4 may be a multi-layer film of pair materials such as platinum/carbon, molybdenum/silicon, tungsten/silicon, and the like. In the case of multilayer films made of these pair materials, several tens to several hundred layers are laminated with a film thickness of several tens of angstroms per pair. It is a type optical element (LEO) and can focus the light L.
FIG. 4 is a diagram showing the directions of the slit holes 3a and 3b in the microhole optical element 1. FIG.

In the slit holes 3a and 3b in the micro-hole optical element 1, each extension line M in the depth direction faces a common intersection point P with respect to the slit holes 3a and 3b. As a result, each extension line M converges at a common intersection point P. FIG. Further, a spherical surface S having a radius of 100 mm or more and 1000 mm or less centered on the common intersection point P intersects with each of the slit holes 3a and 3b. Such an arrangement of the slit holes 3a and 3b is the arrangement in a so-called lobster eye type optical element (LEO), and the light reflected by the inner walls of the slit holes 3a and 3b is collected as described below.
FIG. 5 is an explanatory diagram of the condensing action in LEO.

In the microhole optical element 1 which is LEO, as described above, the light L is reflected 0 to 2 times by the inner walls (the reflection layers 4 thereof) of the slit holes 3a and 3b, and the light L is reflected in a condensing pattern corresponding to the reflection pattern. is focused. Here, it is assumed that light L is incident on the micro-hole optical element 1 in parallel from the same direction. Even if the light L is incident on the micro-hole optical element 1 in parallel from the same direction, the reflection pattern changes depending on the point of incidence.

For example, the light Ld that has been reflected zero times by the inner walls of the slit holes 3a and 3b (that is, the light Ld that has passed through the two stages of the slit holes 3a and 3b without being reflected) travels in the direction of incidence as it is and onto the focal plane FP. reaches each place without being focused.

In addition, the light Lb reflected once by the inner wall of the upper slit hole 3a of the two slit holes 3a and 3b is condensed in the horizontal direction of the drawing, and remains in the incident direction, the light is condensed in a linear region extending in the vertical direction of the figure.

The light Lc reflected once by the inner wall of the lower slit hole 3b of the two slit holes 3a and 3b is condensed in the vertical direction of the figure (the depth direction of the paper surface), and is condensed in the horizontal direction of the figure. remains in the incident direction, the light is condensed in a linear region extending in the lateral direction of the figure.
Also, the light La reflected twice in total by the inner walls of the two-tiered slit holes 3a and 3b, once each, is condensed in both the vertical and horizontal directions, so that it is condensed into a point at the center.
FIG. 6 is a diagram showing an ideal condensed image in LEO.

As a result of the reflection pattern described above, the luminous flux incident on the micro-perforated optical element 1 from the same incident direction forms a cross-shaped condensed image on the condensing surface FP. That is, on the light-condensing surface FP, a halo H that spreads over the cross-shaped background, a light-collecting line FL forming the vertical and horizontal crosses, and a light-condensing spot FS positioned at the center of the cross are formed. Light from a point light source, for example, is detected by measuring such a condensed light image with a light receiving device.
7A and 7B are diagrams showing condensing forms of light incident on the micro-hole optical element 1 from different directions.
Here, as an example, lights L1, L2, and L3 that enter the micro-hole optical element 1 from each of three directions are shown.

Lights L1, L2, L3 from each direction are reflected by the reflection layer 4 of each of the slit holes 3a, 3b that intersect the common spherical surface S, and are condensed at different points on the focal plane FP. The above-described cross-shaped condensed light pattern is formed at each spot where the light is condensed.

In other words, the slit holes 3a and 3b that intersect the common spherical surface S are arranged along the spherical surface S, and the focal plane FP is spherical. Also, the radius of the focal plane FP is half the radius R of the common spherical surface S.
As described above, the microhole optical element 1, which is LEO, can similarly collect any of the lights L1, L2, and L3 incident from each direction, and thus has a wide field of view.

Next, the manufacturing process of this embodiment for manufacturing such a micro-hole optical element 1 will be described. This manufacturing process includes a modification process, an etching process, a polishing process, and a reflective layer forming process.
FIG. 8 is a diagram showing the reforming process.
The reforming process shown in FIG. 8 includes a first reforming process (A-1) and a second reforming process (A-2).

In the first modification step (A-1), the transparent substrate 2 is irradiated with a linear beam pulsed laser beam PL having a linearly expanded focal point, and the linear irradiation area on the transparent substrate 2 is irradiated with the pulsed laser beam PL. modified at the same time. The position, angle, and depth of the irradiation area of the pulsed laser beam PL are determined based on the CAD data of one of the above-described two-step slit holes.

In this embodiment, the modification of the transparent substrate 2 is realized by multiphoton absorption in the pulsed laser beam PL. When multiphoton absorption occurs in the transparent substrate 2, the portion where the multiphoton absorption occurs is specifically modified. When the transparent substrate 2 is, for example, a glass substrate, the local structure due to the bonding of silicon (Si) atoms and oxygen (O) atoms is divided by multiphoton absorption, causing structural changes, etc., and is in a state of being susceptible to chemical reactions. becomes. Further, when the transparent substrate 2 is a glass substrate, the energy required to modify the property by generating multiphoton absorption is 0.2 to 2 μJ, and a laser that causes destructive effects such as ablation. Less energy than required for processing. In addition, since the linear irradiation area is simultaneously modified by the linear beam, the boundary between the modified region and the modified region becomes a smooth boundary with little unevenness, and the productivity is high.

In the second modification step (A-2), the pulsed laser beam PL or the transparent substrate 2 is rotated, for example, 90 degrees with respect to the first modification step (A-1), and the other slit of the two-stage slit hole A linear irradiation area corresponding to the hole is modified by the pulsed laser beam PL.
Details of the reforming step will be described later.
FIG. 9 is a diagram showing an etching process, a polishing process, and a reflective layer forming process.

In the etching step (B), the transparent substrate 2 is immersed in an etchant 5, and the modified region 2a is selectively removed by etching. If the transparent substrate 2 is, for example, a glass substrate, the etchant 5 may be a hydrofluoric acid (HF) solution or a potassium hydroxide solution.

In the present embodiment, wet etching, which is less time-consuming, is used as the etching process, but dry etching using a fluorine (F2)-based gas can also be used as the etching process. In addition, in this embodiment, ultrasonic cleaning, in which ultrasonic waves W are applied to the transparent substrate 2 in the etchant 5, is also used in order to stabilize and expedite the processing. The etching conditions are such that the HF concentration is, for example, 2.5 to 5%, and the etching time is, for example, one hour to several hours, depending on the size of the transparent substrate 2 . The etching time is shortened by vibrating the transparent substrate 2 with the ultrasonic waves W during the etching process.

In the etching step (B), the etchant 5 reacts with the transparent substrate 2 also in the portions other than the modified region 2a, but the etching rate differs greatly between the modified region 2a and the region 2b other than the modified region 2a. Therefore, the modified region 2a is completely removed immediately after the etching step (B) is started, and the slit holes 3a and 3b are formed.

Although FIG. 9 shows the state in which the modified region 2a penetrates the transparent substrate 2 for the sake of simplicity of explanation, in reality, the upper and lower two stages corresponding to the two upper and lower slit holes 3a and 3b are shown. are formed, and the two upper and lower modified regions 2a are connected in the transparent substrate 2 .

In this way, the shape and shape of the slit holes 3a and 3b are changed through the modification process using the multiphoton absorption phenomenon using a pulse laser and the etching process (B) for selectively removing the modified region 2a. The depth and the like can be easily controlled, and the damage to the transparent substrate 2 is less than when the transparent substrate 2 is physically drilled. In addition, since the linear beam of the pulsed laser beam PL is used, the slit holes 3a and 3b having smooth inner wall surfaces can be easily obtained.

In the polishing step (C), a mixture 6 of a magnetic fluid and an abrasive is used to smooth the sidewalls of the slit holes 3a and 3b. A magnetic fluid is a fluid whose viscosity changes when a magnetic field is applied, and has already been put into practical use for polishing optical parts and the like. Specifically, a mixed liquid 6 of a magnetic fluid with an average particle size of about 0.01 μm and a diamond slurry with a particle size of, for example, 1 μm is poured into the slit holes 3a and 3b, and a variable magnetic field is generated perpendicularly to the transparent substrate 2. is applied.

The liquid mixture 6 moves randomly within the slit holes 3a and 3b3 according to the fluctuation of the magnetic field. It is also possible to rotate the transparent substrate 2 around the central axis to promote relative movement between the liquid mixture 6 and the sidewalls of the slit holes 3a and 3b. By polishing the side wall surfaces of the slit holes 3a and 3b with the mixed liquid 6, the roughness of the side wall surfaces is smoothed, and a surface roughness of 1 to 2 nm, for example, is achieved.

In the reflective layer forming step (D), the transparent substrate 2 is placed in a mixed gas 7 of metal vapor and reactant, and a metal reflective layer 4 is formed on the inner walls of the slit holes 3a and 3b by atomic layer deposition (ALD). It is formed. In the atomic layer deposition method, one atomic layer is formed on the entire inner walls of the slit holes 3a and 3b, so the reflective layer 4 is uniformly formed even in the slit holes 3a and 3b having a high aspect ratio.
By such a manufacturing method, the micro-hole optical element 1 shown in FIG. 1 is realized.
Next, the modification process mentioned above will be described in more detail.
10 to 12 are diagrams showing the structure of the laser modification apparatus 10 of the first embodiment that performs the modification process shown in FIG.

FIG. 10 shows a front view of the laser modification apparatus 10, and XYZ coordinate axes are shown in FIG. That is, the right direction in FIG. 10 is the X direction, the downward direction in FIG. 10 is the Y direction, and the front direction perpendicular to the plane of FIG. 10 is the Z direction. In the following description of directions in the laser modification apparatus 10, these coordinate axes will be used.
FIG. 11 shows a view of the laser modification device 10 viewed in the -Y direction, and FIG. 12 shows a view of the laser modification device 10 viewed in the -X direction.

The laser modification device 10 has a laser oscillator 101 that emits a pulsed laser beam PL. As the laser oscillator 101, one having a pulse width of, for example, 200 fs or more and 500 fs or less, a pulse energy of 1 μJ or less, and a repetition frequency of 5 MHz or less is used. Since such a laser oscillator 101 emits an ultrashort pulse laser beam having a high peak power, the pulsed laser beam is focused on the transparent substrate 2 such as glass, so that nonlinearity such as multiphoton absorption can easily occur. produce an effect.

The laser modification apparatus 10 includes a beam expansion system 102 , a cylindrical lens 103 , a galvanomirror 104 , a relay lens system 106 , an objective lens 107 also called a diaphragm lens, and a movable stage 108 .

A pulsed laser beam PL emitted from a laser oscillator 101 in the −X direction is incident on a beam expansion system 102 .

The cylindrical lens 103 is an optical element that does not have a curved surface when viewed in the Z direction and has an arcuate curved surface when viewed in the Y direction. With such a shape, the cylindrical lens 103 converges the pulsed laser beam PL, which travels in the -X direction and spreads in the Z and Y directions, only in the Z direction. This cylindrical lens 103 corresponds to an example of the first condensing element according to the present invention.

The galvanomirror 104 is provided in the vicinity of the condensing position of the pulsed laser beam PL by the cylindrical lens 103 . The galvanomirror 104 is a reflective element that can rotate around a rotation axis extending in the Z direction, and reflects the pulse laser beam PL toward the Y direction. Further, the rotation of the galvanomirror 104 changes the reflection angle of the pulse laser beam PL, and as indicated by the dotted line in FIG. 10, the course of the pulse laser beam PL is swung in the X direction.

Relay lens system 106 guides pulsed laser beam PL reflected by galvano mirror 104 to objective lens 107 . The relay lens system 106 can guide the pulsed laser beam PL to the objective lens 107 even if the course of the pulsed laser beam PL is deflected by the galvanomirror 104 .

The objective lens 107 is an optical element having the ability to converge a parallel light beam to one point, and corresponds to an example of the second condensing element according to the present invention. The objective lens 107 can condense light into a smaller point as the parallel light flux of the incident light beam becomes wider. When the objective lens 107 acts on the pulsed laser beam PL that has passed through the cylindrical lens 103, a linear beam whose focal point linearly extends in the Z direction is formed. Further, when the course of the pulsed laser beam PL is swung by the galvanomirror 104, the irradiation position of the linear beam formed by the objective lens 107 is swung in the X direction.

The movable stage 108 holds the transparent substrate 2 and can move the transparent substrate 2 in the X, Y, and Z directions. Furthermore, the movable stage 108 can also rotate the transparent substrate 2 around the Y-axis.
The principle of forming a linear beam by the optical system of the laser modification apparatus 10 will be further described.

13 and 14 are diagrams showing the principle of linear beam formation. FIG. 13 shows changes in luminous flux in the XY plane direction, and FIG. 14 shows changes in luminous flux in the Z direction. .

A pulsed laser beam PL emitted from a laser oscillator 101 is expanded in both the Y direction and the Z direction by passing through a beam expansion system 102 . As for the Z direction of the luminous flux, as shown in FIG. The condensing position of the pulse laser beam PL by the cylindrical lens 103 is near the reflecting surface of the galvanomirror 104, but the distance from the reflecting surface varies depending on the position of the light flux in the Y direction.

As shown in FIG. 13, the beam of the pulsed laser beam PL incident on the cylindrical lens 103 in the Y direction passes through the cylindrical lens 103 as a parallel beam without being condensed, and is reflected by the galvanomirror 104 . Due to the reflection, the spread of the luminous flux in the Y direction becomes the spread in the X direction.
Pulsed laser beam PL reflected by galvanomirror 104 is guided to objective lens 107 by relay lens system 106 .

As for the Z direction of the pulsed laser beam PL condensed by the cylindrical lens 103, as shown in FIG. When the pulsed laser beam PL condensed in this way is incident on the objective lens 107, the objective lens 107 acts to expand the luminous flux of the pulsed laser beam PL.

As shown in FIG. 13, the X-direction beam of the pulsed laser beam PL reflected by the galvanomirror 104 enters the relay lens system 106 in the form of a parallel beam. It enters the lens 107 in the form of a parallel beam. The objective lens 107 acts to converge the parallel pulsed laser beam PL at one point. Since the luminous flux is expanded by the beam expansion system 102, the NA value of the focusing system in the X direction becomes a large value such as 0.26, and the focused spot is small.

Due to the action of such an optical system, the pulsed laser beam PL is formed on the transparent substrate 2 on the movable stage 108 shown in FIG. will be irradiated.
Next, the details of the modification procedure of such a linear beam by the pulsed laser beam PL will be described.

As described above, the laser modification apparatus 10 shown in FIG. 10 includes a movable stage 108 that three-dimensionally moves the transparent substrate 2, and a galvanomirror 104 that swings a linear focal point extending in the Z direction in the X direction. I have. The movable stage 108 and the galvanomirror 104 converge the pulsed laser beam PL to a designated spot in the transparent substrate 2 to form a condensed spot.
15A and 15B are diagrams showing a procedure example of a modification process performed by the laser modification device 10. FIG.
FIG. 15 schematically shows a procedure from stage (A) to stage (F) as an example of the procedure for forming the modified region 2a in the transparent substrate 2 in the modifying process.

In stage (A), the movable stage 108 is positioned at the start position based on the CAD data, so that the pulse laser beam PL is focused just above the back surface of the transparent substrate 2, and the formation of the modified region 2a is started. be done. It is assumed that the focal point of the pulsed laser beam PL is expanded so as to be raised in the direction perpendicular to the paper surface of FIG. 15, and the modified region 2a is continuous in the direction perpendicular to the paper surface of FIG.

In stage (B), the movable stage 108 moves downward in the figure at an angle at which the slit hole extends, so that the focal point of the pulsed laser beam PL moves toward the inside of the transparent substrate 2, and as a result, the modified region 2a extends to the inner side of the transparent substrate 2; Since the modified region 2a extends from the front side to the rear side of the pulse laser beam PL, the beam is prevented from being disturbed by the modified portion, so that the precision of the modified portion is improved. The movement of the movable stage 108 is continued until the modified region 2a reaches half the thickness of the transparent substrate 2, for example.

In step (C), the pulsed laser beam PL is temporarily stopped, the irradiation position of the pulsed laser beam PL is swung by the galvanomirror 104 (see FIG. 10, etc.), and steps similar to steps (A) and (B) are performed. By performing, a plurality of modified regions 2a are formed. The angle at which each modified region 2a extends into the transparent substrate 2 differs for each modified region 2a.
Steps (A) to (C) are procedures corresponding to the first reforming step (A-1) shown in FIG.

Here, the change of the irradiation position of the pulse laser beam PL by the galvanomirror is used to change the position of the modified region 2a, but the change of the irradiation position by the galvanomirror is the width of the modified region 2a (that is, the slit hole width).
In stage (D), the movable stage 108 is rotated, for example, by 90 degrees, and the direction of spread of the focal point of the pulse laser beam PL with respect to the transparent substrate 2 is changed.

In step (E), the pulsed laser beam PL is focused just above the depth of the transparent substrate 2 that has been modified in steps (A) to (C), and the unmodified depth of the transparent substrate 2 is Formation of the modified region 2a on the part is started. By moving the movable stage 108 downward in the figure at an angle at which the slit hole extends, the focal point of the pulsed laser beam PL moves to the surface side of the transparent substrate 2 , and as a result, the modified region 2 a is formed on the transparent substrate 2 . extending to the surface.

In stage (F), similar to stage (C), the temporary stop of the pulsed laser beam PL, the change of the irradiation position by the galvanomirror 104, and the formation of the modified region 2a are repeated to obtain a plurality of modified regions. A region 2a is formed.
Steps (D) to (F) are procedures corresponding to the second reforming step (A-2) shown in FIG.
Both the modification corresponding to the first modification step (A-1) and the modification corresponding to the second modification step (A-2) are performed by irradiation from one side of the transparent substrate 2. , the number of steps is reduced because the step of turning over the transparent substrate 2 is omitted.

Through the above procedure, the modified regions 2a corresponding to the slit holes 3a and 3b arranged as shown in FIG. 1 and having the shape shown in FIG. 2 and the orientations shown in FIG. 3 are formed. It will be.

As described above, in the method for manufacturing the microporous optical element 1 of the present embodiment, the slit holes 3a and 3b (and the reflective layer 4) having the ideal shape and orientation are formed in the transparent substrate 2 with high accuracy through a simple process. Therefore, no stress is applied to the transparent substrate 2 during the formation of the slit holes 3a and 3b (and the reflective layer 4). Therefore, the microhole optical element 1 has a wide field of view and high imaging performance (quality). In addition, since the slit holes 3a and 3b (and the reflective layer 4) with high accuracy are formed with high productivity by using the linear beam, the productivity of the fine hole optical element 1 is also high.
Next, an optical device in which the micro-hole optical element 1 manufactured in this manner is incorporated will be described.
FIG. 16 is a diagram showing an optical device 100 in which the microhole optical element 1 is incorporated.
The optical device 100 is a device for observing celestial bodies, for example, and includes an optical system portion 110 and an electronic system portion 120 .

The electronic system section 120 has a light receiving device 121 at a position facing the optical system section 110 . The light receiving surface of the light receiving device 121 is a spherical surface along the focal plane FP described above. A main body portion 122 of the electronic system portion 120 incorporates a power source, a control circuit, and the like of the light receiving device 121 .

The optical system portion 110 has a frame 111 on which a plurality of microporous optical elements 1 are arranged and fixed, and the plurality of microporous optical elements 1 are supported by the frame 111 .
FIG. 17 is an assembly drawing of the optical system portion 110 of the optical device 100. As shown in FIG.

A frame hole 112 is provided in the frame 111 , and each microhole optical element 1 is associated with each frame hole 112 to mount the microhole optical element 1 . Transmitted light from each micro-hole optical element 1 passes through the frame hole 112 of the frame 111 and is condensed on the light receiving surface of the light receiving device 121 in the light condensing pattern described above.

The overall shape of the portion where the frame 111 supports each micro-hole optical element 1 is a spherical shape along the common spherical surface S described above, and each micro-hole optical element 1 is aligned with the common spherical surface S. are arranged and supported in a spherical shape along the As a result, the plurality of micro-hole optical elements 1 as a whole functions as one LEO, and a wide field of view of, for example, 30 degrees is realized. In other words, by arranging the plate-shaped micro-hole optical element 1 in a spherical shape, an optical device with a wide field of view that is easy to manufacture is realized.
18 and 19 are diagrams showing a method of fixing the microhole optical element 1 to the frame 111. FIG. 18 shows a sectional view, and FIG. 19 shows a front view.

The square corner portions of the micro-hole optical element 1 are pressed by pressing members 113 , and the pressing members 113 are fixed to the frame 111 by pins 114 . With such a fixing structure, the micro-hole optical element 1 is fixed to the frame 111 in a state in which the area where the through hole 3 is provided and which contributes to light collection is widely exposed to light.
Next, the laser modification device of the second embodiment will be described.
FIG. 20 is a diagram showing the laser modification device 11 of the second embodiment.

As with the laser modification apparatus 10 of the first embodiment, the laser modification apparatus 11 of the second embodiment includes a laser oscillator 101, a beam expanding system 102, a cylindrical lens 103, a relay lens system 106, an aperture It has an objective lens 107 , also called a lens, and a movable stage 108 .
The laser modification apparatus 11 of the second embodiment is provided with a rotation mechanism that rotates the cylindrical lens 103 around a rotation axis extending in the X direction.

Further, the laser modification device 11 of the second embodiment includes a first galvanomirror 105a and a second galvanomirror 105b instead of the galvanomirror 104 in the first embodiment. In the case of the second embodiment, the condensing position of the pulsed laser beam PL by the cylindrical lens 103 is intermediate between the first galvanomirror 105a and the second galvanomirror 105b. Also, the first galvanometer mirror 105a and the second galvanometer mirror 105b are preferably brought as close as possible, for example, within 100 mm.

The first galvanomirror 105a is a reflecting element that reflects the pulse laser beam PL in the Y direction, and is rotatable about a rotation axis extending in the Z direction. The first galvanomirror 105a can swing the traveling direction of the pulse laser beam PL by rotation, and as a result, the irradiation position on the transparent substrate 2 is swung in the X direction.

The second galvanomirror 105b reflects the pulse laser beam PL reflected by the first galvanomirror 105a in the -Z direction and directs it to the relay lens system 106. FIG. The second galvanomirror 105b is a reflective element rotatable around a rotation axis extending in the X direction. The second galvanomirror 105b can also swing the traveling direction of the pulse laser beam PL by rotation, and as a result, the irradiation position on the transparent substrate 2 swings in the Y direction.

The laser modification apparatus 11 of the second embodiment is also used in the modification process described with reference to FIGS. 8 and 15, but in the stage (D) shown in FIG. Rotation of the linear beam is performed by rotation of the cylindrical lens 103 . Due to the rotation of the linear beam, the direction in which the focal point of the pulsed laser beam PL is expanded rotates by 90 degrees with respect to the transparent substrate 2, for example.

When the irradiation position is changed by the galvanomirror as described in stages (C) and (F) shown in FIG. Either one of the first galvanometer mirror 105a and the second galvanometer mirror 105b is used depending on the spreading direction of the . That is, when the focus spreads in the Y direction, the irradiation position is changed by the first galvanomirror 105a, and when the focus spreads in the X direction, the irradiation position is changed by the second galvanomirror 105b. .

Even when such a laser modification apparatus 11 of the second embodiment is used, the slit holes 3a and 3b (and the reflective layer 4) with high accuracy are formed with high productivity by using the linear beam. The productivity of the hole optical element 1 is also high.

Next, another example of the reforming process will be described. In each example described below, a transparent substrate having a size larger than that of the above-described embodiment is used. Therefore, the extending length of the slit holes 3a and 3b is longer than the spread of the focal point of the pulse laser beam PL, and the plurality of slit holes 3a and 3b are arranged over a range wider than the deflection width of the galvanomirror.
The reachable range of the pulsed laser beam PL (that is, the spread and amplitude of the focal point) is limited by the field of view of the objective lens. In addition, it is necessary to use an objective lens with a high NA to produce a fine slit, and the higher the NA objective lens, the narrower the field of view. In general, the reach of the pulsed laser beam PL is about several millimeters to several tens of millimeters, but by using a large objective lens such as a semiconductor stepper lens, the pulse laser beam can reach a range of several tens of centimeters. It is possible to deliver PL. A large transparent substrate used in each example described below is a transparent substrate having a size exceeding this range of several tens of centimeters.
FIG. 21 is a diagram showing a first example of a modification process for a large transparent substrate 2. FIG.

In the first example shown in FIG. 21, for each of the first modification step (A-1) and the second modification step (A-2) shown in FIG. However, modification is performed every 25 substrate regions 20 in total. In each substrate region 20, an irradiation step in which a single modified region 2a is formed by continuously irradiating the linear beam of the pulsed laser beam PL while the movable stage 108 moves in the direction in which the slit hole extends; A plurality of modified regions 2a are formed by repeating a mirror rotation step in which the PL is temporarily stopped and the irradiation position of the pulse laser beam PL is changed by rotating the galvanomirror.
When the formation of the plurality of modified regions 2a in one substrate region 20 is completed, the next substrate region 20 becomes the target of modification by moving the movable stage 108 .

In the first example shown in FIG. 21, the modification starts from, for example, the substrate region 20 located at the lower left corner of the transparent substrate 2, and the substrate region 20 is adjacent to the substrate region 20 in the direction in which the slit holes extend (vertical direction in the drawing). Substrate region 20 is the next modification target. After that, the substrate regions 20 are successively modified, for example, from the bottom to the top of the figure along the direction in which the slit holes extend, and the five substrate regions 20 in one row located at the left end of the transparent substrate 2 are modified. . Here, it is assumed that the substrate regions 20 are adjacent to each other, but the substrate regions 20 may partially overlap with each other particularly in the direction in which the slit holes extend.

When the optical stability of the laser modification apparatuses 10 and 11 is taken into consideration, the procedure of sequentially modifying the substrate region 20 along the direction in which the slit holes extend is effective for highly accurate slit hole formation. preferred for

When the modification of one row of the substrate regions 20 is completed, next five substrate regions 20 in one row adjacent to the one row are sequentially modified, for example, from the top to the bottom of the drawing. Circled numbers in FIG. 21 indicate the order of modification.

In this way, the modification of the substrate regions 20 is performed for each row in the direction in which the slit holes extend, and modification of the 25 substrate regions 20 corresponding to the first modification step (A-1) is completed. After that, the transparent substrate 2 is rotated (that is, the movable stage 108 is rotated) or the linear beam is rotated (that is, the cylindrical lens 103 is rotated), and the direction in which the focal point of the linear beam extends with respect to the transparent substrate 2 is, for example, 90°. degree rotated.

In the second modification step (A-2), similarly to the first modification step (A-1), modification of 25 substrate regions 20 is performed row by row along the direction in which the slit holes extend. be. Further, in the modification of each row, each substrate region 20 is modified in order from one end side of the row in the direction in which the slit holes extend.

Through such a modification step, modification of a large transparent substrate 2 having a slit hole extending longer than the focal point of the linear beam can be efficiently and accurately modified.
22A and 22B are diagrams showing a second example of the modification process for the large transparent substrate 2. FIG.

In the second example shown in FIG. 22, as in the first example, the first modification step (A-1) and the second modification step (A-2) shown in FIG. The modification is performed for every 25 substrate regions 20 arranged in 5 rows and 5 columns. Further, in the second example as well as in the first example, each substrate region 20 includes an irradiation step in which one modified region 2a is formed and a mirror rotation step in which the irradiation position of the pulse laser beam PL is changed. A plurality of modified regions 2a are formed repeatedly. When the formation of the plurality of modified regions 2a in one substrate region 20 is completed, the next substrate region 20 becomes the target of modification by moving the movable stage 108 .

In the second example shown in FIG. 22, the modification is started from, for example, the substrate region 20 located at the lower left corner of the transparent substrate 2, and adjacent to the substrate region 20 in the direction in which the slit holes are arranged (horizontal direction in the drawing). The substrate region 20 thus formed becomes the next modification target. After that, the substrate regions 20 are successively modified, for example, from left to right in the figure along the direction in which the slit holes are arranged, and five substrate regions 20 in one row located at the lower end of the transparent substrate 2 are modified. questioned.

When the modification of one row of the substrate region 20 is completed, next, five substrate regions 20 of one row adjacent to the one row are sequentially modified from right to left in the figure, for example. . In FIG. 22, circled numbers indicate the order of modification.

In this way, the modification of the substrate regions 20 is performed for each row in the direction in which the slit holes are arranged, and modification of the 25 substrate regions 20 corresponding to the first modification step (A-1) is completed. . After that, the transparent substrate 2 is rotated (that is, the movable stage 108 is rotated) or the linear beam is rotated (that is, the cylindrical lens 103 is rotated), and the direction in which the focal point of the linear beam extends with respect to the transparent substrate 2 is, for example, 90°. degree rotated.
In the second modification step (A-2), similarly to the first modification step (A-1), modification of 25 substrate regions 20 is performed for each row in the direction in which the slit holes are arranged. .

According to the modifying process of the second example, the modification of the large transparent substrate 2 having the slit hole extending longer than the spread of the focal point of the linear beam can be efficiently performed.
23A and 23B are diagrams showing a third example of the modification process for the large transparent substrate 2. FIG.

In the third example shown in FIG. 23, similarly to the first and second examples, for each of the first reforming step (A-1) and the second reforming step (A-2) shown in FIG. On the transparent substrate 2, modification is performed for every 25 substrate regions 20 arranged in 5 rows and 5 columns. Further, in the third example as well as in the first and second examples, in each substrate region 20, an irradiation step in which one modified region 2a is formed and a mirror in which the irradiation position of the pulse laser beam PL is changed. The rotation process is repeated to form a plurality of modified regions 2a. When the formation of the plurality of modified regions 2a in one substrate region 20 is completed, the next substrate region 20 becomes the target of modification by moving the movable stage 108 .

In the third example shown in FIG. 23, the modification is started from the substrate region 20 located at the center of the lower end of the transparent substrate 2, for example, and adjacent to the substrate region 20 in the direction in which the slit holes extend (vertical direction in the drawing). The substrate region 20 thus formed becomes the next modification target. After that, the substrate regions 20 are successively modified, for example, from the bottom to the top of the figure along the direction in which the slit holes extend, and the five substrate regions 20 in one row located at the left end of the transparent substrate 2 are modified. .

When the modification of one row of substrate regions 20 is completed, five substrate regions 20 in one row spaced apart from the one row are successively modified, for example, from the top to the bottom of the drawing. . Circled numbers in FIG. 23 indicate the order of modification. That is, in the third example shown in FIG. 23 , adjacent substrate regions 20 are successively modified for one row of substrate regions 20 . The next row to be reformed is the row that is not adjacent to the row. When the thermal stress due to the irradiation of the pulsed laser beam PL is taken into consideration, the procedure of moving the next reforming object to the row with the distance in this manner is preferable for highly accurate slit hole formation.

In this way, the modification of the substrate regions 20 is performed for each row in the direction in which the slit holes extend, and modification of the 25 substrate regions 20 corresponding to the first modification step (A-1) is completed. After that, the transparent substrate 2 is rotated (that is, the movable stage 108 is rotated) or the linear beam is rotated (that is, the cylindrical lens 103 is rotated), and the direction in which the focal point of the linear beam extends with respect to the transparent substrate 2 is, for example, 90°. degree rotated.

In the second modification step (A-2), similarly to the first modification step (A-1), modification of 25 substrate regions 20 is performed row by row along the direction in which the slit holes extend. be. Further, in the modification of each row, each substrate region 20 is modified in order from one end side of the row in the direction in which the slit holes extend, and when the row changes, the target of modification moves to a row with a larger distance. .

Through such a modification step, modification of a large transparent substrate 2 having a slit hole extending longer than the focal point of the linear beam can be efficiently and accurately modified.

In the above description, the micro-hole optical element used for astronomical observation is exemplified, but the micro-hole optical element according to the present invention may be used for observation and imaging of non-astronomical objects.

Further, in the above description, an example in which the extending directions of the two stages of the slit holes 3a and 3b are orthogonal to each other is shown. can be anything.

In the above description, a single-formed transparent substrate is exemplified as the transparent substrate, but the transparent substrate referred to in the present invention may be, for example, a transparent substrate in which a plurality of substrate portions are stacked in the thickness direction, or a transparent substrate in which a plurality of substrate portions are stacked in the direction of spread. It may be a transparent substrate in which a plurality of substrate portions are spliced together.

DESCRIPTION OF SYMBOLS 1... Microhole optical element, 2... Transparent substrate, 3a, 3b... Slit hole, 4... Reflective layer,
DESCRIPTION OF SYMBOLS 10, 11... Laser modification apparatus, 101... Laser oscillator, 102... Beam expansion system,
103... Cylindrical lens, 104, 105a, 105b... Galvanomirror,
106... Relay lens system, 107... Objective lens, 108... Movable stage,
100... Optical device, 111... Frame

Claims (2)

A modifying device for modifying a portion irradiated with a light beam by irradiating a transparent substrate with a light beam to cause multiphoton absorption,
a light source for generating a light beam;
an anisotropic condensing element that has a condensing ability to converge the light beam only in one of two axial directions that intersect with the traveling direction of the light beam, and that acts on the light beam from the light source;
It has the ability to converge a parallel light beam to one point, and by acting on the light beam that has passed through the anisotropic condensing element, the focal point spreads linearly in the direction intersecting the traveling direction of the light beam. an isotropic light-collecting element that forms a linear beam;
a reflecting element that reflects the light beam that has passed through the anisotropic light-collecting element and guides it to the isotropic light-collecting element, and moves the focal point of the linear beam in a direction intersecting the direction in which the focal point spreads by changing the angle of reflection;
A reformer comprising: a substrate holding base that holds the transparent substrate and moves the transparent substrate along the traveling direction of the light beam irradiated onto the transparent substrate to extend a portion modified by the light beam along the traveling direction; The reformer according to claim 1, characterized in that:

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