TW201945110A - Optical device for machining using laser beam, method for machining using laser beam, and method for manufacturing glass article - Google Patents

Abstract

This optical device (1a) is provided with a first lens group (21), an axicon lens (10), and a second lens group (22). A laser beam is incident on the first lens group (21). The laser beam that passes through the first lens group (21) is incident on the axicon lens (10). The laser beam that passes through the axicon lens (10) is incident on the second lens group (22). The first lens group (21) forms a first Bessel beam (A) and a first ring beam (B), and forms a focal surface (f) at which the ring width of the first ring beam (B) is the smallest. The second lens group (22) forms a second ring beam (C) the ring width of which is substantially constant along an optical axis, and forms a second Bessel beam (D).

Description

Optical device for processing using laser beam, processing method using laser beam, and manufacturing method of glass article

The present invention relates to an optical device for processing using a laser beam, a processing method using a laser beam, and a method for manufacturing a glass article.

Conventionally, a processing method using a laser beam is known. For example, Patent Document 1 describes a processing method of glass that irradiates a laser pulse with a wavelength λ to form a deteriorated portion. In this method, the pulse width of the laser pulse is in the range of 1 ns to 200 ns, and the absorption coefficient in the wavelength λ of the glass is 50 cm ^-1 or less. In this method, holes are formed in the glass by etching the deteriorated portion.

Patent Documents 2 and 3 describe a method for manufacturing a glass with holes using a laser pulse. According to this manufacturing method, a predetermined laser processing glass is irradiated with a laser pulse to form a deteriorated portion, and the deteriorated portion is etched to form a hole.

Patent Document 4 describes a system for processing a transparent material. This system includes a laser source and optical components. The laser source emits a pulsed laser beam. The optical component is arranged on the optical path of the pulsed laser beam, so that the pulsed laser beam is changed into a focal line of the laser beam. The focal line of the laser beam is arranged in the block shape of the transparent material and causes multiphoton absorption in the transparent material. Material degradation occurs along the focal line of the laser beam by multiphoton absorption. The optical unit is equipped with a rotary triplex. In Non-Patent Document 1, the influence of the curvature at the front end of the rotating triplet on the intensity distribution in the optical axis direction of the Bessel beam is studied.
Prior Art Literature Prior Art

Patent Document 1: Japanese Patent Application Publication No. 2008-156200 Patent Document 2: International Publication No. 2016/129254 Patent Document 3: International Publication No. 2016/129255 Patent Document 4: International Publication No. 2016/010954

Non-Patent Document 1: Proceedings of SPIE, (US), 2008, Vol. 7141, 714126-1

[Problems to be Solved by the Invention]

Patent Documents 1 to 3 do not describe an optical system having a rotating triplex lens. Patent Document 4 describes an optical system having a rotating triplex. However, there is room for researching a novel optical device for processing using a laser beam which is not described in Patent Document 4. Therefore, the present invention provides a novel optical device having a rotating triplex lens and used for processing using a laser beam. In addition, the present invention provides a novel processing method using a laser beam using a rotating triplex lens. Furthermore, the present invention provides a novel glass article manufacturing method using a rotating triplex lens.
[Technical means to solve the problem]

The present invention provides an optical device for processing using a laser beam, comprising:
A first lens group for incident laser beam;
A rotating triplex lens (axicon lens) for incident the laser beam penetrating the first lens group; and a second lens group for incident of the laser beam penetrating the rotary triplex lens;
The first lens group forms a first Bessel beam behind the rotating triplet lens, and forms a first ring beam behind the first Bessel beam, and is perpendicular to the optical axis. Form a focal plane that minimizes the ring width of the first ring beam,
The second lens group is for the first ring beam to be incident, and a second ring beam having a ring width in a direction perpendicular to the optical axis behind the second lens group is substantially fixed along the optical axis. A second Bessel beam is formed behind the second ring beam.

In addition, the present invention provides a processing method using a laser beam, which includes the following steps:
Making the laser beam incident on the first lens group;
Causing the laser beam that has passed through the first lens group to enter a rotating triplex lens;
With the first lens group, a first Bessel beam is formed behind the rotating triplet lens, and a first ring beam is formed after the first Bessel beam, which is perpendicular to the optical axis. Form a focal plane with the smallest ring width of the first ring beam; and make the first ring beam enter the second lens group, and form a direction perpendicular to the optical axis behind the second lens group. A second ring beam whose ring width is substantially fixed along the optical axis, and a second Bezier beam is formed behind the second ring beam.

Furthermore, the present invention provides a method for manufacturing a glass article, which includes the following steps:
Making the laser beam incident on the first lens group;
Causing the laser beam that has passed through the first lens group to enter a rotating triplex lens;
With the first lens group, a first Bessel beam is formed behind the rotating triplet lens, and a first ring beam is formed after the first Bessel beam, which is perpendicular to the optical axis. Form a focal plane that has a minimum ring width with the first ring beam;
The first ring beam is made incident on the second lens group, and a second ring beam having a ring width in a direction perpendicular to the optical axis is formed substantially along the optical axis behind the second lens group; Forming a second Bessel beam behind the second ring beam; and irradiating the second Bessel beam to glass to form a modified portion on the glass.
[Effect of the invention]

The above-mentioned optical device for processing using a laser beam is, for example, a novel optical device which is advantageous for processing glass. The processing method described above is, for example, a novel method which is advantageous for processing glass. The above-mentioned manufacturing method is a novel method which is advantageous for manufacturing a glass article having a deteriorated portion.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description is an example of the present invention, and the present invention is not limited to the following embodiments.

The processing method of the present invention using a laser beam is performed using, for example, a processing device provided with the optical device 1a shown in FIG. 1. The optical device 1 a includes a first lens group 21, a rotary triplex lens 10, and a second lens group 22. The laser beam LB is incident on the first lens group 21. The laser beam TB that has penetrated the first lens group 21 is incident on the rotating triplex lens 10. The laser beam that has penetrated the rotating triplex lens 10 is incident on the second lens group 22. The first lens group 21 forms a first Bessel beam A behind the rotating triplex lens 10, and forms a first ring beam B behind the first Bessel beam A. In addition, the first lens group 21 forms a focal plane f that minimizes the ring width of the first ring beam B in a direction perpendicular to the optical axis z. The first ring beam B is incident on the second lens group 22, and a second ring beam C having a ring width in a direction perpendicular to the optical axis z is formed behind the second lens group 22, and is substantially fixed along the optical axis z. A second Bessel beam D is formed behind the second ring beam C. In this specification, "rear" refers to a position far away from the reference in the direction of travel of the laser beam, and "front" refers to a position far away from the reference in the direction of travel of the laser beam. In addition, the "Bezier beam" in the strict sense has infinite diffusion and energy, so it cannot be realized. On the other hand, if a rotating triplex lens is used, a quasi-Bessel beam can be realized within a limited range. "Bessel beam" in this specification means "approximate Bessel beam".

A processing method including the following steps can be performed using the optical device 1a.
(Ia) The laser beam LB is made incident on the first lens group 21.
(Ib) The laser beam TB penetrating the first lens group 21 is made incident on the rotary triplex lens 10.
(Ic) With the first lens group 21, a first Bessel beam A is formed behind the rotating triplex lens 10, and a first ring beam B is formed after the first Bessel beam A, and A direction perpendicular to the optical axis z forms a focal plane f that minimizes the ring width of the first ring beam B.
(Id) A first ring beam B is made incident on the second lens group 22, and a second ring beam having a ring width in a direction perpendicular to the optical axis z is formed substantially along the optical axis z behind the second lens group 22 Beam C, and a second Bessel beam D is formed behind the second ring beam C.

For example, by irradiating a predetermined Bessel beam D to a predetermined glass, a deteriorated portion can be formed in the glass. The glass article manufacturing method of the present invention includes the following steps (IIa) in addition to the steps (Ia) to (Id).
(IIa) Irradiating the second Bezier light beam D to the glass to form a deteriorated portion on the glass.

A glass substrate having a through hole having a diameter of several μm to several hundreds of μm or a bottomed hole can be used in various applications such as glass interposer. Therefore, the technical industry for forming such holes in glass substrates is extremely important. In addition, in this specification, "hole" means a through hole and a bottomed hole. As a method for forming holes in glass, the following methods (i) to (vi) are conceived. In particular, the following method (iv) is also described in Patent Documents 1 to 3, and a glass substrate having a thickness of several hundred μm can also form a hole having a diameter of several tens of μm, which is advantageous compared to other methods.
(I) Perforation using tools such as drills (ii) Sandblasting (iii) Processing using laser beams (iv) Combination of processing and etching using laser beams (v) Dry etching (vi) Discharge machining

The laser beam irradiated to the glass is absorbed by the glass and causes heat. Thereby, the glass is melted along the optical axis of the laser beam. The area irradiated with the laser beam in the glass is a narrow area having a size of several μm or less. Therefore, a melting portion having a size corresponding to the area is formed on the glass. When the laser beam is irradiated to the glass, there are also cases in which plasma generation or filamentation occurs. However, in this case, the result is that the glass is melted by heat. After the glass is irradiated with the laser beam, the heat is immediately diffused to the periphery of the melting portion of the glass, whereby the melting portion is solidified (vitrified). At this time, a volume shrinkage occurs in the solidified portion of the melting portion, and therefore, the portion becomes hollower than the surroundings. In some cases, due to the stress caused by the shrinkage of the volume, tiny cracks may occur in this part. The minute cracks are generated in a direction perpendicular to the traveling direction of the laser beam irradiated to the glass by tensile stress. It is considered that the empty portion and the portion having a minute crack become a deteriorated portion that is heterogeneous from the other portions of the glass. In this way, if the glass having a partially deteriorated portion is etched by an acid or an alkali, the etching rate at the deteriorated portion is higher than the etching rate at other portions of the glass. The reason is that the metamorphic part is an empty part or a part having a slight crack. As a result, the modified portion can be more selectively etched to form holes such as through holes in the glass. In the case where the deteriorated portion is a portion having a minute crack, etching is selectively performed from the opening of the minute crack to form a hole having a larger diameter in the direction of the opening of the crack. The reason for this is that, in many cases, a minute crack is generated in a direction perpendicular to the traveling direction of the laser beam. Therefore, in order to make the hole formed in the glass close to a true circular hole, it is desirable to reduce the size of the minute cracks. By reducing the diameter of the laser beam irradiated to the glass, the size of the tiny cracks can be reduced.

For example, a convex lens is used to condense the laser beam of a general Gaussian beam and adjust it to a spot diameter of several μm to irradiate the glass. However, in this case, if the thickness of the glass is several hundred μm or more, from the viewpoint of the depth of focus, the diffusion of the laser beam in the glass has an effect, and the size of the crack in the deteriorated portion may be as large as several tens. μm or more. As a result, in this case, the hole formed by etching the deteriorated portion is likely to be an oval hole.

On the other hand, if an optical system including a rotating triplex lens is used to focus the laser beam, a Bezier beam can be formed. As shown in FIG. 2, if a Gaussian laser beam is incident on a rotating triplet lens, a plane wave of the laser beam is emitted as a light beam having a conical wave surface convergent along an optical axis. Further, in a region close to the rotating triplex lens, a Bezier light beam is formed in a region (z = 0 to _zmax ) where the conical wave surfaces overlap. A ring-shaped beam is formed after the Bezier beam is formed. Bessel beams have a main lobe and a side lobe. The Bessel beam shows high intensity with the optical axis as the center in the main lobe, and a wavy intensity distribution (side lobe) in the side lobe far from the optical axis. The length (effective length) of the Bezier beam held in the direction of the optical axis may be several mm to several tens mm. As shown in FIG. 2, in a region corresponding to the effective length, a Bezier beam having a main lobe and a side lobe continuously exists along the optical axis. In addition, the intensity I (ρ, z) of the light beam after passing through the rotating triplex lens is expressed by the following formula (1), and the half-apex angle α ₀ of the cone surrounded by plane waves of the same intensity constituting the Bezier beam It is expressed by equation (2). ρ is the distance in the radial direction from the optical axis z, P is the overall power of the Gaussian beam such as the laser incident to the rotating triplet lens, k is the angular wave number, w ₀ is the beam waist of the Gaussian beam, z _max = w ₀ cosα ₀ / sinα ₀ . n is the refractive index of the rotational dispersive prism lens, n ₀ is the refractive index of the medium surrounding the lens rotating dispersive prism, τ is a dispersive prism apex angle of rotation of the lens.

In the main lobe of Bessel beams, the light energy density is high. Therefore, if the glass is arranged on the main lobe of the Bezier beam in such a way that a part of the thickness direction of the glass is included or overlapped in the region where the Bezier beam is formed, it will be formed on the glass along the region where the Bezier beam is formed. Deterioration. In the area where the Bezier beam is formed, the length of the focal length of the converted laser beam can cover a few mm and a few μm in the thickness direction of the glass. Thereby, even if the thickness of the glass is several hundred μm or more, the size of cracks in the deteriorated portion is small, and a hole close to a true circular hole can be formed in the glass. The use of a rotating triplex lens has this advantage.

As shown in FIG. 2, a Bezier beam is typically formed after the rotating triplex lens is adjacent to each other. Therefore, if the Bessel beam formed next to the rotating triplex lens is used to form the deteriorated part of the glass, the distance between the rotating triplex lens and the glass is close, and the glass is in contact with the rotating triplex lens. High risk. Therefore, the formation of the Bessel beam formed adjacent to the back of the rotating triplex lens for the formation of the deteriorated part of the glass brings several problems to the actual operation. For example, if the rotating triplex lens is damaged due to inadvertent contact or collision between the front end of the rotating triplex lens and the glass, the optical characteristics of the rotating triplex lens are significantly deteriorated. As a result, it is difficult to industrially form a glass-deteriorated portion. Therefore, it is desirable to lengthen the distance between an optical component such as a rotating triplex lens and a region forming a Bezier beam. According to the processing device and processing method of the present invention, a second Bezier beam can be formed in a region far from the self-rotating triplex lens 10, and the second Bezier beam can be used to form a modified portion on the glass. Therefore, the risk of the rotating triplex lens contacting the glass is low.

As shown in FIG. 1, in the optical device 1 a, for example, the first lens group 21, the rotating triplex lens 10, and the second lens group 22 are sequentially arranged on the optical axis. For example, the first lens group 21 converges a laser beam LB, which is a substantially parallel light beam, to form a convergent light beam TB. The rotating triplex lens 10 is disposed behind the first lens group 21, and a convergent light beam TB is incident, and a light beam having a conical wave surface is emitted, and a first Bezier light beam A is formed at a predetermined interval on the optical axis. The second lens group 22 is disposed behind the rotating triplex lens 10. In addition, the second lens group 22 does not diverge the ring-shaped first ring beam B and forms a ring-shaped second ring beam C having a substantially constant width. In the optical device 1 a, a first ring beam B is formed behind the area where the first Bezier light beam A is formed between the rotating triplex lens 10 and the second lens group 22. The first ring beam B has a focal plane f between the rotating triplet lens 10 and the second lens group 22 that shows the smallest ring width in a direction perpendicular to the optical axis z. The focal plane f is formed between the rotary triplex lens 10 and the second lens group 22. In the second ring beam C, a width bf in a direction perpendicular to the optical axis z is substantially constant along the optical axis z. In the optical device 1a, the second ring beam C overlaps to form a second Bezier beam D at a predetermined interval on the optical axis. In addition, the lens group has an optical element capable of condensing (convex lens function) or diverging (concave lens function) the light beam or light within the range of exerting the effect of the present invention. The lens group may be a lens or two or more lenses A group of lenses. Unless otherwise specified, the lenses constituting the lens group are lenses that are axially symmetric with respect to the optical axis, and when a lens group is formed by a combination of multiple lenses, the central axes of the lenses are arranged so as to be the same.

The processing device includes, for example, an optical device 1 a and a laser oscillator (not shown) for emitting a laser beam LB.

As the interaction between glass and light (laser), it is conceivable to directly cut off the heat generated by the absorption of ordinary light and the molecular bonding inside the glass by multiphoton absorption. The former can be discussed at usual absorption rates. On the other hand, the latter interaction has a low probability. Therefore, for the latter interaction, a state with a high photon density, that is, a state with a high flux, is required. For example, as shown in FIG. 3, the smaller the beam diameter of the laser beam incident on the rotating triple-lens lens, the higher the intensity on the optical axis of the light beam penetrating the rotating triple-lens lens. Therefore, it is conceivable to reduce the beam diameter and increase the spatial density of photons to achieve a high-flux state. On the other hand, as shown in FIG. 3, the larger the beam diameter of the laser beam incident on the rotating triplet lens is, the longer the length of the region forming the Bezier beam in the optical axis direction is. Therefore, based on the balance between the intensity on the optical axis of the light beam penetrating the rotating triplex lens and the length of the area where the Bezier beam is formed in the optical axis direction, the beam diameter of the laser beam is determined. Furthermore, as shown in FIG. 3, if the length of the area where the Bezier beam is formed is longer in the optical axis direction, the energy is dispersed in the optical axis direction. Therefore, in order to keep the intensity on the optical axis high in the area where the Bezier beam is formed, it is effective to increase the energy of the laser beam incident on the rotating triplex lens. Moreover, in FIG. 3, rb refers to the reference beam diameter of the laser beam incident on the rotating triplex lens.

In order to achieve a high-flux state, it is also desirable to shorten the pulse width of the laser beam and increase the time density of the photons. On the other hand, if the molecules in the glass are activated by the heat accompanying the absorption of light, multi-photon absorption is more likely to occur. Therefore, even with a laser beam having a pulse width in the nanosecond range, multiphoton absorption can occur.

The laser beam LB generated by the laser oscillator satisfies the following conditions, for example. Thereby, a modified | denatured part can be formed favorably in glass.
Wavelength: 535 nm or less (ideally including 355 nm)
Central wavelength: 300 ～ 400 nm (ideally 355 nm)
Energy: 100 μJ / pulse or more Pulse width: 1 nanosecond (ns) or more Beam diameter: 0.5-20 mm (ideally 0.5-10 mm)
Pulse number: 1 pulseBeam mode: single mode

The pulse width of the laser beam LB is preferably 1 to 200 ns, more preferably 1 to 100 ns, and even more preferably 1 to 50 ns. If the pulse width of the laser beam LB is greater than 200 ns, there may be a case where the peak-to-peak value of the laser pulse decreases, and the glass cannot be processed smoothly. The beam quality M ₂ value of the laser pulse may be, for example, 2 or less. By using a laser pulse with an M ₂ value of 2 or less, it is easy to form minute pores or minute grooves in glass.

In the step (IIa) above, the laser beam LB may also be a high harmonic of Nd: YAG laser, a high harmonic of Nd: YVO ₄ laser, or a high harmonic of Nd: YLF laser. The high harmonic is, for example, a second high harmonic, a third high harmonic, or a fourth high harmonic. The wavelength of the second high harmonic of these lasers is about 532 to 535 nm. The third high harmonic has a wavelength of about 355 to 357 nm. The fourth highest harmonic has a wavelength of about 266 to 268 nm. By using such a laser, glass can be processed cheaply.

The laser oscillator is, for example, a highly repetitive solid-state pulsed UV laser manufactured by Coherent: AVIA355-4500. In this laser oscillator, the third high harmonic Nd: YVO ₄ laser is obtained, and the maximum laser power of about 6 W is obtained at a repetition frequency of 25 kHz. The third harmonic has a wavelength of 350 to 360 nm.

The wavelength of the laser beam LB can also be in the range of 350 to 360 nm. On the other hand, if the wavelength of the laser beam is greater than 535 nm, the irradiation spot becomes large, making it difficult to produce a minute structure, and the surrounding area of the irradiation spot is easily broken due to the influence of heat.

The first lens group 21 has, for example, the same optical function as a convex lens, and may be constituted by a single lens that functions as a convex lens. In this case, the first lens group 21 may also have an effective diameter that is considerably larger than the beam diameter of the laser beam LB. The laser beam LB generated by the laser oscillator is a substantially parallel beam whose beam diameter is about several mm. When the laser diameter of the laser beam LB is relatively small, the power of the first lens group 21 is appropriately selected, so that even when the first lens group 21 is constituted by a single lens, it can be included in the convergent beam TB. The resulting aberrations are reduced to a problem-free level. Furthermore, if the first lens group 21 is a single lens, it is possible to avoid problems that may occur when the lens group is composed of a plurality of lenses. The problem is as follows. In order to correct the aberrations of the optical system, it is generally considered to form a lens group by combining a plurality of lenses having different refractive indices. However, when the laser beam incident on the lens group mainly has a wavelength in the ultraviolet region, the available lens materials are limited, the degree of freedom in the design of the lens group is reduced, and the correction of aberrations is difficult. In particular, a glass material having a high refractive index, which is conducive to increasing the power of the lens group, has a very low transmittance in the ultraviolet region, so it is difficult to use it for the lens group. Either surface of the lenses constituting the lens group may have an aspherical shape. Generally speaking, a lens having an aspherical surface has a higher degree of freedom in design than a lens composed of a spherical shape or a plane, and is effective for correcting aberrations. The power of a lens or a lens group indicates how much light can be bent, and is expressed by the inverse of the effective focal distance of the lens or lens group.

As described above, the first lens group 21 may be composed of a plurality of lenses appropriately subjected to aberration correction. In the case where the laser beam LB is a divergent beam or a convergent beam having a large diffusion angle, since a light beam inclined at a distance from the optical axis is incident on the lens group, aberration is easily generated. In this case, it is desirable that the first lens group 21 is formed by using a lens having a relatively large effective diameter as described above, or that the first lens group 21 is formed by a plurality of lenses in consideration of the refractive index or shape of the material of the lens. Small aberrations.

The rotary triplex lens 10 includes a conical surface having an apex angle of, for example, 110 to 160 °. As shown in FIG. 4, the larger the vertex angle τ of the rotating triplex lens, the longer the length of the range in which a predetermined intensity is maintained on the optical axis. On the other hand, as shown in FIG. 5, the smaller the vertex angle τ of the rotating triplex lens is, the larger the crossing angle α ₀ of the light passing through the rotating triplex lens is, and the diameter of the main lobe can also be reduced to 1 μm or less. If the apex angle of the rotating triplex lens 10 is in the above range, the laser beam after penetrating the rotating triplex lens can maintain the length of a predetermined intensity range on the optical axis, and the principal of the Bezier beam. The diameter of the valve is adjusted to the desired value. In this specification, the beam diameter refers to the diameter of the area enclosed by an intensity line of 1 / e ² times (13.5%) the maximum intensity of the beam in a plane perpendicular to the optical axis.

The second lens group 22 is not limited to a specific lens as long as it can converge to form the second ring beam C without diverging the first ring beam B. The second lens group 22 has, for example, the same optical function as one convex lens, and may be constituted by a single lens capable of exerting the function of a convex lens. Since the second lens group 22 does not diverge the first ring beam B, it is easy to shorten the total length in the optical axis direction of the optical device 1a. As shown in FIG. 1, light rays inclined away from the optical axis are incident on the second lens group 22, and thus aberrations are likely to occur. Therefore, in some cases, the second lens group 22 may also be a low aberration lens after the aberration is appropriately corrected, and the second lens group 22 is also preferably composed of a plurality of lenses. For example, as the second lens group 22, for example, two plano-convex lenses having the same shape (a lens that is axially symmetrical with respect to the optical axis and includes a convex surface and a plane facing the direction opposite to the convex surface) may be used. In this case, in the second lens group 22, the central axes of the two plano-convex lenses are the same, and the convex surfaces face each other. Thereby, it is possible to relatively easily reduce aberrations caused by light rays penetrating the second lens group 22. Either surface of the lenses constituting the second lens group 22 may have an aspheric shape. Generally speaking, a lens having an aspherical surface has a higher degree of freedom in design than a lens composed of a spherical shape or a plane, and is effective for correcting aberrations.

The processing method of the present invention preferably further includes the following step (Ie).
(Ie) Light rays existing inside the first ring beam B or the second ring beam C in a direction perpendicular to the optical axis z and existing in the first ring beam B in a direction perpendicular to the optical axis z Or at least one of the light rays outside the second ring beam C is shielded between the rotating triplex lens 10 and the second lens group 22, or between the second lens group 22 and the second Bessel beam D.

The method of the present invention more preferably further includes the following (If) step.
(If) the light existing inside the first ring beam B or the second ring beam C in a direction perpendicular to the optical axis z is shielded between the rotating triplet lens 10 and the second lens group 22, or Between the second lens group 22 and the second Bezier light beam D.

The processing method of the present invention may further include, for example, the following step (Ig).
(Ig) A ray existing inside the first ring beam B or the second ring beam C in a direction perpendicular to the optical axis z, and a first ring beam B in a direction perpendicular to the optical axis z Or the light outside the second ring beam C is shielded between the rotating triplex lens 10 and the second lens group 22, or between the second lens group 22 and the second Bezier beam D.

The optical device 1 a includes, for example, a shield 25. The shield 25 is arranged between the rotating triplex lens 10 and the second lens group 22, or between the second lens group 22 and the second Bessel light beam D. The shield 25 includes at least one of a first light shielding portion and a second light shielding portion. The first light-shielding portion is used to shield light rays existing inside the first ring beam B or the second ring beam C. The second light-shielding portion is used to shield light existing outside the first ring beam B or the second ring beam C in a direction perpendicular to the optical axis z. The shield 25 preferably has a first light-shielding portion to shield light rays existing inside the first ring beam B or the second ring beam C. Furthermore, the shield 25 may have a first light-shielding portion and a second light-shielding portion. In this case, the shielding body 25 shields light rays existing inside the first ring beam B or the second ring beam C and light rays outside the first ring beam B or the second ring beam C. The shield 25 is, for example, a plate-shaped member. The shield 25 is preferably a disc-shaped member. In this case, for example, it is arrange | positioned so that the center of the shield 25 may become substantially the same as an optical axis. The shield 25 may have a through hole in the center thereof. The shielding body 25 may also be formed of a material suitable for shielding light existing inside and outside the first ring beam B or the second ring beam C.

The rotary triplex lens 10 preferably has a sharp front end on a conical surface thereof. On the other hand, there is a limit to the precision of the processing of the front end of the rotating triplex lens, and it is not easy to completely sharpen the front end of the rotating triplex lens. The machine or tool used to make the rotary triplex lens has a limited size and has specified tolerances. Therefore, in extreme terms, the front and near parts of the rotary triplex lens may deviate from the ideal cone shape and become spherical, Plane, or a combination of spherical and plane.

If the front end of the rotating triplex lens 10 is not completely sharp, the shapes of the first Bessel beam A and the first ring beam B deviate from the ideal shape. As shown in FIG. 6A, if the front end of the rotating triplex lens is sharp, a clear main lobe is confirmed in the light penetrating the rotating triplex lens. On the other hand, as shown in FIG. 6B, when the front end of the rotating triplex lens is not sharp, becomes spherical, or includes defects such as defects, the main lobe becomes unclear. The reason is that irregular refracted light is generated by including the front end portion of the defect, and this kind of light causes irregular interference. A part of the light affected by the shape of the front end of the rotating triplet lens exists on the opposite inner side of the first ring beam B. Therefore, if the first ring beam B is converged, the shield exists in the first ring beam B. The inner light can prevent the influence caused by the sharpness of the front end of the rotating triplex lens 10 from appearing in the second Bezier light beam D. As a result, the second Bezier light beam D can be appropriately formed.

The glass used in the step (IIa) (hereinafter, also referred to as laser processing glass) has, for example, an absorption coefficient of 1 to 50 cm ^-1 at the center wavelength λc of the laser beam LB, and is preferably at the center wavelength λc has an absorption coefficient of 3 to 40 cm ^-1 . The glass preferably has an absorption coefficient of 1 to 50 cm ^-1 at a specific wavelength in the range of 300 to 400 nm, and more preferably has an absorption coefficient of 3 to 40 cm ^-1 at the specific wavelength. Such glass may be selected from known glass. For example, the glass described in Patent Document 2 or 3 can be selected as the glass used in the step (IIa). The absorption coefficient α of glass can be calculated by measuring the transmittance and reflectance of a glass substrate having a thickness t (cm). For a glass substrate with a thickness t (cm), use a spectrophotometer (for example, UV-Visible Near Red Spectrophotometer V-670 manufactured by JASCO Corporation) to measure the transmittance T ( %) And reflectance R (%) at an incident angle of 12 °. From the obtained measurement values, the absorption coefficient α can be calculated using the following formula (3).
α = (1 / t) * ln {(100－R) / T} (3)

The glass used in the step (IIa) is, for example, sheet glass. In this case, the thickness of the glass is, for example, 2 mm or less, and may be 0.1 to 1.5 mm.

In the step (IIa) described above, the glass can be transformed by a single laser pulse to form a deteriorated portion. For example, in the step (IIa), a deteriorated portion can be formed on the glass by irradiating laser pulses so that the irradiation positions do not overlap. However, the laser pulses may be irradiated in such a manner that the irradiation positions overlap.

In the step (IIa), for example, the above-mentioned optical device 1a is used to condense the laser pulse so that a second Bessel beam is formed inside the glass. For example, when a through-hole is formed in a glass plate, the laser pulse is usually focused so that a second Bessel beam is formed near the center in the thickness direction of the glass plate. Furthermore, when only the upper surface side (the incident side of the laser pulse) of the glass plate is processed, for example, the optical system and the glass may be adjusted by forming a second Bessel beam on the upper surface side of the glass plate. Interval. Conversely, when only the lower surface side of the glass plate is processed (opposite to the incident side of the laser pulse), for example, the optical can be adjusted by forming a second Bessel beam on the lower surface side of the glass plate. Space between system and glass. However, as long as the deteriorated portion can be formed, the laser pulse can also be focused by forming a second Bessel beam outside the glass.

The manufacturing method of the glass article of this invention further includes the following process (IIb).
(IIb) A hole is formed in the glass by removing at least a part of the deteriorated portion by etching.

In the step (IIb), typically, at least a part of the deteriorated portion is removed by wet etching. In the etching solution, the etching rate of the deteriorated portion is typically larger than the etching rate of the glass. The etching solution is, for example, hydrofluoric acid (aqueous solution of hydrogen fluoride (HF)). The etching solution may be sulfuric acid (H ₂ SO ₄ ) or an aqueous solution thereof, nitric acid (HNO ₃ ) or an aqueous solution thereof, or hydrochloric acid (aqueous solution of hydrogen chloride (HCl)). The etchant may be one of these acids or a mixture of two or more acids. In the case where the etching solution is hydrofluoric acid, etching of the deteriorated portion is easily performed, and holes can be formed in a short time. When the etching solution is sulfuric acid, it is not easy to etch glass other than the deteriorated portion, and a straight hole with a small taper angle can be formed.

In the step (IIb), a surface protective film agent may also be coated on one of the main surfaces of the sheet glass to achieve etching from only one side of the sheet glass. As such a surface protective film agent, a commercially available product such as SILITECT II (manufactured by Trylaner International) can be used.

The etching time or the temperature of the etching solution is selected according to the shape of the deteriorated portion or the target processing shape. Furthermore, by increasing the temperature of the etching solution during etching, the etching rate can be increased. The diameter of the hole can be controlled by the etching conditions.

The etching time is not particularly limited because it also depends on the thickness of the plate glass, but it is preferably about 30 to 180 minutes. The temperature of the etching solution is, for example, about 5 to 45 ° C, and may be about 15 to 40 ° C. During the step (IIb), the temperature of the etchant can be changed to adjust the etching rate. It is also possible to perform ultrasonic etching while applying ultrasonic waves to the etching solution. Thereby, the etching rate can be increased, and the stirring effect of the liquid can be expected.

As the glass for laser processing, quartz glass, borosilicate glass, aluminosilicate glass, soda lime glass, or titanium-containing silicate glass is preferable. Furthermore, as the glass for laser processing, a glass such as an alkali-free glass that does not substantially contain an alkaline component (alkali metal oxide) or a low-alkali glass that contains only a trace amount of an alkaline component can be preferably used.

In order to improve the absorption coefficient more effectively, the glass may contain at least one oxide of a metal selected from Bi, W, Mo, Ce, Co, Fe, Mn, Cr, V, and Cu as a coloring component.

Examples of the borosilicate glass include Corning's # 7059 glass (composition expressed by mass% as SiO ₂ 49%, Al ₂ O ₃ 10%, B ₂ O ₃ 15%, RO (alkaline earth metal oxide) 25% ) Or Pyrex (registered trademark) (glass rope 7740), etc.

The first example of aluminosilicate glass may have the following composition.
Expressed as% by mass, including
SiO ₂ 50 ～ 70%,
Al ₂ O ₃ 14 ～ 28%,
Na ₂ O 1 ～ 5%,
MgO 1 ～ 13%, and
ZnO 0-14% glass composition.

The second example of aluminosilicate glass may have the following composition.
Expressed as% by mass, including
SiO ₂ 56 ～ 70%,
Al ₂ O ₃ 7 to 17%,
B ₂ O ₃ 0-9%,
Li ₂ O 4 ～ 8%,
MgO 1 ～ 11%,
ZnO 4 ～ 12%,
TiO ₂ 0 ～ 2%,
Li ₂ O ＋ MgO ＋ ZnO 14 ～ 23%,
CaO + BaO 0 ~ 3% glass composition.

The third example of the aluminosilicate glass may have the following composition.
Expressed as% by mass, including
SiO ₂ 58 ～ 66%,
Al ₂ O ₃ 13 ～ 19%,
Li ₂ O 3 ～ 4.5%,
Na ₂ O 6 ～ 13%,
K ₂ O 0 ～ 5%,
R ₂ O 10 to 18% (where R ₂ O = Li ₂ O + Na ₂ O + K ₂ O),
MgO 0 ～ 3.5%,
CaO 1 ～ 7%,
SrO 0 ～ 2%,
BaO 0 ～ 2%,
RO 2-10% (where RO = MgO + CaO + SrO + BaO),
TiO ₂ 0 ～ 2%,
CeO ₂ 0 ～ 2%,
Fe ₂ O ₃ 0 ～ 2%,
MnO 0 to 1% (where TiO ₂ + CeO ₂ + Fe ₂ O ₃ + MnO = 0.01 to 3%),
SO ₃ 0.05 ~ 0.5% glass composition.

The fourth example of the aluminosilicate glass may have the following composition.
Expressed as% by mass, including
SiO ₂ 60 ～ 70%,
Al ₂ O ₃ 5 ～ 20%,
Li ₂ O ＋ Na ₂ O ＋ K ₂ O 5 ～ 25%,
Li ₂ O 0 ～ 1%,
Na ₂ O 3 ～ 18%,
K ₂ O 0-9%,
MgO ＋ CaO ＋ SrO ＋ BaO 5 ～ 20%,
MgO 0 ～ 10%,
CaO 1 ～ 15%,
SrO 0 ～ 4.5%,
BaO 0 ～ 1%,
TiO ₂ 0 ～ 1%,
ZrO ₂ 0 to 1% of glass composition.

The fifth example of the aluminosilicate glass may have the following composition.
Expressed as% by mass, including
SiO ₂ 59 ～ 68%,
Al ₂ O ₃ 9.5 ～ 15%,
Li ₂ O 0 ～ 1%,
Na ₂ O 3 ～ 18%,
K ₂ O 0 ～ 3.5%,
MgO 0 ～ 15%,
CaO 1 ～ 15%,
SrO 0 ～ 4.5%,
BaO 0 ～ 1%,
TiO ₂ 0 ～ 2%,
ZrO ₂ 1-10% glass composition.

Soda-lime glass is, for example, a glass composition widely used for sheet glass.

The first example of the titanium-containing silicate glass may have the following composition.
According to Mohr%,
Contains 5 to 25% of TiO ₂ and
SiO ₂ ＋ B ₂ O ₃ 50 ～ 79%,
Al ₂ O ₃ + TiO ₂ 5 ～ 25%,
Li ₂ O + Na ₂ O + K ₂ O + Rb ₂ O + Cs ₂ O + MgO + CaO + SrO + BaO 5-20% glass composition.

In the first example of the titanium-containing silicate glass described above, it is preferable to contain 60 to 65% SiO ₂ ,
TiO ₂ 12.5 ～ 15%,
Na ₂ O 12.5 ～ 15%, and
SiO ₂ + B ₂ O ₃ 70 to 75%.

Furthermore, in the first example of the titanium-containing silicate glass, it is more preferable that
(Al ₂ O ₃ + TiO ₂ ) / (Li ₂ O + Na ₂ O + K ₂ O + Rb ₂ O + Cs ₂ O + MgO + CaO + SrO + BaO) ≦ 0.9.

The second example of the titanium-containing silicate glass may have the following composition. According to Mohr%,
Contains B ₂ O ₃ 10-50%,
TiO ₂ 25 ～ 40%, and
SiO ₂ ＋ B ₂ O ₃ 20 ～ 50%,
Li ₂ O + Na ₂ O + K ₂ O + Rb ₂ O + Cs ₂ O + MgO + CaO + SrO + BaO 10 to 40% of a glass composition.

The first example of the low alkali glass may have the following composition.
According to Mohr%,
Contains SiO ₂ 45 ～ 68%,
B ₂ O ₃ 2 ～ 20%,
Al ₂ O ₃ 3 ～ 20%,
TiO ₂ 0.1 ～ 5.0% (except 5.0%),
ZnO 0-9%, and
Li ₂ O + Na ₂ O + K ₂ O 0 to 2.0% (except 2.0%) glass composition.

In the first example of the above-mentioned low-alkali glass, it is preferable to include the following composition as a coloring component:
CeO ₂ 0 ～ 3%,
Fe ₂ O ₃ 0 to 1%.
Still more preferred is an alkali-free glass that does not substantially contain an alkali metal oxide.

The above-mentioned first example of low-alkali glass or alkali-free glass contains TiO ₂ as an essential component. The content of TiO ₂ in the above-mentioned first example of low-alkali glass or alkali-free glass is 0.1 mol% or more and less than 5.0 mol%, and the smoothness of the inner wall surface of the hole obtained by laser irradiation is excellent In particular, it is preferably 0.2 to 4.0 mole%, more preferably 0.5 to 3.5 mole%, and even more preferably 1.0 to 3.5 mole%. When low-alkali glass or alkali-free glass with a specific composition moderately contains TiO ₂ , even if it is irradiated with relatively weak energy such as laser light, a deteriorated portion can be formed, which in turn will cause the deteriorated portion to be supervised in subsequent steps It can be more easily removed when the sonic is irradiated on one side for etching. In addition, the bonding energy of TiO ₂ is substantially the same as the energy of ultraviolet light, and it absorbs ultraviolet light. By appropriately containing TiO ₂ , it is also possible to control the coloring by the interaction with other colorants in the form of charge transfer absorption. Therefore, by adjusting the content of TiO ₂ , a predetermined amount of light can be appropriately absorbed. Since glass has an appropriate absorption coefficient, it is easy to form a deteriorated portion in which a hole is formed by etching. Therefore, from these viewpoints, it is also preferable to include TiO _{2 to a} moderate extent.

The first example of the low-alkali glass or the alkali-free glass may contain ZnO as an optional component. In this case, the content of ZnO is preferably from 0 to 9.0 mole%, more preferably from 1.0 to 8.0 mole%, even more preferably from 1.5 to 5.0 mole%, and even more preferably from 1.5 to 3.5 mole%. ZnO is a component that exhibits absorption in the region of ultraviolet light in the same manner as TiO _2. If ZnO is contained in the glass for laser processing, it will have an effective effect on the glass.

The first example of the low-alkali glass or the alkali-free glass may contain CeO ₂ as a coloring component. In particular, by using CeO ₂ and TiO _{2 together} , it is possible to more easily form a deteriorated portion. The content of CeO ₂ in the above-mentioned first example of low-alkali glass or alkali-free glass is preferably 0 to 3.0 mol%, more preferably 0.05 to 2.5 mol%, further preferably 0.1 to 2.0 mol%, and even more preferably 0.2 to 0.9 mol%.

Fe ₂ O _{3 is} also effective as a coloring component in glass for laser processing, and glass for laser processing may also contain Fe ₂ O ₃ . In particular, by using TiO ₂ and Fe ₂ O _{3 together} , or by using TiO ₂ , CeO _2, and Fe ₂ O _{3 together} , it is easy to form a deteriorated portion. The content of Fe ₂ O ₃ in low-alkali glass or alkali-free glass is preferably 0 to 1.0 mole%, more preferably 0.008 to 0.7 mole%, still more preferably 0.01 to 0.4 mole%, and particularly preferably 0.02 to 0.3. Mohr%.

In the above-mentioned first example of low-alkali glass or alkali-free glass, it is not limited to the components listed above, but by containing a moderate coloring component, the absorption coefficient of the glass at a predetermined wavelength (wavelength 535 nm or less) can also be 1 to 50 cm ^-1 , preferably 3 to 40 cm ^-1 .

The second example of the low alkali glass may have the following composition.
According to Mohr%,
SiO ₂ 45 ～ 70%,
B ₂ O ₃ 2 ～ 20%,
Al ₂ O ₃ 3 ～ 20%,
CuO 0.1 ～ 2.0%,
TiO ₂ 0 ～ 15.0%,
ZnO 0 ～ 9.0%,
Li ₂ O + Na ₂ O + K ₂ O 0 to 2.0% (except 2.0%) glass composition.
Still more preferred is an alkali-free glass that does not substantially contain an alkali metal oxide.

The second example of the low-alkali glass or the alkali-free glass may contain TiO _{2 in the} same manner as the first example of the low-alkali glass or the alkali-free glass. The content of TiO ₂ in the above-mentioned second example of low-alkali glass or alkali-free glass is 0 to 15.0 mol%, and is preferably 0 in terms of excellent smoothness of the inner wall surface of the hole obtained by laser irradiation. 1 to 10.0 mole%, more preferably 1 to 10.0 mole%, further preferably 1.0 to 9.0 mole%, and particularly preferably 1.0 to 5.0 mole%.

The second example of the low-alkali glass or the alkali-free glass may include ZnO. The content of ZnO in the second example of the low alkali glass or the alkali-free glass is 0 to 9.0 mole%, preferably 1.0 to 9.0 mole%, and more preferably 1.0 to 7.0 mole%. ZnO is a component that exhibits absorption in the ultraviolet light region similarly to TiO _2. Therefore, if ZnO is included, it has an effective effect on laser processing glass.

Furthermore, the second example of the low-alkali glass or the alkali-free glass includes CuO. The content of CuO in the above second example of low-alkali glass or alkali-free glass is preferably 0.1 to 2.0 mol%, more preferably 0.15 to 1.9 mol%, further preferably 0.18 to 1.8 mol%, and particularly preferably 0.2. ~ 1.6 mole%. The above-mentioned second example of low-alkali glass or alkali-free glass contains CuO and is colored in the glass, so that the absorption coefficient in a predetermined laser wavelength can be adjusted to an appropriate range, so that it can appropriately absorb the irradiation laser Shot energy. As a result, it is possible to easily form a deteriorated portion that is the basis of hole formation.

In the above-mentioned second example of low-alkali glass or alkali-free glass, it is not limited to the components listed above, but by containing a moderate coloring component, the absorption coefficient of the glass at a specified wavelength (wavelength 535 nm or less) can also be 1 to 50 cm ^-1 , ideally 3 to 40 cm ^-1 .

The above-mentioned first and second examples of low-alkali glass or alkali-free glass may also include MgO as an optional component. MgO also has the characteristics of suppressing the increase of the thermal expansion coefficient in the alkaline-earth metal oxides without reducing the strain point too much, and also improving the melting property. The content of MgO in the above-mentioned first and second examples of low-alkali glass or alkali-free glass is preferably 15.0 mol% or less, more preferably 12.0 mol% or less, and further preferably 10.0 mol% or less, and particularly preferably Below 9.5 mole%. The content of MgO in the above-mentioned first and second examples of low-alkali glass or alkali-free glass is preferably 2.0 mol% or more, more preferably 3.0 mol% or more, and further preferably 4.0 mol% or more, especially Ideally, it is 4.5 mol% or more.

The first and second examples of the low-alkali glass or the alkali-free glass may also include CaO as an optional component. CaO, like MgO, has the characteristics of suppressing an increase in the coefficient of thermal expansion, and does not decrease the strain point too much, and also improves the melting property. The content of CaO in the above-mentioned first and second examples of low-alkali glass or alkali-free glass is preferably 15.0 mol% or less, more preferably 12.0 mol% or less, and further preferably 10.0 mol% or less, and particularly preferably 9.3 mole% or less. In addition, the content of CaO in the above-mentioned first and second examples of low-alkali glass or alkali-free glass is preferably 1.0 mol% or more, more preferably 2.0 mol% or more, and further preferably 3.0 mol% or more, especially Ideally, it is 3.5 mol% or more.

The above-mentioned first and second examples of low-alkali glass or alkali-free glass may also include SrO as an optional component. SrO, like MgO and CaO, has the characteristics of suppressing the increase of the coefficient of thermal expansion, and does not reduce the strain point too much, and also improves the melting property. Therefore, in order to improve devitrification characteristics and acid resistance, glass for laser processing can also be made. contain. The content of SrO in the above-mentioned first and second examples of low-alkali glass or alkali-free glass is preferably 15.0 mol% or less, more preferably 12.0 mol% or less, and further preferably 10.0 mol% or less, and particularly preferably 9.3 mole% or less. The content of SrO in the above-mentioned first and second examples of low-alkali glass or alkali-free glass is preferably 1.0 mol% or more, more preferably 2.0 mol% or more, and further preferably 3.0 mol% or more, and particularly Ideally, it is 3.5 mol% or more.

In the present specification, “substantially not containing” a certain component means that the content of the component in the glass is less than 0.1 mol%, preferably less than 0.05 mol%, and more preferably 0.01 mol% or less. Moreover, in this specification, the numerical range (content of each component, the value calculated from each component, each physical property, etc.) upper limit and a lower limit may be combined suitably.

Laser processing over a thermal expansion coefficient of the glass is 100 × 10 ^-7 / ℃ or less, more preferably of 70 × 10 ^-7 / ℃ less, and further desirably 60 × 10 ^-7 / ℃ less, particularly desirably 50 × 10 ^{- 7} / ℃ or less. The lower limit of the thermal expansion coefficient of the glass for laser processing is not particularly limited, but it is, for example, 10 × 10 ^-7 / ° C or more, and may be 20 × 10 ^-7 / ° C or more.

The thermal expansion coefficient of the glass for laser processing is measured as follows, for example. First, a cylindrical glass sample with a diameter of 5 mm and a height of 18 mm was prepared. This was heated from 25 ° C to the drop point of the glass sample, and the elongation of the glass sample at each temperature was measured to calculate the thermal expansion coefficient. The average value of the thermal expansion coefficient in the range of 50 to 350 ° C can be calculated to determine the average thermal expansion coefficient.

In the step (IIa) above, there is no need to use a so-called photosensitive glass, and a wide range of glass can be processed. That is, in the step (IIa), glass that does not substantially contain gold or silver can be processed.

In particular, when a glass with high rigidity is irradiated with laser light, it is unlikely to crack on any one of the upper surface and the lower surface of the glass, and can be appropriately processed in the step (IIa). Therefore, the Young's modulus of the glass for laser processing is preferably 80 GPa or more.

As for the glass listed above, there are also commercially available cases, and these glasses can be obtained through purchase. When this is not the case, the desired glass may be produced by a known forming method (for example, an overflow method, a float method, a slit down method, a casting method, etc.), and then cut or polished. After the post-treatment, a glass composition having a target shape can be obtained.
Examples

Hereinafter, the present invention will be described in more detail using examples. The present invention is not limited to the following examples.

<Example 1>
In the optical device 1b of Example 1 shown in FIG. 7, a ray tracing simulation was performed when a laser beam of parallel light having a wavelength of 355 nm and a beam diameter of 5 mm was incident. The optical device 1b includes a first lens group 21a, a rotating triplex lens 10a, and a second lens group 22a. The central axis of the first lens group 21a, the rotating triplex lens 10a, and the second lens group 22a is consistent with the optical axis of the light beam, and they are sequentially arranged in the traveling direction of the light beam. The first lens group 21a is composed of an ideal lens L (21a-1) having zero thickness and no aberration, and its effective focal distance EFL (21a-1) is 32.54 mm. The rotating triplex lens 10a includes a conical surface with an apex angle τ of 160 ° and a plane facing the direction opposite to the conical surface. The center thickness CT (10a) of the rotating triplex lens 10a is set to 2.0 mm and the rotating triplex lens The refractive index of the medium of the lens 10a is 1.476. The rotary triplex lens 10a is arranged in a direction in which a light beam is incident on a plane thereof. The distance d (11) between the first lens group 21a composed of the lens L (21a-1) and the rotating triplex lens 10a is 2.0 mm. The second lens group 22a is composed of an ideal lens L (22a-1) having zero thickness and no aberrations, and its effective focal distance EFL (22a-1) is 7.81 mm. The distance d (12) between the rotating triplex lens 10a and the lens L (22a-1) is 35.9 mm. In the optical device 1b, the parallel laser beam penetrates the first lens group 21a and becomes convergent light. The convergent light is incident on the rotating triplet lens 10a and emits a light beam having a conical wave surface. The optical device 1b forms a first Bezier light beam within a range where the conical wave surface overlaps after rotating the triplex lens 10a. Further, the light beam diverges after becoming the first ring beam behind the first Bessel beam, and forms a focal surface with the smallest ring width before reaching the second lens group 22a. The first ring beam is incident on the second lens group 22a, and is emitted from the second ring beam having a width that is substantially constant along the optical axis and converges toward the optical axis. Behind the second lens group 22a, a point on the optical axis at a distance d (13) = 10 mm of the second lens group 22a formed by the free lens L (22a-1) is formed as a fixed starting point to form a fixed interval. Second Bezier beam. The area where the second Bessel beam is formed is the area where the second ring beam (wave front) overlaps. The distance d (13) between the second lens group 22a composed of the lens L (22a-1) and the approximate starting point of the optical axis direction of the area where the Bezier beam is formed is such that the surface of the glass to be processed can be approached The shortest distance of the final exit surface of the optical device 1b is equivalent to the working distance WD (1). The total length on the optical axis of the optical device 1b (the distance from the lens L (21a-1) to the optical axis of the lens L (22a-1)) plus the working distance WD (1) becomes 49.9 mm. A plate-shaped glass is arranged in a region where the second Bezier light beam is formed so that a portion in the thickness direction is included or overlapped, whereby a modified portion can be formed inside the glass.

<Example 2>
In the optical device 1c of Example 2 shown in FIG. 8, a ray tracing simulation was performed when a laser beam of parallel light having a wavelength of 355 nm and a beam diameter of 2.5 mm was incident. The optical device 1c includes a first lens group 21b, a rotating triplex lens 10b, and a second lens group 22b. The central axes of the first lens group 21b, the rotating triplex lens 10b, and the second lens group 22b are consistent with the optical axis of the light beam, and are sequentially arranged in the traveling direction of the light beam. The first lens group 21 b is composed of a lens L (21 b-1), a lens L (21 b-2), and a lens L (21 b-3). These lenses are sequentially arranged in the traveling direction of the light beam. The center thickness CT (21b-1) of the lens L (21b-1) is 1.0 mm, the refractive index of the medium of the lens L (21b-1) is 1.476, and the lens L (21b-1) includes a concave surface formed by a spherical shape And a plane facing in the opposite direction to the concave surface. The lens L (21b-1) is arranged in a direction such that a light beam is incident on its concave surface and a light beam is emitted from its plane. The radius of curvature of the spherical surface of the concave surface of the lens L (21b-1) is -5.00 mm. The center thickness CT (21b-2) of the lens L (21b-2) is 4.0 mm, the refractive index of the medium of the lens L (21b-2) is 1.476, and the lens L (21b-2) includes a convex surface composed of a spherical shape And a plane facing the opposite direction of the convex surface. The lens L (21b-2) is arranged in a direction such that a light beam from the lens L (21b-1) is incident on its plane and the light beam is emitted from its convex surface. The distance d (21) between the lens L (21b-1) and the lens L (21b-2) is 38.00 mm. The convex surface of the lens L (21b-2) has a radius of curvature of -24.33 mm. The center thickness CT (21b-3) of lens L (21b-3) is 4.0 mm, the refractive index of the medium of lens L (21b-3) is 1.476, and lens L (21b-3) includes a convex surface composed of a spherical shape And a plane facing the opposite direction of the convex surface. The lens L (21b-3) is arranged in a direction such that a light beam from the lens (21b-2) is incident on its convex surface and the light beam is emitted from its plane. The distance d (22) between the lens L (21b-2) and the lens L (21b-3) is 0 mm. The lens L (21b-2) and the lens L (21b-3) are arranged such that the convex surfaces thereof face each other and the vertexes of the convex surfaces are in contact. The convex surface of the lens L (21b-3) has a curvature radius of 24.33 mm. The lens L (21b-2) has the same shape as the lens L (21b-3). As shown in FIG. 8, the first lens group 21 b functions as a beam amplifier to expand the beam diameter of the laser beam and converge the beam.

The rotating triplex lens 10b includes a conical surface with a vertex angle τ of 140 ° and a plane facing the opposite direction of the conical surface. The center thickness CT (10b) of the rotating triplex lens 10b is 5.0 mm, and the rotating triplex lens 10b The refractive index of the medium is 1.476. The rotating triplex lens 10b is arranged in a direction such that a light beam from the first lens group 21b enters its plane and the light beam exits from its conical surface. The distance d (23) between the lens (21b-3) of the first lens group 21b and the rotating triplex lens 10b is 2.0 mm.

The second lens group 22b is composed of a lens L (22b-1) and a lens L (22b-2), and these lenses are sequentially arranged in the traveling direction of the light beam. The center thickness CT (22b-1) of the lens L (22b-1) is 5.0 mm, the refractive index of the medium of the lens L (22b-1) is 1.476, and the lens L (22b-1) includes a convex surface composed of a spherical shape And a plane facing the opposite direction of the convex surface. The lens L (22b-1) is arranged in such a direction that a light beam from the rotating triplex lens 10b enters its plane and the light beam exits from its convex surface. The distance d (24) between the rotating triplex lens 10b and the lens L (22b-1) is 36.96 mm. The convex surface of the lens L (22b-1) has a radius of curvature of -14.25 mm. The center thickness CT (22b-2) of the lens L (22b-2) is 5.0 mm, the refractive index of the medium of the lens L (22b-2) is 1.476, and the lens L (22b-2) includes a convex surface and the direction opposite to the convex surface Directional plane. The lens L (22b-2) is arranged in a direction such that a light beam from the lens L (22b-1) enters its convex surface and the light beam exits from its plane. The distance d (25) between the lens L (22b-1) and the lens L (22b-2) is 0 mm. The lens L (22b-1) and the lens L (22b-2) are arranged such that the convex surfaces thereof face each other and the vertexes of the convex surfaces are in contact. The convex surface of the lens L (22b-2) has a radius of curvature of 14.25 mm. The lens L (22b-1) is the same shape as the lens L (22b-2). In the optical device 1c, the parallel laser beam penetrates the first lens group 21b, so that the beam diameter of the laser beam is enlarged and becomes convergent light. The convergent light is incident on the rotating triplex lens 10b and is emitted in a conical shape. Beam of light. The optical device 1c forms a first Bezier light beam within a range where the conical wave surface overlaps after rotating the triplex lens 10b. Further, the light beam diverges after becoming the first ring beam behind the first Bessel beam, and forms a focal surface with the smallest ring width before reaching the second lens group 22b. The first ring beam enters the second lens group 22b, and is emitted from the second ring beam whose width in a direction perpendicular to the optical axis is substantially fixed along the optical axis and converges toward the optical axis. Behind the second lens group 22b, a second Bezier light beam is formed in a fixed interval with a point on the optical axis d (26) = 18 mm from the lens L (22b-2) as an approximate starting point. The area where the second Bessel beam is formed is the area where the second ring beam (wave front) overlaps. d (26) is equivalent to the working distance WD (2). The total length of the optical axis of the optical device 1c and the working distance WD (2) is 118.96 mm. A plate-shaped glass is arranged in a region where the second Bezier light beam is formed so that a portion in the thickness direction is included or overlapped, whereby a modified portion can be formed inside the glass.

〈Comparative example 1〉
In the optical device 100 of Comparative Example 1 shown in FIG. 9, parameters of each optical element were studied in a manner equivalent to that of Example 1, and parallel light having a wavelength of 355 nm and a beam diameter of 5.0 mm was performed. Simulation of ray tracing when a laser beam is incident. The optical device 100 includes a rotating triplex lens 110, a first lens group 121, and a second lens group 122, and a central axis of the rotating triplex lens 110, the first lens group 121, and the second lens group 122 and light beams The axes are the same, and they are sequentially arranged along the optical axis in the traveling direction of the light beam. The rotating triplex lens 110 includes a conical surface with a vertex angle τ of 160 ° and a plane facing the opposite direction of the conical surface. The center thickness CT (110) of the rotating triplex lens 110 is 2.0 mm and the rotating triplex lens 110 The refractive index of the medium is 1.476. The rotating triplex lens 110 is arranged in a direction such that a light beam is incident on its plane and a light beam is emitted from its conical surface. The first lens group 121 is composed of an ideal lens L (121-1) with zero thickness and no aberrations, and its effective focal distance EFL (121-1) is 35.68 mm. The interval d (121) between the rotating triplex lens 110 and the first lens group 121 composed of the lens L (121-1) is 47.48 mm. The second lens group 122 is composed of an ideal lens L (122-1) with zero thickness and no aberration, and its effective focal distance EFL (122-1) is 10.00 mm. The distance d (122) between the first lens group 121 composed of the lens L (121-1) and the second lens group 122 composed of the lens L (122-1) is the effective focal distance EFL (121-1) and The effective focal distance is 45.68 mm of the sum of EFL (122-1). In the optical device 100, a parallel laser beam enters the rotating triplex lens 110, and emits a beam having a conical wave surface. The optical device 100 forms a first Bessel light beam within a range where the conical wave surface overlaps after rotating the triplex lens 110. Furthermore, the light beam diverges after becoming the first ring beam behind the first Bezier beam. The first ring beam enters the first lens group 121 and emits a second ring beam. Furthermore, in the second ring beam, a focal plane having a minimum ring width is formed behind the first lens group 121. The second ring beam is incident on the second lens group 122 and is emitted from a third ring beam whose width in a direction perpendicular to the optical axis is substantially fixed along the optical axis and converges toward the optical axis. Behind the second lens group 122, a second Bezier light beam is formed in a fixed interval with a point on the optical axis d (123) = 10 mm from the lens L (122-1) as a rough starting point. The area where the second Bessel beam is formed is the area where the third ring beam (wave front) overlaps. The distance d (123) between the second lens group 122 and the approximate starting point in the optical axis direction of the area where the Bezier beam is formed corresponds to the working distance WD (21). The total length on the optical axis of the optical device 100 (the distance on the optical axis of the rotating triplex lens 110 to the second lens group 122) plus the working distance WD (21) becomes 105.16 mm. A plate-shaped glass is arranged in a region where the second Bezier light beam is formed so that a portion in the thickness direction is included or overlapped, whereby a modified portion can be formed inside the glass. Furthermore, in Comparative Example 1, according to the relationship with the arrangement of the second optical lens group 122, the final optical system penetrated by the laser beam, the lens group disposed behind the rotating triplex lens 110 is referred to as the first Lens group 121.

<Example 3>
The electric field amplitude when a Gaussian laser beam with a wavelength of 355 nm was incident on the optical device 1d of Example 3 shown in FIG. 10 was simulated. The diameter is set to 2.5 mm, which is 1 / e ² times (13.5%) the maximum intensity at the center of the beam. For this simulation, electromagnetic wave transmission analysis software (Beam PROP "Version 6.0.3) manufactured by Synopsys, Inc. of the United States was used. The optical device 1d has a first lens group 21c, a rotating triplex lens 10c, and a second lens group 22c. The center axis of the lens group 21c, the rotating triplex lens 10c, and the second lens group 22c is the same as the optical axis of the light beam, and is arranged in order in the direction of travel of the light beam. The optical device 1d and the following optical device 1e are performed by the light beam. The operation is the same as that performed by the light beam of the optical device 1b of Example 1. The first lens group 21c forms a convergent light, and the convergent light is incident on the rotating triplex lens 10c, and a first A Bezier beam, a first ring beam, and a focal plane. The first ring beam is incident on the second lens group 22c, and a second ring beam and a second Bezier beam are formed behind it.

The first lens group 21c is composed of a lens L (21c-1). The center thickness CT (21c-1) of lens L (21c-1) is 3.33 mm, the refractive index of the medium of lens L (21c-1) is 1.476, and lens L (21c-1) includes spherical surfaces facing in opposite directions. Two convex surfaces formed by the shape. In any convex surface of the lens L (21c-1), the absolute radius of curvature of the spherical surface of the convex surface is 31.57 mm. The lens L (21c-1) is arranged so that a light beam is incident from a convex surface. The distance d (31) between the origin of the simulation and the lens L (21c-1) is 0.69 mm. Rotary triplex lens 10c includes a conical surface with an apex angle τ of 140 ° and a plane facing the opposite direction of the conical surface. The center thickness CT (10c) of the rotary triplex lens 10c is 4.18 mm, and the rotary triplex lens 10c The refractive index of the medium is 1.476. The rotating triplex lens 10c is arranged in a direction such that a light beam from the lens L (21c-1) enters its plane and the light beam exits from its conical surface. The distance d (32) between the lens L (21c-1) and the rotating triplex lens 10c is 7.42 mm. The distance z1 from the origin on the simulation to the front end of the rotating triplex lens 10c is 15.62 mm.

The second lens group 22c is composed of a lens L (22c-1) and a lens L (22c-2), and these lenses are sequentially arranged in the traveling direction of the light beam. The center thickness CT (22c-1) of the lens L (22c-1) is 3.60 mm, the refractive index of the medium of the lens L (22c-1) is 1.476, and the lens L (22c-1) includes a spherical convex surface and the direction and The convex surface is in the opposite direction. The lens L (22c-1) is arranged in such a direction that a light beam from the rotating triplex lens 10c enters its plane and the light beam exits from its convex surface. The distance d (33) between the rotating triplex lens 10c and the lens L (22c-1) is 26.38 mm. The convex surface of the lens L (22c-1) has a radius of curvature of -13.75 mm. The center thickness CT (22c-2) of the lens L (22c-2) is 3.60 mm, the refractive index of the medium of the lens L (22c-2) is 1.476, and the lens L (22c-2) includes a spherical convex surface and its orientation and The convex surface is in the opposite direction. The lens L (22c-2) is arranged in a direction such that a light beam from the lens L (22c-1) is incident on its convex surface and the light beam is emitted from its plane. The distance d (34) between the lens L (22c-1) and the lens L (22c-2) is 0 mm. The lens L (22c-1) and the lens L (22c-2) are arranged such that the convex surfaces thereof face each other and the vertexes of the convex surfaces are in contact. The convex surface of the lens L (22c-2) has a radius of curvature of 13.75 mm. The lens L (22c-1) has the same shape as the lens L (22c-2). The distance z2 from the origin to the exit surface of the lens L (22c-2) of the second lens group 22c is 49.20 mm. A simulation result of the electric field amplitude on the optical axis in the region where the Bezier beam is formed behind the second lens group 22c and the vicinity of the region is shown in FIG. 13A. In addition, the simulation results of the electric field amplitude in the direction perpendicular to the optical axis in this region and the vicinity thereof are shown in FIG. 13B. The squared value of the electric field amplitude corresponds to the light intensity.

<Example 4>
The electric field amplitude when a Gaussian laser beam with a wavelength of 355 nm was incident on the optical device 1e of Example 4 shown in FIG. 11 was simulated. The conditions of the simulation in Embodiment 4 are the same as those of the simulation in Embodiment 3, except for the cases specifically described. In FIG. 11, the same symbols as those of the optical device 1 d of Example 3 shown in FIG. 10 are used for the symbols indicating the optical element and the distance, except for the rotating triplet lens 10 d and the shield 25. In the optical device 1e, the front end of the rotating triplex lens 10d is spherical as shown in FIG. 12A. In FIG. 12A, α = 20 °, W = 0.2 mm, and R = 0.2924 mm. In addition, as shown in FIG. 11, a relatively thin plate-shaped shield 25 is arranged in plane contact with the incident side of the lens L (22c-1) of the second lens group 22 c. The shield 25 is a circular plate having a diameter of 8.8 mm and a thickness of 10 μm. The axis of the shield 25 is located on the optical axis. The shield 25 shields light passing through the inside of the first ring beam in the radial direction. The complex refractive index of the shield 25 is set to 3.136 + 3.3121i. The complex refractive index is determined by the way in which the shielding body 25 sufficiently shields the light incident on the shielding body 25 in the simulated ray tracing. In the optical device 1e, the simulation results of the electric field amplitudes on the optical axis in the region and the vicinity of the Bessel beam forming area behind the second lens group 22c are shown in FIG. 14A. The simulation results of the electric field amplitudes in the direction perpendicular to the optical axis in this region and its vicinity are shown in FIG. 14B.

<Example 5>
The simulation was performed in the same manner as in Example 4 except that the shape of the front end of the rotating triplex lens 10d was changed to the shape of the rotating triplex lens 10e shown in FIG. 12B. In FIG. 12B, α = 20 °, W = 0.2 mm, and R = 0.1462 mm. In this case, a simulation result of the electric field amplitude on the optical axis in the region behind the second lens group 22c that forms the Bessel beam and the vicinity of the region is shown in FIG. 15A. The simulation results of the electric field amplitudes in the direction perpendicular to the optical axis in this region and its vicinity are shown in FIG. 15B.

〈Comparative example 2〉
A simulation was performed under the same conditions as in Example 4 except that the shield 25 was not provided. In this case, the simulation results of the electric field amplitudes on the optical axis in the region behind the second lens group 22c that forms the Bezier beam and its vicinity are shown in FIG. 16A. The simulation results of the electric field amplitude in the direction perpendicular to the optical axis in this region and its vicinity are shown in FIG. 16B.

〈Comparative example 3〉
The simulation was performed under the same conditions as in Example 5 except that the shield 25 was not provided. In this case, the simulation results of the electric field amplitudes on the optical axis in the region behind the second lens group 22c that forms the Bezier beam and its vicinity are shown in FIG. 17A. The simulation results of the electric field amplitude in the direction perpendicular to the optical axis in this region and its vicinity are shown in FIG. 17B.

(Another embodiment)
FIG. 18 shows an optical device 1f according to another embodiment of the third embodiment. The optical system of the optical device 1f is the same as the optical system 1d of Example 3 in terms of the specifications and arrangement of each lens group and the rotating triplex lens, but further includes plate-shaped shields 26a, 26b, and 26c on the optical axis. , And 26d. The shields 26a, 26b, 26c, and 26d are arranged so as to substantially shield portions other than the optical path of the ring beam. When examining the movement of the light beam or light of the optical device 1f, the diameter of the incident light beam is assumed to be 5 mm here. The reason is that it is considered that the beam diameter (2.5 mm) corresponding to the intensity corresponding to 1 / e ² times of the peak intensity also diffuses outward. The shield 26a is disposed at a distance of 17.3 mm from the front end of the rotating triplex lens. This position corresponds to the position on the optical axis of the focal plane with the smallest width of the first ring beam. As shown in FIG. 19A, the shield 26a has a penetrating portion 27a and a light shielding portion 28a. The penetrating portion 27a is a ring-shaped portion that can be penetrated by the first ring beam. The light-shielding portion 28a includes a first light-shielding portion 28a1, which is a circular portion concentric with the penetrating portion 27a inside the radial penetrating portion 27a. And the second light-shielding portion 28a2, which is a portion including a circular portion concentric with the penetrating portion 27a outside the penetrating portion 27a in the radial direction. The first light shielding portion 28a1 shields light passing through the inside of the first ring beam in the radial direction, and the second light shielding portion 28a2 shields light passing through the outside of the first ring beam in the radial direction. The diameter of the first ring beam at the position (focus surface) where the shield 26a is arranged is 6.3 mm. The inner diameter of the penetrating portion 27a is, for example, 6.0 mm, and the outer diameter of the penetrating portion 27a is, for example, 6.6 mm. Here, the penetrating portion refers to a portion that shows 70% or more, preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more of the penetration rate at the portion. In addition, the light-shielding portion refers to a portion that exhibits 10% or less, preferably 5% or less, more preferably 2% or less, and further preferably 0.5% or less in the portion. In order to maximize the effect of shading, the width of the penetrating portion should be consistent with the width of the ring beam. However, if the design is made to be completely consistent with each other, there is a high possibility that a part of the ring beam is blocked due to an error in production. Therefore, it is preferable that the width of the penetrating portion is such that the error is grasped, and the width is set to a certain margin.

The shield 26b is disposed at a distance of 23.0 mm from the front end of the rotating triplex lens. As shown in FIG. 19B, the shield 26b has a penetrating portion 27b and a light shielding portion 28b. The penetrating portion 27b is a portion through which the first ring beam can penetrate, and the light-shielding portion 28b includes a first light-shielding portion 28b1 which is a circular portion concentric with the penetrating portion 27b inside the radial penetrating portion 27b. The first light-shielding portion 28b1 shields light passing through the inside of the first ring beam in the radial direction. The first ring beam at the position where the shield body 26b is arranged has an inner diameter of 8.38 mm and an outer diameter of 9.34 mm. The inner diameter of the penetrating portion 27b is, for example, 8.0 mm, and the outer diameter of the penetrating portion 27b is not particularly limited. The light rays and the like passing through a position farther from the optical axis may be configured by being shielded by, for example, a housing or the like in which the optical system is integrated.

The shield 26c is arranged on the incident surface of the lens L (22c-1) of the second lens group 22c. The shield 26c includes a penetrating portion 27c and a light shielding portion 28c. The penetrating portion 27c is a ring-shaped portion that can be penetrated by the first ring beam. The light-shielding portion 28c includes a first light-shielding portion 28c1, which is a circular portion concentric with the penetrating portion 27c inside the radial penetrating portion 27c. And a second light-shielding portion 28c2 which is a circular portion concentric with the penetrating portion 27c outside the penetrating portion 27c in the radial direction. The first light shielding portion 28c1 shields light passing through the inside of the first ring beam in the radial direction, and the second light shielding portion 28c2 shields light passing through the outside of the first ring beam in the radial direction. The first ring beam at the position where the shield body 26c is disposed has an inner diameter of 9.61 mm and an outer diameter of 11.2 mm. The inner diameter of the penetrating portion 27c is, for example, 9.4 mm, and the outer diameter of the penetrating portion 27c is, for example, 11.6 mm.

The shield 26d is disposed at a distance of 5.0 mm from the exit surface of the lens L (22c-2). The shield 26d has a penetrating portion 27d and a light shielding portion 28d. The penetrating portion 27d is a ring-shaped portion that can be penetrated by the second ring beam, and the light-shielding portion 28d includes a first light-shielding portion 28d1, which is a circular portion concentric with the penetrating portion 27d inside the radial penetration portion 27d. And the second light-shielding portion 28d2, which is a portion outside the penetrating portion 27d in the radial direction and includes a circular portion concentric with the penetrating portion 27d. The first light shielding portion 28d1 shields light passing through the inside of the second ring beam in the radial direction, and the second light shielding portion 28d2 shields light passing through the outside of the second ring beam in the radial direction. The second ring beam at the position of the shielding body 26d has an inner diameter of 7.56 mm and an outer diameter of 9.69 mm. The inner diameter of the penetrating portion 27d is, for example, 7.3 mm, and the outer diameter of the penetrating portion 27d is, for example, 10.0 mm. By providing the shield 26d in the area where the second ring beam is generated, the substantial working distance becomes shorter, but the optical system can be easily assembled or adjusted.

As the shields 26a, 26b, 26c, and 26d, shielding materials such as quartz glass, which is used to display high transmittance of light with a wavelength of 355 nm, are formed with a metal thin film or the like except for a portion intended to be a penetrating portion. Layers. Further, the shields 26a, 26b, and 26d may be formed by integrating thin shield plates using thin supports 29a, 29b, and 29d, as shown in FIGS. 20A, 20B, and 20C, respectively. In this case, for example, even if it is slight, the effect of absorption or refraction caused by the substrate can be eliminated. The shield 26c may be directly formed on the surface of the lens L (22c-1). Furthermore, one or more shields 26a, 26b, 26c, and 26d may be selected to form the optical system. Furthermore, the shields 26a, 26c, and 26d may be those which do not each include a second light shielding portion. Here, excluding the second light-shielding portion means that the corresponding portion transmits light to the same extent as the penetrating portion. That is, the shielding system that does not include the second light-shielding portion includes a penetrating portion that is unlimited in shape and a first light-shielding portion.

Comparative Example 1 and Comparative Example 1. Note that Example 1 and Comparative Example 1 use a laser beam with the same beam diameter and the same rotating triplex lens. In Example 1, the full length of the optical device (the distance between the first lens group 21a to the second lens group 22a) required to obtain a working distance WD (1) of 10 mm is 39.9 mm. On the other hand, in Comparative Example 1, The total length of the optical device (distance between the rotating triplex lens 110 and the second lens group 122) required to obtain the same working distance WD (21) of 10 mm is 95.16 mm. As is apparent from FIG. 9, in the optical device 100 of Comparative Example 1, the diameter of the ring beam at the middle portion of the rotating triplex lens 110 and the first lens group 121 is substantially increased. The diameter of the ring beam is approximately constant at the middle portion of the first lens group 121 and the second lens group 122 that are connected behind it. In order to form the focus of the ring beam in the middle of the two lens groups, the interval between the two lens groups must be made longer, and the interval is equal to the sum of the focal distances of the two lens groups. On the other hand, in the optical device 1b of Example 1, the diameter of the ring beam at the middle portion of the rotating triplex lens 10a and the second lens group 22a is substantially increased, and the length of this portion is the same as that of Comparative Example 1. There is no big difference in the "ring beam increasing area". However, there is no "region where the diameter of the ring beam is approximately fixed". As a result, the total length of the optical device 1b of Example 1 is much shorter than that of the optical device 100 of Comparative Example 1.

The optical device 1b of Example 1 and the optical device 100 of Comparative Example 1 each have two lens groups. In the optical device 1b of Embodiment 1, the beam diameter of the beam incident on the first lens group 21a is relatively small. On the other hand, in the optical device 100 of Comparative Example 1, it is necessary that the ring beam that has passed through the rotating triplex lens penetrates the first lens group 121. Therefore, the maximum diameter of the light beam incident on the first lens group 121 is necessarily large, and the light beam is inclined to the optical axis. Therefore, the first lens group 121 requires a higher level of performance for correcting aberrations than the performance of correcting aberrations required for the first lens group 21a. For example, in the optical device 1b of Example 1, substantially parallel light having a small beam diameter emitted from the laser light source is incident on the first lens group 21a, so it is easy to achieve performance capable of suppressing generation of aberrations. On the other hand, a light beam having a large number of openings (NA) is incident on the first lens group 121 of the optical device 100 of Comparative Example 1. Therefore, it is considered that it is difficult to correct aberrations such as spherical aberration when the first lens group 121 is constituted by a single lens.

In the optical device 1c of Embodiment 2, the beam diameter of the beam incident on the rotating triplex lens 10b is relatively large. Therefore, the total length (100.96 mm) of the optical device 1c of Example 2 is longer than that of the optical device 1b of Example 1. Instead, in the optical device 1c of Embodiment 2, a longer working distance (WD (2) = 18 mm) than that of the optical device 1b of Embodiment 1 can be achieved. As also shown in FIG. 3, it is shown that by increasing the laser beam incident on the rotating triplet lens, the length held by the Bezier beam in the optical axis direction can be made longer.

Comparative Examples 3 to 5 and Comparative Examples 2 and 3. In Example 3, the front end of the conical surface of the rotating triple-lens lens 10c is sharp. On the other hand, in Comparative Examples 2 and 3, the front end of the rotating triple-lens lens is curved and not sharp. Comparing FIG. 13A with FIGS. 16A and 17A, the distribution of the electric field amplitude on the optical axis in Comparative Examples 2 and 3 is irregularly changed along the optical axis compared with the distribution of the electric field amplitude on the optical axis in Example 3. The intensity of light corresponds to the square of the electric field amplitude, so the state of the electric field amplitude can be regarded as the state of the light intensity. Therefore, it is understood that in Comparative Examples 2 and 3, the light intensity on the optical axis varies irregularly. It is considered that in Comparative Examples 2 and 3, the irregular change in the amplitude of the electric field amplitude on the optical axis by the front end of the rotating triplex lens is not sharp, and even the irregular change in the light intensity on the optical axis. It is considered that if the front end of the rotating triplex lens in the optical device is not sharp like the comparative examples 2 and 3, a modified object is formed inside the processing object by irradiating a light beam penetrating the optical device to a processing object such as plate glass. It is difficult to stabilize the quality of the products obtained during the manufacturing process. The reason is considered to be that the uneven light intensity of the laser beam on the optical axis among the laser beams irradiated to the processing object by such an optical device adversely affects the formation of a uniform deteriorated portion.

In Examples 4 and 5, similarly to Comparative Examples 2 and 3, the front end of the rotating triplex lens was curved and not sharp. However, the shields 25 are arranged in the fourth and fifth embodiments. In Examples 4 and 5, as shown in FIGS. 14A and 15A, irregular changes in the electric field amplitude on the optical axis as observed in Comparative Examples 2 and 3 were basically not observed. In particular, in a range where the distance z from the origin to a maximum of the electric field amplitude is 79 mm ± 1 mm, irregular changes in the electric field amplitude on the optical axis as observed in Comparative Examples 2 and 3 are not observed. Another embodiment is characterized in that one or more shields selected from the plate-shaped shields 26a, 26b, 26c, and 26d are arranged on the optical axis. This suggests that it is more effective to obtain the performance of intercepting light rays that cause irregular changes in the amplitude of the electric field on the optical axis. The shields 26a, 26c, and 26d include a penetrating portion, which is a ring-shaped portion that can be penetrated by the ring beam, as described above, and a circular portion concentric with the penetrating portion on the inner side of the penetrating portion in the radial direction. A light-shielding portion and a second light-shielding portion formed on the outside of the penetrating portion by a portion including a ring-shaped portion concentric with the penetrating portion. The shield 26b includes a penetrating portion and a first light-shielding portion that is a circular portion concentric with the penetrating portion inside the penetrating portion in the radial direction. The shields 26a, 26c, and 26d may not include the second light shielding portion. The effects obtained by using the shield in this case are considered as follows. As described above, a part of the light emitted from the rotating triplex lens with a sharpened front end exists outside the ring beam, etc., and the light passes through a portion corresponding to the second light-shielding portion and reaches the second When the lens group is further behind. The reason is considered to be that since such light travels outside the first and second ring beams, the probability of reaching the area where the second Bessel beam is formed is low, and its influence is small after the second Bessel beam is formed. The shield 26b does not originally have a second light shielding portion. In contrast, when there is light passing through the inside of the ring beam, as shown in Comparative Examples 2 and 3, if the inside of the penetrating portion is shielded by the first light-shielding portion, a second Bessel beam is formed. After that, the influence led by the irregular variation of the electric field amplitude on the axis becomes larger. Moreover, when there is no second light-shielding portion in the shield, it is often the case that the light that is taken away from the optical axis reaches the inner surface of the housing or the like used to integrate or support the optical system. The probability that the intensity is attenuated by absorption or the like is high. Therefore, in the shielding body of another embodiment, it is desirable to form a first light-shielding portion in the light-shielding portion to shield the light passing through the inside of the ring beam, and form a second light-shielding to shield the light passing through the outside of the ring beam. The Ministry can be said to be a more ideal form.

It is considered that in Comparative Examples 2 and 3, because the front end of the rotating triplex lens is not sharp, the light that does not contribute to the formation of the ring beam advances in the area near the optical axis, and the irregularity of the electric field amplitude on the optical axis Changes make a difference. Since the front end of the rotating triplex lens has a conical shape, as described above, a highly advanced technique is required for accurate polishing. Therefore, if, for example, a product with a slight arc remaining at the tip is removed as a defective product, the yield is reduced and the manufacturing cost is increased. In addition, it is also considered that, because the energy of the laser beam is concentrated at the front end, stress concentration due to temperature differences and the like during use causes cracks and defects. Furthermore, it may be damaged by accidental collision. If there are defects such as radians, cracks, and defects at the front end of the rotating triplex lens, the direction of the light passing through this part is different from the case where the front end of the rotating triplex lens is completely conical, so it does not help the ring Irregular light formed by a beam or Bezier beam. If a part of such irregular light reaches the area where the Bezier beam is formed, random interference will occur, and the distribution of the formed Bezier beam will be disordered. Therefore, it is considered that, as in Examples 4 and 5, the shielding does not contribute to the transmission of the rays formed by the ring beam, and it is possible to prevent the irregular change in the amplitude of the electric field in the region where the second Bezier beam is formed. Furthermore, in the embodiment of the present invention, the plane of the rotating triplex lens is arranged to be forward, and the conical surface is arranged to be rear. Therefore, the first Bezier beam is formed in the air. The rotating triplex lens can also be used upside down. However, in this case, the first Bessel beam is formed in the lens. Therefore, there is a possibility that the glass material interacts with light energy to cause deterioration and the like.

It is considered that if any of the optical devices of Examples 1 to 5 or another embodiment is used to irradiate the second Bessel beam to the glass, a deteriorated portion with small cracks can be formed.

1a, 1b, 1c, 1d, 1e, 1f, 100‧‧‧ optical devices

10, 10a, 10b, 10c, 10d, 10e, 110‧‧‧ rotating triplex lens

21, 21a, 21b, 21c, 121‧‧‧ the first lens group

22, 22a, 22b, 22c, 122‧‧‧Second lens group

25, 26a, 26b, 26c, 26d‧‧‧Shield

27a, 27b, 27c, 27d

28a1, 28b1, 28c1, 28d1‧‧‧ the first light-shielding unit

28a2, 28c2, 28d2‧‧‧Second shade section

f‧‧‧ focus plane

TB‧‧‧ (convergent) laser beam

LB‧‧‧laser beam

A‧‧‧First Bessel Beam

B‧‧‧ first ring beam

C‧‧‧Second ring beam

D‧‧‧Second Bezier Beam

FIG. 1 is a diagram schematically showing an example of an optical device of the present invention.

FIG. 2 is a diagram schematically showing generation of an approximate quasi-bessel beam using a rotating triplet lens.

FIG. 3 is a graph showing the intensity on the optical axis of a light beam that penetrates a rotating triplex lens for laser beams having different beam diameters incident on the rotating triplex lens.

FIG. 4 is a graph showing the intensity on the optical axis of a light beam penetrating the rotating triplex lens for the rotating triplex lens having different apex angles.

FIG. 5 is a graph showing a beam intensity at a position on the optical axis where the intensity of the light beam on the optical axis shown in FIG. 4 where the rotation triplet lens with different apex angles is maximized.

FIG. 6A is a graph showing the intensity distribution of light penetrating the rotating triplex lens when the sharpness of the rotating triplex lens is high.

FIG. 6B is a diagram showing the intensity distribution of light passing through the rotating triplex lens when the sharpness of the rotating triplex lens is low.

FIG. 7 is a diagram schematically showing the optical device of the first embodiment.

FIG. 8 is a diagram schematically showing an optical device of Example 2. FIG.

FIG. 9 is a diagram schematically showing an optical device of Comparative Example 1. FIG.

FIG. 10 is a diagram schematically showing an optical device of the third embodiment.

FIG. 11 is a diagram schematically showing an optical device of Example 4. FIG.

FIG. 12A is a diagram showing the shape of the front end of a rotating triplex lens in the optical device of Example 4. FIG.

FIG. 12B is a diagram showing the shape of the front end of the rotating triplex lens in the simulation of Example 5. FIG.

FIG. 13A is a graph showing the magnitude of the electric field amplitude on the optical axis in the simulation in Example 3. FIG.

FIG. 13B is a graph showing the magnitude of the electric field amplitude in the direction perpendicular to the optical axis in the simulation of Example 3. FIG.

FIG. 14A is a graph showing the magnitude of the electric field amplitude on the optical axis in the simulation in Example 4. FIG.

FIG. 14B is a graph showing the magnitude of the electric field amplitude in a direction perpendicular to the optical axis in the simulation of Example 4. FIG.

FIG. 15A is a graph showing the magnitude of the electric field amplitude on the optical axis in the simulation in Example 5. FIG.

FIG. 15B is a graph showing the magnitude of the electric field amplitude in a direction perpendicular to the optical axis in the simulation of Example 5. FIG.

FIG. 16A is a graph showing the magnitude of the electric field amplitude on the optical axis in the simulation of Comparative Example 2. FIG.

16B is a graph showing the magnitude of the electric field amplitude in a direction perpendicular to the optical axis in the simulation of Comparative Example 2. FIG.

FIG. 17A is a graph showing the magnitude of the electric field amplitude on the optical axis in the simulation of Comparative Example 3. FIG.

FIG. 17B is a graph showing the magnitude of the electric field amplitude in the direction perpendicular to the optical axis in the simulation of Comparative Example 3. FIG.

FIG. 18 is a diagram schematically showing an optical device according to another embodiment.

FIG. 19A is a view of a shield body of an optical device according to another embodiment as viewed from the front along the optical axis.

FIG. 19B is a view of another shield of the optical device according to another embodiment viewed from the front along the optical axis.

FIG. 19C is a view of another shield of the optical device according to another embodiment as viewed from the front along the optical axis.

FIG. 19D is a view of another shield of the optical device according to another embodiment as viewed from the front along the optical axis.

20A is a diagram obtained by observing a modified example of the shield body shown in FIG. 19A from the front along the optical axis.

FIG. 20B is a diagram obtained by observing a modified example of the shield body shown in FIG. 19B from the front along the optical axis.

FIG. 20C is a diagram obtained by observing a modified example of the shield body shown in FIG. 19D from the front along the optical axis.

Claims (16)

An optical device for processing using a laser beam, comprising: A first lens group for incident laser beam; A rotating axicon lens for incident on the laser beam passing through the first lens group; and A second lens group for incident on the laser beam that penetrates the rotating triplex lens; The first lens group forms a first Bessel beam behind the rotating triplet lens, and forms a first ring beam behind the first Bessel beam, and is perpendicular to the optical axis. Form a focal plane that minimizes the ring width of the first ring beam, The second lens group is for the first ring beam to be incident, and a second ring beam having a ring width in a direction perpendicular to the optical axis behind the second lens group is substantially fixed along the optical axis. A second Bessel beam is formed behind the second ring beam. The optical device according to claim 1, wherein the first lens group, the rotating triplet lens, and the second lens group are sequentially arranged on the optical axis, and the focal surface is formed on the rotating triangle. Between the mirror lens and the second lens group. The optical device according to claim 1 or 2, further comprising a shield disposed between the rotary triplex lens and the second lens group, or between the second lens group and the second basset. Between the first and second light beams, and has a first light-shielding portion that shields light existing inside the first ring beam or the second ring beam in a direction perpendicular to the optical axis, and shields a light beam that is perpendicular to the optical axis. The direction exists in at least one of the second light shielding portions of the light rays outside the first ring beam or the second ring beam. The optical device according to claim 3, wherein the shield includes the first light-shielding portion. The optical device according to claim 3 or 4, wherein the shield includes the first light-shielding portion and the second light-shielding portion. A processing method using a laser beam includes the following steps: Making the laser beam incident on the first lens group; Causing the laser beam that has passed through the first lens group to enter a rotating triplex lens; With the first lens group, a first Bessel beam is formed behind the rotating triplet lens, and a first ring beam is formed after the first Bessel beam, which is perpendicular to the optical axis. Form a focal plane that minimizes the ring width of the first ring beam; and The first ring beam is made incident on the second lens group, and a second ring beam having a ring width in a direction perpendicular to the optical axis behind the second lens group is substantially fixed along the optical axis; A second Bessel beam is formed behind the second ring beam. The method for processing a laser beam according to claim 6, wherein the first lens group, the rotating triplet lens, and the second lens group are sequentially arranged on the optical axis, and the focal plane is formed on Between the rotating triplex lens and the second lens group. The method for processing a laser beam as described in claim 6 or 7, further comprising the step of: placing light in a direction perpendicular to the optical axis inside the first ring beam or the second ring beam And at least one of the rays existing outside the first ring beam or the second ring beam in a direction perpendicular to the optical axis is shielded between the rotating triplex lens and the second lens group Or between the second lens group and the second Bessel beam. The method for processing a laser beam as described in claim 8, comprising the steps of shielding light in a direction perpendicular to the optical axis existing inside the first ring beam or the second ring beam inside Between the rotating triplex lens and the second lens group, or between the second lens group and the second Bessel beam. The method for processing a laser beam according to claim 8 or 9, comprising the steps of: placing light in a direction perpendicular to the optical axis inside the first ring beam or the inside of the second ring beam, And the light existing outside the first ring beam or the second ring beam in a direction perpendicular to the optical axis is shielded between the rotating triplet lens and the second lens group, or the second Between the lens group and the second Bessel beam. A method for manufacturing a glass article includes the following steps: Making the laser beam incident on the first lens group; Causing the laser beam that has passed through the first lens group to enter a rotating triplex lens; With the first lens group, a first Bessel beam is formed behind the rotating triplet lens, and a first ring beam is formed after the first Bessel beam, which is perpendicular to the optical axis. Form a focal plane that has a minimum ring width with the first ring beam; The first ring beam is made incident on the second lens group, and a second ring beam having a ring width in a direction perpendicular to the optical axis formed along the optical axis is formed behind the second lens group; A second Bessel beam is formed behind the second ring beam; and The second Bezier light beam is irradiated onto the glass to form a modified portion on the glass. The method for manufacturing a glass article according to claim 11, wherein the first lens group, the rotating triplet lens, and the second lens group are sequentially arranged on an optical axis, and the focal surface is formed on the rotating third Between the 稜鏡 lens and the second lens group. The method for manufacturing a glass article according to claim 11 or 12, further comprising the steps of placing light in a direction perpendicular to the optical axis inside the first ring beam or the inside of the second ring beam, And at least one of the rays existing outside the first ring beam or the second ring beam in a direction perpendicular to the optical axis is shielded between the rotating triplet lens and the second lens group, Or between the second lens group and the second Bessel beam. The method for manufacturing a glass article according to claim 13, comprising the steps of shielding light in a direction perpendicular to the optical axis existing inside the first ring beam or the second ring beam from Between the rotating triplex lens and the second lens group, or between the second lens group and the second Bessel beam. The method for manufacturing a glass article according to claim 13 or 14, further comprising the steps of placing light in a direction perpendicular to the optical axis inside the first ring beam or the second ring beam, And the light existing outside the first ring beam or the second ring beam in a direction perpendicular to the optical axis is shielded between the rotating triplet lens and the second lens group, or the second Between the lens group and the second Bessel beam. The method for manufacturing a glass article according to any one of claims 11 to 15, further comprising the step of removing at least a part of the deteriorated portion by etching to form a hole in the glass.