METHOD OF SURFACE STRUCTURING A SUBSTRATE BODY AND SUBSTRATE BODY

Abstract

A method for preparing and/or carrying out the structuring of a predetermined or predeterminable distinguished surface of a substrate body having a substrate material includes exposing the substrate material in at least one curved effective area to an electromagnetic field which in each of the at least one curved effective area causes a non-linear interaction between the electromagnetic field and the substrate material, and thus at least partially influencing the substrate material arranged in the curved effective area. After the structuring of the distinguished surface the distinguished surface has at least in certain areas at least one first curved progression which is at least partially determined and/or influenced by the curved shape of the at least one curved effective area. The nonlinear interaction causes at least one nonlinear absorption of the electromagnetic field in the substrate material.

Claims

1. A method for preparing and/or carrying out the structuring of a predetermined or predeterminable distinguished surface of a substrate body comprising a substrate material, the method comprising: exposing the substrate material in at least one curved effective area to an electromagnetic field which in each of the at least one curved effective area causes a non-linear interaction between the electromagnetic field and the substrate material, and thus at least partially influencing the substrate material arranged in the curved effective area, wherein after the structuring of the distinguished surface the distinguished surface comprises at least in certain areas at least one first curved progression which is at least partially determined and/or influenced by the curved shape of the at least one curved effective area, and wherein the nonlinear interaction causes at least one nonlinear absorption of the electromagnetic field in the substrate material.

2. The method according to claim 1, wherein the substrate material is exposed to an electromagnetic field in a plurality of curved effective areas, and wherein (i) the distinguished surface has the same first curved progression at several areas, determined or influenced by the curved shape of the several curved effective areas, and/or has the first curved progression everywhere, and/or (ii) the curved effective areas are selected to be arranged at a distance from one another, wherein in a cross-sectional plane of the substrate body the centers or centroids of the intersecting surfaces of the curved effective areas with the cross-sectional plane extend along a straight line or along any desired circular, curve, and/or successive effective areas have a distance from one another which is between either 30% and 100% or between 100% and 200% of the maximum extent of the curved effective areas in the cross-sectional plane.

3. The method according to claim 2, wherein the at least partially influencing of the substrate material comprises increasing or decreasing, one or more material properties, including the refractive index, the etch rate and/or the density, of the substrate material at least in certain areas, and/or wherein the at least partially influencing of the substrate material comprises at least partially removing and/or displacing the substrate material from the curved effective area.

4. The method according to claim 3, wherein the distinguished surface is formed by at least partially removing the substrate material by the influencing and/or by at least partially removing at least the influenced substrate material by at least one subsequent etching process or by means of an acid and/or by means of a caustic solution.

5. The method according to claim 1, wherein the electromagnetic field is provided in the form of and/or by a curved line focus of a laser beam, and/or the curved effective area is determined by the shape of the line focus.

6. The method according to claim 5, wherein the laser beam is provided by an ultrashort pulse laser, wherein the phase of the laser beam is adjusted and/or adapted by means of a spatial light modulator, of a diffractive optical element and/or a combination of several cylindrical lenses, wherein the laser beam is focused onto the substrate body by means of a microscope objective or a Fourier lens, wherein said focusing takes place after adjusting or adapting the phase of the laser beam and/or forms the line focus, wherein the line focus is that of an accelerated laser beam, wherein the wavelength of the laser beam is 1064 nm, the microscope objective or the Fourier lens has a focal length of 10-20 mm, the coefficient of the cubic phase (laser parameter beta) has a value between 0.5×10.sup.3/m and 5×10.sup.3/m, the diameter of the raw beam (laser parameter ω.sub.0) has a value between 1 mm and 10 mm, the pulse duration (laser parameter ) has a value of 0.1-10 ps, the pulse energy (laser parameter E.sub.p) has a value between 1 and 1,500 μJ, and/or the number of pulses in the burst (laser parameter N) has a value between 1 and 200, wherein the spatial extent of the curved effective areas is set and/or changed over time by varying the average power range of the laser and/or by changing the phase, and/or wherein the spatial orientation of the curved effective areas is set and/or changed over time by varying the tilting of the optical axis of the laser beam relative to the normal to the substrate surface.

7. The method according to claim 1, wherein at least during the non-linear interaction at least one auxiliary substrate body is arranged at the substrate body and the respective curved effective area and/or the line focus extends at least partially into the auxiliary substrate body, wherein two or more auxiliary substrate bodies are arranged at the substrate body on opposite sides of the substrate body, and the respective curved effective area and/or the line focus extends at least partially into two or more auxiliary substrate bodies.

8. The method according to claim 1, wherein at least one and/or all of the, curved effective area of the at least one curved effective area is completely enclosed within the substrate body at least during the non-linear interaction, and wherein the method further comprises removing at least along a major direction of extension of the curved effective area within the substrate body, and thereby making the substrate material influenced in the enclosed curved effective area at least partially and/or in certain areas accessible from the outside, wherein the removal of material from the substrate body is carried out by means of etching.

9. The method according to claim 1, wherein the substrate material is exposed to the electromagnetic field successively or wholly or partially in parallel in each of the plurality of curved effective areas, wherein the entire substrate material within a curved effective area is simultaneously exposed to the electromagnetic field, and wherein the curved effective areas each have a maximum deflection from a straight progression of more than 20 μm, and/or wherein the length of the curved effective areas is respectively more than 0.1 mm.

10. The method according to claim 1, wherein (i) the substrate body is transparent, is made of glass, comprises a first top surface, and/or comprises a second top surface, which extends parallel to and/or is arranged opposite the first top surface, (ii) the thickness of the substrate body, measured between the first and second top surfaces, is 500 μm or less, and/or (iii) after structuring the distinguished surface a. the distinguished surface extends between the first and second top surfaces, b. the distinguished surface is connected to the first and/or the second top surface at least in certain areas, c. at least one part of at least one lateral surface of the substrate body comprises the distinguished surface, d. at least one part of a surface of a through hole, which extends from the first top surface to the second top surface, comprises the distinguished surface, and the through hole is formed by influencing and/or etching the substrate material, e. at least one surface area of a cavity of the substrate body comprises the distinguished surface, wherein the cavity is accessible from the outside or is completely enclosed in the substrate material, and wherein the cavity is formed by influencing and/or etching the substrate material, f. the distinguished surface represents at least in certain areas an inwardly facing surface of the substrate body, and/or g. the distinguished surface is at least in certain areas an outwardly facing surface of the substrate body.

11. The method according to claim 8, wherein after the structuring of the distinguished surface the first curved progression of the distinguished surface extends perpendicularly to the major direction of extension of the distinguished surface, and/or wherein in the major direction of extension of the distinguished surface, the distinguished surface comprises at least in certain areas a second curved progression.

12. The method according to claim 1, wherein after the structuring the distinguished surface in at least one cross-sectional plane of the substrate body the distinguished surface has a contour which along the first curved progression (i) is at least in sections convexly or concavely curved, (ii) corresponds at least in sections to a contour of the curved effective area, and/or (iii) comprises at least in sections a parabolic progression, a quartic progression, a logarithmic progression, a progression according to a polynomial function of degree n, with n=6, n=8, n=10 or n=12, and/or a C-shaped profile.

13. A substrate body, the substrate body comprising: at least one first top surface and at least one distinguished surface produced or producible by a method according to claim 1, wherein the distinguished surface comprises at least in certain areas at least one first curved progression, wherein the first curved progression lies in a cross-sectional plane of the substrate body which is spanned by a plane having at least one normal vector of the distinguished surface and a normal vector of the top surface, wherein the first curved progression can be described by a parabolic, quartic, logarithmic and/or polynomial phase function, and wherein the substrate body has a thickness of 500 μm or less.

14. The substrate body according to claim 13, wherein said distinguished surface has a strength of at least 100 MPa, and wherein the distinguished surface has been etched in whole or in part, with hydrofluoric acid, sodium hydroxide, a caustic solution, and/or an acid.

15. The substrate body according to claim 13, wherein the distinguished surface is at least in certain areas height-modulated, and has a wave-like and/or calotte-shaped structure along the major direction of extension of the distinguished surface and/or perpendicular thereto.

16. The substrate body according to claim 13, wherein (i) the substrate body is transparent, is made of glass, and/or comprises a second top surface which extends parallel to and/or is arranged opposite the first top surface, (ii) the thickness of the substrate body measured between the first and second top surfaces, is 500 μm or less, and/or (iii) a. the distinguished surface extends between the first and second top surfaces, b. the distinguished surface is connected to the first and/or the second top surface at least in certain areas, c. at least one part of at least one lateral surface of the substrate body comprises the distinguished surface, d. at least one part of a surface of a through hole, which extends from the first top surface to the second top surface comprises the distinguished surface, and wherein the through hole is formed by influencing and/or etching the substrate material, e. at least one surface area of a cavity of the substrate body comprises the distinguished surface, wherein the cavity is accessible from the outside or is completely enclosed in the substrate material, and wherein the cavity is formed by influencing and/or etching the substrate material, f. the distinguished surface represents at least in certain areas an inwardly facing surface of the substrate body, and/or g. the distinguished surface represents at least in certain areas an outwardly facing surface of the substrate body.

17. The substrate body according to claim 13, wherein the first curved progression of the distinguished surface extends perpendicular to the major direction of extension of the distinguished surface, and/or wherein in the major direction of extension of the distinguished surface in the circumferential direction of the substrate body comprises at least in certain areas a second curved progression.

18. The substrate body according to claim 13, wherein in at least one cross-sectional plane of the substrate body the distinguished surface has a contour which, along the first curved progression (i) is convexly or concavely curved at least in sections, (ii) corresponding at least in sections to a contour of the curved effective area, and/or (iii) has at least in sections a parabolic progression, a quartic progression, a logarithmic progression, a progression according to a polynomial function of degree n, with n=6, n=8, n=10 or n=12, and/or a C-shaped progression.

19. The substrate body according to claim 13, wherein the substrate body has at least in certain areas at least one spatial modification of its substrate material selected from the group consisting of: a change in the refractive index, a change in density and/or a cavity, wherein the modification has a curved contour in a cross-sectional plane of the substrate body at least in certain areas, wherein the modification extends from a first top surface of the substrate body into the substrate material in the direction of and/or up to a second top surface of the substrate body, wherein the second top surface is arranged opposite to and/or extends parallel to the first top surface, wherein the substrate body has a thickness of 500 μm or less, which is measured in between the first and the second top surface of the substrate body.

20. The substrate body according to claim 19, wherein the modification has a maximum deflection from a straight progression that is greater than 20 μm, and/or wherein the length of the modification is respectively greater than 0.1 mm.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0269] Further features and advantages of the disclosure will be apparent from the following description, in which preferred embodiments of the disclosure are explained with reference to schematic drawings.

[0270] In the Figures:

[0271] FIG. 1 shows a top view of a first substrate body;

[0272] FIG. 2 shows a first cross-sectional view of the first substrate body;

[0273] FIG. 3 shows a second cross-sectional view of the first substrate body;

[0274] FIG. 4a shows a top view of the first substrate body with influenced substrate material;

[0275] FIG. 4b shows a side view of the first substrate body with influenced substrate material;

[0276] FIG. 5 shows different progressions of the lateral surface of the first substrate body after an etching process in the cross-sectional plane of the first cross-sectional view;

[0277] FIG. 6a shows the first substrate body after the etching process in the cross-sectional plane of the first cross-sectional view;

[0278] FIG. 6b shows the first substrate body after an etching process in the cross-sectional plane of the second cross-sectional view;

[0279] FIG. 7a shows a top view of a second substrate body;

[0280] FIG. 7b shows a cross-sectional view of the second substrate body;

[0281] FIG. 8a shows a top view of a third substrate body;

[0282] FIG. 8b shows a cross-sectional view of the third substrate body;

[0283] FIG. 9 shows the influence of the focal length of the focusing optics for a laser beam;

[0284] FIG. 10 shows line foci for different laser powers;

[0285] FIG. 11 shows different line foci in a substrate body;

[0286] FIGS. 12a-12c show line foci for different phase functions;

[0287] FIG. 13 shows an optical setup of a 2f configuration;

[0288] FIG. 14 shows a gray value coded representation of a phase shift;

[0289] FIG. 15 shows a top view of a processed substrate body;

[0290] FIG. 16 shows a top view of a processed substrate body;

[0291] FIG. 17 shows the substrate body of FIG. 16 with introduced modifications;

[0292] FIG. 18a shows a cross-sectional view of a substrate body with enclosed curved effective area;

[0293] FIG. 18b shows a cross-sectional view of a substrate body with externally accessible material modification; and

[0294] FIG. 18c shows a cross-sectional view of a structured substrate body.

EXAMPLES

[0295] FIG. 1 shows a top view of a cuboid transparent substrate body 1. The substrate body 1 is made of glass, that is, its substrate material is made of glass.

[0296] The lateral surface 3 of the substrate body 1 on the right in FIG. 1 is to be structured. That is, the lateral surface 3 is to be given a new shape.

[0297] FIG. 2 shows a cross-sectional view of the substrate body 1, wherein the cross-sectional plane extends parallel to the first top surface 5 of the substrate body 1.

[0298] In order to structure the new surface of the previously unstructured lateral surface 3, the substrate material of the substrate body 1 is equally exposed to an electromagnetic field in several curved effective areas 7a-7c, which causes there a respective non-linear interaction with the substrate material. As a result of the nonlinear interaction, the substrate material is influenced in the area of the curved effective areas 7a-7c. The influence is accompanied by a change in the refractive index of the substrate material.

[0299] Here, the electromagnetic field is respectively that of a line focus of a laser formed within the substrate material. By moving the line focus relative to the substrate body 1, the line focus of the laser is sequentially formed in different areas of the substrate material. That is, the substrate material is sequentially influenced first in the curved effective area 7a, then in the curved effective area 7b, and then in the curved effective area 7c.

[0300] Here, the electromagnetic field of the line focus just corresponds to the individual curved effective area. And the individual curved effective area respectively corresponds to the area with influenced substrate material.

[0301] The laser beam can be propagated by a spatial light modulator and, depending on the imposed phase, the line focus is also curved and thus the respective curved effective area is shaped.

[0302] The individual curved effective areas are arranged at a distance from one another. In the cross-sectional plane of FIG. 2, the centroids (not shown) of the intersecting surfaces of curved effective areas 7a-7c and the cross-sectional plane extend along a straight line which extends parallel to the edge 9 of the lateral surface 3.

[0303] FIG. 3 shows another cross-sectional view of the substrate body 1, wherein the cross-sectional plane extends perpendicular to the first top surface 5 of the substrate body 1 and intersects the cross-sectional view of FIG. 2 in the intersection line S shown therein in dashed lines. The crescent shape of the curved effective area 7b can be seen in FIG. 3. The other curved effective areas, which are not shown in FIG. 3, have the same shape in a corresponding parallel cross-sectional plane.

[0304] If the respective cross-sectional plane in FIGS. 2 and 3 were respectively shifted parallel, the shape of the intersection surface with the curved effective area(s) would also change. How exactly depends on the three-dimensional shape of the curved effective areas. The spatial shape of the curved effective areas can be adjusted and adapted by the phase of the line focus.

[0305] As can be further seen in FIG. 3, the curved effective areas 7a-7c intersect the first top surface 5, the second top surface 11 and the lateral surface 3 to be structured of the substrate body 1, respectively. Therefore, the influenced substrate material is accessible from the outside at the corresponding intersection surface of the substrate body 1 and the curved effective areas 7a-7c.

[0306] FIG. 4a shows a top view of the substrate body 1, where the curved effective areas 7a-7c with their intersection surfaces with the first cover surface 5 are visible. FIG. 4b shows the substrate body 1 from the side and thus the lateral surface 3 to be structured, where the curved effective areas 7a-7c with their intersection surfaces with the lateral surface 3 are also visible.

[0307] The influenced substrate material is then removed by applying selective laser etching. For this purpose, the substrate body 1 is exposed at least locally to an etching medium.

[0308] Laser selective etching etches away both influenced and uninfluenced substrate material from the substrate body 1. However, the influenced substrate material is etched away faster than the uninfluenced substrate material.

[0309] FIG. 5 shows the substrate body 1 in the same cross-sectional plane as previously shown in FIG. 2, but after the etching process. If the etching process would remove only influenced substrate material, the contour of the structured substrate body would extend in the cross-sectional plane of FIG. 5 according to the solid line. The curved effective areas 7a-7c form circular contours 13 in the substrate material in the cross-sectional plane of FIG. 5.

[0310] However, since the etching process also removes uninfluenced material, the substrate material 15 between the individual curved effective areas and in the edge region is also partially etched away. Thus, in particular, the webs between the areas with influenced material are removed. In addition, for the same reason, overall, the circular contour 13 is also shifted into the substrate material, as is to be indicated by the slightly offset progression of the dashed line.

[0311] The previously unstructured lateral surface 3 of the substrate body 1 therefore has a contour according to the dashed line in the cross-sectional plane of FIG. 5 after structuring.

[0312] FIG. 6a shows in the cross-sectional plane of FIG. 2 and FIG. 6b shows in the cross-sectional plane of FIG. 3 the progression of the structured surface 17 and for comparative purposes in a dashed line the progression of the original, unstructured surface 3. The structured surface 17 is modulated in height and comprises in certain areas a calotte-shaped structure corresponding to the calotte-shaped recesses.

[0313] The structured surface 17 is consequently formed by removing the influenced substrate material and furthermore also uninfluenced substrate material by etching. The structured surface 17 is an distinguished surface in the sense of the present disclosure.

[0314] The structured surface 17 is connected to the first and second top surfaces 5, 11 at least in certain areas. The structured surface 17 is an outer surface.

[0315] The curved progression of the structured lateral surface 17 shown in FIG. 6b is convex and corresponds to a first curved progression. The first curved progression was influenced by the shape of the curved effective area 7b. Thus, although the etching process here has also removed portions of the unaffected substrate material, the basic progression of the structured right-hand lateral surface 17 of the substrate body 1 is co-determined in certain areas by the curved shape of the curved effective area respectively applied there, here curved effective area 7b. Since the curved effective areas 7a-7c contribute to the structuring of the surface at several points, the structured surface 17 has the same first curved progression at several areas. This is because at a plurality of areas, the curved shape of the curved effective areas 7a-7c determines or influences the progression of the structured surface 17. In other words, the first curved progression is achieved by the plurality of curved effective areas at a plurality of areas of the structured or distinguished surface 17.

[0316] In FIGS. 3 and 6b, the first and second top surfaces 5, 11 of the substrate body 1 extend parallel to each other and have a distance of 500 μm from each other.

[0317] If the curved effective areas 7a-7c would have been rotated 180° about an axis perpendicular to the first top surface 5, the first curved progression would be concave in the cross-sectional plane of FIG. 6b.

[0318] When the curved effective areas 7a-7c are positioned away from the surface 3 to be structures toward the center of the substrate body 1, the substrate body 1 can be separated into two parts. At the separating surface, the remaining substrate body then comprises a structured surface such as the structured surface 17 when a corresponding procedure is performed as described above.

[0319] FIG. 7a shows a top view of a substrate body 1′ and FIG. 7b shows a cross-sectional view of the substrate body 1′, wherein the cross-sectional plane extends perpendicular to the first top surface 5′ of the substrate body 1′ and intersects the cross-sectional view of FIG. 7a in the intersection line S′ shown there in dashed lines. In the substrate body 1′, the substrate material is influenced only in a single curved effective area 7′. The curved effective area 7′ extends from the first top surface 5′ in the direction of the second top surface 11′. When the influenced material is etched away, a cavity can be created in the substrate body 1′. The surface thereof is the structured surface and thus the distinguished surface. This is then an inner surface.

[0320] FIG. 8a shows a top view of a substrate body 1″ and FIG. 8b shows a cross-sectional view of the substrate body 1″, wherein the cross-sectional plane extends perpendicular to the first top surface 5″ of the substrate body 1″ and intersects the cross-sectional view of FIG. 8a in the intersection line S″ shown there in dashed lines. In the substrate body 1″, the substrate material is influenced only in a single curved effective area 7″. The curved effective area 7″ extends from the first top surface 5″ to the second top surface 11″. When the influenced material is etched away, a through hole, i.e. a via, can be created in the substrate body 1″. The surface of which is the structured surface and thus the distinguished surface. This is then an inner surface.

[0321] Influence of the focal length of the focusing optics:

[0322] FIG. 9 illustrates the influence of the focal length of the focusing optics for an Airy laser beam. For constant [0323] cubic phase (with beta=3.sup.1/3×10.sup.3/m); [0324] laser wavelength (with lambda=1.030×10.sup.−6 m); and [0325] beam diameter (diameter of the raw beam w.sub.0=5×10.sup.−3 m)
the length of the focus area (in relative definition: decrease to 1/e.sup.2 of the maximum value) increases with increasing focal length (curve with solid line in FIG. 9) and the angle which the focus has at the upper and lower end respectively to the optical axis decreases (curve with dashed line in FIG. 9). The left ordinate therefore refers to the solid line and the right ordinate refers to the dashed line.

[0326] Influence of the laser power on the line focus:

[0327] FIG. 10 shows material areas in a glass substrate influenced by line foci of different laser power. From top to bottom the laser power increases and thus the extent of the respective curved effective area and thus the area of the influenced material.

[0328] Influence of a tilt and offset of a line focus:

[0329] Offset refers to the distance of the vertex of the focus area from the center of the substrate body. Tilt refers to the angle between the surface normal and the tangent at the vertex.

[0330] For a centered, untilted Airy beam, the vertex of the focal area along the normal of the substrate surface is at the center of the substrate body, i.e., at the center of its thickness extension, and the surface normal and the tangent at the vertex are parallel.

[0331] FIG. 11 shows various line foci 23a-23e of laser beams formed at least partially in a substrate body 21. The cross-sectional plane of FIG. 11 shows the thickness region of the substrate body 21.

[0332] Line focus 23a represents a line focus, in particular of an Airy beam, which is centered and has no tilt. Line focus 23a comprises a vertex 25 of the parabolic focus area 23a.

[0333] Line focus 23b shows a line focus, in particular of an Airy beam, that is offset.

[0334] Line focus 23c depicts a line focus, in particular of an Airy beam, that is tilted and offset. Line focus 23d represents a line focus, in particular of a different function than that of an Airy beam, with variable curvature. For example, the curvature could describe a C profile.

[0335] The line focus 23e represents a line focus, in particular of an Airy beam or another function, which modifies an upper part of the substrate material 1 in a first region 27a and which modifies a lower part of the substrate material 1 in a second region 27b.

[0336] In FIG. 11, moreover, the length of each line focus 23a-23e can be determined as the length of the curved progression shown, in particular within the substrate body 1. Also shown with respect to the line focal point 23a is a connecting line 29 that passes through the ends of the line focal point 23a within the substrate body 21. This can be understood as the straight focal line, and the maximum deflection from the straight focal line is just equal to the distance between the connecting line 29 and the vertex 25.

[0337] Phase Functions

[0338] Various exemplary phase functions which can be imparted to a laser beam and according to which the curved effective areas can be formed in a substrate material are shown in the following table:

TABLE-US-00001 Acceleration profile Phase Parabolic: c(z) = az.sup.2 ϕ(y) = −4/3a.sup.1/2ky.sup.3/2 Quarternary: c(z) = az.sup.4 ϕ(y) = −16/21(3a).sup.1/4ky.sup.7/4 Logarithmic: c(z) = a ln(bz) ϕ(y) = e.sup.−1a.sup.2bk(1-exp[−y/a]) Polynomial: c(z) = az.sup.n [00001]$\varphi \left(y\right)={\mathrm{kn}}^2{y}^2\frac{{\left[a\left(1-n\right)/y\right]}^{1/n}}{\left(2n-1\right)\left(1-n\right)}$ (for even n)

[0339] The parameters are described in the publication Froehly, L., Courvoisier, F., Mathis, A., Jacquot, M., Furfaro, L., Giust, R., . . . & Dudley, J. M. (2011), “Arbitrary accelerating micron-scale caustic beams in two and three dimensions”, Optics express, 19(17), 16455-16465.

[0340] FIGS. 12a-12c show exemplary line foci for different phase functions. The horizontal axis has respectively the unit millimeter (mm). The vertical axis has respectively the unit millimeter (mm). FIG. 12a shows a laser beam which comprises a line focus with a parabolic acceleration profile. FIG. 12b shows a laser beam that comprises a line focus with a quaternary acceleration profile. FIG. 12c shows a laser beam that comprises a line focus with a logarithmic acceleration profile. With corresponding line foci, different curved effective areas can be realized and thus the substrate material can be influenced in corresponding spatial areas.

[0341] The entire, theoretical progression of the line focus according to the phase function is respectively shown as a dashed line. The line focus itself is formed only along a section (partly somewhat offset, in order to be able to recognize the theoretical progression). Only where the line focus is formed, a nonlinear interaction can take place. From this, it becomes fundamentally understandable how by use of the line focus a cavity that is accessible from the outside or a completely enclosed cavity can be obtained.

[0342] FIG. 13 shows an optical setup of a 2f configuration as it can preferably be used for the method according to the disclosure. Here, a phase distribution is imparted onto an incoming laser beam 35 having a beam diameter 36 by a phase mask 33 and imaged into a substrate 1 by the downstream focusing optics 31 located at a distance of its input-side focal length 37 from the phase mask 33 at a distance corresponding to its output-side focal length 39, so that a curved line focus 23 is formed within the substrate 1.

[0343] FIG. 14 shows a gray-value coded representation of the exemplary phase shift imparted onto the laser beam 35 by the phase mask 33, which can preferably be realized in the form of an SLM (spatial light modulator) or DOE (diffractive optical element), as a result of which the laser focus obtains its curved contour 23. Here, phase values from 0 to 2 Pi are represented by a gray value from 0 to 255. The phase distribution exists in a cross-sectional plane perpendicular to the major propagation direction of the laser beam.

[0344] FIG. 15 shows a top view of a substrate body structured by the method according to the disclosure. In particular, the normal vector of the distinguished surface extends in the drawing plane of FIG. 15. Therefore, the first curved progression of the distinguished surface can be seen particularly advantageously in FIG. 15.

[0345] Here, the laser beam used for structuring extended parallel to the drawing plane of FIG. 15, as indicated by the arrow.

[0346] The following general parameters and laser parameters were set for the structuring of the distinguished surface: [0347] microscope objective and/or Fourier lens with a focal length of f=10 mm; [0348] wavelength of 1030 nm; [0349] beam diameter of 5.3 mm; [0350] cubic phase φ=exp(i.Math.(x.sup.3+y.sup.3)), equivalent to

[00002]$\phi =\exp \left(\frac{i\beta }{3}*\left(x^3+y^3\right)\right)$

with β=3.sup.1/3 mm.sup.−1 for x and y in mm; [0351] pulse duration =5 ps; [0352] number of pulses in burst N=2; [0353] energy per burst 228 μJ; and [0354] a pitch of 10 μm.

[0355] FIG. 16 shows a top view of a substrate body structured by the method according to the disclosure. In particular, the normal vector of the distinguished surface extends in the drawing plane of FIG. 16. Therefore, the first curved progression of the distinguished surface can also be seen particularly advantageously in FIG. 16.

[0356] The laser beam used for structuring extended parallel to the drawing plane of FIG. 16, as indicated by the arrow.

[0357] The following general parameters and laser parameters were set for the structuring of the distinguished surface: [0358] substrate material with a thickness selected from the range between 900-1000 μm, for example BF33; [0359] a pitch of 40 μm; [0360] microscope objective and/or Fourier lens with a focal length of f=10 mm; [0361] ×2.0 beam expander (for 10 mm diameter of the Gaussian input beam); [0362] pulse duration =5 ps; [0363] number of pulses in burst N=2; [0364] energy per burst of 300 μJ; and [0365] wavelength of 1030 nm; [0366] cubic phase φ=exp(i.Math.(x.sup.3+y.sup.3)), equivalent to

[00003]$\phi =\exp \left(\frac{i\beta }{3}*\left(x^3+y^3\right)\right)$

with β=3.sup.1/3 mm.sup.−1 for x and y in mm;

[0367] By choosing a sufficiently large pitch, as in this case, interactions between adjacent regions in the substrate with modifications are avoided or at least greatly reduced.

[0368] FIG. 17 shows at the left hand top views in transmitted light microscopy onto the substrate after the laser process but prior to etching (the view here is parallel to the laser propagation direction). Here, the lateral characteristics of the modifications can be seen, wherein several modifications being visible for each of three selected, different depths in the substrate. The respective depths are marked in the right part of FIG. 17.

[0369] When introducing the modification, a sufficiently large pitch was selected so that the extensions of the laterally angled/arrow-like shaped modifications overlap only minimally. This ensured that the propagation within the material is not or only slightly disturbed by previous modifications.

[0370] Thus, the “zig-zag” pattern results from the modifications laterally extended near the focus, while the modifications continue to lie on a straight line/line. In addition, the apex of the curved effective area was kept centered between the two top surfaces and the curved effective area was formed entirely within the substrate material.

[0371] FIG. 18a shows a rectangular substrate body 41 in a cross-sectional view. Within the substrate body 41, the substrate material has been exposed to an electromagnetic field in a curved effective area 43 so that, in the corresponding area the substrate material has been modified by a nonlinear interaction between the electromagnetic field and the substrate material due to nonlinear absorption.

[0372] The curved effective area 43, and thus the modification after its introduction, is completely enclosed within the substrate body 41.

[0373] Therefore, in accordance with embodiments of the disclosure, it is envisaged that material is removed from the substrate body, for example by etching. This can be done along the major direction of extension H of the curved effective area 43, which in the present case extends perpendicular to both top surfaces 45. In other words, material is thus removed from the two top surfaces 45 of the substrate body 41. The new top surfaces 45 of the substrate body are thus quasi displaced along the major direction of extension H. This can be seen in FIG. 18b. It can also be seen there that the substrate material 43 influenced in the enclosed curved effective area 43 becomes accessible from the outside as a result of the removal of substrate material, since parts of the influenced substrate material are now located at the surface of the top surfaces 45.

[0374] The curved effective area 43 and/or the substrate material 43 influenced therein have a progression that is not influenced by surface effects (such as of the top surfaces 45), since the interaction takes place entirely within the substrate body 41 (FIG. 18a).

[0375] Due to the accessibility of the modified substrate material 43 (FIG. 18b), the substrate body 41 can subsequently be further processed, as previously described, in order to structure an distinguished surface 47, as illustrated in FIG. 18c. For example the influenced material 43 is removed by etching for this purpose.

[0376] The features disclosed in the foregoing description, claims and drawings can be essential to the disclosure in its various embodiments, both individually and in any combination.