Compact read-write head for superspeed data recording on ceramic materials

Abstract

The invention relates to a compact read-write head for superspeed data recording on a ceramic material.

Description

Technical Field

[0001] The invention relates to a method for recording data in a layer of ceramic material and to a device for recording data in a layer of ceramic material. Background Art

[0002] The applicant of the present invention has developed a method for long-term storage of information and a storage medium thereof (see WO 2021 / 028035 A1 and WO 2022 / 002418 A1). According to one aspect of the method for long-term storage of information, information is encoded on a writable plate comprising a ceramic material by manipulating local areas of the writable plate using a laser beam. Although in principle the method can be performed by a laser beam with a fixed focus by mounting the writable plate on an XY positioning system and moving those local areas of the writable plate to the laser focus to be encoded, the method is cumbersome and time-consuming.

[0003] US 4,069,487 and US 4,556,893 also disclose laser recordable recording media using recording layer materials such as metal oxides and metal carbides. However, the recording in both cases is based on rotating disk technology, which is disadvantageous because pits must be generated one after another along the recording spiral, resulting in a slow recording process. Summary of the invention

[0004] It is therefore an object of the present invention to provide an improved method for recording data in a layer of ceramic material, which method is suitable for recording large amounts of data in a relatively short time. Another object of the present invention is to provide an improved device for recording data in a layer of ceramic material, the improved device having a compact write head.

[0005] This object is achieved by a method as claimed in claim 1 and by a device as claimed in claim 31. Preferred embodiments of the invention are described in the dependent claims.

[0006] Therefore, the present invention relates to a method for recording data in a ceramic material layer. According to the method, a ceramic material layer is provided and a plurality of regions of the ceramic material layer are selectively irradiated with a laser beam using a digital micromirror device (DMD) and at least one scanning device. The parameters of the laser beam and the irradiation time of each of the selected regions are configured so as to ablate each of the selected regions so as to record data in the ceramic material layer by generating a recess in the ceramic material layer.

[0007] The combination of a DMD and at least one scanning device allows extremely fast data writing, since the ablation pattern produced by the DMD can be displaced over the substrate surface at extremely high speed.

[0008] Preferably, the laser beam originates from a picosecond laser or a femtosecond laser. The use of a picosecond laser or a femtosecond laser is very advantageous for producing well-defined recesses. The ablation technique disclosed in US 4,556,893 utilizes a focused, modulated laser diode beam, which produces pits or bubbles depending on the laser power. Since the recording layer material is light-absorbing, the layer is locally heated and thus melts and / or evaporates. However, these processes are rather uncontrolled and often result in unfavorable hole shapes. For example, also as disclosed in US 4,556,893, the ablation technique of the invention is described in US 4,556,893. Figure 4 As shown in , a ring of molten and subsequently solidified material may be formed around the edge of the hole. This is unacceptable when very small recesses are produced in order to increase data density, as these recesses need to be produced reproducibly and allow reproducible readout techniques.

[0009] The inventors of the present invention have conducted many experiments on ceramic materials by different ablation techniques. It turns out that well-defined holes with circular cross-sections and very sharp edges can be produced using picosecond lasers or femtosecond lasers. It is believed that this is due to the ablation process triggered by picosecond lasers or femtosecond lasers. Picosecond or femtosecond laser pulses do not heat the ceramic material, but interact with the electrons of the material. It is assumed that the picosecond or femtosecond laser pulse interacts with the outer valence electrons responsible for chemical bonding, thereby stripping the valence electrons from the atoms, making the latter positively charged. Since the atoms whose chemical bonds have been broken are in a state of mutual repulsion, the material will "explode" into a small plasma cloud composed of high-energy ions, and its speed is higher than the speed seen in thermal emission. This phenomenon is called Coulomb explosion, which is significantly different from conventional laser ablation by, for example, nanosecond lasers, which heat the surface material to melt and evaporate, leaving molten material at the edge of the impact area. Coulomb explosion is a physical process that is obviously limited to the laser impact area, while ablation caused by heat is affected by the unclear heat flow within the material. The Coulomb explosion is therefore ideal in producing a large number of tiny depressions, which allows a significant increase in data density compared to known techniques. Although good results can be achieved using picosecond lasers, the use of femtosecond lasers is advantageous in this regard. Therefore, the laser preferably has a pulse duration of less than 10 ps, ​​more preferably less than 1 ps.

[0010] Preferably, the flux of each of the multiple laser beams emitted by the DMD is greater than 100 mJ / cm 2 , preferably greater than 250 mJ / cm 2 , more preferably greater than 500 mJ / cm 2 Preferably, the flux of each of the multiple laser beams emitted by the DMD is less than 5 J / cm 2 , preferably less than 3 J / cm 2, and most preferably less than 1 J / cm 2 .

[0011] Preferably, the laser beam sequentially passes through a prism or a semi-transparent mirror, hits a digital micromirror device, and passes through a prism or a semi-transparent mirror again before selectively irradiating a plurality of regions of the layer of ceramic material. The use of such a prism or a semi-transparent mirror is particularly advantageous, since this allows a compact arrangement of the various components of the device for recording. Preferably, the laser beam further passes through a λ / 4 plate twice, which is positioned between the prism or the semi-transparent mirror and the digital micromirror device. Changing the polarization of the laser beam by means of such a λ / 4 plate allows the laser beam from the laser to be directed via a prism or a semi-transparent mirror to a digital micromirror device and to pass back through the prism or the semi-transparent mirror again before selectively irradiating a plurality of regions of the layer of ceramic material.

[0012] In the context of the present invention, the term "recess" relates to a hole, groove or indentation in a ceramic material. In other words, the recess forms a volume in which no ceramic material is present. This volume is in fluid communication with the atmosphere. In other words, each recess is open to the atmosphere and is not covered or closed.

[0013] Such open recesses are advantageous over the technique described in US 4,069,487 which utilizes a protective layer covering the information recording portion, because the open recesses allow for clean complete ablation of material already present in the recesses prior to ablation. This is particularly important when creating extremely small recesses to increase data density, as these recesses need to be reproducibly created and allow for reproducible readout techniques.

[0014] The DMD includes an array or matrix of micromirrors that allows for selective illumination of predetermined pixels on a ceramic material by adjusting the corresponding micromirrors of the array or matrix. Thus, a large number of pixels on a ceramic material can be illuminated simultaneously and in a well-controlled manner, which can be easily automated. Depending on the number of micromirrors present in the DMD, millions of selected areas (i.e., pixels) of a layer of ceramic material can be manipulated simultaneously during a time span sufficient to ablate one selected area to record data. Such digital micromirror devices are readily available and can be easily implemented into a recording device.

[0015] Alternatively, the present invention can utilize a ferroelectric spatial light modulator (SLM) or a liquid crystal SLM with a repetition rate of at least 200 Hz, preferably at least 500 Hz to replace the DMD. The ferroelectric SLM allows switching on and off at a frequency of up to 5 kHz and can therefore replace the DMD of the present invention. Therefore, in all methods and devices described herein, the term "DMD" can be replaced by the term "ferroelectric SLM" or the term "liquid crystal SLM with a repetition rate of at least 200 Hz, preferably at least 500 Hz".

[0016] Preferably, the pixels on the ceramic material (i.e., predetermined locations at which recesses can be formed in a subset) are arranged in a regular matrix or array, i.e., in a repeating two-dimensional pattern having a lattice structure or a lattice-like structure. Particularly preferred matrices or arrays include, for example, square patterns or hexagonal patterns. Such matrices or arrays allow for optimized data densities that are substantially greater than the data density of, for example, CDs, DVDs or Blu-Ray Discs, because the individual pixels or bits are not spaced apart by a track pitch (e.g., 320 nm for Blu-Ray), but rather have a size that is more than twice the size of the individual pixel bits (e.g., 150 nm for Blu-Ray Discs). Conventional disc-shaped recording media are also limited in the maximum rotational speed that can be safely achieved during recording or reading. Therefore, the write / read speeds that can be achieved by such matrices or arrays are much greater than the write / read speeds that could be achieved with pits arranged in a spiral shape.

[0017] Preferably, the recess has a circular cross section. The recess may extend only partially into the ceramic layer or a through hole may be formed in the ceramic layer. In the former case, recesses or holes of different depths may be produced, each of which corresponds to a predefined information bit, as described in WO 2022 / 002418 A1. For this purpose, the ceramic material layer may be irradiated with two or more laser pulses, wherein the micromirrors of the DMD are adjusted between subsequent pulses to achieve (i) from an area of ​​the ceramic material layer that is not irradiated, (ii) once by a single laser pulse, (iii) twice by two laser pulses, and so on.

[0018] Previous experiments by the applicant have shown that a CrN layer with a thickness of 5 μm can be manipulated significantly and reliably by a single femtosecond laser pulse (see WO 2022 / 002418 A1). The method of the invention thus allows encoding of at least several thousand and up to several million pixels within a few hundred femtoseconds. The recording speed of the method of the invention is therefore limited only by the number of micromirrors of the DMD and the time required to adjust the micromirrors.

[0019] Preferably, the layer of ceramic material is laterally moved or translated during recording, for example by means of an XY positioning system (z-axis perpendicular to the surface of the layer), such as a scanning stage. Thus, once a pixel array or matrix has been recorded, an adjacent pixel array or matrix can be recorded by simply moving the layer of ceramic material to an adjacent area.

[0020] Therefore, the method of the present invention preferably includes the following steps: using a DMD to selectively irradiate multiple regions within a first area of ​​the ceramic material layer with a laser beam, wherein the first area can be covered by the DMD; translating the ceramic material layer so that a second area different from the first area can be covered by the DMD; and using the DMD to selectively irradiate multiple regions within the second area of ​​the ceramic material layer with a laser beam.

[0021] If both the DMD and the XY positioning system are properly controlled, data recording speeds of at least 10 MB / s, preferably at least 100 MB / s, preferably at least 1 GB / s, and more preferably at least 10 GB / s can be achieved.

[0022] Preferably, the laser beam (i.e., the plurality of laser beams emitted from the DMD) is focused onto the ceramic material layer with the aid of a lens (or more complex optics) having a high numerical aperture (preferably a numerical aperture of at least 0.5, more preferably at least 0.8). Preferably, immersion optics are used to further increase the numerical aperture. If immersion optics are used, the numerical aperture may be at least 1.0, preferably at least 1.2.

[0023] It is further preferred that a beam shaping device is used to generate certain beam shapes that are beneficial for data recording. For example, a matrix of laser zone plates can be transmitted by multiple laser beams originating from the DMD. These laser zone plates can, for example, be suitable for generating a needle-shaped Bessel beam for each of the multiple laser beams.

[0024] The advantage of a Bessel beam is that the focal depth is substantially increased. While the focal length of a regular Gaussian beam is comparable to the wavelength of the focused light, the focal length achievable with a Bessel beam is at least 4 times the wavelength of the focused light. At the same time, the focal width is approximately half that achievable with a Gaussian beam.

[0025] In general, the size of features that can be achieved by the method of the present invention (e.g. the diameter of a recess in a ceramic material) varies between 2 / 3λ (air) and ½λ (immersion) for a Gaussian beam and between 1 / 3λ (air) and ¼λ (immersion) for a Bessel beam (where λ is the wavelength of the laser). The advantage of the Bessel beam shape is therefore that smaller process features can be achieved and, therefore, a greater recorded data density can be achieved. Furthermore, the increased focal length of the Bessel beam is advantageous, for example, deeper recesses can be produced. This is particularly relevant if features of different depths are to be produced in order to encode information by means of, for example, the depth of the recess. Since the focus of the Gaussian beam is conical, increasing the depth of the recess means increasing the diameter of the recess at the surface. In contrast, the cylindrical focus of the Bessel beam allows deeper recesses to be produced with an almost constant diameter.

[0026] Such Bessel beams can also be generated with the aid of other beam shaping devices.A particularly preferred example of a beam shaping device is a spatial light modulator, which is particularly versatile as it can be used to generate Bessel beams, to allow optical proximity control and to provide phase shift shielding.

[0027] Preferably, the ceramic material layer comprises metal nitrides such as CrN, CrAlN, TiN, TiCN, TiAlN, ZrN, AlN, VN, Si3N4, ThN, HfN, BN; and / or metal carbides such as TiC, CrC, Al4C3, VC, ZrC, HfC, ThC, B4C, SiC; and / or metal oxides such as Al2O3, TiO2, SiO2, ZrO2, ThO2, MgO, Cr2O3, Zr2O3, V2O3; and / or metal borides such as TiB2, ZrB2, CrB2, VB2, SiB6, ThB2, HB2, WB2, WB4; and / or metal silicides such as TiSi2, ZrSi2, MoSi2, WSi2, PtSi, Mg2Si. Particularly preferred materials are B4C, HfC, Cr2O3, ZrB2, CrB2, SiB6, Si3N4, ThN, CrN and CrAlN. These materials provide sufficient hardness and resistance to environmental degradation for long-term storage of recorded data.

[0028] In addition to using ceramic materials, the present invention can also be implemented using metals. Particularly preferred metals are metals with a melting point of more than 1,000°C, such as B, Cr, Co, Cu, Fe, Hf, Ir, Nb, Ni, Mn, Mg, Mo, Os, Pt, Pd, Rh, Si, Ta, Th, Ti, V, W and Zr. Further preferred metals are Al, Au and Ag. Therefore, in all methods and devices described herein, the term "ceramic material" can be replaced by one or a combination of the metals mentioned above.

[0029] Preferably, the step of providing a layer of ceramic material comprises: providing a substrate; and coating the substrate with a layer of ceramic material that is different from the material of the ceramic substrate. Thus, only a small amount of potentially more expensive coating material is required, while achieving structural integrity through a strong and potentially cheaper substrate. The thickness of the layer of ceramic material is preferably no more than 10 μm, more preferably no more than 5 μm, more preferably no more than 2 μm, more preferably no more than 1 μm, even more preferably no more than 100 nm, and most preferably no more than 10 nm.

[0030] Preferably, the thickness of the substrate is less than 1 mm, preferably less than 250 μm, more preferably less than 200 μm, and most preferably less than 150 μm.

[0031] In addition, the use of a substrate can allow an optical contrast to be created between the substrate (wherein the holes are created in the coating) and the surrounding coating material. Therefore, selectively irradiating multiple areas of the ceramic material layer with a laser beam using a digital micromirror device preferably includes ablating sufficient material at each of the areas where the recess extends toward the substrate. Preferably, the manipulation of the selected areas makes these areas distinguishable from the surrounding material. For some applications, this can include achieving optical distinguishability. However, in other cases (particularly if the coding structure is too small), these areas can only be distinguished from the surrounding material by means of, for example, scanning electron microscopy or measuring changes in other physical parameters (e.g., magnetic, dielectric or conductive properties).

[0032] Preferably, the ceramic substrate comprises an oxide ceramic, more preferably, the ceramic substrate comprises at least 90%, most preferably at least 95% by weight of one or a combination of the following: Al2O3, TiO2, SiO2, ZrO2, ThO2, MgO, Cr2O3, Zr2O3, V2O3. These materials are known to be particularly durable and / or resistant to environmental degradation in various situations. Therefore, these materials are particularly suitable for long-term storage under different conditions. Particularly preferably, the ceramic substrate comprises one or a combination of the following: sapphire (Al2O3), silicon dioxide (SiO2), zirconium silicate (Zr(SiO4)), zirconium oxide (ZrO2), boron monoxide (BO), boron trioxide (BO3), sodium oxide (Na2O), potassium oxide (KO), lithium oxide (Li2O), zinc oxide (ZnO), magnesium oxide (MgO).

[0033] Preferably, the ceramic substrate comprises a non-oxidic ceramic, more preferably, the ceramic substrate comprises at least 90%, most preferably at least 95% by weight of one or a combination of the following: metal nitrides such as CrN, CrAlN, TiN, TiCN, TiAlN, ZrN, AlN, VN, Si3N4, ThN, HfN, BN; metal carbides such as TiC, CrC, Al4C3, VC, ZrC, HfC, ThC, B4C, SiC; metal borides such as TiB2, ZrB2, CrB2, VB2, SiB6, ThB2, HfB2, WB2, WB4; and metal silicides such as TiSi2, ZrSi2, MoSi2, WSi2, PtSi, Mg2Si. These materials are known to be particularly durable and / or resistant to environmental degradation in various environments. Therefore, these materials are particularly suitable for long-term storage under different conditions. Particularly preferably, the ceramic substrate comprises one or a combination of the following: BN, CrSi2, SiC and SiB6.

[0034] Preferably, the ceramic substrate comprises one or a combination of Ni, Cr, Co, Fe, W, Mo or other metals having a melting point above 1400° C. Preferably, the ceramic material and the metal form a metal matrix composite material, wherein the ceramic material is dispersed in the metal or metal alloy. Preferably, the metal accounts for 5 to 30%, preferably 10 to 20% by weight of the ceramic substrate (i.e., the metal matrix composite material). Particularly preferred metal matrix composite materials are: WC / Co-Ni-Mo, BN / Co-Ni-Mo, TiN / Co-Ni-Mo and / or SiC / Co-Ni-Mo.

[0035] Preferably, the ceramic material layer is directly applied to the ceramic substrate, i.e., without any intermediate layer, to achieve a strong bond between the ceramic substrate and the ceramic material layer. Preferably, the applied ceramic substrate is tempered before and / or after recording to achieve such a strong bond. Tempering can produce a sintered interface between the ceramic substrate and the ceramic material layer. The sintered interface can include at least one element from both the substrate material and the ceramic material, because one or more elements from one of the two adjacent layers may diffuse into the other of the two adjacent layers. The presence of the sintered interface can further enhance the bond between the ceramic substrate and the ceramic material layer.

[0036] Preferably, tempering the coated ceramic substrate involves heating the coated ceramic substrate to a temperature in the range of 200° C. to 4,000° C., more preferably in the range of 1,000° C. to 2,000° C. The tempering process may include a heating phase with a temperature increase of at least 10 K per hour, a stabilization phase at the peak temperature for at least 1 minute, and finally a cooling phase with a temperature decrease of at least 10 K per hour. The tempering process may help to harden the ceramic substrate and / or permanently bond the ceramic material to the ceramic substrate.

[0037] Laser ablation of selected areas of the layer of ceramic material may reveal the underlying ceramic substrate, resulting in an (optically) distinguishable contrast of the manipulation area relative to the remainder of the layer of ceramic material.

[0038] According to a particularly preferred embodiment of the present invention, the substrate is transparent to the wavelength of the laser beam. Preferably, the substrate has a transmittance of at least 95%, more preferably at least 97%, and most preferably at least 99% for light having the wavelength of the laser beam. The substrate may, for example, comprise a glassy transparent ceramic material or a crystalline ceramic material, such as sapphire (Al2O3), silicon dioxide (SiO2), zirconium silicate (Zr(SiO4)), zirconium oxide (ZrO2), boron monoxide (B2O3), boron trioxide (B2O3), sodium oxide (Na2O), potassium oxide (K2O), lithium oxide (Li2O), zinc oxide (ZnO), magnesium oxide (MgO).

[0039] Particularly suitable crystalline ceramic materials are sapphire (Al2O3), silicon dioxide (SiO2), zirconium silicate (Zr(SiO4)), zirconium oxide (ZrO2), magnesium oxide (MgO).

[0040] Such a transparent material is particularly advantageous because it allows selective illumination of areas of the layer of ceramic material (coated onto the substrate) through the transparent substrate. Thus, any debris generated during recording is generated on the surface of the coated substrate opposite the recording optics. Thus, this surface can be easily cleaned and / or cooled without affecting the recording optics.

[0041] Due to the high transmission factor of the transparent substrate material, the laser does not interact with the substrate, but simply passes through the substrate, so as to, for example, only ablate the coating. In particular, the substrate material is substantially not heated by the laser beam.

[0042] Preferably, the laser beam (ie, each of the multiple laser beams emitted from the DMD) has a minimum focal spot diameter of no greater than 400 nm, more preferably no greater than 300 nm, even more preferably no greater than 200 nm, and most preferably no greater than 100 nm.

[0043] Preferably, the wavelength of the laser beam is less than 700 nm, preferably less than 650 nm, more preferably less than 600 nm, even more preferably less than 500 nm, and most preferably less than 400 nm. Smaller wavelengths can produce smaller structures, thereby obtaining greater data density. In addition, the energy per photon (action quantum) increases for smaller wavelengths.

[0044] Preferably, the method includes the following steps: using a DMD to selectively irradiate multiple regions of the ceramic material layer with a laser beam, wherein the multiple regions are confined within a first region of the ceramic material layer; shifting the focus to a second region of the ceramic material layer adjacent to the first region of the ceramic material layer by means of a first scanning device; and using a digital micromirror device to selectively irradiate multiple regions of the ceramic material layer with a laser beam, wherein the multiple regions are confined within the second region of the ceramic material layer.

[0045] Preferably, the steps of shifting the focus to a second region of the ceramic material layer adjacent to the first region of the ceramic material layer by means of a first scanning device and selectively irradiating multiple regions of the ceramic material layer with a laser beam using a DMD are repeated for other adjacent regions of the ceramic material layer, wherein these regions are preferably arranged linearly along the first axis.

[0046] Preferably, the method further includes: shifting the focus to a third region of the ceramic material layer adjacent to the regional lines constituting the first region and the second region of the ceramic material layer by means of a second scanning device; and selectively irradiating multiple regions of the ceramic material layer with a laser beam using a digital micromirror device, wherein the multiple regions are confined within the third region of the ceramic material layer.

[0047] Again, the steps of shifting the focus to a third region of the ceramic material layer adjacent to the regional lines constituting the first region and the second region of the ceramic material layer with the aid of a second scanning device and selectively irradiating multiple regions of the ceramic material layer with a laser beam using a DMD can be repeated for other adjacent regions of the ceramic material layer, wherein these regions are preferably arranged linearly along a second axis perpendicular to the first axis.

[0048] Preferably, the method further comprises: displacing the layer of ceramic material along a second axis perpendicular to the first axis by means of a transport mechanism, wherein the displacing is preferably performed by an XY table or continuously by means of a conveyor belt.

[0049] Preferably, the first scanning device is a polygon scanner or an acousto-optic deflector. Preferably, the second scanning device is a galvanometer scanner.

[0050] The present invention further relates to a device for recording data in a layer of ceramic material. The device comprises: a laser source; a digital micromirror device (DMD) adapted to emit a plurality of laser beams; a prism or a semi-transparent mirror positioned between the laser source and the DMD; a substrate support for mounting a substrate; a focusing optical device adapted to focus each of the plurality of laser beams emitted by the DMD onto a substrate mounted on the substrate support; and one or more scanning devices for manipulating a pattern of the plurality of laser beams emitted by the digital micromirror device on the substrate.

[0051] Preferably, the apparatus further comprises collimating optics for collimating laser light emitted by the laser source onto the DMD.

[0052] Preferably, the apparatus further comprises a λ / 4 plate positioned between the prism or semi-transparent mirror and the DMD.

[0053] Preferably, a prism or semi-transparent mirror is positioned between the laser source and the DMD so that light emitted from the laser source sequentially passes through the prism or semi-transparent mirror, optionally a λ / 4 plate, hits the DMD, and passes through the optional λ / 4 plate and prism or semi-transparent mirror again before selectively irradiating multiple areas of the substrate.

[0054] The flux of each of the multiple laser beams emitted by the DMD is preferably greater than 100 mJ / cm 2 , preferably greater than 400 mJ / cm 2 , more preferably greater than 800 mJ / cm 2 , and most preferably greater than 1 J / cm 2 .

[0055] Preferably, the laser source comprises a picosecond laser or a femtosecond laser.Preferably, the laser source has a pulse duration of less than 10 ps, ​​more preferably less than 1 ps.

[0056] All preferred features discussed above in the context of the method of the invention may also be analogously applied to the device of the invention, and vice versa.

[0057] The fluence of the laser beam is preferably suitable for manipulating the layer of ceramic material sufficiently to record data on or in the layer of ceramic material.Preferably, the fluence of the laser beam allows ablation of the ceramic material described above.

[0058] Preferably, the focusing optics comprises a lens (or more complex optics) with a high numerical aperture, preferably a numerical aperture of at least 0.5, more preferably at least 0.8. If immersion optics are used, the numerical aperture may be at least 1.0, more preferably at least 1.2.

[0059] Preferably, the device further comprises a beam shaping device, preferably a laser zone plate matrix or a spatial light modulator, in order to generate a plurality of Bessel beams, e.g. as described above. Preferably, such a beam shaping device is positioned before the focusing optics. In this case, preferably a plurality of lenses, preferably Fresnel lenses, are located directly after the beam shaping device in order to focus e.g. the Bessel beams. Preferably, the device further comprises a flat top beam shaper, which is preferably located before the prism or the semi-transparent mirror in the optical path.

[0060] At the substrate, each of the plurality of laser beams is preferably a Bessel beam. At the substrate, each of the plurality of laser beams preferably has a minimum focus diameter of no greater than 400 nm, more preferably no greater than 300 nm, even more preferably no greater than 200 nm, and most preferably no greater than 100 nm.

[0061] Preferably, the substrate support is mounted on an XY positioning system, such as a scanning stage.Preferably, the apparatus comprises a processor configured to control the DMD and the XY positioning system to sequentially illuminate adjacent areas or pixel arrays of a substrate mounted on the substrate support.

[0062] Preferably, this processor (or additional processing unit) is adapted and configured to receive a set of data to be recorded (i.e., analog or digital data, such as text, numbers, pixel arrays, QR codes, etc.) and control components of the device (specifically, the DMD and XY positioning system, and optionally, the beam shaping device) to perform the method of the present invention so as to record the received data set on or in the ceramic material layer.

[0063] Preferably, the wavelength of the laser source is less than 700 nm, preferably less than 650 nm, more preferably less than 600 nm, even more preferably less than 500 nm, and most preferably less than 400 nm.

[0064] Preferably, the device further comprises a reading device configured to image the recorded data. Thus, a single read / write head can be used to encode (write) data in the ceramic material layer and to decode (read) data encoded in such a data carrier. The use of a prism or a semi-transparent mirror as discussed above allows such a combined read / write head to be designed in a particularly compact shape.

[0065] Preferably, the device further comprises a beam splitter between the prism or semi-transparent mirror and the focusing optics for allowing light emitted from the substrate to pass to the reading device. Preferably, the device further comprises another light source (e.g., an LED) adapted to illuminate the substrate via the prism or semi-transparent mirror and the DMD during reading / decoding. Preferably, the light source emits linearly polarized light.

[0066] The reading device may include a digital camera or other optical detector. Preferably, the reading device includes a single optical sensor, wherein each "pixel" on the data carrier is addressed by means of a DMD that allows each "pixel" to be illuminated once. In another reading mode, the DMD can produce a specific illumination pattern ("structured illumination") using SIM or SSIM. In this case, the reading device should include a digital camera or other multi-pixel detector. In other reading modes, planar illumination can be provided by simply providing all micromirrors of the DMD as "ON". Likewise, in this case, the reading device should include a digital camera or other multi-pixel detector.

[0067] Preferably, the apparatus further comprises a processor configured to decode the imaging recording data.The processor may for example be adapted to perform a SIM and / or SSIM analysis and control the DMD accordingly.

[0068] Preferably, the one or more scanning devices include one or a combination of one or more galvanometer scanners, one or more polygon scanners, and one or more acousto-optic deflectors, preferably a combination of a galvanometer scanner and a polygon scanner.

[0069] Preferably, one or more scanning devices are arranged between the DMD and the focusing optics.

[0070] The focusing optics may include a focal reducer and an f-theta objective. Using a scanning system in conjunction with a standard lens will produce a spherical focal plane that may not be ideal. To achieve a flat focal plane, an f-theta objective may be utilized. Preferably, the focal reducer is disposed between the DMD and one or more scanning devices. Preferably, one or more scanning devices are disposed between the focal reducer and a flat-field theta objective.

[0071] The apparatus may further comprise a controller adapted to control the laser source, the one or more scanning devices and the digital micromirror device to produce a number of illumination patterns on adjacent areas of the substrate to produce corresponding recess patterns. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Preferred embodiments of the present invention will be further explained with reference to the accompanying drawings, which show:

[0073] Figure 1is a schematic diagram of a data recording device illustrating the basic principle of the present invention;

[0074] Figure 2a A first record substitution is schematically shown;

[0075] Figure 2b A second record alternative is schematically shown;

[0076] Figure 3 Schematically shows an apparatus for recording data according to a preferred embodiment;

[0077] Figure 4 Schematically shows a data recording device according to another preferred embodiment of the present invention;

[0078] Figure 5 A recording scheme for a large area is schematically shown; and

[0079] Figure 6 A device for recording data according to another preferred embodiment is schematically shown. DETAILED DESCRIPTION

[0080] Figure 1 A schematic diagram of an apparatus for recording data in a layer of ceramic material is shown, illustrating the basic principle of the invention. The apparatus comprises a laser source 2 which emits laser light onto a DMD 3, which comprises a plurality of micromirrors 3a arranged in an array. The DMD 3 is adapted to emit a plurality of laser beams 4 in a first direction (i.e., for recording) or in a second direction (indicated by component symbol 9), each micromirror being in an "off" state, and redirecting these laser beams 9 to a beam collector (not shown). Typically, the apparatus will further comprise collimating optics ( Figure 1 The device further comprises a substrate support 6 for mounting a substrate 6a, and a focusing optical device 8 adapted to focus each of the plurality of laser beams 4 emitted by the DMD onto the substrate 6a mounted on the substrate support 6. The focusing optical device 8 may, for example, comprise a standard microscope optical device with a high numerical aperture. The substrate support 6 is adapted to support and preferably mount the substrate 6a and may be mounted on an XY stage or as part of an XY stage.

[0081] As discussed above, the device preferably includes a beam shaping device to achieve, for example, a Bessel beam. For example, a matrix of laser zone plates 12 may be provided between the DMD 3 and the focusing optics 8 so as to shape each laser beam 4 into a Bessel beam shape. Each Bessel beam is then focused onto the substrate 6a by means of a corresponding lens (e.g., a Fresnel lens). In order to properly illuminate the matrix of laser zone plates 12, additional collimating optics may be provided. By using such a Bessel beam, a focal length of at least 4 times the laser wavelength may be achieved. In addition, the shape of the focus is more cylindrical than a Gaussian beam.

[0082] exist Figure 1 In the example shown, the substrate 6a comprises a ceramic coating or a layer of ceramic material 1 (see Figure 2a ), the ceramic coating or ceramic material layer 1 is locally ablated by means of a focused laser beam 4. Figure 1 In the embodiment, a ceramic coating 1 is provided on top of a substrate 6a (see also Figure 2a Alternatively, a ceramic coating may be provided on the bottom or back side of the substrate 6a, such as Figure 2b As shown. Since the laser beam 4 must pass through the substrate 6a in this case, the material of the substrate 6a needs to be transparent to the wavelength of the laser in this case. In addition, in this case, it is preferred that the substrate support 6 includes a frame 6b that supports only the outer edge of the substrate 6a (in the case of Figure 2a In the case of top ablation as shown, the substrate can be fully supported). Therefore, the portion of the ceramic coating 1 exposed to the ablation is unsupported due to the free space 6c below this portion (see Figure 2b ).

[0083] This is a particularly preferred embodiment, since any debris generated during ablation will be separated from the focusing optics 8 by means of the substrate 6a. Instead, any material ablated from the ceramic layer 1 will be emitted into the free space 6c of the sample holder 6 and can be extracted or aspirated therefrom. Thus, the focusing optics 8 will not be negatively affected by this debris, and it is easier to clean the surface of the ceramic coating 1 after or even during recording.

[0084] Preferably, the thickness of the substrate is adapted to the focusing optics of the device in which it is used. For example, the thickness of the substrate should be smaller than the focal length of the focusing optics in order to reach the ceramic coating.

[0085] also, Figure 2bThe arrangement shown also allows cooling of the ceramic coating 1 during ablation, for example by letting a cooling fluid flow along the ceramic coating 1. This will improve the accuracy of the ablation process, because heat transfer from the laser focus to the surrounding area can be eliminated. For example, cross jets of air (e.g., air blades) or liquids such as water or other immersion liquids can be provided for this purpose. In addition, the lateral jets can expel debris generated during ablation.

[0086] exist Figure 2a Such a cross nozzle can also be provided in the case of the arrangement shown. However, the cross nozzle in this embodiment must be designed so as not to interfere with the optics. For example, if immersion optics are used, the immersion liquid can be provided in a cross flow, preferably laminar, to avoid any optical effects due to turbulence within the immersion liquid.

[0087] Since such cross-jet of air or liquid may generate vibrations, which may compromise the recording accuracy, and since Figure 2a The embodiment shown would be complicated by the use of cross-jetting, so it is preferred to provide a negatively charged grid or sheet, such as Figure 2a and Figure 2b As explained above, using a picosecond or femtosecond laser will generate a plasma in the ceramic material to be ablated. In short, part of the atomic shell of the ceramic material is removed by the interaction with the laser pulse. The remaining positively charged nuclei are then expelled in a so-called Coulomb explosion process. These positively charged nuclei can then be attracted by the negatively charged grid or sheet 15. This Figure 2a This is particularly advantageous in the case of the embodiment shown, where the laser beam 4 can pass through an opening in the grid or sheet. All debris will then be collected by the charged grid or sheet and will therefore not negatively affect, for example, the focusing optics 8.

[0088] Preferred embodiments of the device of the present invention are Figure 3 In particular, Figure 3 The device shown comprises two scanning devices 7a and 7b. As mentioned previously, these scanning devices 7a and 7b allow the pattern of the multiple laser beams emitted by the DMD to be manipulated on the relevant area of ​​the ceramic material layer. Figure 3 In the preferred embodiment shown, a combination of a galvanometer scanner (7b) and a polygon scanner (7a) is used. Using two scanners allows scanning along two axes (preferably perpendicular axes), such as the x-axis and the y-axis (see Figure 5 ). Then, a scan may be performed along a first axis (eg, the y-axis), and upon completion of a line along the first axis (eg, Figure 5After scanning a line (e.g., DMD patterns 1 to 5 in the image), a line is scanned along a second axis (e.g., the x-axis) and then again along the first axis (e.g., DMD patterns 6 to 10). Figure 5 As is evident from the scheme shown, it may be beneficial to utilize a fast scanning process for the y-axis, while scanning along the x-axis may be performed at a reduced speed. It is therefore preferred to utilize a polygon scanner (7a) for the first axis and a galvanometer scanner (7b) for the second axis. Alternatively, an acousto-optic deflector may be used for either or both of these scanning devices.

[0089] Figure 3 Additional preferred features are shown, however, these features are not essential in the context of the present invention. For example, Figure 3 Collimation optics 5 for collimating the laser light emitted by the laser source 2 onto the DMD 3 are shown, as well as other optical components such as an actuator 10 and a polarizer 11 .

[0090] Figure 3 Further shown is an optional flat-top beam shaper 21 arranged between the collimating optics 5 and the DMD 3. More importantly, Figure 3 The preferred embodiment shown includes a prism 16. The optional prism 16 (which may also be replaced by a semi-transparent mirror) is positioned between the laser source 2 and the DMD 3, so that the light emitted from the laser source 2 sequentially passes through the prism 16, the λ / 4 plate 17a, hits the DMD 3, and passes through the λ / 4 plate 17a and the prism 16 again before selectively irradiating multiple areas of the substrate 6a.

[0091] The linearly polarized light that hits the prism 16 from the top optical path will be reflected to the right, that is, toward the DMD 3. By passing through the λ / 4 plate 17a twice, the polarization axis of the laser light is rotated by 90° in total. Therefore, the linearly polarized light that hits the prism 16 from the right optical path will pass through the prism 16 again.

[0092] Another λ / 4 plate 17b may be provided (see Figure 4 ) to convert linearly polarized light into circularly polarized light, which is particularly advantageous for generating Bessel beams with the laser zone plate 12. As mentioned above, the Bessel beam allows the generation of well-defined cylindrical recesses. Of course, if the laser zone plate 12 already includes an optical component 12a for generating circularly polarized light, the presence of the additional λ / 4 plate 17b is not required (see Figure 3 ).

[0093] Figure 3The preferred embodiment shown further comprises a reading device 18, which is configured to image the recorded data. Thus, a single read / write head can be used to encode (write) data in a layer of ceramic material and to decode (read) data encoded in such a data carrier. A wavelength-dependent beam splitter 19 reflects the wavelength of the laser light emitted from the laser source 2 and passes the wavelength emitted by the further light source 20 between the prism 16 and the focusing optical device 8b, thereby allowing the light emitted from the substrate with a wavelength different from that of the laser source 2 to be transmitted to the reading device 18. The further light source 20 (e.g., an LED) is suitable for illuminating the substrate via the beam splitter 24 during reading / decoding. By passing through the λ / 4 plate 17b twice, the polarization axis of the laser light originating from the light source 20 is rotated again by 90°. Therefore, the re-linearly polarized light impinging on the beam splitter 24 will pass through the beam splitter 24 towards the reading device 18.

[0094] Of course, it is also conceivable Figure 3 Other arrangements of the optical components of the device shown. For example, the reading device 18 is not as Figure 3 As shown, it is arranged on the optical axis of the focusing optical device 8b, but it can also be arranged as shown. Figure 4 The arrangement is shown on the fourth side of the prism 16. In this case, although the beam splitter 19 is still shown, it is no longer required and can be replaced by a mirror that always reflects. This λ / 4 plate 17a and 17b again ensures that the laser light originating from the light source 20 is rotated by a total of 180°. Therefore, the re-linearly polarized light impinging on the prism 16 will be reflected towards the reading device 18. Figure 4 In the embodiment shown, the mirror 23 should be a wavelength-dependent beam splitter which reflects the wavelength of the laser light emitted from the laser source 2 and passes the wavelength emitted by the further light source 20 .

[0095] In the reading mode, the DMD 3 can be used in different ways to illuminate the data carrier with light emitted by another light source 20. As discussed above, the data carrier can be illuminated pixel by pixel using the DMD 3. In this case, only a single detector is required in the reading device, and the scanning of the image is performed by the DMD 3.

[0096] In another reading mode, by using SIM or SSIM, the DMD 3 will generate a specific illumination pattern ("structured illumination"). In this case, the reading device 18 should comprise a digital camera or other multi-pixel detector.

[0097] In a further reading mode, a planar illumination may be provided by simply providing all micromirrors of the DMD 3 to be "ON." Also in this case, the reading device 18 should comprise a digital camera or other multi-pixel detector.

[0098] The focusing optics (8) may optionally include a focal reducer (8a) and an f-theta objective (8b), such as Figure 3 and Figure 4 As shown. Using a scanning system in conjunction with a standard lens will produce a spherical focal plane that may not be ideal. In order to achieve a flat focal plane, an f-theta objective lens (8b) may be used. In addition, a focal reducer (8a) may be present to reduce the area of ​​the illumination pattern produced by the DMD 3 to a predetermined area size acceptable to the scanning devices 7a and 7b.

[0099] As mentioned above, the device of the present invention does not require Figure 3 and Figure 4 For example, if data is to be recorded on a long and narrow strip of material, such as a roll of thin ceramic material or a roll of substrate with a thin ceramic coating, the slow axis discussed above can be achieved by a transport mechanism for the long and narrow strip of material. For example, a roll of ceramic material 6a can be unwound from itself and transported along the x-axis for recording, such as Figure 6 The fast y-axis can still be scanned by means of a scanning device 7a, which is preferably a polygon scanner 7a. However, if the single DMD pattern does not extend over the entire width of the material strip, the transport mechanism can even be combined with two scanning devices, such as Figure 6 As shown above. Figure 3 and Figure 4 The other optical components discussed can be similarly Figure 6 adopted in the context of.

Claims

1. A method for recording data in a ceramic material layer, the method comprising the following steps: providing a layer of ceramic material; as well as selectively irradiating a plurality of regions of the layer of ceramic material with a laser beam using a digital micromirror device and at least one scanning device; wherein parameters of the laser beam and the irradiation time of each of the selected regions are configured to ablate each of the selected regions to record data in the ceramic material layer by creating recesses in the ceramic material layer; and The laser beam originates from a picosecond laser or a femtosecond laser and sequentially passes through a prism or a semi-transparent mirror, hits the digital micromirror device, and passes through the prism or the semi-transparent mirror again before selectively irradiating multiple areas of the ceramic material layer.

2. The method of claim 1, wherein the laser beam is a Bessel beam, preferably generated by a laser zone plate or a spatial light modulator.

3. A method as claimed in claim 1 or 2, wherein the recess is open to the atmosphere.

4. The method according to any one of the preceding claims, wherein the laser beam further passes through a λ / 4 plate twice, the λ / 4 plate being positioned between the prism or the semi-transparent mirror and the digital micromirror device.

5. A method as described in any of the preceding claims, wherein the ceramic material layer comprises at least one of the following: a metal nitride such as CrN, CrAlN, TiN, TiCN, TiAlN, ZrN, AlN, VN, Si3N4, ThN, HfN, BN; a metal carbide such as TiC, CrC, Al4C3, VC, ZrC, HfC, ThC, B4C, SiC; a metal oxide such as Al2O3, TiO2, SiO2, ZrO2, ThO2, MgO, Cr2O3, Zr2O3, V2O3; a metal boride such as TiB2, ZrB2, CrB2, VB2, SiB6, ThB2, HfB2, WB2, WB4; or a metal silicide such as TiSi2, ZrSi2, MoSi2, WSi2, PtSi, Mg2Si.

6. A method as claimed in any one of the preceding claims, wherein providing a layer of ceramic material comprises providing a ceramic substrate, and coating the substrate with the layer of ceramic material, the layer of ceramic material being different from the material of the ceramic substrate, wherein the layer of ceramic material preferably has a thickness of not more than 10 μm, more preferably not more than 5 μm, more preferably not more than 2 μm, more preferably not more than 1 μm, even more preferably not more than 100 nm and most preferably not more than 10 nm.

7. The method of claim 6, wherein the ceramic substrate comprises at least 90%, preferably at least 95%, by weight of one or a combination of: Al2O3, TiO2, SiO2, ZrO2, ThO2, MgO, Cr2O3, Zr2O3, V2O3; and / or wherein the ceramic substrate comprises at least 90%, preferably at least 95%, by weight of one or a combination of: metal nitrides such as CrN, CrAlN, TiN, TiCN , TiAlN, ZrN, AlN, VN, Si3N4, ThN, HfN, BN; metal carbides such as TiC, CrC, Al4C3, VC, ZrC, HfC, ThC, B4C, SiC; metal borides such as TiB2, ZrB2, CrB2, VB2, SiB6, ThB2, HfB2, WB2, WB4; and metal silicides such as TiSi2, ZrSi2, MoSi2, WSi2, PtSi, Mg2Si.

8. The method of any one of claims 6 to 7, wherein the ceramic substrate has a thickness of less than 1 mm, preferably less than 500 μm, more preferably less than 200 μm and most preferably less than 10 μm.

9. The method of any one of claims 6 to 8, wherein the ceramic substrate is transparent to the wavelength of the laser beam.

10. The method of claim 9, wherein the ceramic substrate comprises a glassy transparent ceramic material or a crystalline ceramic material, and / or wherein the ceramic substrate comprises one or a combination of the following: sapphire (Al2O3), silicon dioxide (SiO2), zirconium silicate (Zr(SiO4)), zirconium oxide (ZrO2), boron oxide (B2O), boron trioxide (B2O3), sodium oxide (Na2O), potassium oxide (K2O), lithium oxide (Li2O), zinc oxide (ZnO), magnesium oxide (MgO).

11. The method of claim 9 or 10, wherein selectively irradiating a plurality of regions of the layer of ceramic material with a laser beam using a digital micromirror device comprises irradiating the layer of ceramic material through the transparent substrate.

12. The method of any one of claims 6 to 11, wherein selectively irradiating a plurality of regions of the layer of ceramic material with a laser beam using a digital micromirror device comprises ablating sufficient material at each of the regions where the recess extends toward the substrate.

13. The method according to any one of claims 6 to 12, wherein the coated ceramic substrate is tempered before and / or after recording.

14. The method of any of the preceding claims, wherein the laser beam further passes through a flat-top beam shaper before striking the digital micromirror device.

15. The method according to any one of the preceding claims, wherein the wavelength of the laser beam is less than 700 nm, preferably less than 650 nm.

16. A method as claimed in any preceding claim, wherein the recesses are produced at a subset of predetermined locations, and wherein the predetermined locations are arranged in a regular matrix or array.

17. The method of claim 16, wherein the regular matrix or array is a square pattern or a hexagonal pattern.

18. A method as claimed in any preceding claim, wherein the recess has a circular cross-section.

19. A method as claimed in any preceding claim, further comprising collecting the positively charged fragments using a negatively charged grid or sheet.

20. The method of claim 19, wherein the layer of ceramic material is positioned between the digital micromirror device and the negatively charged grid or sheet.

21. The method of claim 19, wherein the negatively charged grid or sheet is positioned between the digital micromirror device and the layer of ceramic material.

22. The method of claim 21, wherein the negatively charged grid or sheet comprises openings that allow the laser beam to pass through.

23. A method as claimed in any one of the preceding claims, wherein the method comprises the following steps: a) selectively irradiating a plurality of regions of the layer of ceramic material with the laser beam using the digital micromirror device, wherein the plurality of regions are confined within a first region of the layer of ceramic material; b) shifting a focal point by means of a first scanning device to a second region of the layer of ceramic material adjacent to the first region of the layer of ceramic material; as well as c) selectively irradiating a plurality of regions of the layer of ceramic material with the laser beam using the digital micromirror device, wherein the plurality of regions are confined within the second region of the layer of ceramic material.

24. The method of claim 23, wherein steps b) and c) are repeated for other adjacent regions of the layer of ceramic material, wherein the regions are arranged linearly along the first axis.

25. The method of claim 24, wherein the method further comprises: d) shifting the focus to a third region of the ceramic material layer adjacent to a region line constituting the first region and the second region of the ceramic material layer by means of a second scanning device; as well as e) selectively irradiating a plurality of regions of the layer of ceramic material with the laser beam using the digital micromirror device, wherein the plurality of regions are confined within the third region of the layer of ceramic material.

26. The method of claim 25, wherein steps d) and e) are repeated for other adjacent regions of the layer of ceramic material, wherein these regions are linearly arranged along a second axis perpendicular to the first axis.

27. The method of claim 23 or 24, wherein the method further comprises displacing the layer of ceramic material along a second axis perpendicular to the first axis by means of a transport mechanism.

28. The method of claim 27, wherein the displacement is performed continuously by means of a conveyor belt.

29. The method of any one of claims 23 to 28, wherein the first scanning device is a polygon scanner or an acousto-optic deflector.

30. The method of any one of claims 23 to 29, wherein the second scanning device is a galvanometer scanner.

31. A device for recording data in a layer of ceramic material (1), the device comprising: A laser source (2), including a picosecond laser or a femtosecond laser; A digital micromirror device (3) adapted to emit a plurality of laser beams (4); a prism (16) or a semi-transparent mirror positioned between the laser source (2) and the digital micromirror device (3); A substrate support (6) for mounting a substrate (6a); a focusing optical device (8) adapted to focus each of the plurality of laser beams (4) emitted by the digital micromirror device (3) onto a substrate (6a) mounted on the substrate holder (6); as well as One or more scanning devices (7a, 7b) for manipulating the pattern of the plurality of laser beams (4) emitted by the digital micromirror device (3) on the substrate.

32. An apparatus as claimed in claim 31, wherein the focusing optics (8) comprises a lens having a numerical aperture of at least 0.5, more preferably at least 0.

8.

33. The device of claim 31 or 32, wherein the device further comprises a beam shaping device, preferably a flat-top beam shaper (21), a laser zone plate matrix (12) or a spatial light modulator.

34. The device according to any one of claims 31 to 33, wherein the device further comprises a λ / 4 plate (17a), the λ / 4 plate (17a) being positioned between the prism (16) or the semi-transparent mirror and the digital micromirror device (3).

35. The apparatus of any one of claims 31 to 34, further comprising a processor configured to control the digital micromirror device and optionally an XY positioning system on which the substrate support is mounted.

36. The device according to any one of claims 31 to 35, further comprising collimating optics (5) for collimating the laser light emitted by the laser source (2) onto the digital micromirror device (3).

37. The device of any one of claims 31 to 36, further comprising a negatively charged grid or sheet (15) for collecting positively charged debris.

38. Apparatus as claimed in claim 37, wherein the substrate support (6) is positioned between the focusing optics (8) and the negatively charged grid or sheet (15).

39. The device of claim 37, wherein the negatively charged grid or sheet (15) is positioned between the focusing optics (8) and the substrate support (6).

40. The device of any one of claims 31 to 39, wherein the flux of each of the plurality of laser beams (4) emitted by the digital micromirror device (3) is greater than 100 mJ / cm 2 .

41. A device as claimed in any one of claims 31 to 40, wherein the prism (16) or semi-transparent mirror is positioned between the laser source (2) and the digital micromirror device (3) so that light emitted from the laser source (2) sequentially passes through the prism (16) or semi-transparent mirror, hits the digital micromirror device (3), and passes through the prism (16) or semi-transparent mirror again before selectively irradiating multiple areas of the substrate.

42. The device according to any one of claims 31 to 41, further comprising a reading device (18) configured to image the recorded data.

43. The device as claimed in claim 42, further comprising a beam splitter (19) between the prism (16) or the semi-transparent mirror and the focusing optics (8) for allowing light emitted from the substrate to pass to the reading device (18).

44. The device as claimed in claim 42 or 43, further comprising a further light source (20) adapted to illuminate the substrate via the prism (16) or the semi-transparent mirror and the digital micromirror device (3) and / or via the beam splitter (19).

45. A device as claimed in claim 43, wherein the reading device (18) comprises a single digital micromirror device.

46. ​​Apparatus as claimed in claim 43, wherein the further light source (20) is positioned to illuminate the substrate via a further λ / 4 plate (17b) and via the beam splitter (19).

47. A device as claimed in claim 46, wherein the further [lambda] / 4 plate (17b) and the beam splitter (19) are positioned between the reading device (18) and the focusing optics (8).

48. The apparatus of any one of claims 41 to 44, further comprising a processor configured to decode the imaged recorded data.

49. The apparatus of claim 48, wherein the processor is adapted to perform SIM and / or SSIM analysis.

50. An apparatus as described in any one of claims 31 to 49, wherein the one or more scanning devices include one or a combination of one or more galvanometer scanners (7b), one or more polygon scanners (7a) and one or more acousto-optic deflectors, preferably a combination of a galvanometer scanner and a polygon scanner.

51. A device as claimed in any one of claims 31 to 50, wherein the one or more scanning devices are arranged between the DMD (3) and the focusing optical device (8).

52. The device according to any one of claims 31 to 50, wherein the focusing optics (8) comprises a focal reducer (8a) and an f-theta objective (8b).

53. A device as claimed in claim 52, wherein the defocuser (8a) is arranged between the DMD (3) and the one or more scanning devices (7).

54. Apparatus according to claim 52 or 53, wherein the one or more scanning devices (7) are arranged between the focus reducer (8a) and the f-theta objective (8b).

55. Apparatus as claimed in any one of claims 31 to 54, further comprising a conveying mechanism for conveying the elongate layer of ceramic material.

56. The device as described in any one of claims 31 to 55 further comprises a controller suitable for controlling the laser source (2), the one or more scanning devices, the digital micromirror device (3) and optionally the conveying mechanism so as to produce a number of illumination patterns on adjacent areas of the substrate, thereby producing corresponding recessed patterns.

57. The method of any one of claims 1 to 30, wherein the method utilizes the apparatus of any one of claims 31 to 54.

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