Information storage method and information storage medium with improved storage density by multi-bit coding method

Abstract

An information storage method and information storage medium are provided that have improved storage density through a multi-bit coding method. A method for storing information comprises providing a substrate and encoding information on the substrate by using a laser and / or a focused particle beam to form a plurality of recesses in a surface of the substrate, the recesses having different shapes and / or sizes and, optionally, different depths, each recess corresponding to a predetermined information value.

Description

[Technical Field]

[0001] The present invention relates to a method for storing information and an information storage medium with a large storage capacity. [Background technology]

[0002] As the amount of data generated every day increases, improvements in storage technology are of paramount importance. In particular, it is important to provide methods for storing data more efficiently, by increasing the data storage capacity per area or per storage device. For decades, CDs, DVDs, and Blu-ray Discs have been important digital information storage media, and their storage capacity has increased over time largely due to the size of their structures and the wavelengths used for decoding. Summary of the Invention [Problem to be solved by the invention]

[0003] Nevertheless, there is a need to provide improved information storage methods and media in terms of storage capacity. The present invention provides various approaches that, alone or in combination, may achieve this goal. [Means for solving the problem]

[0004] In a first aspect, the present invention relates to a method for storing information, comprising: providing a substrate; and using a laser and / or focused particle beam to form a plurality of recesses in a surface of the substrate, thereby encoding information on the substrate, the recesses having different shapes and / or sizes, each corresponding to a predetermined information value. In other words, the present invention utilizes a third dimension: not only does the method encode information using specific locations (e.g., the x- and y-dimensions) (i.e., the presence or absence of a recess), but the shape and / or size of each recess encodes additional information. For example, different circular recesses with different diameters can encode different information values. Alternatively, different elliptical recesses (corresponding to recesses of different shapes) can encode information values. Furthermore, combining these concepts, e.g., using elliptical shapes with both different orientations and different sizes, can further increase storage capacity.

[0005] Optionally, the recesses may be of different depths, each corresponding to a predetermined information value. This concept is described in detail in relation to ceramic substrates in PCT / EP2020 / 068892, which is incorporated herein by reference in its entirety, particularly for the disclosure that describes and details how information is encoded by recess depth. As will be appreciated by those skilled in the art, the concept may also be applied to substrates other than ceramic substrates.

[0006] The concept of this first aspect of the invention can also be applied to stacks of material layers. Accordingly, the invention further relates to a method for storing information, comprising the steps of: providing a substrate; coating the substrate with a layer of a second material different from the material of the substrate; and using a laser and / or a focused particle beam to form a plurality of recesses in the surface of the layer of the second material, thereby encoding information in the layer of the second material, the recesses having different shapes and / or sizes, each corresponding to a predetermined information value. Again, the recesses may have different depths, each corresponding to a predetermined information value. The coated substrate may optionally be subjected to a tempering treatment before and / or after encoding information to improve the durability of the coated substrate. This tempering treatment is particularly advantageous for certain ceramic substrates and certain second materials. This is explained in detail in PCT / EP2019 / 071805, the entire contents of which are incorporated herein by reference, in particular with respect to the disclosure of suitable combinations of such materials and the advantages and effects of the tempering process.

[0007] The substrate and coating (and possibly additional layers) on the substrate are advantageous when the coating is made of exotic and potentially expensive materials that can be very easily modified with a laser or focused particle beam. The substrate simply serves as a durable base for the coating, which is the actual encoding of information. The substrate and coating also provide an optical contrast (or other contrast that can be read by an appropriate reading device) between areas where the coating is present and areas where it is not present, allowing the substrate to be read. This effect is explained in detail in connection with ceramic substrates in PCT / EP2019 / 071805, the contents of which are incorporated herein by reference.

[0008] If a stack of further material layers is used, and the recesses have different depths, the differences in material between subsequent layers can be used together with the depth of the recesses to encode further information, for example by creating color effects. This is explained in detail in PCT / EP2020 / 068892, the contents of which are incorporated by reference in particular with respect to these points mentioned herein. The present invention therefore also relates to a method for storing information, comprising the steps of: providing a substrate; coating the substrate with two or more layers of different second materials different from the material of the substrate; and forming a plurality of recesses in the layer of the second material using a laser and / or a focused particle beam, thereby encoding information in the layer of the second material, the recesses having different shapes and / or sizes and different depths extending into different ones of the two or more layers, each shape and / or size and each depth corresponding to a predetermined information value. Again, the coated substrate may optionally be tempered before and / or after encoding information to improve the durability of the coated substrate, which, as mentioned above, is highly advantageous when certain ceramic substrates and certain second materials are used.

[0009] When two or more layers are coated on the substrate, the thickness of each of the two or more layers is preferably less than 1 μm, preferably less than 100 nm, more preferably less than 10 nm. Also, preferably, the two or more layers include a metal layer and a metal oxide layer, and preferably, the metal element of the metal layer is the same as the metal element of the metal oxide layer.

[0010] In all three options of this first aspect of the invention, preferably the recesses of different shapes have different cross-sectional shapes perpendicular to the depth direction. Alternatively or additionally, the recesses of different sizes have different cross-sectional sizes perpendicular to the depth direction, preferably different cross-sectional areas. Thus, when imaging or reading the different shapes and / or sizes, imaging or reading along an axis perpendicular to the surface of the substrate or coating may be most effective.

[0011] Preferably, the recesses are arranged in a regular two-dimensional pattern. A particularly preferred regular two-dimensional pattern is a rectangular, preferably square, matrix or array, with one or no recesses for each rectangle or square in the matrix or array. Such an arrangement allows for increased storage density compared to, for example, optical disks, which require a certain track pitch, thereby consuming a large portion of the total surface for storing data. A preferred regular two-dimensional pattern, which further increases storage density, is a hexagonal pattern.

[0012] The recesses may have at least two, at least three, at least four, at least five, at least six, at least seven, at least eight, at least sixteen, or at least thirty-two different shapes, sizes, and / or depths, each corresponding to a predetermined information value. Of course, the number of different sizes does not necessarily correspond to the number of different shapes and / or depths. For example, if an elliptical shape is selected for each recess, there may be four different orientations, two different sizes, and eight different depths, allowing each recess to encode six different bits of information, i.e., 64 different information values. As a result, the storage density of this example is increased by a factor of six compared to a pattern of recesses with a single shape, size, and depth.

[0013] Of course, the different shapes do not have to be created by varying the orientation of recesses of the same basic shape, such as an ellipse. Rather, for example, square recesses, circular recesses, or even linear recesses of various orientations can be used. It is also possible to use two or more different types of recesses that differ in size and shape. For example, when using a laser to generally form circular recesses using the method of the present invention, either a recess consisting of a single circle or a recess formed by placing two circles adjacent to each other to form a slightly elongated shape can be created. The latter differs in size and shape from the circular recesses.

[0014] Preferably, each recess is formed by one or more pulses of the laser and / or focused particle beam. The shape of each recess can be controlled by one or a combination of optical proximity control, polarization ablation, variable shaped beam techniques, or by overlapping two or more circular recesses with a predetermined orientation. For example, a triangular shape can be created by arranging three recesses in a triangular pattern with sufficient overlap such that a triangular recess is generally formed. Similarly, creating four recesses can create rectangular or square recesses. Also, two or more recesses can create linear recesses that can have various orientations.

[0015] The size of each recess can be controlled by one or a combination of pulses, intensity level, or focus size. For example, if a laser beam with a conical focus is used, multiple pulses and / or pulses with increased intensity levels will increase the depth of the recess while simultaneously increasing the cross-sectional area of ​​the upper end (surface portion) of the recess due to the conical shape. If the depth and size of each recess need to be controlled independently, the size of the recess can be changed by manipulating the focus. Because adjusting the focus of the laser beam for each recess is tedious and time-consuming, it is preferable to first form all recesses of a first size, and then manipulate the focus to form all recesses of a second size.

[0016] The depth of each recess may be controlled by one or a combination of the following parameters: energy of the pulse, length of the pulse, number of pulses of the laser and / or focused particle beam.

[0017] When different depths are used, the minimum difference in depth between the plurality of recesses is 1 nm or more, preferably 10 nm or more, more preferably 30 nm or more, more preferably 50 nm or more, even more preferably 70 nm or more, and most preferably 100 nm or more. The minimum difference in depth between the plurality of recesses is 5 μm or less, preferably 1 μm or less, more preferably 500 nm or less, more preferably 300 nm or less, even more preferably 200 nm or less, and most preferably 100 nm or less.

[0018] Generally, the substrate of the present invention may be any material that is stable and durable enough to be manipulated by a laser and / or particle beam or to serve as a substrate to be coated as described above, however, ceramic substrates are particularly preferred as described in PCT / EP2019 / 071805.

[0019] Preferably, the ceramic substrate is an oxide ceramic substrate. Preferably, the ceramic substrate contains at least 90% by weight, preferably at least 95% by weight, of one or a combination of Al2O3, TiO2, SiO2, ZrO2, ThO2, MgO, Cr2O3, Zr2O3, V2O3, or any other oxide ceramic material. Preferably, the ceramic substrate contains a transparent vitreous or crystalline ceramic material. Preferably, the ceramic substrate contains at least one or a combination of sapphire (Al2O3), silica (SiO2), zirconium (Zr(SiO4)), and ZrO2. Particularly preferred substrate materials, particularly those that can achieve substrate thicknesses of less than 200 μm, include silicon oxide, aluminum oxide, boron oxide, sodium oxide, potassium oxide, lithium oxide, zinc oxide, and magnesium oxide. In this regard, see EP 21 15 6858.9.

[0020] Preferably, the ceramic substrate is a non-oxide ceramic substrate containing at least 90 wt%, preferably at least 95 wt%, of one or a combination of metal nitrides such as CrN, CrAlN, TiN, TiCN, TiAlN, ZrN, AlN, VN, Si3N4, ThN, HfN, and BN, metal carbides such as TiC, CrC, Al4C3, VC, ZrC, HfC, ThC, B4C, and SiC, metal borides such as TiB2, ZrB2, CrB2, VB2, SiB6, ThB2, HfB2, WB2, and WB4, metal silicides such as TiSi2, ZrSi2, MoSi2, MoSi, WSi2, PtSi, and Mg2Si, or any other type of non-oxide ceramic material. Preferably, the ceramic substrate contains one or a combination of Ni, Cr, Co, Fe, W, Mo, or other metals with a melting point above 1,400°C. Preferably, the ceramic material and the metal form a metal matrix composite. Preferably, the metal accounts for 5 to 30 wt %, more preferably 10 to 20 wt %, of the ceramic substrate. Particularly preferably, the ceramic substrate contains WC / Co-Ni-Mo and / or BN / Co-Ni-Mo and / or TiN / Co-Ni-Mo and / or SiC / Co-Ni-Mo.

[0021] The second material may be any material that can be suitably manipulated by a laser and / or particle beam to generate the recesses of the present invention. However, as detailed in PCT / EP2019 / 071805, certain materials are particularly preferred as the second material, especially when used in combination with the substrate of a ceramic material as described above. Preferably, the second material is selected from the group consisting of metals such as Cr, Co, Ni, Fe, Al, Ti, Si, W, Zr, Ta, Th, Nb, Mn, Mg, Hf, Mo, and V; metal nitrides such as CrN, CrAlN, TiN, TiCN, TiAlN, ZrN, AlN, VN, Si3N4, ThN, HfN, and BN; metal carbides such as TiC, CrC, Al4C3, VC, ZrC, HfC, ThC, B4C, and SiC; Al2O3, TiO2, SiO2, ZrO2, and ThO 2、The second material contains at least one ceramic material such as a metal oxide such as MgO, Cr2O3, Zr2O3, V2O3, a metal boride such as TiB2, ZrB2, CrB2, VB2, SiB6, ThB2, HfB2, WB2, WB4, a metal silicide such as TiSi2, ZrSi2, MoSi2, MoSi, WSi2, PtSi, Mg2Si, or any other type of ceramic material, and preferably the second material contains CrN and / or Cr2O3 and / or CrAlN.

[0022] The method for forming the recesses is not critical for the present invention, as long as it allows good control of the size, shape and, optionally, depth. Preferably, the process for forming the recesses comprises locally heating the surface (of the substrate or of the coating) to a temperature above the melting and / or decomposition temperature of the second material, preferably above 3,000°C, more preferably above 3,200°C, even more preferably above 3,500°C, most preferably above 4,000°C. Preferably, the recesses are formed by treating the surface of the (coated) substrate with a femtosecond laser, causing a so-called Coulomb explosion leading to material ablation.

[0023] Preferably, the layer of the second material and / or the two or more layers of different second materials has a thickness of 5 μm or less, preferably 2 μm or less, more preferably 1 μm or less, even more preferably 100 nm or less, and most preferably 10 nm or less.

[0024] The process of forming the recess may involve locally heating and / or decomposing and / or oxidizing and / or ablating and / or vaporizing the surface of the substrate or coating.

[0025] As mentioned above, and as discussed in detail in PCT / EP2019 / 071805, it may be beneficial to subject the coated substrate to a tempering treatment before and / or after encoding information to improve the durability of the coated substrate. This is particularly preferred when a ceramic substrate is used. Preferably, this tempering treatment creates a sintered interface between the ceramic substrate and the layer of the second material or two or more layers of different second materials. Preferably, the sintered interface contains at least one element from both the substrate material and the second material. The tempering treatment may be carried out in an oxygen atmosphere, which may oxidize at least the top layer of the second material.

[0026] The method of the present invention may enable large storage capacities. Preferably, the (coated) substrate has an area of ​​1 cm 2 More than 1 megabyte of information per cm, preferably 1 cm 2 10 megabytes or more of information per cm, preferably 1 cm 2 100 megabytes or more of information per cm, preferably 1 cm 2 More than 1 gigabyte of information per cm, most preferably 1 cm 2 Each contains over 10 gigabytes of information.

[0027] The invention according to this first aspect also relates to a corresponding data storage medium resulting from the method described above. That is, the invention relates to a data storage medium comprising a substrate, the surface of which has a plurality of recesses for encoding information on the data storage medium, the recesses having different shapes and / or sizes, each shape and / or size corresponding to a predetermined information value. As mentioned above, the recesses may also be of different depths, each depth corresponding to a predetermined information value.

[0028] The present invention further relates to an information storage medium comprising a substrate coated with a layer of a second material, the second material being different from the material of the substrate, the layer of the second material having a plurality of recesses for encoding information on the information storage medium, the recesses having different shapes and / or sizes, each corresponding to a predetermined information value. The information storage medium may optionally further comprise a sintered interface between the substrate and the layer of the second material, the sintered interface containing at least one element from both the material of the substrate and the second material. This sintered interface is particularly preferred when the substrate is made of a ceramic material. As previously mentioned, the recesses may further have different depths, each corresponding to a predetermined information value.

[0029] The present invention further relates to an information storage medium comprising a substrate coated with two or more layers of a second material different from that of the substrate, the second material being different from that of the substrate, the information storage medium further comprising a plurality of recesses for encoding information in the information storage medium, the recesses having different shapes and / or sizes and different depths extending through different ones of the two or more layers, each shape and / or size and each depth corresponding to a predetermined information value.Again, there may optionally be a sintered interface between the substrate and a bottom layer of the two or more layers, the sintered interface containing at least one element from both the material of the substrate and the material of the bottom layer.

[0030] Naturally, any of the configurations and preferred configurations already described in the context of the method of the present invention may also be applied to the information storage medium of the present invention.

[0031] When two or more layers are coated on the information recording medium, the thickness of each of the two or more layers is preferably less than 1 μm, preferably less than 100 nm, more preferably less than 10 nm. Also, preferably, the two or more layers include a metal layer and a metal oxide layer, and preferably, the metal element of the metal layer is the same as the metal element of the metal oxide layer.

[0032] Also, preferably, the recesses of different shapes have different cross-sectional shapes perpendicular to the depth direction, and / or the recesses of different sizes have different cross-sectional sizes perpendicular to the depth direction, preferably different cross-sectional areas.

[0033] Also, preferably, the plurality of recesses have at least two, preferably at least three, more preferably at least four, even more preferably at least five, even more preferably at least six, even more preferably at least seven, even more preferably at least eight, even more preferably at least 16, and most preferably at least 32 different shapes and / or sizes and / or depths, each shape and / or size and / or depth corresponding to a predetermined information value.

[0034] Preferably, the minimum difference in depth between the plurality of recesses is 1 nm or more, preferably 10 nm or more, more preferably 30 nm or more, more preferably 50 nm or more, even more preferably 70 nm or more, and most preferably 100 nm or more. Preferably, the minimum difference in depth between the plurality of recesses is 5 μm or less, preferably 1 μm or less, more preferably 500 nm or less, more preferably 300 nm or less, even more preferably 200 nm or less, and most preferably 100 nm or less.

[0035] Preferably, the ceramic substrate contains an oxide ceramic. Preferably, the ceramic substrate contains at least 90% by weight, preferably at least 95% by weight, of one or a combination of Al2O3, TiO2, SiO2, ZrO2, ThO2, MgO, Cr2O3, Zr2O3, VO3, or any other oxide ceramic material. Preferably, the ceramic substrate contains a transparent vitreous or crystalline ceramic material. Preferably, the ceramic substrate contains at least one or a combination of sapphire (Al2O3), silica (SiO2), zirconium (Zr(SiO4)), and ZrO2. Particularly preferred substrate materials, particularly those capable of achieving a substrate thickness of less than 200 μm, include silicon oxide, aluminum oxide, boron oxide, sodium oxide, potassium oxide, lithium oxide, zinc oxide, and magnesium oxide.

[0036] Preferably, the ceramic substrate contains a non-oxide ceramic, preferably 90% by weight or more, and more preferably 95% by weight or more, of one or a combination of metal nitrides such as CrN, CrAlN, TiN, TiCN, TiAlN, ZrN, AlN, VN, Si3N4, ThN, HfN, and BN; metal carbides such as TiC, CrC, Al4C3, VC, ZrC, HfC, ThC, B4C, and SiC; metal borides such as TiB2, ZrB2, CrB2, VB2, SiB6, ThB2, HfB2, WB2, and WB4; metal silicides such as TiSi2, ZrSi2, MoSi2, MoSi, WSi2, PtSi, and Mg2Si; or any other type of non-oxide ceramic material. Preferably, the ceramic substrate contains one or a combination of Ni, Cr, Co, Fe, W, Mo, or other metals with a melting point above 1,400°C. Preferably, the ceramic material and the metal form a metal matrix composite. Preferably, the metal accounts for 5 to 30 wt %, more preferably 10 to 20 wt %, of the ceramic substrate. Particularly preferably, the ceramic substrate contains WC / Co-Ni-Mo and / or BN / Co-Ni-Mo and / or TiN / Co-Ni-Mo and / or SiC / Co-Ni-Mo.

[0037] Preferably, the second material is selected from the group consisting of metals such as Cr, Co, Ni, Fe, Al, Ti, Si, W, Zr, Ta, Th, Nb, Mn, Mg, Hf, Mo, and V; metal nitrides such as CrN, CrAlN, TiN, TiCN, TiAlN, ZrN, AlN, VN, Si3N4, ThN, HfN, and BN; metal carbides such as TiC, CrC, Al4C3, VC, ZrC, HfC, ThC, B4C, and SiC; and metal carbides such as Al2O3, TiO2, SiO2, ZrO2, and ThO. 2、The second material may contain at least one ceramic material such as a metal oxide such as MgO, Cr2O3, Zr2O3, or V2O3, a metal boride such as TiB2, ZrB2, CrB2, VB2, SiB6, ThB2, HfB2, WB2, or WB4, a metal silicide such as TiSi2, ZrSi2, MoSi2, MoSi, WSi2, PtSi, or Mg2Si, or any other ceramic material. Particularly preferred second materials consist of CrN and / or Cr2O3 and / or CrAlN.

[0038] Preferably, the information storage medium further comprises an oxide layer on the second material, and preferably the oxide layer contains one or more oxides of the second material or one or more oxides of the material of the uppermost layer of the two or more layers made of different second materials.

[0039] Preferably, the layer of said second material has a thickness of 10 μm or less, preferably 3 μm or less, more preferably 1 μm or less, more preferably 100 nm or less, more preferably 10 nm or less.

[0040] Preferably, the information storage medium has an area of ​​1 cm 2 At least 1 megabyte of information per cm, preferably 1 cm 2 More than 10MB of information per cm, preferably 1cm 2 100 megabytes or more of information per cm, preferably 1 cm 2 More than 1 gigabyte of information per cm, preferably 1 cm 2 Each contains over 10 gigabytes of information.

[0041] Preferably, the substrate, preferably a ceramic substrate, the sintered layer and the layer of the second material or the two or more layers of different second materials have a melting temperature above 1000° C., preferably above 1200° C., more preferably above 1300° C. Preferably, the melting temperature of the substrate, preferably a ceramic substrate, is equal to or higher than the melting temperature of the layer of the second material or the two or more layers of different second materials.

[0042] The information storage medium of the present invention can be used for long-term storage of information, particularly when the substrate is made of a ceramic material. That is, the present invention further relates to the use of the aforementioned information storage medium for long-term storage of information. Preferably, the information storage medium is stored for a period of 10 years or more, preferably 100 years or more, more preferably 1,000 years or more, more preferably 10,000 years or more, and even more preferably 100,000 years or more.

[0043] The present invention further relates to a method for decoding information encoded on the aforementioned information storage medium, the decoding method comprising the steps of: providing the aforementioned information storage medium; measuring the shape and / or size, and optionally the depth, of at least some of the recesses; and decoding the information value corresponding to the measured shape and / or size, and optionally the measured depth.

[0044] Preferably, the step of measuring said shape and / or size and, optionally, said depth is performed using a laser beam and / or a focused particle beam, such as an electron beam.

[0045] Preferably, the process of measuring the shape and / or size, and optionally the depth, is based on one or a combination of the following techniques: interference, reflection, absorption, ellipsometry, frequency comb technology, fluorescence microscopy such as STED, STORM, structured illumination microscopy, super-resolution microscopy, optical coherence tomography, ptychography, scanning electron microscopy, digital (immersion) microscopy (using reflected or transmitted light). The high resolution achieved by such optical methods can be even further improved by pattern recognition using well-known AI techniques.

[0046] In the first aspect of the present invention described above, a third dimension (in addition to the x and y coordinates of the recesses) is utilized to achieve increased storage capacity. This "third dimension" can be either the depth of the recesses or the type (shape and / or size) of the recesses. By combining depth and type, even more information can be stored within the same surface area.

[0047] In a second aspect of the present invention, which will be described later as another aspect, the pattern of the recesses (in the xy plane) is changed to enable an increase in the number of permutations of the recess pattern, thereby achieving a large storage capacity.

[0048] In particular, the invention according to this second aspect, an exemplary embodiment of which is depicted schematically in Figures 5a and 5b, refers to a method for storing information, comprising: providing a substrate; and forming a plurality of recesses in a surface of said substrate using a laser and / or a focused particle beam, thereby encoding information in said substrate. The plurality of recesses are located at a subset of first predetermined locations and / or at a subset of second predetermined locations, the first predetermined locations defining a regular pattern in which the center-to-center distance between directly adjacent locations is between 75% and 150% of the maximum cross-sectional dimension of the recesses, the second predetermined locations defining a regular pattern in which the center-to-center distance between directly adjacent locations is between 75% and 150% of the maximum cross-sectional dimension of the recesses, the center-to-center distance between any one of the first predetermined locations and a directly adjacent second predetermined location is less than 75% of the maximum cross-sectional dimension of the recesses, and in each pair of directly adjacent first and second predetermined locations, only one of the directly adjacent first and second predetermined locations is occupied by a recess.

[0049] Ultimately, this aspect of the invention is based on the concept of utilizing inter-matrix positions to provide additional candidate locations for recesses for encoding additional data bits. For example, if the first predetermined locations are a square matrix, then typically there can be one circular recess for each square unit cell in the square matrix, with adjacent circular recesses just touching or barely touching each other. Thus, if the side length of the square matrix is ​​such that N recesses can be placed next to each other, then there can be N predetermined placements. 2 The present invention further utilizes a set of second predetermined locations that also define a regular pattern in which the center-to-center distance between directly adjacent locations is equal to or greater than 75% and equal to or less than 150% of the maximum cross-sectional dimension of the recess. However, the center-to-center distance between any of the first predetermined locations and directly adjacent second predetermined locations is less than 75% of the maximum cross-sectional dimension of the recess. That is, the set of second predetermined locations are offset (shifted) with respect to the set of first predetermined locations. For example, this offset can be equal to half the center-to-center distance between directly adjacent first predetermined locations. That is, the positions where additional recesses can be placed are provided exactly between two existing recess locations. Since the situation where two adjacent first predetermined locations are occupied and the situation where not only the first two locations but also a third location between them are occupied may be indistinguishable during decoding, the present invention proposes the use of only one of these two cases. That is, for each pair of directly adjacent first and second predetermined locations, only one of the directly adjacent first and second predetermined locations is occupied by a recess. From a decoding perspective, it is only necessary to distinguish between a circular recess at a first location and another circular recess at a location offset, for example, by a radius from the circular recess. This approach can result in significantly increased storage capacity per surface area.

[0050] Because there may be some variation in the center-to-center distances and / or the maximum cross-sectional dimension of the recesses, the above condition may apply only to average values, i.e., the first predetermined locations may define a regular pattern in which the average center-to-center distance between directly adjacent locations is equal to or greater than 75% and equal to or less than 150% of the average maximum cross-sectional dimension of the recesses, and the second predetermined locations may define a regular pattern in which the average center-to-center distance between directly adjacent locations is equal to or greater than 75% and equal to or less than 150% of the average maximum cross-sectional dimension of the recesses, and the center-to-center distance between any first predetermined location and any directly adjacent second predetermined location is less than 75% of the average maximum cross-sectional dimension of the recesses.

[0051] A more conservative approach would be to define more stringent conditions: the first predetermined locations may define a regular pattern in which the maximum center-to-center distance between directly adjacent locations is between 75% and 150% of the minimum maximum cross-sectional dimension of the recesses, and the second predetermined locations may define a regular pattern in which the maximum center-to-center distance between directly adjacent locations is between 75% and 150% of the minimum maximum cross-sectional dimension of the recesses, and the center-to-center distance between any first predetermined location and any directly adjacent second predetermined location is less than 75% of the minimum maximum cross-sectional dimension of the recesses.

[0052] To ensure that the first and second locations can be distinguished reliably, the center-to-center distance between any said first predetermined location and an immediately adjacent second predetermined location is preferably less than 70%, preferably less than 65%, more preferably less than 60%, and even more preferably less than 55% of the (minimum or average) maximum cross-sectional dimension of the recess.

[0053] Furthermore, to ensure that adjacent recesses are appropriately spaced apart, the first predetermined positions preferably define a regular pattern in which the (average value of) center-to-center distance between directly adjacent positions corresponds to 105% or more, preferably 110% or more, more preferably 115% or more of the (average value or maximum value of) maximum cross-sectional dimension of the recesses, and the second predetermined positions preferably define a regular pattern in which the center-to-center distance between directly adjacent positions corresponds to 105% or more, preferably 110% or more, more preferably 115% or more of the (average value or maximum value of) maximum cross-sectional dimension of the recesses.

[0054] As with the first aspect of the invention described above, this second aspect of the invention may be applied to both recesses in a substrate and recesses in a coating.

[0055] Therefore, the present invention further relates to a method for storing information, an exemplary embodiment of which is schematically depicted in Figure 6, comprising the steps of: providing a substrate; coating the substrate with a layer of a second material different from the material of the substrate; and forming a plurality of recesses in the surface of the layer of the second material using a laser and / or a focused particle beam, thereby encoding information in the layer of the second material. The plurality of recesses are located at some of the first predetermined locations and / or some of the second predetermined locations, the first predetermined locations defining a regular pattern in which the center-to-center distance between directly adjacent locations is equal to or greater than 75% and equal to or less than 150% of the maximum cross-sectional dimension of the recesses, and the second predetermined locations defining a regular pattern in which the center-to-center distance between directly adjacent locations is equal to or greater than 75% and equal to or less than 150% of the maximum cross-sectional dimension of the recesses, the center-to-center distance between any one of the first predetermined locations and directly adjacent second predetermined locations is less than 75% of the maximum cross-sectional dimension of the recesses, and in each pair of directly adjacent first and second predetermined locations, only one of the directly adjacent first and second predetermined locations is occupied by a recess.

[0056] Naturally, the features already described for limits and averages also apply to this method.

[0057] Even more locations can be used for additional recesses if, during decoding, it is possible to optically (or in any other way) distinguish between the cases where two recesses are directly adjacent and where a third recess is present between them. Thus, the present invention further relates to a method for storing information, comprising: providing a substrate; and using a laser and / or a focused particle beam to form a plurality of recesses in a surface of the substrate, thereby encoding information on the substrate, the plurality of recesses being located at some of first predetermined locations and / or some of second predetermined locations, the first predetermined locations defining a regular pattern in which the center-to-center distance between directly adjacent locations corresponds to between 75% and 150% of a maximum cross-sectional dimension of the recesses, and / or certain second predetermined locations defining a regular pattern in which the center-to-center distance between directly adjacent locations corresponds to between 75% and 150% of a maximum cross-sectional dimension of the recesses, and the center-to-center distance between any said first predetermined location and directly adjacent second predetermined location is less than 75% of the maximum cross-sectional dimension of the recesses.

[0058] Again, the same concept can be applied to recesses in a substrate and recesses in a coating. Accordingly, the present invention further relates to a method for storing information, comprising the steps of: providing a substrate; coating the substrate with a layer of a second material different from the material of the substrate; and using a laser and / or a focused particle beam to form a plurality of recesses in a surface of the layer of second material, thereby encoding information in the layer of second material, the plurality of recesses being located at some of first predetermined locations and / or some of second predetermined locations, the first predetermined locations defining a regular pattern in which the center-to-center distance between directly adjacent locations corresponds to between 75% and 150% of a maximum cross-sectional dimension of the recesses, and the second predetermined locations defining a regular pattern in which the center-to-center distance between directly adjacent locations corresponds to between 75% and 150% of a maximum cross-sectional dimension of the recesses, and the center-to-center distance between any said first predetermined location and directly adjacent second predetermined location is less than 75% of the maximum cross-sectional dimension of the recesses.

[0059] The preferred ranges already mentioned for the distances also apply to this variant.

[0060] In the two previous cases, preferably, the regular pattern of the first predetermined locations defines a pattern of voids when all of the first predetermined locations are occupied, and one void is completely filled for each of the second predetermined locations. Also, preferably, the center of each of the second predetermined locations corresponds to the center of one of the voids.

[0061] As mentioned above, the regular pattern of the first predetermined locations may be, for example, a square pattern, however, other regular patterns may also be used, such as, for example, a hexagonal pattern.

[0062] Preferably, the shape of the recess is cylindrical or conical. Cylindrical or nearly cylindrical recesses are particularly preferred because they are less likely to cause decoding errors, especially in the case of dense patterns. Therefore, preferably, the cross-sectional area of ​​the recess at its bottom is 50% or more, more preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more of the cross-sectional area of ​​the recess at its top or edge. Preferably, the recess is formed using a laser beam having a Bessel-type beam shape that can form cylindrical or nearly cylindrical recesses.

[0063] The preferences and options already mentioned with respect to the first aspect of the invention are equally applicable to this second aspect of the invention, in particular the concept of intermediate matrix locations as recess locations may also be combined with recesses having different shapes and / or sizes and / or depths.

[0064] Preferably, the ceramic substrate contains an oxide ceramic. Preferably, the ceramic substrate contains at least 90% by weight, preferably at least 95% by weight, of one or a combination of Al2O3, TiO2, SiO2, ZrO2, ThO2, MgO, Cr2O3, Zr2O3, VO3, or any other oxide ceramic material. Preferably, the ceramic substrate contains a transparent vitreous or crystalline ceramic material. Preferably, the ceramic substrate contains at least one or a combination of sapphire (Al2O3), silica (SiO2), zirconium (Zr(SiO4)), and ZrO2. Particularly preferred substrate materials, particularly those capable of achieving a substrate thickness of less than 200 μm, include silicon oxide, aluminum oxide, boron oxide, sodium oxide, potassium oxide, lithium oxide, zinc oxide, and magnesium oxide.

[0065] Preferably, the ceramic substrate contains a non-oxide ceramic, preferably 90% by weight or more, and more preferably 95% by weight or more, of one or a combination of metal nitrides such as CrN, CrAlN, TiN, TiCN, TiAlN, ZrN, AlN, VN, Si3N4, ThN, HfN, and BN; metal carbides such as TiC, CrC, Al4C3, VC, ZrC, HfC, ThC, B4C, and SiC; metal borides such as TiB2, ZrB2, CrB2, VB2, SiB6, ThB, HfB2, WB2, and WB4; metal silicides such as TiSi2, ZrSi2, MoSi2, MoSi, WSi2, PtSi, and Mg2Si; or any other type of non-oxide ceramic material. Preferably, the ceramic substrate contains one or a combination of Ni, Cr, Co, Fe, W, Mo, or other metals with a melting point above 1,400°C. Preferably, the ceramic material and the metal form a metal matrix composite. Preferably, the metal accounts for 5 to 30 wt %, more preferably 10 to 20 wt %, of the ceramic substrate. Particularly preferably, the ceramic substrate contains WC / Co-Ni-Mo and / or BN / Co-Ni-Mo and / or TiN / Co-Ni-Mo and / or SiC / Co-Ni-Mo.

[0066] Preferably, the second material is selected from the group consisting of metals such as Cr, Co, Ni, Fe, Al, Ti, Si, W, Zr, Ta, Th, Nb, Mn, Mg, Hf, Mo, and V; metal nitrides such as CrN, CrAlN, TiN, TiCN, TiAlN, ZrN, AlN, VN, Si3N4, ThN, HfN, and BN; metal carbides such as TiC, CrC, Al4C3, VC, ZrC, HfC, ThC, B4C, and SiC; and metal carbides such as Al2O3, TiO2, SiO2, ZrO2, and ThO. 2、The second material preferably contains at least one of the following ceramic materials: metal oxides such as MgO, Cr2O3, Zr2O3, V2O3, metal borides such as TiB2, ZrB2, CrB2, VB2, SiB6, ThB2, HfB2, WB2, WB4, metal silicides such as TiSi2, ZrSi2, MoSi2, MoSi, WSi2, PtSi, Mg2Si, or any other ceramic material. Preferably, the second material contains CrN and / or Cr2O3 and / or CrAlN.

[0067] Preferably, the layer of the second material and / or the two or more layers of different second materials has a thickness of 5 μm or less, preferably 2 μm or less, more preferably 1 μm or less, even more preferably 100 nm or less, and most preferably 10 nm or less.

[0068] Preferably, the recesses have different depths, each depth corresponding to a predetermined information value.

[0069] Preferably, the minimum difference in depth between the plurality of recesses is 1 nm or more, preferably 10 nm or more, more preferably 30 nm or more, more preferably 50 nm or more, even more preferably 70 nm or more, and most preferably 100 nm or more. Preferably, the minimum difference in depth between the plurality of recesses is 5 μm or less, preferably 1 μm or less, more preferably 500 nm or less, more preferably 300 nm or less, even more preferably 200 nm or less, and most preferably 100 nm or less.

[0070] The present invention according to this second aspect further relates to an information storage medium comprising a substrate, a surface of the substrate having a plurality of recesses for encoding information on the information storage medium, the recesses being located at some first predetermined locations and some second predetermined locations, the first predetermined locations defining a regular pattern in which the center-to-center distance between directly adjacent locations corresponds to 75% to 150% of a maximum cross-sectional dimension of the recesses, the second predetermined locations defining a regular pattern in which the center-to-center distance between directly adjacent locations corresponds to 75% to 150% of a maximum cross-sectional dimension of the recesses, the center-to-center distance between any one first predetermined location and a directly adjacent second predetermined location is less than 75% of the maximum cross-sectional dimension of the recesses, and in each pair of directly adjacent first and second predetermined locations, only one of the directly adjacent first and second predetermined locations is occupied by a recess.

[0071] Again, the concept can be extended to substrates with coatings and overlapping codes between matrices as described above in connection with the method.

[0072] That is, the present invention according to this second aspect further relates to an information storage medium comprising a substrate coated with a layer of a second material and an optional sintered interface between the substrate and the layer of the second material, the second material being different from the material of the substrate, the optional sintered interface containing at least one element from both the material of the substrate and the second material, the layer of the second material having a plurality of recesses for encoding information on the information storage medium, the plurality of recesses being located at some of first predetermined locations and some of second predetermined locations, the first predetermined locations defining a regular pattern in which the center-to-center distance between directly adjacent locations corresponds to 75% to 150% of a maximum cross-sectional dimension of the recesses, and the second predetermined locations defining a regular pattern in which the center-to-center distance between directly adjacent locations corresponds to 75% to 150% of a maximum cross-sectional dimension of the recesses. The center-to-center distance between any said first predetermined location and its immediately adjacent second predetermined location is less than 75% of the maximum cross-sectional dimension of the recess, and in each pair of directly adjacent first and second predetermined locations, only one of the directly adjacent first and second predetermined locations is occupied by a recess.

[0073] Naturally, as with the method and medium according to the first aspect of the invention, the preferred and optional features already described for the method according to the second aspect of the invention may also be applied to the information medium according to this second aspect of the invention.

[0074] Preferably, the regular pattern of the first predetermined locations is a square pattern, however, other patterns may also be used, such as for example a hexagonal pattern.

[0075] Preferably, the shape of the recess is cylindrical, approximately cylindrical, or conical. As described above, it is particularly preferred that the cross-sectional area of ​​the bottom of the recess corresponds to 50% or more, preferably 60% or more, more preferably 70% or more, even more preferably 80% or more, and particularly preferably 90% or more of the cross-sectional area of ​​the top or edge of the recess.

[0076] Preferably, the ceramic substrate contains an oxide ceramic. Preferably, the ceramic substrate contains at least 90% by weight, preferably at least 95% by weight, of one or a combination of Al2O3, TiO2, SiO2, ZrO2, ThO2, MgO, Cr2O3, Zr2O3, VO3, or any other oxide ceramic material. Preferably, the ceramic substrate contains a transparent vitreous or crystalline ceramic material. Preferably, the ceramic substrate contains at least one or a combination of sapphire (Al2O3), silica (SiO2), zirconium (Zr(SiO4)), and ZrO2. Particularly preferred substrate materials, particularly those capable of achieving a substrate thickness of less than 200 μm, include silicon oxide, aluminum oxide, boron oxide, sodium oxide, potassium oxide, lithium oxide, zinc oxide, and magnesium oxide.

[0077] Preferably, the ceramic substrate contains a non-oxide ceramic, preferably 90% by weight or more, and more preferably 95% by weight or more, of one or a combination of metal nitrides such as CrN, CrAlN, TiN, TiCN, TiAlN, ZrN, AlN, VN, Si3N4, ThN, HfN, and BN; metal carbides such as TiC, CrC, Al4C3, VC, ZrC, HfC, ThC, B4C, and SiC; metal borides such as TiB2, ZrB2, CrB2, VB2, SiB6, ThB, HfB2, WB2, and WB4; metal silicides such as TiSi2, ZrSi2, MoSi2, MoSi, WSi2, PtSi, and Mg2Si; or any other type of non-oxide ceramic material. Preferably, the ceramic substrate contains one or a combination of Ni, Cr, Co, Fe, W, Mo, or other metals with a melting point above 1,400°C. Preferably, the ceramic material and the metal form a metal matrix composite. Preferably, the metal accounts for 5 to 30 wt %, more preferably 10 to 20 wt %, of the ceramic substrate. Particularly preferably, the ceramic substrate contains WC / Co-Ni-Mo and / or BN / Co-Ni-Mo and / or TiN / Co-Ni-Mo and / or SiC / Co-Ni-Mo.

[0078] Preferably, the second material is selected from the group consisting of metals such as Cr, Co, Ni, Fe, Al, Ti, Si, W, Zr, Ta, Th, Nb, Mn, Mg, Hf, Mo, and V; metal nitrides such as CrN, CrAlN, TiN, TiCN, TiAlN, ZrN, AlN, VN, Si3N4, ThN, HfN, and BN; metal carbides such as TiC, CrC, Al4C3, VC, ZrC, HfC, ThC, B4C, and SiC; and metal carbides such as Al2O3, TiO2, SiO2, ZrO2, and ThO. 2、The second material preferably contains at least one of the following ceramic materials: metal oxides such as MgO, Cr2O3, Zr2O3, V2O3, metal borides such as TiB2, ZrB2, CrB2, VB2, SiB6, ThB2, HfB2, WB2, WB4, metal silicides such as TiSi2, ZrSi2, MoSi2, MoSi, WSi2, PtSi, Mg2Si, or any other ceramic material. Preferably, the second material contains CrN and / or Cr2O3 and / or CrAlN.

[0079] Preferably, the layer of the second material and / or the two or more layers of different second materials has a thickness of 5 μm or less, preferably 2 μm or less, more preferably 1 μm or less, even more preferably 100 nm or less, and most preferably 10 nm or less.

[0080] Preferably, the recesses have different depths, each depth corresponding to a predetermined information value.

[0081] Preferably, the minimum difference in depth between the plurality of recesses is 1 nm or more, preferably 10 nm or more, more preferably 30 nm or more, more preferably 50 nm or more, even more preferably 70 nm or more, and most preferably 100 nm or more, and / or the minimum difference in depth between the plurality of recesses is 5 μm or less, preferably 1 μm or less, more preferably 500 nm or less, more preferably 300 nm or less, even more preferably 200 nm or less, and most preferably 100 nm or less.

[0082] The subject matter of the present invention will now be described in detail with reference to exemplary preferred embodiments thereof as illustrated in the accompanying drawings. [Brief explanation of the drawings]

[0083] [Figure 1] 1 is a cross-sectional view showing an outline of an information storage medium according to a preferred embodiment of the present invention. [Figure 2] 1 is a cross-sectional view showing an outline of an information storage medium according to a preferred embodiment of the present invention. [Figure 3a] The diagram (top) shows a schematic diagram of the 16 types of code elements in a typical 2x2 square matrix code, and the bottom shows a transmission microscope photograph of a sample taken at 100x magnification. [Figure 3b] In addition to the 16 types of code elements in Figure 3a, the following figure (top) shows a schematic diagram of 19 types of code elements that are possible with the non-overlapping code between matrices according to the present invention, and (bottom) shows a transmission microscope photograph of a sample taken at 100x magnification. [Figure 4] This is a diagram (top) that shows a schematic diagram of the principle of codes with overlap between matrices in the case of a 4x4 square matrix code in a preferred embodiment of the present invention, and a transmission microscope photograph (bottom) of a sample taken at 150x magnification. [Figure 5a] The diagram (top) shows a schematic diagram of the method for setting the reference depth of the non-overlapping matrix code, and the transmission microscope photograph of the sample taken at 150x magnification (bottom). [Figure 5b] The diagram (top) shows a schematic diagram of the method for setting the reference depth of overlapping matrix codes, and the (bottom) is a transmission microscope photograph of the sample taken at 150x magnification. [Figure 6] FIG. 1 shows a schematic diagram (top) illustrating an example of various shapes and sizes of recesses in a preferred embodiment of the present invention, and a transmission microscope photograph (bottom) of a sample taken at 50x magnification. [Figure 7] FIG. 1 shows a schematic diagram (top) illustrating how recesses of various shapes can be realized using multiple circular recesses in a preferred embodiment of the present invention, and a transmission microscope photograph (bottom) of a sample taken at 100x magnification. [Figure 8] This is a schematic diagram comparing alphanumeric and kanji character codes based on square segments with dot matrix codes and intermediate matrix codes in terms of information capacity (bits). [Figure 9] FIG. 10 is a diagram showing how the maximum storage capacity is estimated based on the spatial frequency, the phase shift, and the amplitude of the recesses. [Figure 10a]This is a diagram (top) showing a schematic diagram of 80 types of code elements possible in the code with overlap between matrices according to the present invention, and a transmission microscope photograph (bottom) of a sample taken at 100x magnification. [Figure 10b] FIG. 1 is a diagram showing all possible types of code elements in a code with overlapping matrices according to the present invention, as shown in a transmission microscope photograph of a sample taken at 100x magnification. DETAILED DESCRIPTION OF THE INVENTION

[0084] As a general rule, the same parts in the drawings are given the same reference numerals.

[0085] FIG. 1 is a schematic cross-sectional view of a preferred embodiment of an information storage medium according to the present invention. The information storage medium includes a substrate 150, preferably a ceramic substrate, coated with a layer of a second material 170. The second material 170 is different from the material of the substrate 150. As mentioned above, particularly when the substrate 150 is made of a ceramic material, an optional sintered interface (not shown) may exist between the substrate 150 and the layer of the second material 170 due to a tempering process. The layer of the second material 170 includes multiple recesses 10 (four are shown in the figure) with different depths, each corresponding to a predetermined information value. In the embodiment shown in FIG. 1, four bits of information can be encoded. For example, the smallest depth of the recesses 10 (or, alternatively, the surface without recesses) can correspond to the information value "0000." For example, the deepest depth of the recesses 10 extending from the second layer 170 to the substrate 150 can correspond to the information value or code "1111." Similarly, each depth therebetween corresponds to a particular predetermined information value or code. Although Figure 1 depicts the depth difference between successive codes as being constant, this is not necessarily the case.

[0086] Of course, the 4-bit code shown in Figure 1 is only one example: more or fewer bits can be coded, as long as the thickness of the second layer 170 and the depth differences between the various recesses 10 can be reliably produced for coding and reliably measured for decoding.

[0087] Techniques for producing such substrates with coatings and for forming recesses of various depths within such coatings (or just the substrate) are described in detail in PCT / EP2019 / 071805 and PCT / EP2020 / 068892, the entire contents of which are incorporated herein by reference, in particular with regard to such techniques.

[0088] The recess 10 shown in FIG. 1 is merely schematic. However, as detailed above, the recesses herein encode information by being of different shapes and / or sizes, each corresponding to a predetermined information value. FIG. 6 shows an example of various recess shapes and sizes in a preferred embodiment of the present invention, with a schematic diagram (top) and a sample (bottom) on which they were produced. Specifically, the first four sketches in the top row of FIG. 6 depict three differently sized circular recesses (and a no-recess example on the far left), which are clearly distinguishable from one another. In this example, three information values ​​can be encoded by the recess size. Similarly, two bits (corresponding to four information values) can be encoded by using different recess shapes, such as those shown in the last four sketches in the top row of FIG. 6 and the first four sketches in the bottom row of FIG. 6. These different shapes can also be achieved by varying the orientation of a single basic shape (e.g., an ellipse or a triangle in the example of FIG. 6). Of course, the various shapes shown in FIG. 6 can be used in combination. For example, ten different information values ​​can be encoded by one type of circular recess and one type of square recess, as well as four differently oriented triangular recesses and four differently oriented elliptical recesses, among those shown in the upper and lower rows of Figure 6. Additionally or alternatively, information may be encoded by recesses of different sizes.

[0089] As will be apparent from the summary of the first aspect of the invention given above, the various recesses need not be of different depths as shown in Figure 1, but may differ only in shape and / or size, for example as shown in Figure 6. Also, the recesses may not be present in the layer of second material 170 as shown in Figure 1, but may be present in the material of the substrate (without any coating).

[0090] However, when recesses of different depths are used, it is advantageous to provide a reference depth. This reference depth allows, during decoding, the height difference between the surface of the substrate or coating and, for example, the bottom of each recess to be measured. For this purpose, for example, the recesses arranged in a square pattern can be provided within a reference frame 1 surrounding the entire pattern, as shown schematically in FIG. 5a (where 16 circular recesses are roughly arranged in a square pattern). In this figure, 16 circular recesses are schematically arranged in a square pattern. Alternatively, the reference frame may be present on only one, two, or three sides of the pattern. In this way, the optical decoding system can measure, for example, the distance between a reference point of the optical decoding system and the reference frame, and also the distance between the reference point and the bottom of each recess. This allows the distance between the bottom of each recess and the reference frame to be determined.

[0091] Alternatively or additionally, other portions of the pattern where no recesses exist may be used as a reference height. For example, the reference height may be set by the "gap" 2 shown in Figure 5a.

[0092] FIG. 2 is a schematic cross-sectional view of a data storage medium according to a further preferred embodiment of the present invention. The data storage medium includes a substrate 150, preferably a ceramic substrate, coated with four layers 171-174 of different second materials, each of which is different from the material of the substrate 150. Again, a sintered interface (not shown) may exist between at least the substrate 150 and the bottom layer 171 of the four layers. The sintered interface may contain at least one element from both the material of the substrate and the material of the bottom layer 171. Similar to the embodiment shown in FIG. 1, the data storage medium of the embodiment shown in FIG. 2 includes multiple recesses 10 for encoding information on the data storage medium, each having a different depth, each corresponding to a predetermined information value. Similarly, FIG. 2 depicts 16 different depths corresponding to a 4-bit code.

[0093] However, unlike the embodiment shown in Figure 1, the embodiment shown in Figure 2 encodes four different bits (at different depths) in each of the four layers 171-174. If the four layers 171-174 are made of different materials, the optical response of each layer may be different. This allows the depth information obtained to be correlated with, for example, the optical response, thereby increasing the accuracy of decoding.

[0094] Of course, the number of layers of different second materials may be increased or decreased from four depending on the number of bits that one wishes to encode.

[0095] A particularly preferred example of a multilayer coating, shown in FIG. 2, is a two-layer coating in which a metal layer 171 is coated on a substrate 150 and a metal oxide layer 172 (of the same metal) is coated on the metal layer 171. As explained in PCT / EP2020 / 068892, when white incident light is irradiated onto such a two-layer coating, part of the incident light is reflected by the oxide layer, and another part of the incident light is refracted within the oxide layer and reflected at the oxide / metal interface. If the light beam reflected by the oxide layer and the light beam reflected by the metal layer are in phase, a visible color can be produced; if they are out of phase, the color is not visible. That is, as explained in PCT / EP2020 / 068892, a specific color (depending on the refractive index of both the oxide and metal layers and the thickness of the oxide layer) will be visible where the oxide layer is present, but will not be visible if the depth of a particular recess in that location causes destructive interference.

[0096] As detailed above in the description of the first aspect of the invention, this concept of extending various recesses into different ones of two or more layers can be advantageously combined with the inventive concept illustrated in Figure 6 of providing multiple recesses having different shapes and / or sizes.

[0097] Figure 3 is a diagram showing the concept of recesses at intermediate matrix positions according to the second embodiment of the present invention. Figure 3a is a diagram showing 16 code elements in a conventional 2x2 square matrix code, with the circles representing recess positions in the square matrix. These 16 arrangements allow encoding of 4 bits of information. Figure 3b is a diagram showing 19 code elements (bottom) possible with a non-overlapping code between matrices according to the present invention in addition to the 16 code elements (top) of Figure 3a.

[0098] The bottom of Figure 3b depicts the same 2x2 square matrix as Figure 3a. However, here the intermediate matrix positions, which correspond to the symmetrical positions exactly between the two positions in the regular square matrix of Figure 3a, are occupied by recesses. This allows for encoding 19 additional code elements, bringing the total to 35 code elements, corresponding to 5.13 bits. In other words, by utilizing the intermediate matrix positions, a significant increase in the storage capacity of the 2x2 square matrix is ​​achieved.

[0099] The scheme shown in Figure 3 assumes that adjacent recesses do not overlap each other to ensure accurate reading without failure. However, if such overlap were allowed (e.g., due to improved decoding resolution), even greater storage capacities could be achieved. This is illustrated in Figure 4. The leftmost part of the figure shows a schematic representation of a 16-bit code in a conventional 4x4 square matrix, with 16 circles representing the 16 possible recess positions in the square matrix when no overlap is present. If two adjacent circular recesses are allowed to overlap by one recess radius, each recess position can be shifted one radius to the right. This results in 12 additional recess positions (within the original square), as depicted in the second sketch in Figure 4. These 12 additional positions represent 12 additional bits of information. Similarly, the positions of the depressions can be shifted down by one radius, as shown in the third sketch in Figure 4, or one radius to the right and one radius down, as shown in the rightmost part of Figure 4. This can provide an additional 12 bits and 9 bits. In total, overlapping codes between 4x4 matrices can encode a total of 49 bits, compared to the 16 bits for a regular 4x4 square matrix.

[0100] This scheme can be generalized to any M × N rectangular matrix, as shown in Figure 4. Compared to the MN-bit encoding of a regular M × N rectangular matrix, by shifting the same pattern in the three ways above, such a matrix can be encoded using M × N + N × (M-1) + M × (N-1) + (N-1) × (M-1) = [4MN-2(N+M)+1] bits.

[0101] Alternatively, as an intermediate option between these two extremes, only one specific overlapping configuration can be selected. For example, the leftmost position in Figure 4 may be combined only with the rightmost position in Figure 4. From a decoding perspective, the only requirement for the leftmost pattern in Figure 4 is that the pattern be generated with high reproducibility to ensure that gaps where no material is removed remain between each square pattern of four recesses (i.e., the "gaps" correspond to protrusions of material on the surface of the data storage medium). If the size and position of each recess can be precisely controlled to ensure that a gap exists in the center of each square arrangement of four recesses, additional recesses can be precisely positioned relative to the gaps to form additional code elements. These are the positions depicted in the rightmost position in Figure 4. By allowing such overlap, an MxN matrix has an additional (M-1)x(N-1) positions for the additional recess positions, for a total of 2MN-M-N+1 bits (i.e., N for an NxN square matrix). 2 +(N-1) 2 bits).

[0102] An example of such an overlapping code between matrices is shown in Figure 5b, which is a schematic diagram of a 4x4 square matrix of recesses, with 7 of the 9 interstices occupied by additional recesses. As described above with respect to Figure 5a, the reference frame 1 or one of the unoccupied interstices 2 may serve as a height reference for measuring the depth of each recess.

[0103] As discussed above in connection with FIG. 6, the recesses herein may be of different shapes to encode information, with each shape corresponding to a predetermined information value. The bottom portion of FIG. 6 shows experimental implementations of the various shapes shown schematically in the top portion of FIG. 6. In this example, a 100-nm-thick CrN coating was applied to a sapphire (Al2O3) ceramic substrate (dimensions: 10 × 10 mm, thickness: 100 μm) by physical vapor deposition (PVD). A 200-femtosecond laser (wavelength: 515 nm) was used to ablate circular recesses (diameter: approximately 1 μm) in the coating (i.e., dimensions much smaller than the desired shape) to create the desired geometric shape by removing the coating.

[0104] The obtained information storage medium was photographed using an Olympus BX-51 (magnification: 50x). As can be seen by comparing the upper and lower parts of Figure 6, the various shapes can be produced with high reproducibility and precision, and the differences in shape can be easily distinguished with the naked eye. In addition to forming the shapes shown in the figures by connecting multiple circular recesses, such shapes can also be realized by laser beam shaping using, for example, a spatial light modulator (SLM).

[0105] FIG. 7 clearly illustrates, in a preferred embodiment of the present invention, the realization of various recess shapes using multiple circular recesses using the method described in the context of FIG. 6 , through a schematic diagram (top) and the samples on which they were produced (bottom). For example, the four different pattern configurations of overlapping two circular recesses depicted in the first four sketches in the top row of FIG. 7 can result in four different elliptical shapes with different orientations, as depicted in the bottom row of FIG. 6 . Similarly, overlapping three circular recesses, as depicted in the rightmost bottom row of FIG. 7 , can result in a triangular shape, as depicted in the rightmost top row of FIG. 6 . As depicted in other configurations in the bottom row of FIG. 7 , the triangular shape can also be oriented differently. The bottom part of FIG. 7 shows experimental examples of the various shapes shown schematically in the top part of FIG. 7 . In this example, a ceramic substrate (dimensions: 10 × 10 mm, thickness: 100 μm) made of sapphire (Al2O3) was coated with a CrN coating (thickness: 100 nm) by PVD. A circular recess (diameter: approximately 1 μm) was ablated from the coating using a 200 femtosecond laser (wavelength: 515 nm).

[0106] The resulting data storage medium was imaged using an Olympus BX-51 (magnification: 100x). Each individual dot had a diameter of 1 μm. As can be seen by comparing the upper and lower parts of Figure 7, the various shapes can be produced with high reproducibility and precision, and the differences in shape are easily distinguishable with the naked eye. In this example, it may also be possible to distinguish the individual circular recesses that make up each shape, but this is clearly not necessary; it is sufficient that the shapes after interconnection of the recesses are distinguishable from one another using appropriate imaging and / or detection techniques.

[0107] In Figure 8, alphanumeric and Kanji character codes based on square segments are compared with dot-matrix and intermediate-matrix codes in terms of information capacity in bits.

[0108] A 5 × 7 square matrix can display 256 different alphanumeric characters (8 bits) in UTF-8 format, readable by the human eye. An 8 × 8 square matrix can display approximately 27,550 Chinese characters (14.75 bits), readable by a fluent Chinese reader. In contrast, a 5 × 7 or 8 × 8 square matrix using circular recesses can increase the number of combinations that can be displayed and recognized by a digital reading system by approximately 4.4 or 4.3 times. Even greater storage capacity can be achieved by employing the intermediate matrix positions of the present invention, which allow for up to M × N + M × (N-1) + N × (M-1) + (M-1) × (N-1) different patterns, as illustrated in Figure 4. According to this formula, the information capacity of a 5 × 7 matrix can be increased from 35 bits to 117 bits, or an additional 3.3 times. For larger 8x8 matrices, the intermediate matrix coding method increases this ratio by a factor of 3.5, allowing 225 bits. For larger matrices, such as a 32x32 matrix, the intermediate matrix method allows 3969 bits compared to 1024 bits for the standard dot matrix, bringing the ratio closer to about 4. While it may be difficult to employ all of these patterns with reliable discrimination, due to the ultra-high resolution required for the optics and detectors when matrices overlap, even realistic approaches using only around 3000 bits offer significant advantages over prior art methods.

[0109] From Figure 9, 1 mm 2 A more general method can be derived to estimate the maximum storage capacity per mm, assuming a two-dimensional surface defined by the x and y axes, by the spatial frequency (number of lines / mm), the number of phase shift positions along those axes, and half the number of recess depth levels. 2 Since 1 bit corresponds to two different depth levels, a factor of 1 / 2 is required to convert the number of depth levels to bits.

[0110] Data storage density ≦(F x ·|P x |)·(F y ·|P y |)·(1 / 2|A|)·Bits / mm 2

[0111] Figure 10a shows a schematic diagram (top) of the 80 possible code elements of a typical 2x2 square matrix for a matrix-to-matrix overlap code according to the present invention, along with the sample from which they were generated (bottom). As can be seen, the use of overlap dramatically increases the number of possible code elements compared to the 35 possible code elements without overlap (see Figure 3b). Of course, this large number of code elements can only be utilized if they can be produced with high reproducibility and precision, and can be accurately read by a corresponding reading system with a sufficiently low error rate.

[0112] To prove this is practical, we conducted an experiment to fabricate all possible code elements using an intermediate matrix code with overlapping into a regular 2 × 2 square matrix. In this example, a ceramic substrate (dimensions: 10 × 10 mm, thickness: 100 μm) made of sapphire (Al2O3) was coated with a CrN coating (thickness: 100 nm) by PVD. A 200 femtosecond laser (wavelength: 515 nm) was used to ablate a circular recess (diameter: approximately 1 μm) into the coating.

[0113] The obtained information storage medium was imaged using an Olympus BX-51 (magnification: 100x). Each individual dot had a diameter of 1 μm. Figure 10b shows the results of the experiment. As can be seen (comparison of the upper and lower parts of Figure 10a), each code element can be produced with high reproducibility and precision, and the differences in their shapes can be easily distinguished with the naked eye. The present invention includes the following aspects. [Aspect 1] The process of preparing the substrate, forming a plurality of recesses in a surface of the substrate using a laser and / or a focused particle beam, thereby encoding information on the substrate; wherein the recesses have different shapes and / or sizes and optionally different depths, each shape and / or size and optionally each depth corresponding to a predetermined information value. [Aspect 2] The process of preparing the substrate, coating the substrate with a layer of a second material different from the material of the substrate; forming a plurality of depressions in the surface of the layer of second material using a laser and / or a focused particle beam, thereby encoding information in the layer of second material; wherein the recesses have different shapes and / or sizes, and optionally different depths, each shape and / or size, and optionally each depth, corresponding to a predetermined information value; A method for storing information, wherein the coated substrate is optionally subjected to a tempering treatment before and / or after encoding the information, which improves the durability of the coated substrate. Aspect 3 The process of preparing the substrate, coating the substrate with two or more layers of a second, distinct material different from the material of the substrate; forming a plurality of recesses in the layer of second material using a laser and / or a focused particle beam, thereby encoding information in the layer of second material; the plurality of recesses having different shapes and / or sizes and different depths extending into different ones of the two or more layers, each shape and / or size and each depth corresponding to a predetermined information value; A method for storing information, wherein the coated substrate is optionally subjected to a tempering treatment before and / or after encoding the information, which improves the durability of the coated substrate. Aspect 4 A method according to aspect 3, wherein the thickness of each of the two or more layers is less than 1 μm, preferably less than 100 nm, and more preferably less than 10 nm. Aspect 5 5. The method of claim 3 or 4, wherein the two or more layers comprise a metal layer and a metal oxide layer, and preferably, the metal element of the metal layer is the same as the metal element of the metal oxide layer. Aspect 6 The method according to any one of aspects 1 to 5, wherein the recesses of different shapes have different cross-sectional shapes perpendicular to the depth direction, and / or the recesses of different sizes have different cross-sectional sizes perpendicular to the depth direction, preferably different cross-sectional areas. Aspect 7 The method of any one of aspects 1 to 6, wherein the plurality of recesses have at least two, more preferably at least three, more preferably at least four, even more preferably at least five, more preferably at least six, more preferably at least seven, even more preferably at least eight, even more preferably at least 16, and most preferably at least 32 different shapes and / or sizes and / or depths, each shape and / or size and / or depth corresponding to a predetermined information value. Aspect 8 8. The method of any one of aspects 1 to 7, wherein each recess is formed by one or more pulses of the laser and / or focused particle beam, and the shape of each recess is controlled by one or a combination of optical proximity control, polarization ablation, variable shaped beam techniques, or by forming two or more overlapping circular recesses to form a predetermined shape. Aspect 9 9. The method of any one of aspects 1 to 8, wherein each recess is formed by one or more pulses of the laser and / or focused particle beam, and the size of each recess is controlled by one or a combination of a number of pulses, an intensity level of the pulses, or a focal spot size. Aspect 10 10. The method of any one of claims 1 to 9, wherein each recess is formed by one or more pulses of the laser and / or focused particle beam, and the depth of each recess is controlled by one or a combination of the following parameters: energy of the pulse, length of the pulse, number of pulses of the laser and / or focused particle beam. Aspect 11 11. The method of any one of aspects 1 to 10, wherein the minimum difference in depth between the plurality of recesses is 1 nm or more, preferably 10 nm or more, more preferably 30 nm or more, more preferably 50 nm or more, even more preferably 70 nm or more, and most preferably 100 nm or more; and / or the minimum difference in depth between the plurality of recesses is 5 μm or less, preferably 1 μm or less, more preferably 500 nm or less, more preferably 300 nm or less, even more preferably 200 nm or less, and most preferably 100 nm or less. Aspect 12 12. The method of any one of aspects 1 to 11, wherein the substrate is a ceramic substrate, preferably the ceramic substrate comprises an oxide ceramic, preferably the ceramic substrate comprises 90% or more by weight, preferably 95% or more by weight, of one or a combination of Al2O3, TiO2, SiO2, ZrO2, ThO2, MgO, Cr2O3, Zr2O3, VO3, boron oxide, sodium oxide, potassium oxide, lithium oxide, zinc oxide, and magnesium oxide; and / or the substrate comprises a transparent vitreous or crystalline ceramic material; and / or the substrate comprises one or a combination of sapphire (Al2O3), silica (SiO2), zirconium (Zr(SiO4)), ZrO2. Aspect 13 13. The method of any one of the preceding aspects, wherein the substrate is a ceramic substrate, and preferably the ceramic substrate comprises a non-oxide ceramic, preferably the ceramic substrate comprises 90 wt. % or more, preferably 95 wt. % or more, of one or a combination of metal nitrides such as CrN, CrAlN, TiN, TiCN, TiAlN, ZrN, AlN, VN, Si3N4, ThN, HfN, BN, etc.; 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; metal silicides such as TiSi2, ZrSi2, MoSi2, MoSi, WSi2, PtSi, Mg2Si, or any other non-oxide ceramic material. Aspect 14 14. The method of any one of the preceding aspects, wherein the substrate is a ceramic substrate, preferably comprising one or a combination of Ni, Cr, Co, Fe, W, Mo, or other metals having a melting point above 1,400° C. Aspect 15 15. The method of claim 14, wherein the ceramic material and the metal form a metal matrix composite. Aspect 16 16. The method of any one of claims 14 to 15, wherein the metal is 5 to 30 wt %, preferably 10 to 20 wt %, of the ceramic substrate. Aspect 17 17. The method of any one of embodiments 14 to 16, wherein the ceramic substrate comprises WC / Co—Ni—Mo and / or BN / Co—Ni—Mo and / or TiN / Co—Ni—Mo and / or SiC / Co—Ni—Mo. Aspect 18 18. The method of any one of aspects 1 to 17, wherein the second material is selected from the group consisting of metals such as Cr, Co, Ni, Fe, Al, Ti, Si, W, Zr, Ta, Th, Nb, Mn, Mg, Hf, Mo, and V; metal nitrides such as CrN, CrAlN, TiN, TiCN, TiAlN, ZrN, AlN, VN, SiN, ThN, HfN, and BN; metal carbides such as TiC, CrC, AlC, VC, ZrC, HfC, ThC, BC, and SiC; AlO, TiO, SiO, ZrO, and ThO. 2、 1. A method according to claim 1, wherein the second material comprises at least one of the following ceramic materials: metal oxides such as MgO, Cr2O3, Zr2O3, V2O3, metal borides such as TiB2, ZrB2, CrB2, VB2, SiB6, ThB2, HfB2, WB2, WB4, metal silicides such as TiSi2, ZrSi2, MoSi2, MoSi, WSi2, PtSi, Mg2Si, or any other type of ceramic material, and preferably wherein said second material comprises CrN and / or Cr2O3 and / or CrAlN. Aspect 19 19. The method of any one of the preceding aspects, wherein forming the recess comprises locally heating the surface to a temperature at or above the melting and / or decomposition temperature of the second material, preferably at least 3,000°C, preferably at least 3,200°C, more preferably at least 3,500°C, and most preferably at least 4,000°C. Aspect 20 20. The method of any one of claims 1 to 19, wherein forming the recesses comprises treating the surface of the coated substrate with a femtosecond laser to create a Coulomb explosion leading to material ablation. Aspect 21 21. The method of any one of claims 1 to 20, wherein the layer of the second material and / or the two or more layers of different second materials have a thickness of 5 μm or less, preferably 2 μm or less, more preferably 1 μm or less, even more preferably 100 nm or less, and most preferably 10 nm or less. Aspect 22 22. The method of any one of the preceding embodiments, wherein forming the recess comprises locally heating and / or decomposing and / or oxidizing and / or ablating and / or vaporizing the surface. Aspect 23 23. The method of any one of claims 1 to 22, wherein tempering the coated substrate, preferably a ceramic substrate, creates a sintered interface between the substrate and the layer of the second material or the two or more layers of different second materials. Aspect 24 24. The method of claim 23, wherein the sintered interface contains at least one element from both the substrate material and the second material. Aspect 25 25. The method of any one of the preceding aspects, wherein the coated substrate, preferably a ceramic substrate, is tempered in an oxygen atmosphere to oxidize at least the topmost layer of the second material. Aspect 26 26. The method of any one of the preceding claims, wherein the coated substrate has an area of ​​1 cm 2 At least 1 megabyte of information per cm, preferably 1 cm 2 More than 10MB of information per cm, preferably 1cm 2 100 megabytes or more of information per cm, preferably 1 cm 2 More than 1 gigabyte of information per cm, preferably 1 cm 2 containing more than 10 gigabytes of information per method. Aspect 27 An information storage medium comprising a substrate, the surface of which has a plurality of recesses for encoding information on the information storage medium, the recesses having different shapes and / or sizes, and optionally different depths, each shape and / or size, and optionally each depth, corresponding to a predetermined information value. Aspect 28 1. An information storage medium comprising: a substrate coated with a layer of a second material; and a sintered interface between the substrate and the layer of the second material, the second material being different from the material of the substrate, the sintered interface containing at least one element from both the material of the substrate and the second material; and the layer of the second material having a plurality of recesses encoding information in the information storage medium, the plurality of recesses having different shapes and / or sizes, and optionally different depths, each shape and / or size, and optionally each depth, corresponding to a predetermined information value. Aspect 29 1. An information storage medium comprising: a substrate coated with two or more layers of a second material different from each other; and a sintered interface between the substrate and at least a bottom layer of the two or more layers, the second material being different from the material of the substrate, the sintered interface containing at least one element from both the material of the substrate and the material of the bottom layer; the information storage medium further comprising a plurality of recesses encoding information in the information storage medium, the plurality of recesses having different shapes and / or sizes and different depths extending into different layers of the two or more layers, each shape and / or size and each depth corresponding to a predetermined information value. Aspect 30 30. An information storage medium according to aspect 29, wherein each of the two or more layers has a thickness of less than 1 μm, preferably less than 100 nm, and more preferably less than 10 nm. Aspect 31 An information storage medium according to aspect 29 or 30, wherein the two or more layers include a metal layer and a metal oxide layer, and preferably the metal element of the metal layer is the same as the metal element of the metal oxide layer. Aspect 32 In an information storage medium described in any one of aspects 27 to 31, recesses of different shapes have different cross-sectional shapes perpendicular to the depth direction, and / or recesses of different sizes have different cross-sectional sizes perpendicular to the depth direction, preferably different cross-sectional areas. Aspect 33 In an information storage medium described in any one of aspects 27 to 32, the plurality of recesses have at least two, preferably at least three, more preferably at least four, even more preferably at least five, even more preferably at least six, even more preferably at least seven, even more preferably at least eight, even more preferably at least 16, and most preferably at least 32 different shapes and / or sizes and / or depths, each shape and / or size and / or depth corresponding to a predetermined information value. Aspect 34 In an information storage medium described in any one of aspects 27 to 33, the minimum difference in depth between the multiple recesses is 1 nm or more, preferably 10 nm or more, more preferably 30 nm or more, more preferably 50 nm or more, even more preferably 70 nm or more, and most preferably 100 nm or more, and / or the minimum difference in depth between the multiple recesses is 5 μm or less, preferably 1 μm or less, more preferably 500 nm or less, more preferably 300 nm or less, even more preferably 200 nm or less, and most preferably 100 nm or less. Aspect 35 35. The information storage medium of any one of aspects 27 to 34, wherein the substrate is a ceramic substrate, and preferably the ceramic substrate contains an oxide ceramic, and preferably the ceramic substrate contains 90% by weight or more, preferably 95% by weight or more, of one or a combination of Al2O3, TiO2, SiO2, ZrO2, ThO2, MgO, Cr2O3, Zr2O3, VO3, boron oxide, sodium oxide, potassium oxide, lithium oxide, zinc oxide, and magnesium oxide; and / or the substrate contains a transparent vitreous ceramic material or a crystalline ceramic material; and / or the substrate contains one or a combination of sapphire (Al2O3), silica (SiO2), zirconium (Zr(SiO4)), and ZrO2. Aspect 36 35. The information storage medium of any one of aspects 27 to 35, wherein the substrate is a ceramic substrate. Preferably, the ceramic substrate comprises a non-oxide ceramic, and preferably the ceramic substrate comprises 90% by weight or more, preferably 95% by weight or more, of one or a combination of metal nitrides such as CrN, CrAlN, TiN, TiCN, TiAlN, ZrN, AlN, VN, Si3N4, ThN, HfN, and BN; metal carbides such as TiC, CrC, Al4C3, VC, ZrC, HfC, ThC, B4C, and SiC; metal borides such as TiB2, ZrB2, CrB2, VB2, SiB6, ThB, HfB2, WB2, and WB4; metal silicides such as TiSi2, ZrSi2, MoSi2, MoSi, WSi2, PtSi, and Mg2Si; or any other type of non-oxide ceramic material. Aspect 37 An information storage medium according to any one of aspects 27 to 36, wherein the substrate is a ceramic substrate, and preferably the ceramic substrate contains one or a combination of Ni, Cr, Co, Fe, W, Mo, or other metals having a melting point above 1,400°C. Aspect 38 38. The information storage medium of claim 37, wherein the ceramic material and the metal form a metal matrix composite. Aspect 39 39. The information storage medium according to aspect 37 or 38, wherein the metal accounts for 5 to 30% by weight, and preferably 10 to 20% by weight, of the ceramic substrate. Aspect 40 40. The information storage medium of any one of aspects 37 to 39, wherein the ceramic substrate contains WC / Co—Ni—Mo and / or BN / Co—Ni—Mo and / or TiN / Co—Ni—Mo and / or SiC / Co—Ni—Mo. Aspect 41 In an information storage medium according to any one of aspects 27 to 40, the second material may be selected from the group consisting of metals such as Cr, Co, Ni, Fe, Al, Ti, Si, W, Zr, Ta, Th, Nb, Mn, Mg, Hf, Mo, and V; metal nitrides such as CrN, CrAlN, TiN, TiCN, TiAlN, ZrN, AlN, VN, SiN, ThN, HfN, and BN; metal carbides such as TiC, CrC, AlC, VC, ZrC, HfC, ThC, BC, and SiC; AlO, TiO, SiO, ZrO, and ThO 2、 An information storage medium containing at least one ceramic material such as a metal oxide, such as MgO, Cr2O3, Zr2O3, or V2O3; a metal boride, such as TiB2, ZrB2, CrB2, VB2, SiB6, ThB2, HfB2, WB2, or WB4; or a metal silicide, such as TiSi2, ZrSi2, MoSi2, MoSi, WSi2, PtSi, or Mg2Si; and preferably, the second material contains CrN and / or Cr2O3 and / or CrAlN. Aspect 42 An information storage medium described in any one of aspects 27 to 41, further comprising an oxide layer on the layer of the second material or on the topmost layer of the two or more layers made of a different second material, preferably wherein the oxide layer contains one or more oxides of the second material or one or more oxides of the material of the topmost layer of the two or more layers made of a different second material. Aspect 43 In an information storage medium described in any one of aspects 27 to 42, the layer thickness of the second material is 10 μm or less, preferably 3 μm or less, more preferably 1 μm or less, even more preferably 100 nm or less, and even more preferably 10 nm or less. Aspect 44 44. The information storage medium according to any one of aspects 27 to 43, wherein the information storage medium has an area of ​​1 cm 2 At least 1 megabyte of information per cm, preferably 1 cm 2 More than 10MB of information per cm, preferably 1cm 2100 megabytes or more of information per cm, preferably 1 cm 2 More than 1 gigabyte of information per cm, preferably 1 cm 2 An information storage medium containing 10 gigabytes or more of information per medium. Aspect 45 In an information storage medium described in any one of aspects 27 to 44, the substrate, preferably a ceramic substrate, the sintered layer, and the layer of the second material or the two or more layers of different second materials have melting temperatures greater than 1,000°C, preferably greater than 1,200°C, and more preferably greater than 1,300°C. Aspect 46 In an information storage medium described in any one of aspects 27 to 45, the melting temperature of the substrate, preferably a ceramic substrate, is higher than the melting temperature of the layer of the second material or the two or more layers of different second materials. Aspect 47 Use of an information storage medium according to any one of aspects 27 to 46 for long-term storage of information, wherein the information storage medium is preferably stored for a period of 10 years or more, preferably 100 years or more, more preferably 1,000 years or more, more preferably 10,000 years or more, and even more preferably 100,000 years or more. Aspect 48 A method for decoding information encoded on an information storage medium according to any one of aspects 27 to 46, comprising: providing an information storage medium according to any one of aspects 27 to 46; measuring the shape and / or size and, optionally, the depth of at least some of the recesses; decoding said information values ​​corresponding to said measured shape and / or size and, optionally, said measured depth; A method comprising: Aspect 49 A method according to embodiment 48, wherein the process of measuring the shape and / or size, and optionally the depth, is performed using a focused particle beam such as a laser beam and / or an electron beam. Aspect 50 50. The method of claim 48 or 49, wherein the process of measuring the shape and / or size, and optionally the depth, is based on one or a combination of interference, reflectance, absorption, ellipsometry, frequency comb technology, fluorescence microscopy such as STED, STORM, structured illumination microscopy, super-resolution microscopy, optical coherence tomography, scanning electron microscopy, ptychography, digital (immersion) microscopy using reflected or transmitted light. Aspect 51 The process of preparing the substrate, forming a plurality of recesses in a surface of the substrate using a laser and / or a focused particle beam, thereby encoding information on the substrate; the plurality of recesses are located at some of the first predetermined locations and / or some of the second predetermined locations, the first predetermined locations defining a regular pattern wherein the center-to-center distance between directly adjacent locations is equal to or greater than 75% and equal to or less than 150% of a maximum cross-sectional dimension of the recesses, and the second predetermined locations defining a regular pattern wherein the center-to-center distance between directly adjacent locations is equal to or greater than 75% and equal to or less than 150% of a maximum cross-sectional dimension of the recesses, the center-to-center distance between any said first predetermined location and directly adjacent second predetermined location is less than 75% of the maximum cross-sectional dimension of the recesses, and for each pair of directly adjacent first and second predetermined locations, only one of the directly adjacent first and second predetermined locations is occupied by a recess. Aspect 52 The process of preparing the substrate, coating the substrate with a layer of a second material different from the material of the substrate; forming a plurality of depressions in the surface of the layer of second material using a laser and / or a focused particle beam, thereby encoding information in the layer of second material; the plurality of recesses are located at some of the first predetermined locations and / or some of the second predetermined locations, the first predetermined locations defining a regular pattern wherein the center-to-center distance between directly adjacent locations is equal to or greater than 75% and equal to or less than 150% of a maximum cross-sectional dimension of the recesses, and the second predetermined locations defining a regular pattern wherein the center-to-center distance between directly adjacent locations is equal to or greater than 75% and equal to or less than 150% of a maximum cross-sectional dimension of the recesses, the center-to-center distance between any said first predetermined location and directly adjacent second predetermined location is less than 75% of the maximum cross-sectional dimension of the recesses, and for each pair of directly adjacent first and second predetermined locations, only one of the directly adjacent first and second predetermined locations is occupied by a recess. Aspect 53 The process of preparing the substrate, forming a plurality of recesses in a surface of the substrate using a laser and / or a focused particle beam, thereby encoding information on the substrate; the plurality of recesses are located at some of first predetermined locations and / or some of second predetermined locations, the first predetermined locations defining a regular pattern wherein the center-to-center distance between directly adjacent locations is equal to or greater than 75% and equal to or less than 150% of a maximum cross-sectional dimension of the recesses, and the second predetermined locations defining a regular pattern wherein the center-to-center distance between directly adjacent locations is equal to or greater than 75% and equal to or less than 150% of a maximum cross-sectional dimension of the recesses, and the center-to-center distance between any said first predetermined location and any directly adjacent second predetermined location is less than 75% of the maximum cross-sectional dimension of the recesses. Aspect 54 The process of preparing the substrate, coating the substrate with a layer of a second material different from the material of the substrate; forming a plurality of depressions in the surface of the layer of second material using a laser and / or a focused particle beam, thereby encoding information in the layer of second material; the plurality of recesses are located at some of first predetermined locations and / or some of second predetermined locations, the first predetermined locations defining a regular pattern wherein the center-to-center distance between directly adjacent locations is equal to or greater than 75% and equal to or less than 150% of a maximum cross-sectional dimension of the recesses, and the second predetermined locations defining a regular pattern wherein the center-to-center distance between directly adjacent locations is equal to or greater than 75% and equal to or less than 150% of a maximum cross-sectional dimension of the recesses, and the center-to-center distance between any said first predetermined location and any directly adjacent second predetermined location is less than 75% of the maximum cross-sectional dimension of the recesses. Aspect 55 In a method described in aspect 53 or 54, the regular pattern of the first predetermined positions defines a pattern of gaps when all of the first predetermined positions are occupied, and one gap is completely filled each time each of the second predetermined positions is occupied. Aspect 56 In a method according to aspect 55, the center of each of the second predetermined positions corresponds to the center of one of the gap portions. Aspect 57 A method according to any one of aspects 51 to 56, wherein in the regular pattern of the first and / or second predetermined locations, the center-to-center distance between directly adjacent locations corresponds to 85% or more, preferably 95% or more, more preferably 100% or more, and even more preferably 105% or more of the maximum cross-sectional dimension of the recess. Aspect 58 A method according to any one of aspects 51 to 57, wherein in the regular pattern of the first and / or second predetermined locations, the center-to-center distance between directly adjacent locations corresponds to 140% or less, preferably 130% or less, more preferably 120% or less, and even more preferably 110% or less of the maximum cross-sectional dimension of the recess. Aspect 59 A method according to any one of aspects 51 to 58, wherein the center-to-center distance between any first predetermined location and an immediately adjacent second predetermined location is less than 70%, preferably less than 65%, more preferably less than 60%, and even more preferably less than 55% of the maximum cross-sectional dimension of the recess. Aspect 60 A method according to any one of aspects 51 to 59, wherein the regular pattern at the first predetermined position is a square-shaped pattern. Aspect 61 61. The method of any one of embodiments 51 to 60, wherein the shape of the recess is cylindrical or conical. Aspect 62 62. The method of any one of embodiments 51 to 61, wherein the recesses are formed using a laser beam having a Gaussian or Bessel beam shape. Aspect 63 63. The method of any one of claims 51 to 62, wherein the substrate is a ceramic substrate and / or comprises a transparent vitreous or crystalline ceramic material and / or comprises one or a combination of sapphire (Al2O3), silica (SiO2), zirconium (Zr(SiO4)), ZrO2, boron oxide, sodium oxide, potassium oxide, lithium oxide, zinc oxide, and magnesium oxide. Aspect 64 64. The method of claim 63, wherein the ceramic substrate contains WC / Co—Ni—Mo and / or BN / Co—Ni—Mo and / or TiN / Co—Ni—Mo and / or SiC / Co—Ni—Mo. Aspect 65 65. The method of any one of aspects 51 to 64, wherein the second material is selected from the group consisting of metals such as Cr, Co, Ni, Fe, Al, Ti, Si, W, Zr, Ta, Th, Nb, Mn, Mg, Hf, Mo, and V; metal nitrides such as CrN, CrAlN, TiN, TiCN, TiAlN, ZrN, AlN, VN, SiN, ThN, HfN, and BN; metal carbides such as TiC, CrC, AlC, VC, ZrC, HfC, ThC, BC, and SiC; AlO, TiO, SiO, ZrO, and ThO. 2、 1. A method according to claim 1, wherein the second material comprises at least one of the following ceramic materials: metal oxides such as MgO, Cr2O3, Zr2O3, V2O3, metal borides such as TiB2, ZrB2, CrB2, VB2, SiB6, ThB2, HfB2, WB2, WB4, metal silicides such as TiSi2, ZrSi2, MoSi2, MoSi, WSi2, PtSi, Mg2Si, or any other type of ceramic material, and preferably wherein said second material comprises CrN and / or Cr2O3 and / or CrAlN. Aspect 66 A method according to any one of aspects 51 to 65, wherein the layer of the second material and / or the two or more layers of different second materials have a thickness of 5 μm or less, preferably 2 μm or less, more preferably 1 μm or less, even more preferably 100 nm or less, and most preferably 10 nm or less. Aspect 67 67. The method of any one of embodiments 51 to 66, wherein the plurality of recesses have different depths, each depth corresponding to a predetermined information value. Aspect 68 67. The method of claim 67, wherein the minimum difference in depth between the plurality of recesses is 1 nm or more, preferably 10 nm or more, more preferably 30 nm or more, more preferably 50 nm or more, even more preferably 70 nm or more, and most preferably 100 nm or more; and / or the minimum difference in depth between the plurality of recesses is 5 μm or less, preferably 1 μm or less, more preferably 500 nm or less, more preferably 300 nm or less, even more preferably 200 nm or less, and most preferably 100 nm or less. Aspect 69 1. An information storage medium comprising a substrate, a surface of the substrate having a plurality of recesses for encoding information on the information storage medium, the plurality of recesses being located at some first predetermined locations and some second predetermined locations, the first predetermined locations defining a regular pattern in which the center-to-center distance between directly adjacent locations corresponds to 75% or more and 150% or less of a maximum cross-sectional dimension of the recesses, the second predetermined locations defining a regular pattern in which the center-to-center distance between directly adjacent locations corresponds to 75% or more and 150% or less of a maximum cross-sectional dimension of the recesses, the center-to-center distance between any one of the first predetermined locations and directly adjacent second predetermined locations being less than 75% of the maximum cross-sectional dimension of the recesses, and in each pair of directly adjacent first and second predetermined locations, only one of the directly adjacent first and second predetermined locations is occupied by a recess. Aspect 70 1. An information storage medium comprising: a substrate coated with a layer of a second material; and a sintered interface between the substrate and the layer of the second material, the second material being different from a material of the substrate, the sintered interface containing at least one element from both the material of the substrate and the second material; the layer of the second material having a plurality of recesses for encoding information on the information storage medium, the plurality of recesses being located at some first predetermined locations and some second predetermined locations, the first predetermined locations having a center-to-center distance between directly adjacent locations that is at least 75% of a maximum cross-sectional dimension of the recesses. the second predetermined locations define a regular pattern such that the center-to-center distance between directly adjacent locations is greater than or equal to 75% and less than or equal to 150% of the maximum cross-sectional dimension of the recess, the center-to-center distance between any one of the first predetermined locations and a directly adjacent second predetermined location is less than 75% of the maximum cross-sectional dimension of the recess, and for each pair of directly adjacent first and second predetermined locations, only one of the directly adjacent first and second predetermined locations is occupied by a recess. Aspect 71 1. An information storage medium comprising a substrate, a surface of the substrate having a plurality of recesses for encoding information on the information storage medium, the plurality of recesses being located at some first predetermined locations and some second predetermined locations, the first predetermined locations defining a regular pattern in which the center-to-center distance between directly adjacent locations corresponds to 75% or more and 150% or less of a maximum cross-sectional dimension of the recesses, the second predetermined locations defining a regular pattern in which the center-to-center distance between directly adjacent locations corresponds to 75% or more and 150% or less of a maximum cross-sectional dimension of the recesses, and the center-to-center distance between any of the first predetermined locations and directly adjacent second predetermined locations is less than 75% of the maximum cross-sectional dimension of the recesses. Aspect 72 1. An information storage medium comprising: a substrate coated with a layer of a second material; and a sintered interface between the substrate and the layer of the second material, the second material being different from a material of the substrate, the sintered interface containing at least one element from both the material of the substrate and the second material; the layer of the second material having a plurality of recesses that encode information in the information storage medium, the plurality of recesses being located at some first predetermined locations and some second predetermined locations, the first predetermined locations defining a regular pattern wherein the center-to-center distance between directly adjacent locations corresponds to 75% or more and 150% or less of a maximum cross-sectional dimension of the recesses; the second predetermined locations defining a regular pattern wherein the center-to-center distance between directly adjacent locations corresponds to 75% or more and 150% or less of a maximum cross-sectional dimension of the recesses; and the center-to-center distance between any first predetermined location and any directly adjacent second predetermined location is less than 75% of the maximum cross-sectional dimension of the recesses. Aspect 73 In an information storage medium described in any one of aspects 69 to 72, in the regular pattern of the first and / or second predetermined positions, the center-to-center distance between directly adjacent positions corresponds to 85% or more of the maximum cross-sectional dimension of the recess, preferably 95% or more, more preferably 100% or more, and even more preferably 105% or more. Aspect 74 In an information storage medium described in any one of aspects 69 to 73, in the regular pattern of the first and / or second predetermined positions, the center-to-center distance between directly adjacent positions corresponds to 140% or less, preferably 130% or less, more preferably 120% or less, and even more preferably 110% or less of the maximum cross-sectional dimension of the recess. Aspect 75 In an information storage medium described in any one of aspects 69 to 74, the center-to-center distance between any one of the first predetermined locations and the directly adjacent second predetermined location is less than 70% of the maximum cross-sectional dimension of the recess, preferably less than 65%, more preferably less than 60%, and even more preferably less than 55%. Aspect 76 In an information storage medium according to any one of aspects 69 to 75, the regular pattern at the first predetermined position is a square pattern. Aspect 77 An information storage medium according to any one of aspects 69 to 76, wherein the shape of the recess is cylindrical or conical. Aspect 78 In an information storage medium described in any one of aspects 69 to 77, the substrate is a ceramic substrate, and / or the substrate contains a transparent glass ceramic material or a crystalline ceramic material, and / or the substrate contains one or a combination of sapphire (Al2O3), silica (SiO2), zirconium (Zr(SiO4)), ZrO2, boron oxide, sodium oxide, potassium oxide, lithium oxide, zinc oxide, and magnesium oxide. Aspect 79 79. An information storage medium according to claim 78, wherein the ceramic substrate contains WC / Co—Ni—Mo and / or BN / Co—Ni—Mo and / or TiN / Co—Ni—Mo and / or SiC / Co—Ni—Mo. Aspect 80 79. An information storage medium according to any one of aspects 69 to 79, wherein the second material is selected from the group consisting of metals such as Cr, Co, Ni, Fe, Al, Ti, Si, W, Zr, Ta, Th, Nb, Mn, Mg, Hf, Mo, and V; metal nitrides such as CrN, CrAlN, TiN, TiCN, TiAlN, ZrN, AlN, VN, SiN, ThN, HfN, and BN; metal carbides such as TiC, CrC, AlC, VC, ZrC, HfC, ThC, BC, and SiC; AlO, TiO, SiO, ZrO, and ThO. 2、 1. An information storage medium comprising at least one ceramic material such as a metal oxide, such as MgO, Cr2O3, Zr2O3, or V2O3; a metal boride, such as TiB2, ZrB2, CrB2, VB2, SiB6, ThB2, HfB2, WB2, or WB4; a metal silicide, such as TiSi2, ZrSi2, MoSi2, MoSi, WSi2, PtSi, or Mg2Si; or any other type of ceramic material, wherein the second material preferably comprises CrN and / or Cr2O3 and / or CrAlN. Aspect 81 In an information storage medium described in any one of aspects 69 to 80, the layer of the second material and / or the two or more layers of different second materials have a layer thickness of 5 μm or less, preferably 2 μm or less, more preferably 1 μm or less, even more preferably 100 nm or less, and most preferably 10 nm or less. Aspect 82 An information storage medium according to any one of aspects 69 to 85, wherein the recesses have different depths, each depth corresponding to a predetermined information value. Aspect 83 In the information storage medium described in aspect 82, the minimum difference in depth between the multiple recesses is 1 nm or more, preferably 10 nm or more, more preferably 30 nm or more, more preferably 50 nm or more, even more preferably 70 nm or more, and most preferably 100 nm or more, and / or the minimum difference in depth between the multiple recesses is 5 μm or less, preferably 1 μm or less, more preferably 500 nm or less, more preferably 300 nm or less, even more preferably 200 nm or less, and most preferably 100 nm or less.

Claims

1. The process of preparing the substrate, forming a plurality of recesses in a surface of the substrate using a laser and / or a focused particle beam, thereby encoding information on the substrate; wherein the recesses have different shapes and / or sizes and optionally different depths, each shape and / or size and optionally each depth corresponding to a predetermined information value.

2. providing a ceramic substrate containing one or a combination of Ni, Cr, Co, Fe, W, Mo, or other metals with a melting point above 1,400°C; coating the substrate with a layer of a second material different from the material of the substrate; forming a plurality of depressions in the surface of the layer of second material using a laser and / or a focused particle beam, thereby encoding information in the layer of second material; wherein the recesses have different shapes and / or sizes, and optionally different depths, each shape and / or size, and optionally each depth, corresponding to a predetermined information value; A method for storing information, wherein the coated substrate is optionally subjected to a tempering treatment before and / or after encoding the information, which improves the durability of the coated substrate.

3. providing a ceramic substrate containing one or a combination of Ni, Cr, Co, Fe, W, Mo, or other metals with a melting point above 1,400°C; coating the substrate with two or more layers of a second material different from the material of the substrate; forming a plurality of recesses in the layer of second material using a laser and / or a focused particle beam, thereby encoding information in the layer of second material; the plurality of recesses having different shapes and / or sizes and different depths extending into different ones of the two or more layers, each shape and / or size and each depth corresponding to a predetermined information value; A method for storing information, wherein the coated substrate is optionally subjected to a tempering treatment before and / or after encoding the information, which improves the durability of the coated substrate.

4. 4. The method of claim 3, wherein each of the two or more layers has a thickness of less than 1 μm.

5. 5. The method according to claim 3 or 4, wherein the two or more layers include a metal layer and a metal oxide layer, and the metal element of the metal layer is the same as the metal element of the metal oxide layer.

6. 6. The method according to claim 1, wherein the recesses of different shapes have different cross-sectional shapes perpendicular to the depth direction, and / or the recesses of different sizes have different cross-sectional sizes perpendicular to the depth direction.

7. 7. The method according to claim 1, wherein the plurality of recesses have at least two different shapes and / or sizes and / or depths, each shape and / or size and / or depth corresponding to a predetermined information value.

8. 8. The method of claim 1, wherein each recess is formed by one or more pulses of the laser and / or focused particle beam, and the shape of each recess is controlled by one or a combination of optical proximity control, polarization ablation, variable shaped beam techniques, or by forming two or more overlapping circular recesses to form the predetermined shape.

9. 9. The method of claim 1, wherein each recess is formed by one or more pulses of the laser and / or focused particle beam, and the size of each recess is controlled by one or a combination of the number of pulses, the intensity level of the pulses, or the focal spot size.

10. 10. The method of claim 1, wherein each recess is formed by one or more pulses of the laser and / or focused particle beam, and the depth of each recess is controlled by one or a combination of the following parameters: energy of the pulse, length of the pulse, number of pulses of the laser and / or focused particle beam.

11. 11. The method according to claim 1, wherein a minimum difference in depth between the plurality of recesses is 1 nm or more and / or a minimum difference in depth between the plurality of recesses is 5 μm or less.

12. 12. The method of claim 1, wherein the substrate is a ceramic substrate, the ceramic substrate comprising an oxide ceramic, the ceramic substrate comprising 90% by weight or more of one or a combination of Al2O3, TiO2, SiO2, ZrO2, ThO2, MgO, Cr2O3, Zr2O3, VO3, boron oxide, sodium oxide, potassium oxide, lithium oxide, zinc oxide, and magnesium oxide; and / or the substrate comprises a transparent vitreous or crystalline ceramic material; and / or the substrate comprises one or a combination of sapphire (Al2O3), silica (SiO2), zirconium (Zr(SiO4)), and ZrO2.

13. 13. The method of any one of claims 1 to 12, wherein the substrate is a ceramic substrate, the ceramic substrate comprising a non-oxide ceramic, the ceramic substrate comprising 90% by weight or more of one or a combination of metal nitrides, metal carbides, metal borides, metal silicides, or any other type of non-oxide ceramic material.

14. 14. The method of claim 1 or any one of claims 6 to 13 when dependent on claim 1, wherein the substrate is a ceramic substrate containing one or a combination of Ni, Cr, Co, Fe, W, Mo, or other metals with a melting point above 1,400°C.

15. 15. The method of claim 14, wherein the ceramic material and the metal form a metal matrix composite.

16. The method of claim 14 or 15, wherein the metal is 5 to 30% by weight of the ceramic substrate.

17. 17. The method according to any one of claims 14 to 16, wherein the ceramic substrate comprises WC / Co-Ni-Mo and / or BN / Co-Ni-Mo and / or TiN / Co-Ni-Mo and / or SiC / Co-Ni-Mo.

18. 18. The method of claim 2, claim 3, or any one of claims 4 to 17 when dependent on claim 2 or 3, wherein the second material comprises a metal, a metal nitride, a metal carbide, a metal oxide, a metal boride, or a metal silicide.

19. 19. The method of claim 2, claim 3, or any one of claims 4 to 18 when dependent on claim 2 or 3, wherein forming the recess comprises locally heating the surface above the melting and / or decomposition temperature of the second material.

20. 20. The method of claim 2, claim 3, or any one of claims 4 to 19 when dependent on claim 2 or 3, wherein forming the recesses comprises treating the surface of the coated substrate with a femtosecond laser to create a Coulomb explosion leading to ablation of material.

21. 21. The method of claim 2, claim 3, or any one of claims 4 to 20 when dependent on claim 2 or 3, wherein the layer of the second material and / or the two or more layers of different second materials have a layer thickness of 5 μm or less.

22. 22. The method of any one of claims 1 to 21, wherein forming the recess comprises locally heating and / or decomposing and / or oxidizing and / or ablating and / or vaporizing the surface.

23. 23. The method of claim 2, claim 3, or any one of claims 4 to 22 when dependent on claim 2 or 3, wherein tempering the coated substrate creates a sintered interface between the substrate and the layer of the second material or the two or more layers of different second materials.

24. 24. The method of claim 23, wherein the sintered interface contains at least one element from both the substrate material and the second material.

25. 25. The method of claim 2, claim 3, or any one of claims 4 to 24 when dependent on claim 2 or 3, wherein the coated substrate is tempered in an oxygen atmosphere to oxidize at least the uppermost layer of the second material.

26. 26. The method of claim 2, claim 3, or any one of claims 4 to 25 when dependent on claim 2 or 3, wherein the coated substrate contains 1 megabyte or more of information per cm2 of area.

27. 1. An information storage medium comprising a substrate, the surface of which has a plurality of recesses for encoding information on the information storage medium, the recesses having different shapes and / or sizes, and optionally different depths, each shape and / or size, and optionally each depth, corresponding to a predetermined information value.

28. 1. An information storage medium comprising: a substrate coated with a layer of a second material; and a sintered interface between the substrate and the layer of the second material, the second material being different from the material of the substrate, the sintered interface containing at least one element from both the material of the substrate and the second material; and the layer of the second material having a plurality of recesses encoding information in the information storage medium, the plurality of recesses having different shapes and / or sizes, and optionally different depths, each shape and / or size, and optionally each depth, corresponding to a predetermined information value.

29. 1. An information storage medium comprising: a substrate coated with two or more layers of a second material different from each other; and a sintered interface between the substrate and at least a bottom layer of the two or more layers, the second material being different from the material of the substrate, the sintered interface containing at least one element from both the material of the substrate and the material of the bottom layer; the information storage medium further comprising a plurality of recesses for encoding information in the information storage medium, the plurality of recesses having different shapes and / or sizes and different depths extending into different layers of the two or more layers, each shape and / or size and each depth corresponding to a predetermined information value.

30. 30. The information storage medium according to claim 29, wherein each of the two or more layers has a thickness of less than 1 μm.

31. 31. The information storage medium according to claim 29, wherein the two or more layers include a metal layer and a metal oxide layer, and the metal element of the metal layer is the same as the metal element of the metal oxide layer.

32. 32. An information storage medium according to any one of claims 27 to 31, wherein recesses of different shapes have different cross-sectional shapes perpendicular to the depth direction, and / or recesses of different sizes have different cross-sectional sizes perpendicular to the depth direction.

33. 33. An information storage medium according to any one of claims 27 to 32, wherein the plurality of recesses have at least two different shapes and / or sizes and / or depths, each shape and / or size and / or depth corresponding to a predetermined information value.

34. 34. An information storage medium according to any one of claims 27 to 33, wherein the minimum difference in depth between the plurality of recesses is 1 nm or more, and / or the minimum difference in depth between the plurality of recesses is 5 μm or less.

35. 35. The information storage medium according to claim 27, wherein the substrate is a ceramic substrate, the ceramic substrate contains an oxide ceramic, the ceramic substrate contains 90% by weight or more of one or a combination of Al2O3, TiO2, SiO2, ZrO2, ThO2, MgO, Cr2O3, Zr2O3, VO3, boron oxide, sodium oxide, potassium oxide, lithium oxide, zinc oxide, and magnesium oxide, and / or the substrate contains a transparent vitreous ceramic material or a crystalline ceramic material, and / or the substrate contains one or a combination of sapphire (Al2O3), silica (SiO2), zirconium (Zr(SiO4)), and ZrO2.

36. 36. An information storage medium according to any one of claims 27 to 35, wherein the substrate is a ceramic substrate, the ceramic substrate contains a non-oxide ceramic, and the ceramic substrate contains 90% by weight or more of one or a combination of metal nitrides, metal carbides, metal borides, metal silicides, or any other type of non-oxide ceramic material.

37. 37. An information storage medium according to any one of claims 27 to 36, wherein the substrate is a ceramic substrate, and the ceramic substrate contains one or a combination of Ni, Cr, Co, Fe, W, Mo, or other metals having a melting point above 1,400°C.

38. 38. An information storage medium according to claim 37 when dependent on claim 35 or 36, wherein the ceramic material and the metal form a metal matrix composite.

39. 39. An information storage medium according to claim 37 or 38, wherein the metal accounts for 5 to 30% by weight of the ceramic substrate.

40. 40. The information storage medium according to any one of claims 37 to 39, wherein the ceramic substrate contains WC / Co-Ni-Mo and / or BN / Co-Ni-Mo and / or TiN / Co-Ni-Mo and / or SiC / Co-Ni-Mo.

41. 41. An information storage medium according to claim 28, claim 29, or any one of claims 30 to 40 when dependent on claim 28 or 29, wherein the second material contains a metal, a metal nitride, a metal carbide, a metal oxide, a metal boride, or a metal silicide.

42. 42. An information storage medium according to claim 28, claim 29, or any one of claims 30 to 41 when dependent on claim 28 or 29, further comprising an oxide layer on the layer of the second material or on a top layer of the two or more layers made of a different second material, the oxide layer containing one or more oxides of the second material or one or more oxides of the material of the top layer of the two or more layers made of a different second material.

43. 43. An information storage medium according to claim 28, claim 29, or any one of claims 30 to 42 when dependent on claim 28 or 29, wherein the layer of the second material has a thickness of 10 μm or less.

44. 44. An information storage medium according to any one of claims 27 to 43, wherein the information storage medium contains 1 megabyte or more of information per cm2 of area.

45. 45. An information storage medium according to claim 28, claim 29, or any one of claims 30 to 44 when dependent on claim 28 or 29, wherein the substrate, the sintered layer, and the layer of the second material or the two or more layers of different second materials have melting temperatures above 1,000°C.

46. 46. ​​An information storage medium according to claim 28, claim 29, or any one of claims 30 to 45 when dependent on claim 28 or 29, wherein the melting temperature of the substrate is equal to or higher than the melting temperature of the layer of the second material or the two or more layers of different second materials.

47. 47. The information storage medium according to any one of claims 27 to 46, wherein the information storage medium is used for long-term storage of information and is archived for a period of 10 years or more.

48. 47. A method of decoding information encoded on an information storage medium according to any one of claims 27 to 46, comprising the steps of: providing an information storage medium according to any one of claims 27 to 46; measuring the shape and / or size and, optionally, the depth of at least some of the recesses; decoding said information values ​​corresponding to said measured shape and / or size and, optionally, said measured depth; A method comprising:

49. 49. The method of claim 48, wherein the step of measuring the shape and / or size, and optionally the depth, is performed using a laser beam and / or a focused particle beam.

50. 50. The method of claim 48 or 49, wherein the process of measuring the shape and / or size, and optionally the depth, is based on one or a combination of interference, reflection, absorption, ellipsometry, frequency comb technology, fluorescence microscopy, structured illumination microscopy, super-resolution microscopy, optical coherence tomography, scanning electron microscopy, ptychography, digital microscopy using reflected or transmitted light.

51. The process of preparing the substrate, forming a plurality of recesses in a surface of the substrate using a laser and / or a focused particle beam, thereby encoding information on the substrate; the plurality of recesses are located at some of the first predetermined locations and / or some of the second predetermined locations, the first predetermined locations defining a regular pattern wherein the center-to-center distance between directly adjacent locations corresponds to 75% or more and 150% or less of a maximum cross-sectional dimension of the recesses, and the second predetermined locations defining a regular pattern wherein the center-to-center distance between directly adjacent locations corresponds to 75% or more and 150% or less of a maximum cross-sectional dimension of the recesses, the center-to-center distance between any said first predetermined location and a directly adjacent second predetermined location is less than 75% of the maximum cross-sectional dimension of the recesses, and for each pair of directly adjacent first and second predetermined locations, only one of the directly adjacent first and second predetermined locations is occupied by a recess.

52. The process of preparing the substrate, coating the substrate with a layer of a second material different from the material of the substrate; forming a plurality of depressions in the surface of the layer of second material using a laser and / or a focused particle beam, thereby encoding information in the layer of second material; the plurality of recesses are located at some of the first predetermined locations and / or some of the second predetermined locations, the first predetermined locations defining a regular pattern wherein the center-to-center distance between directly adjacent locations corresponds to 75% or more and 150% or less of a maximum cross-sectional dimension of the recesses, and the second predetermined locations defining a regular pattern wherein the center-to-center distance between directly adjacent locations corresponds to 75% or more and 150% or less of a maximum cross-sectional dimension of the recesses, the center-to-center distance between any said first predetermined location and a directly adjacent second predetermined location is less than 75% of the maximum cross-sectional dimension of the recesses, and for each pair of directly adjacent first and second predetermined locations, only one of the directly adjacent first and second predetermined locations is occupied by a recess.

53. The process of preparing the substrate, forming a plurality of recesses in a surface of the substrate using a laser and / or a focused particle beam, thereby encoding information on the substrate; the plurality of recesses are located at some of first predetermined locations and / or some of second predetermined locations, the first predetermined locations define a regular pattern in which the center-to-center distance between directly adjacent locations is equal to or greater than 75% and equal to or less than 150% of a maximum cross-sectional dimension of the recesses, and the second predetermined locations define a regular pattern in which the center-to-center distance between directly adjacent locations is equal to or greater than 75% and equal to or less than 150% of the maximum cross-sectional dimension of the recesses, and the center-to-center distance between any of the first predetermined locations and directly adjacent second predetermined locations is less than 75% of the maximum cross-sectional dimension of the recesses.

54. The process of preparing the substrate, coating the substrate with a layer of a second material different from the material of the substrate; forming a plurality of depressions in the surface of the layer of second material using a laser and / or a focused particle beam, thereby encoding information in the layer of second material; the plurality of recesses are located at some of first predetermined locations and / or some of second predetermined locations, the first predetermined locations define a regular pattern in which the center-to-center distance between directly adjacent locations is equal to or greater than 75% and equal to or less than 150% of a maximum cross-sectional dimension of the recesses, and the second predetermined locations define a regular pattern in which the center-to-center distance between directly adjacent locations is equal to or greater than 75% and equal to or less than 150% of the maximum cross-sectional dimension of the recesses, and the center-to-center distance between any of the first predetermined locations and directly adjacent second predetermined locations is less than 75% of the maximum cross-sectional dimension of the recesses.

55. 55. A method according to claim 53 or 54, wherein the regular pattern of first predetermined locations defines a pattern of gaps when all of the first predetermined locations are occupied, and wherein one gap is completely filled for each of the second predetermined locations that are occupied.

56. 56. The method of claim 55, wherein the center of each of the second predetermined locations corresponds to the center of one of the gaps.

57. 57. A method according to any one of claims 51 to 56, wherein the centre-to-centre distance between any said first predetermined location and an immediately adjacent second predetermined location is less than 70% of the maximum cross-sectional dimension of the recess.

58. 58. The method of any one of claims 51 to 57, wherein the regular pattern at the first predetermined location is a square-shaped pattern.

59. 59. The method of any one of claims 51 to 58, wherein the shape of the recess is cylindrical or conical.

60. 60. The method of any one of claims 51 to 59, wherein the recesses are formed using a laser beam having a Gaussian or Bessel type beam shape.

61. 61. The method of any one of claims 51 to 60, wherein the substrate is a ceramic substrate and / or the substrate comprises a transparent vitreous or crystalline ceramic material and / or the substrate comprises one or a combination of sapphire (Al2O3), silica (SiO2), zirconium (Zr(SiO4)), ZrO2, boron oxide, sodium oxide, potassium oxide, lithium oxide, zinc oxide, and magnesium oxide.

62. 62. The method of claim 61, wherein the ceramic substrate comprises WC / Co-Ni-Mo and / or BN / Co-Ni-Mo and / or TiN / Co-Ni-Mo and / or SiC / Co-Ni-Mo.

63. 63. The method of claim 52, claim 54, or any one of claims 55 to 62 when dependent on claim 52 or 54, wherein the second material comprises a metal, a metal nitride, a metal carbide, a metal oxide, a metal boride, or a metal silicide.

64. 64. The method of claim 52, claim 54, or any one of claims 55 to 63 when dependent on claim 52 or 54, wherein the layer of the second material and / or the two or more layers of different second materials have a layer thickness of 5 μm or less.

65. 65. The method of any one of claims 51 to 64, wherein the plurality of recesses have different depths, each depth corresponding to a predetermined information value.

66. 66. The method of claim 65, wherein the minimum difference in depth between the plurality of recesses is 1 nm or more and / or the minimum difference in depth between the plurality of recesses is 5 μm or less.

67. 1. An information storage medium comprising a substrate, a surface of the substrate having a plurality of recesses for encoding information on the information storage medium, the plurality of recesses being located at some first predetermined locations and some second predetermined locations, the first predetermined locations defining a regular pattern in which the center-to-center distance between directly adjacent locations corresponds to 75% or more and 150% or less of a maximum cross-sectional dimension of the recesses, the second predetermined locations defining a regular pattern in which the center-to-center distance between directly adjacent locations corresponds to 75% or more and 150% or less of a maximum cross-sectional dimension of the recesses, the center-to-center distance between any one of the first predetermined locations and a directly adjacent second predetermined location being less than 75% of the maximum cross-sectional dimension of the recesses, and

68. 1. An information storage medium comprising: a substrate coated with a layer of a second material; and a sintered interface between the substrate and the layer of the second material, the second material being different from a material of the substrate, the sintered interface containing at least one element from both the material of the substrate and the second material; the layer of the second material having a plurality of recesses for encoding information on the information storage medium, the plurality of recesses being located at some first predetermined locations and some second predetermined locations, the first predetermined locations having a center-to-center distance between directly adjacent locations that is at least 75% of a maximum cross-sectional dimension of the recesses. the second predetermined locations define a regular pattern in which the center-to-center distance between directly adjacent locations is equal to or greater than 75% and equal to or less than 150% of the maximum cross-sectional dimension of the recess, the center-to-center distance between any of the first predetermined locations and a directly adjacent second predetermined location is less than 75% of the maximum cross-sectional dimension of the recess, and in each pair of directly adjacent first and second predetermined locations, only one of the directly adjacent first and second predetermined locations is occupied by a recess.

69. 1. An information storage medium comprising a substrate, a surface of the substrate having a plurality of recesses for encoding information on the information storage medium, the plurality of recesses being located at some first predetermined locations and some second predetermined locations, the first predetermined locations defining a regular pattern in which the center-to-center distance between directly adjacent locations corresponds to 75% or more and 150% or less of a maximum cross-sectional dimension of the recesses, the second predetermined locations defining a regular pattern in which the center-to-center distance between directly adjacent locations corresponds to 75% or more and 150% or less of a maximum cross-sectional dimension of the recesses, and the center-to-center distance between any of the first predetermined locations and directly adjacent second predetermined locations is less than 75% of the maximum cross-sectional dimension of the recesses.

70. 1. An information storage medium comprising: a substrate coated with a layer of a second material; and a sintered interface between the substrate and the layer of the second material, the second material being different from the material of the substrate, the sintered interface containing at least one element from both the material of the substrate and the second material; the layer of the second material having a plurality of recesses that encode information in the information storage medium, the plurality of recesses being located at some first predetermined locations and some second predetermined locations; the first predetermined locations defining a regular pattern in which the center-to-center distance between directly adjacent locations corresponds to 75% or more and 150% or less of a maximum cross-sectional dimension of the recesses; the second predetermined locations defining a regular pattern in which the center-to-center distance between directly adjacent locations corresponds to 75% or more and 150% or less of a maximum cross-sectional dimension of the recesses; and the center-to-center distance between any first predetermined location and a directly adjacent second predetermined location is less than 75% of the maximum cross-sectional dimension of the recesses.

71. 71. An information storage medium according to any one of claims 67 to 70, wherein the center-to-center distance between any said first predetermined location and an immediately adjacent second predetermined location is less than 70% of the maximum cross-sectional dimension of the recess.

72. 72. The information storage medium according to claim 67, wherein the regular pattern at the first predetermined position is a square pattern.

73. 73. An information storage medium according to any one of claims 67 to 72, wherein the shape of the recess is cylindrical or conical.

74. 74. An information storage medium according to any one of claims 67 to 73, wherein the substrate is a ceramic substrate, and / or the substrate contains a transparent vitreous ceramic material or a crystalline ceramic material, and / or the substrate contains one or a combination of sapphire (Al2O3), silica (SiO2), zirconium (Zr(SiO4)), ZrO2, boron oxide, sodium oxide, potassium oxide, lithium oxide, zinc oxide, and magnesium oxide.

75. 75. An information storage medium according to claim 74, wherein the ceramic substrate comprises WC / Co-Ni-Mo and / or BN / Co-Ni-Mo and / or TiN / Co-Ni-Mo and / or SiC / Co-Ni-Mo.

76. 76. An information storage medium according to claim 68, claim 70, or any one of claims 71 to 75 when dependent on claim 68 or 70, wherein the second material contains a metal, a metal nitride, a metal carbide, a metal oxide, a metal boride, or a metal silicide.

77. 76. An information storage medium according to claim 68, claim 70, or any one of claims 71 to 76 when dependent on claim 68 or 70, wherein the layer of the second material and / or the two or more layers of different second materials have a layer thickness of 5 μm or less.

78. 78. An information storage medium according to any one of claims 67 to 77, wherein the recesses have different depths, each depth corresponding to a predetermined information value.

79. 79. An information storage medium according to claim 78, wherein the minimum difference in depth between the plurality of recesses is 1 nm or more, and / or the minimum difference in depth between the plurality of recesses is 5 μm or less.

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