DE102022107151A1 - Method for providing glass targets with an optically perceptible marking, glass product and use of a titanium-silicon glass - Google Patents

Abstract

The invention relates to a method for providing glass targets (24) with an optically perceptible marking, comprising the steps: - providing a glass target (24), - irradiating the glass target (24) with laser radiation in the ultraviolet spectral range at a fluence between 200 and 450 mJ/cm2. The invention is characterized in that a body is provided as said glass target (24), which is at least partially made of titanium-silicon glass with a silicon dioxide content between 10 and 70 % by weight and a ratio of the proportions by weight of titanium dioxide to silicon dioxide between 0.1 and 1.5.

Description

Field of invention

• - Bereitstellen eines Glas-Targets,
• - Bestrahlen des Glas-Targets mit Laserstrahlung des ultravioletten Spektralbereichs bei einer Fluenz zwischen 200 und 450 mJ/cm².

The invention relates to a method for providing glass targets with an optically perceptible marking, comprising the steps:

• - providing a glass target,
• - Irradiating the glass target with laser radiation in the ultraviolet spectral range at a fluence between 200 and 450 mJ/cm ² .

The invention further relates to a glass product which carries a laser-induced, optically perceptible marking.

The invention further relates to a novel use of titanium-silicon glass.

State of the art

A generic process and generic glass products are known from Panahinbakhsh, S.; Jelvani, Saeid; Jaberi, Mohammad: “Micro- and nanostructures formation on glass surface with different parameters of excimer laser irradiation”, Opt. Eng. 58(1), 011005 (2018); doi:10.1117/1.OE.58.1.011005.

The modification of glass surfaces by irradiation with intense laser light has established itself as a proven means of marking and/or functionalizing glass substrates or, more generally, glass products. In particular, it is known to provide glass surfaces with a laser-induced pattern, which is often macroscopically perceptible to the viewer because the interaction of the glass surface with incident light changes with regard to the transmission and/or reflection behavior. Such modifications are usually based micromechanically on the principle of ablation, in which thin-layered surface areas of the glass are blasted off and/or vaporized by absorbed laser energy. The patterning can be extremely delicate. For example, the DE 10 2015 216 342 B3 proposes to irradiate the surface of a substrate chosen as a glass target through a phase mask, by means of which interferometrically periodic patterns are projected onto the substrate and structures in the micrometer or submicrometer range are created by ablation. Such miniaturized structures can be used, for example, as security features. On the other hand, larger-area markings, for example on drinking glasses, which can also serve as a glass target, can also be used for purely aesthetic decorative purposes. Such large-area markings are usually created by successively structuring smaller areas “pixel by pixel”. A corresponding system is e.g. B. disclosed in Beckmann, CM and Ihlemann, J.: “Figure correction of borosilicate glass substrates by nanosecond UV excimer laser irradiation” Opt. Express, vol. 28, no. 13, p. 18681, 2020, doi: 10. 1364/oe.393626. According to the teachings of the publications mentioned, the specific type of surface modification depends primarily on the specifically selected radiation parameters. The special chemistry of the glass target therefore hardly plays a role.

From the generic document mentioned at the beginning it is known to use silicon glasses with an ArF excimer laser with a wavelength of 193 nm with pulsed laser radiation between 50 and 1200 mJ/cm ² , a pulse duration of 15 ns and a pulse repetition rate of 2 Hz with 100 to 1000 pulses below the ablation threshold of the glass, so that an optically perceptible marking of the glass surface results. Such a process, which can be carried out under normal atmospheric conditions, ie under air and at room temperature, would in principle be very well suited for rapid and economical marking of glass surfaces. For example, for labeling purposes, to create security features or for purely decorative purposes. The disadvantage, however, is that the resulting roughening of the glass surface primarily leads to a changed scattering behavior, so that the marking created appears to the observer in whitish tones. However, unless they have a dark background and are specially illuminated, these only have a low contrast, so that marking as such is inefficient, especially if it is used for labeling or security purposes.

Alternatively, it is generally known to introduce high-contrast markings into glass surfaces by first coating them with pigments, for example soot or metal powder, and then irradiating them with intense laser radiation, which leads to a laser-induced implantation of the pigments into the substrate material. However, such a technology cannot be used in all areas of application. Especially when labeling glass vessels in the medical and pharmaceutical industry, for example when labeling vaccine ampoules or similar, a coating with pigments is out of the question for reasons of contamination.

Task

It is the object of the present invention to propose a quick and economical approach to providing glass products with high contrast markings.

Presentation of the invention

This object is achieved in conjunction with the features of the preamble of claim 1 in that a body is provided as said glass target, which is at least partially made of titanium-silicon glass with a silicon dioxide content between 10 and 70% by weight, preferably between 20 and 60% by weight, and a ratio of the proportions by weight of titanium dioxide to silicon dioxide between 0.1 and 1.5.

• - Bereitstellen eines Glas-Targets,
• - Bestrahlen des Glas-Targets mit Laserstrahlung des ultravioletten Spektralbereichs bei einer Fluenz zwischen 200 und 450 mJ/cm²,

wobei als das Glas-Target ein Körper bereitgestellt wird, der wenigstens bereichsweise aus Titan-Silizium-Glas mit einem Siliziumdioxid-Anteil zwischen 10 und 70 Gew.-%, bevorzugt zwischen 20 und 60 Gew.-%, und einem Verhältnis der Gewichtanteile von Titandioxid zu Siliziumdioxid zwischen 0,1 und 1,5 besteht.The object is further solved according to claim 9 by a glass product which is obtained by said method, namely by a method comprising the steps:

• - providing a glass target,
• - irradiating the glass target with laser radiation in the ultraviolet spectral range at a fluence between 200 and 450 mJ/cm ² ,

wherein a body is provided as the glass target, which is at least partially made of titanium-silicon glass with a silicon dioxide content of between 10 and 70% by weight, preferably between 20 and 60% by weight, and a ratio of the weight proportions of Titanium dioxide to silicon dioxide is between 0.1 and 1.5.

Such a glass product can also be described without reference to its specific manufacturing process. In conjunction with the features of the preamble of claim 10, it is characterized in that the glass product is at least partially made of titanium-silicon glass with a silicon dioxide content of between 10 and 70% by weight, preferably between 20 and 60% by weight. , and a ratio of the proportions by weight of titanium dioxide to silicon dioxide between 0.1 and 1.5, with the marking appearing black.

• - Bereitstellen des Glas-Targets,
• - Bestrahlen des Glas-Targets mit Laserstrahlung des ultravioletten Spektralbereichs bei einer Fluenz zwischen 200 und 450 mJ/cm².

According to claim 11, the core of the invention lies in the use of titanium-silicon glass with a silicon dioxide content between 10 and 70% by weight, preferably between 20 and 60% by weight, and a ratio of the weight proportions of titanium dioxide Silicon dioxide between 0.1 and 1.5 as a material for a glass target, which is used as part of a method for providing glass targets with an optically perceptible marking, comprising the steps:

• - providing the glass target,
• - Irradiating the glass target with laser radiation in the ultraviolet spectral range at a fluence between 200 and 450 mJ/cm ² .

Preferred embodiments are the subject of the dependent claims.

Surprisingly, it has been shown that the same type of marking with regard to the irradiation parameters, which leads to surface modifications in conventional silicon glasses that appear whitish when viewed macroscopically, leads to very high-contrast, blackish markings when choosing silicon-titanium glasses. provided that the weight ratio of titanium dioxide and silicon dioxide in the glass is within the specified value limits. A final physical and chemical explanation for this effect cannot yet be given. However, it is assumed that the blackening effect is based, among other things, on a partial reduction reaction of the oxidic titanium contained in the glass material, a phase separation and the formation of a microscopic roughening, which work together in a favorable manner so that a mark that appears black when viewed macroscopically results. Compliance with the irradiation parameters mentioned appears to be essential. In particular, significantly lower fluences lead to the absence of the effect, whereas significantly higher fluences lead to ablations that destroy the desired blackening effect.

A particular charm of the present invention is that it can be implemented under normal atmospheric conditions, i.e. with normal air and in particular an air temperature between 0 ° C and 100 ° C, preferably at room temperature.

The choice of ultraviolet light is imperative because silicon-titanium glasses only show sufficient absorption in this region of the spectrum. In particular, far UV light between 180 and 220 nm, especially between 190 and 200 nm, has proven to be suitable. In practice, an ArF excimer laser with a wavelength of 193 nm is recommended.

Generating the required fluences is practical and economically only possible with pulsed lasers. The glass target is therefore preferably irradiated with pulsed laser radiation with a pulse duration between 1 and 100 ns, in particular between 10 and 30 ns. A pulse duration of 20 ns has proven to be particularly advantageous, although the specific choice of pulse duration is currently not viewed as a highly critical criterion.

The number of pulses with which a point on the glass target to be modified is irradiated can also be varied over a wide range. Irradiation with 100 to 1000 pulses, in particular with 100 to 750 pulses, especially with 100 to 500 pulses, is considered advantageous. The expert will choose the number of pulses primarily based on the intensity of the black color he intends. Only after irradiation of approx. 100 pulses does a clearly noticeable effect occur. Irradiation of well over 1000 pulses does not lead to a significant improvement in the marking contrast. The pulse number ranges mentioned therefore reflect intervals optimized with regard to the efficiency and economic viability of the invention.

The glass target is expediently irradiated through mask optics, by means of which a pattern corresponding at least in some areas to the marking with which the glass target is to be provided is projected onto the glass target. The concept of projecting is to be understood broadly. For example, it can be provided that a simple aperture is imaged using suitable optics in an image plane that can lie on the Traget surface or slightly in front of or behind it. Alternatively, it can also be provided that the mask optics have a phase mask which is designed to generate a plurality of equidistant, parallel lines through interference in an object plane of the glass target, which can also lie on the surface or slightly in front of or behind it. The specific choice of projection optics plays no role for the present invention as long as the above-mentioned irradiation parameters can be achieved with it.

As is fundamentally known from the prior art, it is also advantageous in the context of the present invention if the area-wise irradiation of the glass target takes place one after the other for different areas of the marking with which the glass target is to be provided. In other words, only a small section of the intended marking is preferably generated and the entire area of the marking is successively scanned. This technology allows the use of significantly lower-power lasers compared to the large-scale implementation of the above-mentioned required irradiation parameters.

Further details and advantages of the invention emerge from the following specific description and the drawings.

Brief description of the drawings

• 1: eine aus dem Stand der Technik grundsätzlich bekannte Apparatur zur Lasermodifizierung von Glasoberflächen, die auch im Rahmen der vorliegenden Erfindung einsetzbar ist,
• 2: ein Mosaik aus mikroskopischen Darstellungen von Markierungen auf Glasoberflächen, erzeugt mit unterschiedlichen Bestrahlungsparametern sowie eine rasterelektronenmikroskopische Vergrößerung einer dieser Markierungen sowie
• 3: ein erfindungsgemäß erzeugter QR-Code auf der Oberfläche eines Glas-Targets,
  1. a) in direkter Draufsicht,
  2. b) in rückwärtiger Ansicht durch den Körper des Glas-Targets,
  3. c) in ausschnittsweiser Vergrößerung.

Show it:

• 1 : an apparatus for laser modification of glass surfaces that is fundamentally known from the prior art and can also be used in the context of the present invention,
• 2 : a mosaic of microscopic representations of markings on glass surfaces, created with different irradiation parameters as well as a scanning electron microscopic enlargement of one of these markings
• 3 : a QR code generated according to the invention on the surface of a glass target,
  1. a) in direct top view,
  2. b) in a rear view through the body of the glass target,
  3. c) in partial enlargement.

Description of preferred embodiments

1 shows an apparatus for the surface modification of glass targets, which is basically known from the prior art already mentioned and which is suitable for implementing the present invention and is preferably used. The arrangement includes a laser 10, which is designed in particular as an ArF excimer laser with a nominal wavelength of 193 nm. The laser 10 preferably delivers a pulsed beam 12, for example with a pulse duration of approximately 20 ns at a repetition rate of 2 Hz. However, if particularly high process speeds are aimed for, significantly higher repetition rates, typically between 100 Hz and 1 kHz, are also possible. The beam 12 is preferably collimated and can be adjusted in terms of its beam strength, in particular with regard to the fluence striking the glass target, by means of an adjustable attenuator 14, which reflectively couples out part of the steel 12, as illustrated by the decoupling arrow 16. The collimated and possibly attenuated beam 12 falls on a mask 18, which is preferably designed as a simple transmission mask with a round or rectangular, in particular square, cross section. This mask 18 is imaged in a reduced size onto a glass target 22 using a lens 20, which can be designed, for example, as a quartz glass lens with a focal length of 100 mm. The image size can be in the range of 300 µm, for example. In order to be able to successively irradiate a larger area of the glass target 22, the latter is clamped into an XY translator 24, by means of which different surface areas can be pushed into the imaging area of the mask 18 as required. A large-area marking can thus be built pixel by pixel. With the apparatus described, when using a square aperture Mask 18 square pixels of approximately 300 x 300 µm ² size.

According to the invention, the glass target consists of a silicon-titanium glass with the chemical composition explained in the general part of the description, which is in 1 however, is not recognizable.

2 shows a mosaic of microscopic images of round markings as seen when irradiating a glass target with a silicon dioxide weight fraction of 55% and a titanium dioxide weight fraction of 15%, ie with a weight ratio of titanium dioxide to silicon dioxide of approximately 0.27 with the in 1 The apparatus shown and described above and the choice of a mask 18 designed as a round aperture arise at different fluences and different pulse numbers. The results are shown at fluences of 200, 250, 300, 350, 362 and 500 mJ/cm ² and pulse numbers Np of 10, 50, 100, 200, 500 and 1000. An area of optimal black coloration can clearly be seen. If the fluence is too low, the desired effect either does not occur or only occurs after many irradiation pulses. If the fluence is too high and the ablation threshold is exceeded, the effect does not occur either. The optimal number of pulses depends on the degree of black coloring desired, with saturation occurring above a certain number of pulses.

The expert will recognize that the mosaic shown is basically typical, but can vary in detail depending on the specific choice of material for the glass target. Different silicon-titanium glasses within the material spectrum according to the invention have different ablation thresholds, so that different maximum fluences than in 2 shown can occur. The same applies to the sensitivity of different silicon-titanium glasses, so that minimum fluences or minimum pulse numbers other than those shown can also occur. However, the person skilled in the art will easily be able to determine the optimal parameter constellation for his specific application within the claimed spectrum of variable parameters.

2 further shows a scanning electron micrograph of the spot generated at a fluence of 250 mJ /cm ² after 1000 pulses at a viewing angle of 45°. An irregular hill structure can be seen, which certainly modifies the scattering behavior of the surface of the glass target, but is not alone responsible for the characteristic black color according to the invention.

3 shows three views of a QR code, which was composed by successive irradiation of a glass target according to the invention made of silicon-titanium glass with the image of a square aperture, ie pixel by pixel from square pixels. Subfigures a) and b) each show the entire QR code. c ) shows an enlarged section of approx. 4 pixels. Each pixel corresponds to an image area of the mask 18. When comparing subfigures a) and b), a clear difference in contrast can be seen. Partial figure a) shows the QR code in a direct top view of the modified surface. This is where the in 2 illustrated hill structure may increase scattering and therefore reduce contrast. Partial figure b), on the other hand, shows the same QR code in a rear view through the transparent body of the glass target. Here there is no scattering amplification due to the hill structure. The contrast of the black marking is therefore better. The conclusion can be drawn from this that if a particularly high-contrast marking is desired, it may be advantageous to provide the glass target in question with the marking on its rear side, which is ultimately facing away from the viewer, ie during typical use.

Of course, the embodiments discussed in the special description and shown in the figures only represent illustrative embodiments of the present invention. In the light of the disclosure here, the person skilled in the art is provided with a wide range of possible variations. In particular, the spectrum of possible applications of the present invention is extremely wide. In addition to the medical ampoules already mentioned at the beginning, syringes or vials for medical or pharmaceutical substances, implantable medical devices, encapsulations for active electronic implants, hermetically sealed glass capsules for medical technology, so-called “smart containers” for pharmaceutical substances, microfluidic chips, etc. can also be used. Technical glass targets are marked according to the invention, with high-contrast, high-resolution and thermally and chemically stable marking being possible in a quick and economical manner. The invention can also be used for delicate security features on glass substrates or for purely decorative purposes, for example on drinking glasses.

Reference symbol list

10

Laser

12

beam

14

adjustable attenuator

16

Decoupling arrow

18

mask

20

lens

22

Glass target

24

XY translator

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102015216342 B3 [0005]

Claims (11)

Method for providing glass targets (24) with an optically perceptible marking, comprising the steps: - providing a glass target (24), - irradiating the glass target (24) with laser radiation in the ultraviolet spectral range at a fluence between 200 and 450 mJ/cm ² , characterized in that a body is provided as said glass target (24), which is at least partially made of titanium-silicon glass with a silicon dioxide content between 10 and 70% by weight and a ratio of the weight proportions of titanium dioxide to silicon dioxide is between 0.1 and 1.5. Procedure according to Claim 1 , characterized in that the glass target (24) is irradiated with laser radiation with a wavelength between 180 and 220 nm, in particular between 190 and 200 nm. Method according to one of the preceding claims, characterized in that the glass target (24) is irradiated with pulsed laser radiation with a pulse duration between 1 and 100 ns, in particular between 10 and 30 ns. Procedure according to Claim 3 , characterized in that each point of the marking with which the glass target (24) is to be provided is irradiated with 100 to 1000 pulses, in particular with 100 to 750, in particular up to 100 to 500 pulses. Method according to one of the preceding claims, characterized in that the irradiation of the glass target (24) takes place through mask optics, by means of which a pattern corresponding at least in some areas to the marking with which the glass target (24) is to be provided is formed the glass target (24) is projected. Procedure according to Claim 5 , characterized in that the mask optics has a phase mask which is designed to generate a plurality of equidistant, parallel lines in an object plane of the glass target (24) by interference. Procedure according to one of the Claims 5 until 6 , characterized in that the area-wise irradiation of the glass target (24) takes place one after the other for different areas of the marking with which the glass target (24) is to be provided. Method according to one of the preceding claims, characterized in that the irradiation of the glass target (24) takes place under normal air, in particular at an air temperature between 0°C and 100°C. Glass product which carries a laser-induced, optically perceptible marking, obtained by a method comprising the steps: - providing a glass target (24), - irradiating the glass target (24) with laser radiation in the ultraviolet spectral range at a fluence between 200 and 450 mJ/cm ² , whereby a body is provided as the glass target (24), which is at least partially made of titanium-silicon glass with a silicon dioxide content between 10 and 70% by weight and a ratio of the weight proportions of titanium dioxide to silicon dioxide between 0.1 and 1.5. Glass product which carries a laser-induced, optically perceptible marking, characterized in that the glass product is at least partially made of titanium-silicon glass with a silicon dioxide content between 10 and 70% by weight and a ratio of the weight proportions of titanium dioxide to silicon dioxide between 0. 1 and 1.5, with the marking appearing black. Use of titanium-silicon glass with a silicon dioxide content between 10 and 70% by weight and a ratio of the weight proportions of titanium dioxide to silicon dioxide between 0.1 and 1.5 as a material for a glass target (24), which is used as part of a method for providing glass targets (24) with an optically perceptible marking, comprising the steps: - providing the glass target, - irradiating the glass target (24) with laser radiation in the ultraviolet spectral range at a fluence between 200 and 450 mJ/cm ² .

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