WO2015082836A1

WO2015082836A1 - Method for measuring the temperature of a glass

Info

Publication number: WO2015082836A1
Application number: PCT/FR2014/053139
Authority: WO
Inventors: Pierre Lombard; Florent Michel; René Gy
Original assignee: Saint-Gobain Glass France
Priority date: 2013-12-02
Filing date: 2014-12-02
Publication date: 2015-06-11
Also published as: FR3014193A1; FR3014193B1

Abstract

This contact-free method for measuring the temperature of a glass having a given composition containing iron comprises steps that involve: (a) irradiating the glass with radiation making it possible to observe an absorption band of the glass in the spectral band 300 nm to 900 nm, and measuring the position of the absorption edge of the glass in this spectral band; (b) determining the temperature of the glass by using a reference curve giving, for the given glass composition, the change in the position of the absorption edge of the glass in at least a part of the spectral band 300 nm to 900 nm depending on the temperature.

Description

MEASURING METHOD

TEMPERATURE OF A GLASS

The present invention relates to a non-contact measurement method of the temperature or redox of a glass.

It is known to measure the temperature of a glass by non-contact methods using the infrared radiation emitted by the glass. A conventional method is, in particular, the use of an infrared pyrometer, which determines the temperature by quantifying the radiative energy emitted by the glass in the infrared. Obtaining the temperature of the glass from the detected infrared radiative energy requires knowledge of the emissivity of the glass. However, emissivity is a poorly known quantity, which is difficult to measure, especially when it is not at ambient temperature. In addition, the detection of the infrared radiation emitted by the glass is disturbed by the parasitic infrared radiation emitted by all the hot bodies situated near the glass, such as the walls of an oven in the case of a molten glass, or surrounding surfaces in the case of glazing. It is therefore difficult to access a reliable measurement of the temperature of a glass by methods using infrared radiation.

In addition, it is difficult to measure the redox of a glass by a contactless method. The redox of a glass is defined as the ratio of the weight content of FeO (ferrous iron) to the weight content of total iron oxide (expressed as Fe2O3).

It is these drawbacks that the invention intends to remedy more particularly by proposing a method for measuring without contact the temperature or the redox of a glass, reliably, simply and rapidly, whether a liquid glass, for example a molten glass in an oven, or a solid glass, for example a building glazing or a glass being formed.

For this purpose, the subject of the invention is a non-contact measurement method of a first characteristic, among the temperature and the redox, of a glass having a given composition containing iron and having a given value of its second characteristic among the temperature and the redox, characterized in that it comprises steps in which:

(a) irradiating the glass with radiation enabling observation of a glass absorption band in the 300 nm to 900 nm spectral band, and measuring the position of the absorption front of the glass in this spectral band;

(b) using a reference curve giving, for the given glass composition and the given value of the second characteristic, evolution of the position of the glass absorption front in at least a part of the spectral band 300 nm to 900 nm depending on the first characteristic, the first characteristic of the glass is determined.

According to one aspect of the invention, the reference curve for the given glass composition and the given value of the second characteristic are obtained beforehand.

(i) applying the following procedure for at least two given values distinct from the first characteristic: for each given value of the first characteristic, a glass sample is irradiated, which has the given composition and the given value of the second characteristic and which is maintained at the given value of the first characteristic, with radiation comprising at least a portion of the spectral band 300 nm to 900 nm, and measuring the position of the absorption front of the glass in this spectral band; then

(ii) plotting the curve giving, for the given glass composition and the given value of the second characteristic, the evolution of the position of the absorption front of the glass as a function of the first characteristic.

In the context of the invention, the position of the absorption front of a glass in the spectral band 300 nm to 900 nm can be defined as being the wavelength for which the slope of the tangent to the curve of Glass absorption in the 300 nm to 900 nm spectral band is negative and maximum in absolute value. Other criteria may be chosen to define the position of the absorption front, provided that the same criterion is applied for the measurement of step (a) and for establishing the reference curve used in step (b). ). We here "glass absorption curve" means a curve giving the evolution of a quantity representative of the absorption of the glass as a function of the wavelength, in which the magnitude representative of the absorption may be, in particular, absorbance, linear absorption coefficient or molar absorption coefficient.

Of course, the determination of the wavelength for which the slope of the tangent to the absorption curve of the glass in the 300 nm to 900 nm spectral band is negative and maximum in absolute value can be automated and carried out at the same time. using any appropriate electronic computing unit. In particular, the slope of the tangent at each point of the absorption curve is equal to the derivative of the absorption curve. Therefore, the step of determining the wavelength for which the slope of the tangent to the absorption curve of the glass in the spectral band 300 nm to 900 nm is negative and maximum in absolute value can be realized, in the scope of the invention, calculating the derivative at each point of the absorption curve in the spectral band 300 nm to 900 nm and by searching among the negative slopes the maximum value in absolute value.

In practice, it is not always possible to acquire the totality of the absorption curve of the glass in the spectral band 300 nm at 900 nm, because of technical constraints, which can be linked in particular to a too large thickness of glass or saturation of the detectors used. In cases where the wavelength for which the slope of the tangent to the absorption curve of the glass in the spectral band 300 nm to 900 nm is negative and maximum in absolute value is not present on the curve of absorption actually measured, the position of the absorption edge of the glass in the spectral band 300 nm to 900 nm can be defined as being the wavelength for which the slope of the tangent to the absorption curve actually measured is negative and maximum in absolute value, which corresponds in general to the largest observed value of the magnitude representative of the absorption of the glass. As explained above, if this criterion is chosen to define the position of the absorption front, this criterion must be applied both for the measurement of step (a) and for establishing the reference curve used in step (b).

The invention is based on the presence, in the absorption spectrum of any glass whose composition contains iron, of a charge transfer band between Fe ³⁺ and its oxygen ligand, which is a very intense band because it is formed by the permissible transition of an electron from Fe ³⁺ to a 2p orbital of its oxygen ligand. When the glass is at a temperature of 25 ° C, the negative slope edge of the Fe ³⁺ - O charge transfer band is between 300 nm and 500 nm. As used herein, the flanks of a band in an absorption spectrum are the non-zero slope portions that enclose the top of the strip. It has been found that the negative slope edge of the Fe ³⁺ -O charge transfer band shifts strongly towards the long wavelengths as the temperature of the glass increases, while remaining in the 300 nm to 900 spectral band. nm.

It has been found that, similarly, for a glass kept at a constant temperature, the negative slope edge of the Fe ³⁺ -O charge transfer band shifts strongly towards the long wavelengths as the glass redox increases. .

The invention takes advantage of this phenomenon to propose a new non-contact measurement method of the temperature or redox of a glass, which works for all glasses containing iron, whether in liquid or solid form. This method, which only requires the measurement of the absorption spectrum of the glass in at least a part of the spectral band 300 nm to 900 nm, is simple and quick to implement. It also makes it possible to achieve a good measurement sensitivity, especially less than 10 ° in the case of measuring the temperature of the glass, thanks to the intensity and the high temperature shift of the Fe ³⁺ charge transfer band. -O. The method according to the invention also has the advantage, compared to known methods of measuring temperature using the infrared radiation emitted by the glass, to be less disturbed by the infrared radiation of the surrounding hot objects.

The glass may be, in particular, a silico-soda-lime, borosilicate, aluminosilicate or alumino-borosilicate type glass. Preferably, in order to have a sufficient intensity of the charge transfer band Fe ³⁺ -O and thus to obtain a correct accuracy on the measurement of the temperature of the glass, the iron oxide content of the glass is greater than 0.01% (100 ppm).

Preferably, the absorbers of the glass composition in the 300 nm to 900 nm spectral band consist essentially of iron species (ferrous iron, ferric iron). The term "absorbing agents in the spectral band 300 nm to 900 nm essentially consists of iron species" means that any other absorbing agents are present in such quantities that they do not substantially affect the position of the forehead. absorption of glass in the spectral band 300 nm to 900 nm. By way of example, for an iron oxide content of 100 ppm: the CuO content does not exceed 200 ppm; the en2 content does not exceed 0.2%; the Cr ₂ O ₃ content does not exceed 20 ppm; the NiO content does not exceed 20 ppm; the CoO content does not exceed 10 ppm; the MnO2 content does not exceed 200 ppm; the V2O3 content does not exceed 500 ppm; the Sb2O3 content does not exceed 1000 ppm; the content of CeO 2 does not exceed 50 ppm.

The invention also relates to a non-contact temperature measurement method of a glass having a given composition containing iron, comprising steps in which:

(b) using a reference curve giving, for the given glass composition, the evolution of the position of the absorption front of the glass in at least a part of the spectral band 300 nm to 900 nm in depending on the temperature, the temperature of the glass is determined.

As mentioned above, the glass may be, in particular, a glass of silico-soda-lime, borosilicate, aluminosilicate or alumino-borosilicate type. Preferably, in order to have a sufficient intensity of the charge transfer band Fe ³⁺ -O and thus to obtain a correct accuracy on the measurement of the temperature of the glass, the iron oxide content of the glass is greater than 0.01% (100 ppm).

Preferably, the absorbent agents of the glass composition in the 300 nm to 900 nm spectral band consist essentially of the iron species (ferrous iron, ferric iron), that is to say as before that of any other agents. Absorbents are present in amounts such that they do not substantially affect the position of the glass absorption front in the 300 nm to 900 nm spectral band.

According to one aspect of the invention, the reference curve for the given glass composition is obtained beforehand.

(i) by applying the following procedure for at least two distinct given temperatures: for each given temperature, a glass sample, which has the given composition and which is maintained at the given temperature, is irradiated with radiation comprising at least a part from the spectral band 300 nm to 900 nm, and the position of the absorption edge of the glass sample in this spectral band is measured; then

(ii) plotting the curve giving, for the given glass composition, the evolution of the position of the absorption edge of the glass sample as a function of the temperature.

The reference curve can be established for a temperature range in the range of -270 ° C to 1600 ° C, for practical reasons preferably for a temperature range in the range of -70 ° C to 1600 ° C, further preferably for a temperature range in the range of -10 ° C to 1600 ° C.

In order to obtain a good position of the absorption front of the glass, it is necessary to correct the emission of the black body from 700 ° C for the glass matrices mentioned above. For this purpose, the absorption of the glass in the spectral band 300 nm to 900 nm is measured whereas the glass is not irradiated, that is to say while the radiation source used to irradiate the glass in this spectral band is off; we measure the absorption of the glass in the spectral band 300 nm to 900 nm whereas the glass is irradiated with the radiation comprising at least a part of the spectral band 300 nm at 900 nm, that is to say while the source of radiation is on; the position of the absorption front of the glass in the 300 nm to 900 nm spectral band is then determined from the measured absorption while the glass is irradiated from which the measured absorption has been subtracted while the glass is not not irradiated.

Preferably, the procedure of step (i) is applied for a plurality of different temperatures, in particular with a pitch of 100 ° C. in the temperature range of interest, in order to increase the accuracy of the temperature measurement obtained. according to the invention.

Advantageously, when it is desired to establish the reference curve for a given temperature range in the range of 25 ° C to 1000 ° C, it suffices to apply the procedure of step (i) for two temperatures distinct in the given range. Indeed, it has been measured that the evolution of the position of the glass absorption front as a function of temperature is linear in the temperature range of 25 ° C to 1000 ° C.

The evolution of the position of the absorption edge of the glass sample as a function of the temperature may depend on the redox of the glass if it changes with temperature. As mentioned previously, redox is defined as the ratio of the weight content of FeO (ferrous iron) to the weight content of total iron oxide (expressed as Fe2O3). This number can vary between 0 and 0.9, zero redox corresponding to a totally oxidized glass. In practice, it has been found experimentally that, for a measurement lasting 7 hours on a glass sample having a volume of the order of 100 mm ³ in an air atmosphere, the redox of the glass sample does not vary. significantly during the temperature rise of the glass in the range -10 ° C to 800 ° C.

Preferably, for measuring the temperature of a glass having a given composition and a given redox, the reference curve used in step (b) is established for this given glass composition and given redox. Advantageously, the position of the absorption edge of the glass in the spectral band 300 nm to 900 nm can be measured using a spectrometer. The spectrometer may have, in particular, a CCD detector (Charge Coupled Device), PDA (Photodiode Array), PbS or InSb, preferably a combination of such detectors to allow the detection of radiation over a wide range of lengths. wave from ultraviolet to near infrared.

In one embodiment of the invention, the radiation source used to irradiate the glass and the detector used to measure the absorption of the glass in step (a), respectively in step (i), are located in on both sides of a glass thickness. This arrangement corresponds to a transmission configuration, where the detected radiation has been transmitted by the glass. Such an assembly is suitable, in particular, for measuring the temperature of a glazing unit, such as a building or vehicle glazing, or a glass being formed, for example by a Float process, in particular at the Float outlet, by a rolling process, or by a bending process. In the case of a measurement on a glass passing on metal rollers, it is ensured that the source and the detector are positioned on both sides of a glass thickness away from the rollers, in particular between successive rolls, so as to avoid radiation reflections on the rollers.

In another embodiment, the radiation source used to irradiate the glass and the detector used to measure the absorption of the glass in step (a), respectively in step (i), are located next to the same surface of the glass. This arrangement corresponds to a configuration in reflection, where the detected radiation has been reflected while having passed through the glass. Such an arrangement is particularly suitable for measuring the temperature of a molten glass, especially in an oven. The path of the radiation, which passes through the glass and out through the glass surface through which it initially entered the glass, can be obtained by positioning a reflecting surface of ultraviolet radiation and visible at the rear of the entrance surface of the glass. radiation in the glass, either inside the glass or behind the glass. In the case of a measurement on a glass passing on metal rolls, for example a glass being formed, the reflective surface may be formed by one of the rollers. In a variant, this path of the radiation can be obtained thanks to a variation in the refractive index of the glass, particularly in the case of a molten glass bath.

When the two steps (a) and (i) are implemented with a fitting corresponding to a reflection configuration, it is preferable that the angle of reflection of the radiation on the surface of the glass is the same between step (a) and ) and step (i). This allows steps (a) and (i) to be performed under similar polarization conditions of the radiation.

In one embodiment of the invention, the radiation used to irradiate the glass in step (a) is a polychromatic radiation corresponding to at least a portion of the 300 nm to 900 nm spectral band.

Alternatively, in step (a), the radiation used to irradiate the glass may be monochromatic radiation whose wavelength is between 300 nm and 900 nm, including radiation emitted by a laser source. An application involving monochromatic radiation is, for example, the control of the temperature of a glass to prevent the temperature from passing a certain threshold of critical temperature. The wavelength of the monochromatic radiation used to irradiate the glass can then advantageously be chosen to correspond, on the reference curve, to the critical temperature, while the detector designed to measure the absorption of the glass can be connected to a system. alarm, particularly sound or visual, which is triggered when the detector no longer detects the wavelength of the monochromatic radiation.

The radiation used to irradiate the glass in step (i) is itself a polychromatic radiation corresponding to all or part of the spectral band 300 nm to 900 nm, so as to allow the measurement of the position of the absorption front. of the glass sample for several different temperatures, in particular for at least two different temperatures, of the sample. According to a variant, both for the determination of the first characteristic of a glass among the temperature and the redox and for the establishment of the reference curve, the glass is irradiated with the same monochromatic radiation of wavelength included between 300 nm and 900 nm, in particular radiation emitted by a laser source. In this case, a curve showing the evolution of the absorption value (or intensity) of the glass at the wavelength of the monochromatic radiation as a function of the first characteristic is established as a reference curve and the first characteristic of the glass studied from the measurement of the value (or intensity) of absorption of the glass at the wavelength of the monochromatic radiation.

According to one aspect of the invention, it is possible to obtain a map of the temperature of a glass by imposing a relative displacement between, on the one hand, the glass and, on the other hand, the radiation source used for irradiating the glass and the detector used to measure the absorption of the glass in step (a), where the source and the detector are positioned relative to one another permanently adapted for the detector to receive radiation who went through the glass.

The invention also relates to a device for implementing a method as described above, comprising a radiation source capable of emitting radiation corresponding to at least a portion of the 300 nm to 900 nm spectral band. and a radiation detector capable of detecting radiation in at least a portion of the 300 nm to 900 nm spectral band.

In order to obtain a map of the temperature of a glass, this device may comprise displacement means able to impose a relative displacement between, on the one hand, the glass and, on the other hand, the source and the detector , where the source and the detector have a positioning relative to each other permanently adapted so that the detector receives radiation that has passed through the glass.

The characteristics and advantages of the invention will appear in the following description of several embodiments of a method and a device for measuring the temperature of a glass according to the invention, given solely by way of example and with reference to the accompanying drawings in which:

- Figure 1 is a schematic view of a device used to establish the reference curve for a given glass composition;

FIG. 2 is a graph showing the change in temperature of the absorption spectrum in the 320 nm to 500 nm spectral band of the glass sample of FIG. 1 having the given glass composition, from 25.degree. C. to 700.degree. ° C with a step of 100 ° C;

FIG. 3 is the reference curve giving, for the given glass composition, the evolution of the position of the absorption edge of the glass sample as a function of temperature, which has been obtained from the graph of Figure 2;

FIG. 4 is a schematic view of a device used for measuring the temperature of a glass having the given glass composition, corresponding to a transmission configuration;

FIG. 5 is the absorption spectrum obtained with the device of FIG. 4;

FIG. 6 is a schematic view of another device used to measure the temperature of a glass having the given glass composition, corresponding to a reflection configuration; and

FIG. 7 is the absorption spectrum obtained with the device of FIG. 6.

FIG. 1 shows a device 9 used to establish a reference curve giving, for a given glass composition, the evolution of the position of the absorption front of the glass in at least a part of the spectral band 300 nm to 900 nm depending on the temperature.

In this example, the device 9 comprises a radiation source 1, formed by a deuterium lamp and a halogenated tungsten lamp, which provide a radiation spectrum of 180 nm to 1200 nm, and a radiation detector 5, formed by a photomultiplier and PbS detectors, which are capable of detecting radiation from 175 nm to 3300 nm. The device 9 also comprises a heating plate 3, intended to hold a glass sample 8 at different levels of distinct temperatures, as well as radiation redirecting mirrors 2 and 4 respectively between the source 1 and the sample 8 and between the sample 8 and the detector 5.

In this example, the sample 8 is a parallel fragment of silico-soda-lime clear glass, sold under the name SGG Planilux by Saint-Gobain Glass, having a thickness of 4 mm and having an optical polish so as to guarantee a good flatness of its main surfaces.

Using the device 9, the absorption spectrum of the sample 8 is acquired in the spectral band 320 nm at 500 nm for several different temperature levels of the sample 8 taken in the temperature range of 25 ° C. at 700 ° C, with a step of 100 ° C. The temperature acquisition is limited with this device at 700 ° C because the radiation of the heating plate 3 and the sample 8 at higher temperatures dazzle the detector 5. The measurement can also be disturbed below 700 ° C and, to correct this problem, an acquisition sequence of the following absorption spectra is used for each temperature step:

- spectrum of sample 8 with source 1 on (A _{sample wo%} ); - spectrum of sample 8 with source 1 extinguished (A _{sample 0%} );

- S ectre of the heating stage 3 with the source 1 on

- S ectre of the heating stage 3 with the source 1 extinguished

The linear absorption coefficient of the sample 8 is then equal to:

FIG. 2 is the graph showing, for each temperature step from 25 ° C. to 700 ° C., the absorption spectrum Abs = ί (λ) of the sample 8 in the spectral band 320 nm at 500 nm obtained with the device 9. In this figure 2, the position of the absorption front for each temperature level is marked as the wavelength λ for which the slope of the tangent to the absorption curve actually measured is negative and maximum in absolute value, which corresponds for each temperature step to a value of the linear absorption coefficient Abs of 5 cm ^"1 .

It is thus possible to establish, from the graph of FIG. 2, the evolution curve of the position of the absorption front of the sample 8 as a function of the temperature T, as shown in FIG. 3, which corresponds to FIG. value of the linear absorption coefficient Abs of 5 cm ^-1 .The curve of FIG. 3 is a reference curve which can be used, in accordance with the method of the invention, to measure the temperature of a glass having the PLANILUX composition, regardless of the state of the glass, in particular liquid for a molten glass in a furnace or solid for a glass being formed or already formed.

FIG. 4 shows a device 19 that can be used to measure the temperature of a substrate 10. The substrate 10 is a clear silico-soda-lime glass substrate marketed under the name SGG Planilux by the company Saint-Gobain Glass, having a thickness of 6 mm. The substrate 10 is at an unknown temperature T, which it is desired to measure according to the method of the invention.

In this example, the device 19 comprises a radiation source 11, which is a commercial lamp of the LDLS ™ EQ-99FC type providing, via a fiber, a radiation spectrum of 170 nm to 2100 nm, and a radiation detector 15 , which is a commercial AvaSpec-ULS2048L type CCD detector spectrometer capable of detecting, via a fiber, a radiation of 200 nm at 1100 nm.

As shown in Figure 4, the source 1 1 and the detector 15 are located on either side of the substrate 10, each facing a main surface of the substrate. In practice, the fiber of the source 1 1 is positioned facing a first main surface 10A of the substrate and the fiber of the detector 15 facing the opposite main surface 10B of the substrate, each fiber being at a distance from the order 1 m from the corresponding surface of the substrate due to heat. The radiation emitted by the source 11 is incident on the main surface 10A of the substrate 10 and spring of the substrate by the main surface 10B. The device 19 thus corresponds to a transmission measurement configuration, where the radiation detected by the detector 15 has been transmitted by the substrate 10.

FIG. 5 shows the absorption spectrum in the spectral band 300 nm at 600 nm of the substrate 10, obtained using the device 19. In this FIG. 5, the position of the absorption front of the substrate 10 in the spectral band 300 nm at 900 nm, which is marked as being the wavelength for which the value of the linear absorption coefficient Abs is 5 cm ^-1, in which case a position of the substrate absorption front is obtained. 10: λ = 400 nm.

The temperature of the substrate 10 is then deduced using the reference curve of FIG. 3, by plotting the position of the absorption front λ = 400 nm on the reference curve. In this example, the temperature T of the substrate 10 is thus 650 ° C.

FIG. 6 shows another device 29 that can be used to measure the temperature of the substrate 10, which is the same substrate as that of FIG. 4 but whose temperature has been allowed to evolve with respect to FIG. 4. The device 29 differs from the device 19 previously described only in that the source 1 1 and the detector 15 are located this time opposite a same main surface 10A of the substrate 10, while a reflective surface 27 formed by an aluminum plate is positioned at the rear of the substrate 10, facing the main surface 10B of the substrate opposite to the surface 10A. The radiation emitted by the source 11 is incident on the main surface 10A of the substrate 10, passes through the substrate 10 and leaves the substrate by the main surface 10B, then it is reflected by the reflecting surface 27 so that it returns to incidence on the main surface 10B, crosses the substrate 10 and leaves through the main surface 10A. The device 29 thus corresponds to a measurement configuration in reflection, where the radiation detected by the detector 15 has been reflected while having passed through the substrate 10.

FIG. 7 shows the absorption spectrum in the spectral band 300 nm at 600 nm of the substrate 10, obtained using the device 29. FIG. 7 determines the position of the absorption front of the substrate 10 in the spectral band 300 nm at 900 nm, which is marked as being the wavelength for which the value of the linear absorption coefficient Abs is 5 cm. . ^"1 obtained in this example a position of the absorption edge of the substrate 10: λ = 370 nm.

The temperature of the substrate 10 is then deduced using the reference curve of FIG. 3, by plotting the position of the absorption front λ = 370 nm on the reference curve. In this example, the temperature T of the substrate 10 is thus 375 ° C.

The invention is not limited to the examples described and shown. In particular, the invention allows a non-contact measurement of the temperature of any glass containing iron, including, but not limited to, glasses of the silico-soda-lime, borosilicate, aluminosilicate, and aluminosilicate type.

Claims

1. Non-contact measuring method of a first characteristic, among temperature and redox, of a glass having a given composition containing iron and having a given value of its second characteristic among temperature and redox, characterized in that it includes steps in which:

2. Method according to claim 1, characterized in that, beforehand, the reference curve for the given glass composition and the given value of the second characteristic are obtained.

3. Non-contact measurement method of the temperature of a glass having a given composition containing iron, characterized in that it comprises steps in which: (a) irradiating the glass with radiation enabling observation of a glass absorption band in the 300 nm to 900 nm spectral band, and measuring the position of the absorption front of the glass in this spectral band;

4. Method according to claim 3, characterized in that, beforehand, the reference curve for the given glass composition is obtained.

5. Method according to any one of claims 3 or 4, characterized in that the reference curve is established for a range of temperatures in the range of -270 ° C to 1600 ° C.

6. Method according to any one of claims 3 to 5, characterized in that the glass whose temperature is measured at a given redox, the reference curve used in step (b) being established for this given redox.

7. Method according to any one of the preceding claims, characterized in that the position of the absorption edge of the glass in the spectral band 300 nm to 900 nm is measured using a spectrometer.

8. Method according to any one of the preceding claims, characterized in that, in step (a), the source of radiation used to irradiate the glass and the detector used to measure the absorption of the glass are located on both sides of a glass thickness.

9. Method according to any one of claims 1 to 7, characterized in that, in step (a), the radiation source used to irradiate the glass and the detector used to measure the absorption of the glass are located in look at the same surface of the glass.

10. Method according to any one of claims 2 to 9, characterized in that, in step (i), the radiation source used to irradiate the glass sample and the detector used to measure the absorption of the glass sample are located on either side of the glass sample.

1 1. Method according to any one of claims 2 to 9, characterized in that, in step (i), the radiation source used to irradiate the glass sample and the detector used to measure the absorption of the sample of glass are located opposite one and the same surface of the glass sample.

12. Method according to any one of the preceding claims, characterized in that, in step (a), the radiation used to irradiate the glass is a polychromatic radiation corresponding to at least a portion of the spectral band 300 nm to 900 nm.

13. Method according to any one of claims 1 to 1 1, characterized in that, in step (a), the radiation used to irradiate the glass is a monochromatic radiation whose wavelength is between 300 nm and 900 nm, in particular radiation emitted by a laser source.

14. Process according to any one of Claims 2 to 13, characterized in that, in step (i), the radiation used to irradiate the glass is a polychromatic radiation corresponding to at least a part of the 300 nm spectral band. at 900 nm.

15. Method according to any one of the preceding claims, characterized in that imposes a relative displacement between, on the one hand, the glass and, on the other hand, the radiation source used to irradiate the glass and the detector. used to measure the absorption of glass, where the source and the detector have a positioning relative to each other permanently adapted so that the detector receives radiation that has passed through the glass.

16. Device for implementing a method according to any one of claims 1 to 15, characterized in that it comprises a radiation source capable of emitting radiation corresponding to at least a portion of the spectral band 300 nm at 900 nm and a radiation detector capable of detecting radiation in at least a portion of the spectral band 300 nm at 900 nm.

17. Device according to claim 16, characterized in that it comprises displacement means able to impose a relative displacement between, on the one hand, the glass and, on the other hand, the source and the detector, where the source and the detector have a positioning relative to each other permanently adapted so that the detector receives radiation that has passed through the glass.