Sensor and method for simultaneously measuring pressure by crystalline luminescence and velocity by laser Doppler interferometry

Abstract

Sensor and method for simultaneously measuring pressure by crystalline luminescence and velocity by laser Doppler interferometry. The invention relates to a sensor (1) for simultaneously measuring pressure and velocity comprising: - a crystal (2) comprising a face covered with a reflective layer (3), - a pumping laser (4) configured to emit a pumping beam (F1) towards the crystal and having a wavelength within an absorption band of the crystal such that the illumination of the crystal by the pumping beam excites a portion of the electrons of the crystal, - a spectrometer (6) for receiving a luminescence signal (S1), resulting from a de-excitation of the electrons of the crystal, and for measuring the variation over time in wavelength of the lines of the light spectrum of said luminescence signal.- an interferometry system (12) configured to measure the velocity variations of the reflective layer over time by laser Doppler interferometry velocimetry. Figure for the abstract: Fig. 1,

Description

Title of the invention: Sensor and method for simultaneously measuring pressure by crystalline luminescence and velocity by laser Doppler interferometry technical field

[0001] The present invention relates to the field of pressure sensors and that of speed sensors. In particular, the present invention relates to both the field of pressure sensors by crystalline luminescence, in particular by ruby ​​luminescence (PRL), and the field of surface laser velocimeters, also called laser Doppler interferometry velocimeters (VIDL). Previous technique

[0002] When studying the behavior of materials under extreme conditions, it is common to measure the pressure exerted on the material or the material's deformation rate. In particular, during relatively slow compression tests, i.e., tests lasting on the order of seconds or even hours, it is customary to measure the pressure exerted on the material. During very rapid dynamic compression tests, i.e., tests lasting on the order of nanoseconds, for example in the form of a shock wave, it is customary to measure the material's deformation rate.

[0003] A known method of pressure measurement is pressure measurement by crystal luminescence, in particular ruby ​​luminescence pressure measurement (RLP). Ruby is an alumina crystal (Al₂O₃) containing chromium impurities and whose light absorption spectrum in the visible range exhibits two distinct absorption bands, one around 407 nm and the other around 551 nm [1]. Pressure measurement by crystal luminescence, particularly RLPP, is based on the principle of natural fluorescence of a target crystal, for example ruby, which is sensitive to the pressure exerted on said crystal.

[0004] When ruby ​​is irradiated in these absorption bands, some of its electrons become excited. This is followed by successive de-excitations of the excited electrons, during which photons are emitted by the ruby; this phenomenon is called luminescence. This ruby ​​luminescence exhibits two lines, known as the characteristic Ri and R2 lines of ruby ​​luminescence, with wavelengths at which the light intensity is maximum. At ambient temperature and pressure, these characteristic Ri and R2 lines of ruby ​​luminescence have wavelengths of 694.25 nm and 692.85 nm, respectively.

[0005] A variation in pressure exerted on the ruby ​​results in a variation in length The wavelength of photons emitted by ruby ​​luminescence is measured. In particular, the wavelengths of the characteristic Ri and R2 lines vary depending on the pressure exerted on the ruby. Thus, PRL measurement consists of measuring the variation in wavelength of the characteristic Ri and R2 lines over time and deducing the variation in pressure exerted on the ruby ​​over time.

[0006] Since the first static compression tests carried out with diamond anvil cells [2], PRL measurement has been commonly used to measure the pressure variation during static compression tests, particularly under extreme conditions. Static compression tests are relatively slow, i.e., they are on the order of a second, or even an hour.

[0007] Tests were carried out to determine whether single-crystal rubies of different orientations were suitable for dynamic compression tests [3], [4], [5], [6] and [7]. However, the use of PRL measurement to measure the pressure exerted on a material during a dynamic compression test is not known.

[0008] During dynamic compression tests, it is common to measure the rate of deformation of the material and, if necessary, to deduce the pressure exerted by using known models.

[0009] A known method for measuring the rate of deformation is surface laser velocimetry, also called laser Doppler interferometry velocimetry measurement (VIDL).

[0010] The VIDL measurement comprises illuminating a target surface with a laser and collecting the light reflected by said target surface using an interferometer in order to create interference patterns from said reflected light. The movement of the target surface, particularly during the passage of a shock wave, induces a Doppler shift in the optical frequency of the light reflected by the target surface. This shift in the optical frequency induces a change in the interference pattern created by the interferometer. It is thus possible to deduce the Doppler shift in the optical frequency of the reflected light from the change in the interference pattern created by the interferometer and thereby determine the velocity of the target surface over time.The VIDL measurement therefore includes measuring the time evolution of the interferences created by the interferometer and determining, from this measurement, the velocity of the target surface over time.

[0011] A common interferometer for performing a VIDL measurement is the velocity interferometer for any reflector, also known as the VISAR interferometer, for "Velocity Interferometer System for Any Reflector" [8]. The VISAR interferometer has the advantages of high measurement accuracy and being non-intrusive.

[0012] Another interferometer known for performing VIDL measurements is the Heterodyne Velocimetry (HV) interferometer, also known as the "Photon Doppler Velocimetry Interferometer" in English [9]. The HV interferometer has the advantages of being fully fiber-optic and more compact. It is therefore simple to implement in experimental protocols.

[0013] The VIDL measurement is often reserved for dynamic compression tests.

[0014] There are model equations for calculating the speed of the ruby ​​from a Measurement of pressure evolution by PRL, and model equations allowing calculation of the pressure exerted on a ruby ​​from a measurement of its velocity by VIDL,

[10] ,

[11] ,

[12] and

[13] . However, there are uncertainties regarding the velocities and pressures deduced by these models.

[0015] There is therefore a need to overcome these uncertainties. More broadly, there is a need to know precisely the pressure exerted on a crystal and its velocity over time during a test, particularly in compression, under extreme conditions.

[0016] In particular, there is a need for a device and / or a method for simultaneously measuring the pressure exerted on a crystal and its velocity during tests, particularly in static or dynamic compression.

[0017] The object of the invention is to meet, at least in part, this need(s). Description of the invention

[0018] To this end, the invention relates to a sensor for simultaneously measuring pressure and velocity comprising: - a crystal comprising one face covered with a reflective layer, - a pumping laser configured to emit a pumping beam towards the crystal and having a wavelength within an absorption band of the crystal such that the illumination of the crystal by the pumping beam excites some of the electrons in the crystal, - a spectrometer to receive a luminescence signal, resulting from the de-excitation of electrons in the crystal, and to measure the variation over time in wavelength of the lines of the light spectrum of said luminescence signal, - an interferometry system configured to measure the velocity variations of the reflective layer over time by laser Doppler interferometry velocimetry.

[0019] Preferably, the crystal is a ruby ​​crystal, preferably comprising a mass percentage of Cr3+ ions and / or chromium oxide between 0.05 and 0.5%.

[0020] Preferably, the reflective layer is a silver layer.

[0021] Preferably, the reflective layer has a thickness between 100 and 1000 nm.

[0022] Preferably, the pumping laser is a pulsed laser. Preferably, the pulsed laser is adapted to emit laser pulses with a duration between 5 ns and 50 ps and / or an average energy between 1 and 1000 rnJ.

[0023] Preferably, the wavelength of the pumping beam is between 500 and 560 nm.

[0024] Preferably, the sensor comprises a dichroic mirror transparent at the wavelength of the pumping beam and configured to select a portion of the luminescence signal whose wavelength falls within a predetermined range and direct only said selected portion to the spectrometer. Preferably, the predetermined range extends from 680 nm to 720 nm.

[0025] Preferably, the spectrometer comprises: - a spectroscope configured to decompose the luminescence signal into a plurality of light lines distributed according to their wavelength, forming the light spectrum, and, - a photodetector to capture and record the light spectrum over time.

[0026] According to a first variant, the interferometry system may include: - a sounding laser adapted to emit a sounding beam towards the crystal so as to be reflected by the reflective layer after transmission through the crystal, - a heterodyne velocimetry interferometer adapted to create interferences from the reflected part of the sounding beam, called the sounding signal, and to measure the time evolution of said interferences.

[0027] According to this first variant, the sensor preferably comprises a dielectric mirror that is reflective at the wavelength of the sounding beam and transparent at the wavelength of the pumping beam, the dielectric mirror being arranged between the crystal and the pumping laser so as to direct the sounding beam towards the crystal.

[0028] According to a second variant, the interferometry system may include a VISAR interferometer adapted to create interferences from a sounding signal, and to measure the time evolution of said interferences, the sounding signal being made up of a part of the pumping beam by the reflective layer.

[0029] According to this second variant, the sensor preferably includes a perforated mirror arranged between the crystal and the pumping laser so as to allow the pumping beam emitted by the pumping laser to pass to the crystal and to redirect the part of the pumping beam, reflected by the reflective layer, to the VISAR interferometer.

[0030] Preferably, the sensor includes an optical lens adapted to focus the pumping beam on the reflective layer, and where appropriate, to focus the probing beam on the reflective layer.

[0031] The invention also relates to a method for simultaneously measuring a pressure exerted on a crystal and with a speed of movement of said crystal, the crystal comprising a face covered with a reflective layer, the process comprising the following steps: a) illumination of the crystal by a pumping beam having a wavelength within an absorption band of the crystal so as to excite a portion of the electrons in the crystal, b) emission of a luminescence signal resulting from the de-excitation of electrons in the crystal, c) measurement of the variation over time in wavelength of the lines in the light spectrum of the luminescence signal, and, determination, from this variation, of the pressure exerted on the crystal over time, d) concurrently with steps a) to c), reception of a light signal, called a sounding signal, resulting from the reflection of a laser beam on the reflective layer, and determination of the speed of the reflective layer over time by monitoring the temporal evolution of interferences created from the sounding signal.

[0032] Preferably, the method is implemented by a sensor according to the present invention.

[0033] The invention also relates to the use of a sensor according to the present invention or of a method according to the present invention, for a static or dynamic compression test, a pulsed electrical discharge test, a ballistic resistance test, in particular simulating the impacts of space debris in orbit, or a mechanical test in which the pressure and velocity measured are induced by magnetic fields.

[0034] The present invention therefore essentially consists of a sensor and a method for simultaneously measuring the evolution of the pressure exerted on a crystal and the speed of movement of said crystal, in particular during a static or dynamic compression test.

[0035] Thus, it is possible to link and compare the measured pressure and velocity trends in order to reduce measurement uncertainties. It is also possible to validate or refute certain models of equations relating the pressure exerted on a crystal to the crystal's velocity. Furthermore, the crystal can serve as a gauge during a mechanical test of a material, particularly under extreme conditions.

[0036] Advantageously, the sensor according to the present invention may have a pumping laser with sufficient power to allow rapid and adequate excitation of the electrons in the crystal, for example on the order of nanoseconds or even less, so that said crystal emits, in less than 1 ns, a luminescence signal of sufficient intensity to be detected by the spectrometer, the temporal resolution of the spectrometer being less than 1 ns. Thus, the sensor is suitable for measuring pressure exerted on the crystal during a dynamic compression test. Brief description of the drawings

[0037] Other advantages and features will become clearer upon reading the detailed description, given by way of illustration and not limitation, with reference to the following figures:

[0038] [Fig-1] [Fig. 1] is a schematic view of a sensor for simultaneously measuring pressure and velocity according to a first embodiment of the invention in which the interferometry system for VIDL measurement comprises a probing laser and a VH interferometer;

[0039] [Fig.2A] [Fig.2A] represents the evolution over time of the light spectrum of the luminescence of a ruby, comprising 0.1% chromium oxide, following its illumination by a pumping laser emitting a continuous beam of wavelength equal to 532 nm and power equal to 5 W;

[0040] [Fig.2B] [Fig.2B] represents the evolution over time of the light spectrum of the luminescence of a ruby, comprising 0.1% chromium oxide, following its illumination by a pumping laser emitting laser pulses of wavelength equal to 532 nm, of duration equal to 10 ps and of average energy equal to 30 mJ;

[0041] [Fig.3] [Fig.3] represents the evolution over time, during a dynamic compression test, of the light spectrum of ruby ​​luminescence captured by the spectroscope of a sensor according to the present invention;

[0042] [Fig.4] [Fig.4] is a schematic view of a sensor for simultaneous measurement pressure and velocity according to a second embodiment of the invention in which the interferometry system for VIDL measurement includes a VISAR interferometer. Detailed description

[0043] For reasons of clarity, the different elements of the figures are represented to a free scale, the actual dimensions of the different parts not necessarily being respected.

[0044] Figure 1 illustrates a sensor 1 for simultaneously measuring pressure and speed according to a first embodiment of the invention.

[0045] The sensor 1 comprises a crystal 2, one face of which is coated with a reflective layer 3. The crystal 2 is ruby, i.e., an alumina crystal (Al₂O₃) containing chromium impurities, for example in the form of Cr³⁺ ions and / or chromium oxide (Cr₂O₃). Preferably, the crystal 2 is ruby ​​containing a mass fraction of Cr³⁺ ions and / or chromium oxide between 0.05% and 0.5%, for example, 0.1%. The reflective layer 3 is made of silver and has a thickness between 100 and 1000 nm.

[0046] The sensor 1 also includes a pumping laser 4 configured to emit a pumping beam Fi to crystal 2. The pumping laser 4 is a pulsed laser suitable for emitting laser pulses of duration between 5 ns and 50 ps and of average energy between 1 and 100 mJ.

[0047] The wavelength of the pumping beam Fi is included in one of the absorption bands of the crystal 2 so that the illumination of the crystal 2 by the pumping beam Fi excites a part of the electrons of the crystal 2. In particular, the wavelength of the pumping beam Fi is included in the absorption band at 551 nm of the ruby, for example between 500 and 560 nm, preferably equal to 532 nm.

[0048] The use of a pulsed laser as a pumping laser 4 in a crystal luminescence pressure measurement, particularly a PRL measurement, significantly increases the luminescence signal-to-noise ratio of the measurement. The pulsed laser also makes it possible to rapidly emit a high-power pumping beam Fi and thus obtain rapid and significant excitation of the electrons in the crystal 2.

[0049] The inventors obtained light spectra of the luminescence signal of a ruby, containing 0.1% chromium oxide, following its illumination by two different pumping lasers emitting a beam with a wavelength of 532 nm. Figures 2A and 2B show the results of these tests.

[0050] Fig. 2A shows the light spectrum, including the characteristic Ri and R2 luminescence lines of ruby, obtained by a continuous pumping laser emitting a beam with a power of 5 W.

[0051] Fig. 2B shows the light spectrum, including the characteristic Ri and R2 luminescence lines of ruby, obtained by a pulsed pumping laser emitting laser pulses of duration equal to 10 ps and of average energy equal to 30 mJ.

[0052] As can be seen from Figures 2A and 2B, the characteristic Ri and R2 luminescence lines of ruby ​​exhibit a greater light intensity relative to noise when ruby ​​is illuminated by a pulsed laser compared to when ruby ​​is illuminated by a continuous laser.

[0053] The sensor 1 also includes an optical lens 5 for focusing the pumping beam Fi emitted by the pumping laser 4 onto the reflective layer 3, the reflective layer 3 covering the face of the crystal 2 opposite the face of the crystal 2 facing the optical lens 5. Thus, the beam Fi passes through the crystal 2 before being focused onto the reflective layer 3.

[0054] During its passage, the pumping beam Fi excites a part of the electrons of the crystal 2 which then emits a luminescence signal Si, part of which is recovered by the optical lens 5 and directed towards a spectrometer 6 included by the sensor 1.

[0055] The sensor 1 may include a dichroic mirror 7 configured to select the part S'i of the luminescence signal Si whose wavelength is within a The predetermined range is directed to the spectrometer 6, with the remaining luminescence signal Si not directed to the spectrometer 6. The predetermined range includes the wavelength lines for which the luminous intensity of the luminescence signal Si is maximum. Preferably, the predetermined range extends from 680 nm to 720 nm, thus including the characteristic Ri and R2 luminescence lines of ruby.

[0056] The spectrometer 6 is configured to measure the wavelength variation of the received luminescence signal lines over time, in particular to measure the wavelength variation of the characteristic Ri and R2 luminescence lines of ruby. For this purpose, the spectrometer 6 may include a spectroscope 8 configured to decompose the received signal into a plurality of light lines distributed according to their wavelength, forming a light spectrum, and a photodetector 9 to capture and record the light spectrum over time.

[0057] Preferably, the spectroscope 8 is configured so as to focus, during the decomposition forming the light spectrum, on the characteristic Ri and R2 luminescence lines of ruby.

[0058] Preferably, the photodetector 9 has a temporal resolution of less than 1 ns.

[0059] The photodetector 9 can be a slit-scanning camera, preferably comprising a multi-alkaline photocathode, preferably the photocathode being of type S25. Such a photodetector 9 has a very low temporal resolution, in particular less than 1 ns, and a high sensitivity for measuring the light intensity of lines with wavelengths between 680 and 720 nm.

[0060] The spectrometer 6 may include an optical fiber 10, for conveying the part S'i of the luminescence signal Si selected by the dichroic mirror 7 to the spectroscope 8, and a fitting 11, for injecting the part S'i of the luminescence signal Si into the optical fiber 10.

[0061] The sensor 1 may include a calculation unit for calculating the evolution of the pressure exerted on the crystal 2 over time from the variations in wavelength of the luminescence signal lines measured by the spectrometer 6.

[0062] Figure 3 illustrates the wavelength evolution over time, during a dynamic compression test, of the characteristic RI and R2 lines of ruby ​​luminescence measured by the spectroscope of sensor 1 according to the present invention. As shown in Figure 3, sensor 1 has a suitable temporal resolution for measuring the pressure exerted on crystal 2 during a dynamic compression test.

[0063] The sensor 1 also includes an interferometry system 12 configured to measure the velocity variations of the reflective layer 3 over time by laser Doppler interferometry velocimetry (VIDL).

[0064] The interferometry system 12 comprises a sounding laser 13 and a Heterodyne Velocimetry (HV) interferometer 14. The sounding laser 13 is adapted to emit a sounding beam F2 directed so as to be reflected by the reflective layer 3 after being transmitted through the crystal 2. Preferably, the optical lens 5 focuses the sounding beam F2 onto the reflective layer 3. Preferably, the wavelength of the sounding beam F2 is between 1540 and 1560 nm, preferably equal to 1550 nm. Advantageously, ruby ​​is transparent at these wavelengths.

[0065] The sensor 1 may include a dielectric mirror 15 reflective at the wavelength of the probing beam S2 and transparent at the wavelength of the pumping beam Fi and at the wavelengths of the luminescence signal Sp. In particular, the dielectric mirror 15 is reflective in the infrared, especially at 1550 nm, and transparent in the visible.

[0066] The dielectric mirror 15 is arranged so as to direct the sounding beam F2 towards the crystal 2, in particular towards the optical lens 5 which focuses the sounding beam F2 onto the reflective layer 3. In particular, the dielectric mirror 15 is arranged between the optical lens 5 and the pumping laser 4, where appropriate between the optical lens 5 and the dichroic mirror 7.

[0067] The reflection of the sounding beam F2, called the sounding signal S2, is recovered by the optical lens 5 and directed towards the VH interferometer 14. In particular, the sounding signal S2 is reflected, after collimation by the optical lens 5, by the dielectric mirror 15 towards the VH interferometer 14.

[0068] The VH 14 interferometer is adapted to create interferences from the sounding signal S2 and to measure the time evolution of said interferences over time so as to deduce the variation of the velocity of the reflective layer 3 over time.

[0069] The interferometry system 12 may include an optical fiber 16, to carry the sounding signal S2 from the dielectric mirror 15 to the VH interferometer 14, and a fitting 17, to inject the sounding signal S2 into the optical fiber 16.

[0070] Figure 4 illustrates a sensor 1 for simultaneously measuring pressure and velocity according to a second embodiment of the invention. The sensor 1 of Figure 4 is similar to that of Figure 1 and differs from the latter in that the interferometry system 12 comprises a VISAR interferometer 18 instead of the sounding laser 13 and the VH interferometer 14.

[0071] In the embodiment illustrated in [Fig.4] it is a part of the pumping beam Fh reflected by the reflective layer 3, which serves as the sounding signal S2.

[0072] The sensor 1 may include a perforated mirror 19 arranged so as to allow the pumping beam Fi emitted by the pumping laser 4 to pass to the crystal 2 and to redirect the part of the pumping beam Fb reflected by the reflective layer 3 and forming the probing signal S2, to the VISAR interferometer 18. In particular, the perforated mirror 19 is arranged between the pumping laser 4 and the optical lens 5, where appropriate between the pumping laser 4 and the dichroic mirror 7.

[0073] The VISAR 18 interferometer is adapted to create interferences from the sounding signal S2 and to measure the temporal evolution of said interferences over time so as to deduce the variation of the velocity of the reflective layer 3 over time.

[0074] Other variations and improvements may be envisaged without departing from the scope of the invention as defined by the following claims. In particular, the present invention is not limited to ruby ​​as a crystal. Other crystals, exhibiting pressure-sensitive fluorescence under dynamic stress, may be considered. List of cited references

[0075] [1] C. Degli Esposti et al.: “Absorption and emission spectroscopy of a lasing material: ruby”, Journal of Chemical Education, 84(8): 1316-1318, 2007.

[0076] [2] RA Forman et al.: “Pressure measurement made by the utilization of ruby ​​sharp- line luminescence”, Science, 176(4032): 284-285, 1972.

[0077] [3] PD Horn et al.: “Wavelength shift of the ruby ​​luminescence R Unes under shock compression”, Applied Physics Letter, 49(14): 856-858, 1986.

[0078] [4] Y.M. Gupta et al.: “Potential use of the r2 line shift for static high-pressure ca libration”, Applied Physics Letter, 58(6): 583-585, 1991.

[0079] [5] S.M. Sharma et al.: “Theoretical analysis of R-line shifts of ruby subjected to different deformation conditions”, Physical Review B, 43(1): 879-893, 1991.

[0080] [6] X.A. Shen et al.: “Effect of crystal orientation on ruby R-line shifts under shock compression and tension”, Physical Review B, 48(5): 2929-2940, 1993.

[0081] [7] J.K. Hyun et al.: “Ruby R-line for shock compression along (1102)”, Journal of Applied Physics, 84(4): 1947-1952, 1998.

[0082] [8] L.M. Barker et al.: “Shock-wave studies of pmma, fused, silica, and saphire”, Journal of Applied Physics, 41(4208), 1970.

[0083] [9] D.H. Dolan: “Accuracy and précision in photon doppler velocimetry”, Review of Scientific Instruments, 81(053905), 2010.

[0084]

[10] P.D. Horn et al.: “Luminescence R-line spectrum of ruby crystals shocked to 125 kbar along the crystal c axis”, Physical Review B, 38(2): 973-979, 1989.

[0085]

[11] V.N. Korobenko et al.: “Electrical resistivity and équation of State mea- surements on hot expanded aluminum in the metal-nonmetal transition range”, Physical Review B, 75(064208), 2007.

[0086]

[12] J. Clérouin et al.: “Direct measurements and ab initio stimulations for expanded fluid aluminum in the metal-nonmetal transition rage”, Physical Review B, 78(224203): 59-66, 2008.

[0087]

[13] L.D. Landau et al.: “Téorétitcheskaïa fizika v 10 tomakh : Tom IV Guidro- dinamika”, Mir - Ellipses, 3, isbn 2-7298-9423-3 édition, 1994.

Claims

Demands

1. Sensor (1) for simultaneously measuring pressure and velocity comprising: - a crystal (2) comprising a face covered with a reflective layer (3), - a pumping laser (4) configured to emit a pumping beam (Fi) towards the crystal and having a wavelength within an absorption band of the crystal such that the illumination of the crystal by the pumping beam excites a portion of the electrons of the crystal, - a spectrometer (6) for receiving a luminescence signal (Si), resulting from a de-excitation of the electrons of the crystal, and for measuring the variation over time in wavelength of the lines of the light spectrum of said luminescence signal, - an interferometry system (12) configured to measure the variations in velocity of the reflective layer over time by laser Doppler interferometry velocimetry.

2. Sensor according to claim 1, the crystal being a ruby ​​crystal, preferably comprising a mass percentage of Cr3+ ions and / or chromium oxide between 0.05 and 0.5%.

3. Sensor according to claim 1 or 2, the reflective layer being a silver layer, preferably with a thickness between 100 and 1000

4. llili. Sensor according to any one of the preceding claims, the pumping laser being a pulsed laser, preferably adapted to emit laser pulses of duration between 5 ns and 50 ps and / or of average energy between 1 and 1000 mJ.

5. Sensor according to any one of the preceding claims, the wavelength of the pumping beam being between 500 and 560 nm.

6. Sensor according to any one of the preceding claims, comprising a dichroic mirror (7) transparent to the wavelength of the pumping beam and configured to select a portion (S'i) of the luminescence signal whose wavelength is within a predetermined range and direct only said selected portion to the spectrometer, preferably the predetermined range extending from 680 nm to 720 nm.

7. Sensor according to any one of the preceding claims, the spectrometer comprising: - a spectroscope (8) configured to decompose the luminescence signal into a plurality of light lines distributed according to their wavelength, forming the light spectrum, and, - a photodetector (9) to capture and record the light spectrum over time.

8. Sensor according to any one of the preceding claims, the interferometry system comprising: - a sounding laser (13) adapted to emit a sounding beam (F2) towards the crystal so as to be reflected by the reflective layer after transmission through the crystal, - a heterodyne velocimetry interferometer (14) adapted to create interferences from the reflected part of the sounding beam, called the sounding signal (S2), and to measure the time evolution of said interferences.

9. Sensor according to the preceding claim, comprising a dielectric mirror (15) reflective at the wavelength of the sounding beam and transparent at the wavelength of the pumping beam, the dielectric mirror being arranged between the crystal and the pumping laser so as to direct the sounding beam towards the crystal.

10. Sensor according to any one of claims 1 to 8, the interferometry system comprising a VISAR interferometer (18) adapted to create interferences from a sounding signal (S2), and to measure the time evolution of said interferences, the sounding signal being made up of a part of the pumping beam by the reflective layer.

11. Sensor according to the preceding claim, comprising a perforated mirror (19) arranged between the crystal and the pumping laser so as to allow the pumping beam emitted by the pumping laser to pass to the crystal and to redirect the portion of the pumping beam, reflected by the reflective layer, to the VISAR interferometer.

12. Sensor according to any one of the preceding claims, comprising an optical lens (5) adapted to focus the pumping beam on the reflective layer, and where appropriate, to focus the probing beam (F2) on the reflective layer.

13. A method for simultaneously measuring the pressure exerted on a crystal (2) and the speed of movement of said crystal, the crystal comprising a face covered with a reflective layer (3), the method comprising the following steps: a) illumination of the crystal by a pumping beam (Fi) having a wavelength within an absorption band of the crystal so as to excite a part of the electrons of the crystal, b) emission of a luminescence signal (Si) resulting from a de-excitation of the electrons of the crystal, c) measurement of the variation over time in wavelength of the lines of the light spectrum of the luminescence signal, and, determination, from this variation, of the pressure exerted on the crystal over time, d) concomitantly with steps a) to c), reception of a light signal, called the sounding signal (S2), resulting from the reflection of a laser beam on the reflective layer, and determination of the velocity of the reflective layer over time by monitoring the temporal evolution of interferences created from the sounding signal.

14. Method according to the preceding claim, being implemented by a sensor according to any one of claims 1 to 12.

15. Use of a sensor according to any one of claims 1 to 12 or of a method according to claim 13 or 14, for a static or dynamic compression test, a pulsed electrical discharge test, a ballistic resistance test, in particular simulating the impacts of space debris in orbit, or a mechanical test in which the pressure and velocity measured are induced by magnetic fields.

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