FOR HIGH-RESOLUTION X-RAY IMAGING - LIF DETECTORS-POLYCAPILLARY LENS COMBINATION

FOR HIGH-RESOLUTION X-RAY IMAGING - LIF DETECTORS-POLYCAPILLARY LENS COMBINATION

FOR HIGH-RESOLUTION X-RAY IMAGING - LIF DETECTORS-POLYCAPILLARY LENS COMBINATION

INFN-LNF, Frascati 10 April 2018 LiF DETECTORS-POLYCAPILLARY LENS COMBINATION FOR HIGH-RESOLUTION X-RAY IMAGING F. Bonfigli1, D. Hampai2, S.B. Dabagov2,3,4, R. M. Montereali1 1 ENEA C.R. Frascati, Fusion and Technologies for Nuclear Safety and Security Dep., Photonics Micro‐ and Nano‐structures Laboratory, FSN‐TECFIS‐MNF, V. E. Fermi, 45, 00044 Frascati (Rome), Italy 2 INFN ‐ LNF, Via E. Fermi 40, I‐00044 Frascati, Italy 3RAS PN Lebedev Physical Institute, Leninsky pr. 53, 119991 Moscow, Russia 4 NR Nuclear University MEPhI, Kashirskoe sh. 31, 115409 Moscow, Russia

FOR HIGH-RESOLUTION X-RAY IMAGING - LIF DETECTORS-POLYCAPILLARY LENS COMBINATION

Titolo della presentazione - Luogo e data Outline LiF-based radiation detectors LiF: material properties and color centers Principle of operation – optical reading Peculiarities and applications LiF detectors for X-ray imaging - X-ray tubes combined with polycapillary optics and LiF detectors as a compact X-ray imaging facility 2D contact X-ray micro-radiographies on LiF detectors by X-ray tubes combined with X-ray polycapillary optics (test and geological samples) 2D and 3D characterizations of X-ray polycapillary optics by using confocal fluorescence microscopy as advanced optical reading of LiF detectors Conclusions F.

Bonfigli, INFN-LNF, 10 April 2018

FOR HIGH-RESOLUTION X-RAY IMAGING - LIF DETECTORS-POLYCAPILLARY LENS COMBINATION

Titolo della presentazione - Luogo e data Color centers in LiF 3 This detector is based on the photoluminescence of color centers in lithium fluoride (LiF) films and crystals. LiF is of particular interest because : •it is almost non-hygroscopic •it can host point defects stable at room temperature •it can host laser active color centers tunable in a broad wavelength range in the VIS and NIR. Optically active defects in LiF can be generated by ionizing radiation like charged particles (electrons and ions), as well as gamma and X-rays. F2 and F3 + centers are optically active F-aggregates consisting in two electrons bound to two and three close anion vacancies, respectively.

F center is an anion vacancy occupied by an electron; they are not optically active centers F - Li+ e- F2 CC F center F2 center F3 center 3 F. Bonfigli, INFN-LNF, 10 April 2018

FOR HIGH-RESOLUTION X-RAY IMAGING - LIF DETECTORS-POLYCAPILLARY LENS COMBINATION

Titolo della presentazione - Luogo e data Optical properties of color centers in LiF 4 Color centers in lithium fluoride Absorption and Emission bands F. Bonfigli, INFN-LNF, 10 April 2018

FOR HIGH-RESOLUTION X-RAY IMAGING - LIF DETECTORS-POLYCAPILLARY LENS COMBINATION

Titolo della presentazione - Luogo e data LiF radiation detector operation 5 Irradiation process Reading process 300 400 500 600 700 800 900 1000 0.0 0.2 0.4 0.6 0.8 1.0  (nm) Abs F2 Abs F3 + 300 400 500 600 700 800 900 1000 0.0 0.2 0.4 0.6 0.8 1.0 Abs F2 Abs F3 + Emiss F3 + Emiss F2  (nm) F. Bonfigli, INFN-LNF, 10 April 2018

FOR HIGH-RESOLUTION X-RAY IMAGING - LIF DETECTORS-POLYCAPILLARY LENS COMBINATION

Titolo della presentazione - Luogo e data LiF radiation detectors operation 6 Contact X-ray imaging configuration and color center (CCs) formation in a LiF film detector during the exposure process.

Contact X-ray imaging configuration and color center (CCs) formation in a LiF film detector during the exposure process. Irradiation process Reading process X-rays F. Bonfigli, INFN-LNF, 10 April 2018

FOR HIGH-RESOLUTION X-RAY IMAGING - LIF DETECTORS-POLYCAPILLARY LENS COMBINATION

Titolo della presentazione - Luogo e data Fluorescence microscopy as reading instrument 7 7 Among the main features of the LiF-based detector, there is the high spatial resolution. The intrinsic spatial resolution of this 2D detector is related to the size of CC produced by X-rays. In practice, the spatial resolution is essentially limited by the optical microscope and the technique utilized for PL detection in the optical reading process. F. Bonfigli, INFN-LNF, 10 April 2018

FOR HIGH-RESOLUTION X-RAY IMAGING - LIF DETECTORS-POLYCAPILLARY LENS COMBINATION

Titolo della presentazione - Luogo e data LiF-based radiation imaging detectors 8 PECULIARITIES  Multi-purpose: X-ray (20 eV-30 keV), thermal neutrons, low-energy electrons,...

 high spatial resolution (intrinsic < 2 nm, standard < 250 nm)  large field of view ( > 1 cm2 )  wide dynamic range ( > 103)  efficient optical readout process (optical fluorescence microscopy)  easy handling: no development needs and no sensitivity to visible light  versatility: film geometry compatible with protective layers and different substrates Novel radiation imaging detectors based on photoluminescence (PL) of radiation-induced ligth-emitting color centers in lithium fluoride (LiF) thin layers and crystals

FOR HIGH-RESOLUTION X-RAY IMAGING - LIF DETECTORS-POLYCAPILLARY LENS COMBINATION

Titolo della presentazione - Luogo e data X-ray tubes combined with X-ray polycapillary optics and LiF detectors as a compact X-ray imaging facility 9 Microfocus X-ray tube (Oxford Apogee 5000, Cu target, 50 Watt, spot size 50m) (XLab – INFN-LNF) (XLab – INFN-LNF) X-ray tubes Cu anode contact mode (absorption contrast) X-ray source is combined with a polycapillary semi-lens. With the polycapillary semi-lens it is possible to obtain a quasi-parallel beam from a divergence source. Polycapillary optics F. Bonfigli, INFN-LNF, 10 April 2018

FOR HIGH-RESOLUTION X-RAY IMAGING - LIF DETECTORS-POLYCAPILLARY LENS COMBINATION

Titolo della presentazione - Luogo e data X-ray polycapillary optics 10 Photo of polycapillary lens and half-lens (http://unisantis.com/kumakhov-optics.html) Transformation of a divergent beam from X-ray source into a parallel (half-lens) or a focused (full-lens) beam by a polycapillary lens Full-lens Half-lens Electron microscope image of polycapillary lens transversal section (http://unisantis.com/kumakhov-optics.html) F.

Bonfigli, INFN-LNF, 10 April 2018

Titolo della presentazione - Luogo e data X-ray tubes combined with X-ray polycapillary optics and LiF detectors 11 X-ray microscopy configuration: contact mode (absorption contrast) X-ray source is combined with a polycapillary semi- lens. With the polycapillary semi-lens it is possible to obtain a quasi-parallel beam from a divergence source. sample X-ray tube Semi-lens 26 cm 9.5 cm F. Bonfigli, INFN-LNF, 10 April 2018

Titolo della presentazione - Luogo e data LiF detectors and X-ray polycapillary optics as a new approach for advanced X-Ray imaging 12 CCD CCD LiF LiF CCD: Photonic Science - FDI 1.61:1, sensitive area of (4×3)mm2 and (3.5×3.5) m2 pixel size, 12-bit LiF: crystal (5x5x0.5) mm3 The better quality of X-ray radiography on LiF detector with respect to the CCD one, in terms of resolution and contrast, is evident, although the signal digitalization (12 bits) is the same.

X-ray image of Au mesh 1000 lines/inch (hole width: 19 μm - wire width: 6 μm) acquired by a CCD camera and by a LiF crystal read by a CLSM system. The X-ray micro-radiography stored in the LiF crystal has been read by a CLSM in fluorescence mode 0 20 40 60 80 100 120 200 400 600 800 1000 1200 1400 1600 1800 2000 grey level m 6.5 m D. Hampai, et al., Europhysics Letters 96 (2011) 60010 p1-p4. F. Bonfigli, INFN-LNF, 10 April 2018

Titolo della presentazione - Luogo e data 13 Contact X-ray micro-radiographies of geological samples on LiF detectors X-ray micro-radiography stored in a LiF crystal and read by a CLSM in fluorescence mode X-ray micro-radiography stored in a LiF crystal and read by a CLSM in fluorescence mode Sample: fragment of a magnesium-hastingsite amphibole – ideal composition NaCa2 (Mg4Fe3+) (Si6Al2) O22 (OH,O)2 Optical image under white light illumination in transmission mode Optical image under white light illumination in transmission mode LiF LiF LiF LiF D. Hampai, S.B. Dabagov, G. Della Ventura, F.

Bellatreccia, M. Magi, F. Bonfigli and R. M. Montereali, Europhysics Letters 96 (2011) 60010p1-p4. F. Bonfigli, INFN-LNF, 10 April 2018 X-ray image on LiF detector: high resolved map of microinclusions

Titolo della presentazione - Luogo e data Contact X-ray micro-radiographies of geological samples on LiF detectors 14 14 X-ray micro-radiography stored in a LiF crystal and read by a CLSM in fluorescence mode X-ray micro-radiography stored in a LiF crystal and read by a CLSM in fluorescence mode Optical image under white light illumination in transmission mode Optical image under white light illumination in transmission mode LiF LiF LiF LiF D. Hampai, S.B. Dabagov, G. Della Ventura, F. Bellatreccia, M. Magi, F. Bonfigli and R. M. Montereali, Europhysics Letters 96 (2011) 60010p1-p4. Sample: Cordierite section (140 m) – Silicate with ideal composition (Mg, Fe)2 Al4Si5 O18x (H2O, CO2).

F. Bonfigli, INFN-LNF, 10 April 2018 1 – absorbing dots 2- straight inclusions 3 – absorbing area 4- more trnsparent straight inclusions

Titolo della presentazione - Luogo e data Characterization of X-ray polycapillary optics with LiF detectors Electron microscope image of polycapillary lens transversal section (http://unisantis.com/kumakhov-optics.html) The polycapillary optics is composed by many bundles containing thousands of channels with a length of about 60 mm; each single channel is characterized by an average diameter of about 4 µm. F. Bonfigli, INFN-LNF, 10 April 2018 15 15 LiF crystal placed at the semi-lens exit LiF detector Poly-capillary semi-lens Transformation of a divergent beam from X-ray source into a parallel beam by a polycapillary lens

Titolo della presentazione - Luogo e data Detection by LiF detectors of the transmitted X-rays by a policapillary semi-lens 16 The fluorescence image is obtained by an optical reading of LiF detector by a confocal microscope in fluorescence mode at different magnifications The fluorescence image is obtained by an optical reading of LiF detector by a confocal microscope in fluorescence mode at different magnifications D. Hampai, F. Bonfigli, S.B. Dabagov, R.M. Montereali, G. Della Ventura, F. Bellatreccia and M. Magi, Nuclear Instruments & Methods In Physics Research A, Vol. 720, p. 113-115, (2013).

Each glass channel, even if it is stretched due to the melting during the lens drawing process transports effectively X-radiation resulting in a quite uniform X-ray distribution behind the optics.

Additionally, it confirms that the channels remain mainly opened along the entire optics length. The possibility of LiF detectors to store images with high spatial resolution on a wide field of view simultaneously, in this case allowed to obtain images of the transmitted X-rays through the entire lens and through the single channels. Fluorescence image stored in a LiF detector of the transmitted X-ray by a polycapillary semi-lens Fluorescence image stored in a LiF detector of the transmitted X-ray by a polycapillary semi-lens F. Bonfigli, INFN-LNF, 10 April 2018

Titolo della presentazione - Luogo e data Single channel X-ray transmission of the semi-lens stored by LiF detector 17 17 100 110 120 130 140 150 2600 2800 3000 3200 PL signal (arb.

un.) m 4 m 0 50 100 150 200 250 300 500 1000 1500 2000 2500 3000 Pholominescence signal (arb. un.) m CCs PL signal produced by transmitted X-rays from a single channel of the optics

Titolo della presentazione - Luogo e data The working scheme of point scanning confocal microscope 18 Objective Dicrhoic mirror Sample Pinhole Laser PMT Focal plane The basic key to the confocal approach is the use of spatial filtering techniques to eliminate out-of-focus light. Confocal microscopy eliminates the background signal by incorporating a pinhole near the detector that resides in a plane conjugate with the focus point. Only in focus ligth (red lines) arrives at the detector; all out-of-focus ligth (green lines) is eliminated F. Bonfigli, INFN-LNF, 10 April 2018 F. Bonfigli, INFN-LNF, 10 April 2018

Titolo della presentazione - Luogo e data 3D reconstruction by scanning confocal microscope 19 In addition to the possibility to observe a single plane of a thick specimen with good contrast, optical sectioning allows a great number of slices to be cut and recorded at different planes of the specimen, with the specimen being moved along the optical axis by controlled spatial increments. By computation, various aspects of the object can be generated from the tri-dimensional (3D) data set. F. Bonfigli, INFN-LNF, 10 April 2018

Titolo della presentazione - Luogo e data Investigation by 3D confocal fluorescence microscopy of coloured LiF crystals by a focused X-ray beam 20 LiF crystal X-ray source Polycapillary lens CCs produced by X-rays Z-stack of 2D confocal fluorescence images of the irradiated LiF crystal The optical sectioning was performed by an objective 20x (N.A.

0.5). The samples were analysed over a Z interval of 500 μm acquiring 50 2D-images with a step size of 10 μm. F. Bonfigli, D. Hampai, S. B. Dabagov, R. M. Montereali, Optical Materials 58 (2016) 398-405 Z-stack LiF crystal Colored volume by focusing X-ray beam F. Bonfigli, INFN-LNF, 10 April 2018

Titolo della presentazione - Luogo e data 21 F. Bonfigli, INFN-LNF, 10 April 2018

Titolo della presentazione - Luogo e data 22 Investigation by 3D confocal fluorescence microscopy of coloured LiF crystals by a focused X-ray beam 3D confocal fluorescence image of CCs produced in LiF a crystal by the focused X-ray beam F. Bonfigli, INFN-LNF, 10 April 2018

Titolo della presentazione - Luogo e data 23 Investigation by 3D confocal fluorescence microscopy of coloured LiF crystals by a focused X-ray beam 23 F. Bonfigli, INFN-LNF, 10 April 2018

Titolo della presentazione - Luogo e data Investigation by 3D confocal fluorescence microscopy of coloured LiF crystals by a focused X-ray beam 0 100 200 300 400 500 600 500 1000 1500 2000 2500 3000 3500 PL signal (arb. un.) m X profile FWHM = 145 m 100 200 300 400 500 600 500 1000 1500 2000 2500 3000 3500 FWHM = 142 m Y profile PL signal (arb. un.) m Z=0 Z= -500 m front surface back surface Y profile X profile X profile – FWHM = 145 m Y profile – FWHM = 142 m Y profile – FWHM = 130 m X profile – FWHM = 122 m Y profile X profile 0 100 200 300 400 500 600 20 40 60 80 100 120 140 160 PL signal (arb.

un.) m X profile FWHM = 122 m 100 200 300 400 500 600 20 40 60 80 100 120 140 160 Y profile FWHM = 130 m m PL signal (arb. un.) Focusing angle (measured   x) 18 mrad y) 11 mrad F. Bonfigli, INFN-LNF, 10 April 2018

Titolo della presentazione - Luogo e data F. Bonfigli, INFN-LNF, 10 April 2018 CLSM Z distributions of CCs in a LiF crystal depth coloured by a X-ray beam 25 25 X-ray source Polycapillary optics LiF detector Z F X-ray source Polycapillary optics LiF detector Z F X-ray source Polycapillary optics LiF detector Z F F= 36 mm F= 40 mm F= 44 mm Z F= 32 mm Y X FWHM (F=44 mm) = 240 m focus FWHM (F=32 mm) 605 m out of focus focusing angle (x) = 15 mrad focusing angle (y) = 16 mrad 5000 10000 15000 20000 25000 30000 35000 40000 45000 30 32 34 36 38 40 42 44 46 48 200 250 300 350 400 450 500 550 600 650 FWHM (m) F (mm) 32 34 36 38 40 42 46 F (mm) PL signal Intensity 44

Titolo della presentazione - Luogo e data 26 CLSM Z distributions of CCs in a LiF crystal depth coloured by a X-ray beam CLSM Z distributions of CCs in a LiF crystal depth of a irradiated LiF crystal by a focused X-ray beam. LiF detector Poly-capillary semi-lens X-ray source Polycapillary optics LiF detector X-ray source Z Z Z Z CLSM Z distributions of CCs in a LiF crystal depth of a irradiated LiF crystal by a parallel X-ray beam. 0 100 200 300 400 500 600 700 50 100 150 200 LiF crystal edge LiF crystal edge experimental data fitting curve PL Intensity (arb.

un.) z (m) F. Bonfigli, INFN-LNF, 10 April 2018

Titolo della presentazione - Luogo e data 27 Investigation by 3D confocal fluorescence microscopy of coloured depth in X-ray irradiated LiF crystals 0 100 200 300 400 500 600 700 50 100 150 200 LiF crystal edge LiF crystal edge experimental data fitting curve PL Intensity (arb. un.) z (m) 1/e of the maximum the exponential curve ~ 325 m Assuming this value as the X- rays attenuation length in LiF, a X-ray energy of ~ 8.1 keV was derived. Z distribution of CCS PL intensity profile along the coloured depth of LiF crystal CLSM 2D (x,y) fluorescence images of the X-ray coloured LiF crystal together with two Z distributions visualized along a constant X coordinate (X0) and along a constant Y coordinate (Y0) 100 1000 10000 0,01 0,1 1 10 100 1000 10000 ~ 8 keV ~ 325 m fluorine K edge Atten Length in LiF (um) E (eV) F.

Bonfigli, INFN-LNF, 10 April 2018

Titolo della presentazione - Luogo e data 28 Conclusions 28 Thank you for your attention We presented high performance X-ray imaging detectors based on photoluminescence of CCs in LiF for X- ray imaging. High-resolution solid-state imaging detectors based on photoluminescent colour centres in lithium fluoride have been successfully used for X-ray imaging performed by conventional X-ray tube combined with poly- capillary optics. Contact X-ray micro-radiographies of geological samples and test objects by means of a low divergent X- ray beam from a poly-capillary semi-lens with LiF crystals detectors have been successfully performed.

High-resolution fluorescent images stored in LiF crystal detectors of the transmitted X-ray beam by a poly-capillary semi-lens were obtained to characterize both propagation and transmission of X-rays through these optics. The peculiarity of LiF combined with the performances of the optical reading system allow obtaining high spatial resolution images on a wide field of view, that is fundamental for the full optics characterization.

Confocal fluorescence microscopy was used as powerful tool for advanced optical reading of LiF detectors and 3D imaging reconstruction of X-ray image stored in LiF detectors. The peculiarities of LiF detectors, like high spatial resolution over a large field of view, wide dynamic range, simplicity of use, and efficiency of the reading technique, can be exploited for contact X-ray microscopy (soft and hard), compact X-ray imaging facility, X-ray optics characterization, X-ray source characterization, etc.

We presented high performance X-ray imaging detectors based on photoluminescence of CCs in LiF for X- ray imaging.

High-resolution solid-state imaging detectors based on photoluminescent colour centres in lithium fluoride have been successfully used for X-ray imaging performed by conventional X-ray tube combined with poly- capillary optics. Contact X-ray micro-radiographies of geological samples and test objects by means of a low divergent X- ray beam from a poly-capillary semi-lens with LiF crystals detectors have been successfully performed. High-resolution fluorescent images stored in LiF crystal detectors of the transmitted X-ray beam by a poly-capillary semi-lens were obtained to characterize both propagation and transmission of X-rays through these optics.

The peculiarity of LiF combined with the performances of the optical reading system allow obtaining high spatial resolution images on a wide field of view, that is fundamental for the full optics characterization.

Confocal fluorescence microscopy was used as powerful tool for advanced optical reading of LiF detectors and 3D imaging reconstruction of X-ray image stored in LiF detectors. The peculiarities of LiF detectors, like high spatial resolution over a large field of view, wide dynamic range, simplicity of use, and efficiency of the reading technique, can be exploited for contact X-ray microscopy (soft and hard), compact X-ray imaging facility, X-ray optics characterization, X-ray source characterization, etc.

F. Bonfigli, INFN-LNF, 10 April 2018

Titolo della presentazione - Luogo e data LiF film deposition by thermal evaporation 29 29 29 Vacuum pump Oscillating quartz Substrate holder crucible Deposition parameters Pressure P < 10-6 mbar Evaporation rate R = 0.5-2 nm/s Total film thickness t up to 6 m Substrate temperature Ts = 30-350 °C Deposition parameters Pressure P < 10-6 mbar Evaporation rate R = 0.5-2 nm/s Total film thickness t up to 6 m Substrate temperature Ts = 30-350 °C SEM micrograph of the surface of a LiF film 1.8 m thick thermally evaporated on a silicon substrate at Ts = 250 °C Polycrystalline LiF films are grown by thermal evaporation on amorphous (glass, silica, silica on silicon, plastics) and crystalline (LiF single crystals, NaF, MgF2, silicon, …) substrates.

The structural, morphological and optical properties of the films are strongly dependent on the nature of the substrate and the deposition parameters: Ts , t, R GP20 evaporation system at Photonic Micro- and Nano-structures Laboratory of ENEA C.R. Frascati.

200 400 600 800 1000 1200 1400 20 40 60 80 100 R&T (%) Wavelength (nm) T R LiF film on Si substrate

Titolo della presentazione - Luogo e data 30 Investigation by 3D confocal fluorescence microscopy of coloured LiF crystals by a X-ray beam

Titolo della presentazione - Luogo e data High resolution contact X-ray microscopy on LiF read by confocal microscopy 32 250 nm Spatial resolution Contact X-ray micro-radiography of a Phase Fresnel Zone Plate stored on a LiF film (1.4 m) observed by an optical microscope in fluorescence mode.

a) 50  10 m 50 m 50 m S. Almaviva et al, Applied Physics Letters 89, 054102-4 (2006). The modulation is clearly seen up to a radius of about 90 m, which corresponds to a zone width of about 270 nm Reading microscope: Confocal Laser Scanning Microscope F. Bonfigli, INFN-LNF, 10 April 2018

Titolo della presentazione - Luogo e data High resolution contact X-ray microscopy on LiF read by Scanning Near Field Microscope 33 SNOM image of contact X-ray micro-radiography of a mask stored in a LiF film  75 nm Spatial resolution A. Ustione, et al, Appl. Phys. Lett. 88 (2006), 141107-9. The used SNOM is an aperture reflection system working in the “collection mode”. It uses uncoated tip, that we produce tapering an optical fiber, to collect the near field generated illuminating the sample with laser light. To obtain SNOM images of fluorescent samples, we put a high-pass filter at the end of the optical fiber, before the light reaches the photomultiplier.

For each scan we obtain a topographical and an optical image of the examined surface.

Contact X-ray micro-radiography of a copper mesh stored in a LiF film (214 nm) on Si substrate observed by a SNOM. Reading microscope: Scanning Near Field Microscope SNOM (CNR-ISM) F. Bonfigli, INFN-LNF, 10 April 2018

You can also read