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

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




INFN-LNF, Frascati 10 April 2018
FOR HIGH-RESOLUTION X-RAY IMAGING - LIF DETECTORS-POLYCAPILLARY LENS COMBINATION
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




           Titolo della presentazione
            F. Bonfigli,              - Luogo
                         INFN-LNF, 10 April    e data
                                            2018
FOR HIGH-RESOLUTION X-RAY IMAGING - LIF DETECTORS-POLYCAPILLARY LENS COMBINATION
Color centers in LiF
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.

                                                                                              F-
 Optically active defects in LiF can be generated by ionizing radiation like
                                                                                              Li+
 charged particles (electrons and ions), as well as gamma and X-rays.
                                                                                              e-

  F center is an anion vacancy occupied by an electron;
  they are not optically active centers

                                                                                  F2 CC
  F2 and F3+ centers are optically active F-aggregates consisting in two
  electrons bound to two and three close anion vacancies, respectively.


            F center                       F2 center                  F3 center




              Titolo della presentazione
               F. Bonfigli,              - Luogo
                            INFN-LNF, 10 April    e data
                                               2018                                       3
FOR HIGH-RESOLUTION X-RAY IMAGING - LIF DETECTORS-POLYCAPILLARY LENS COMBINATION
Optical properties of color centers in LiF

                            Color centers in lithium fluoride
                             Absorption and Emission bands




                                                                4
       F. Bonfigli,
      Titolo        INFN-LNF, 10 April
             della presentazione       2018e data
                                  - Luogo
FOR HIGH-RESOLUTION X-RAY IMAGING - LIF DETECTORS-POLYCAPILLARY LENS COMBINATION
LiF radiation detector operation

Irradiation process                                                                             Reading process

                                               1.0                                     Abs F2
                                                                                      Abs F2
                                               0.8                                     Abs F3+
                                                                                      Abs F3+
                                               0.6                                     Emiss F3+
                                                                                       Emiss F2
                                               0.4

                                               0.2

                                               0.0
                                                 300   400   500   600   700   800   900 1000
                                                                   (nm)
                                                                      (nm)




                                                                                                                  5
         F. Bonfigli,
        Titolo        INFN-LNF, 10 April
               della presentazione       2018e data
                                    - Luogo
FOR HIGH-RESOLUTION X-RAY IMAGING - LIF DETECTORS-POLYCAPILLARY LENS COMBINATION
LiF radiation detectors operation


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




                                                                                         6
               F. Bonfigli,
              Titolo        INFN-LNF, 10 April
                     della presentazione       2018e data
                                          - Luogo
FOR HIGH-RESOLUTION X-RAY IMAGING - LIF DETECTORS-POLYCAPILLARY LENS COMBINATION
Fluorescence microscopy as reading instrument




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.

                                                                                   7
                                                                                                              7
                  F. Bonfigli,
                 Titolo        INFN-LNF, 10 April
                        della presentazione       2018e data
                                             - Luogo
FOR HIGH-RESOLUTION X-RAY IMAGING - LIF DETECTORS-POLYCAPILLARY LENS COMBINATION
LiF-based radiation imaging detectors

Novel radiation imaging detectors based on photoluminescence (PL) of radiation-induced ligth-emitting
color centers in lithium fluoride (LiF) thin layers and crystals
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




                                                                                                8
                Titolo della presentazione - Luogo e data
FOR HIGH-RESOLUTION X-RAY IMAGING - LIF DETECTORS-POLYCAPILLARY LENS COMBINATION
X-ray tubes combined with X-ray polycapillary optics
 and LiF detectors as a compact X-ray imaging facility


                     X-ray tubes                                         (XLab – INFN-LNF)
                                          Microfocus X-ray tube
                     Cu anode             (Oxford Apogee 5000, Cu target, 50 Watt, spot size 50m)




X-ray source is combined with a
polycapillary semi-lens. With the             Polycapillary optics
polycapillary semi-lens it is possible
to obtain a quasi-parallel beam from                                                 contact mode
a divergence source.                                                              (absorption contrast)



                                                                                                          9

                F. Bonfigli,
               Titolo        INFN-LNF, 10 April
                      della presentazione       2018e data
                                           - Luogo
FOR HIGH-RESOLUTION X-RAY IMAGING - LIF DETECTORS-POLYCAPILLARY LENS COMBINATION
X-ray polycapillary optics

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

Photo of polycapillary lens and half-lens                        Electron microscope image of polycapillary lens transversal section
(http://unisantis.com/kumakhov-optics.html)                      (http://unisantis.com/kumakhov-optics.html)




                                                                                                                          10
                    F. Bonfigli,
                   Titolo        INFN-LNF, 10 April
                          della presentazione       2018e data
                                               - Luogo
X-ray tubes combined with X-ray polycapillary optics
  and LiF detectors


X-ray microscopy configuration: contact mode (absorption contrast)



                                                    9.5 cm

                                                            sample   X-ray source is combined
                                                                     with a polycapillary semi-
 X-ray tube               Semi-lens                                  lens. With the polycapillary
                                                                     semi-lens it is possible to obtain
                                                                     a quasi-parallel beam from a
                                                                     divergence source.


                                     26 cm




                                                                                                 11
               F. Bonfigli,
              Titolo        INFN-LNF, 10 April
                     della presentazione       2018e data
                                          - Luogo
LiF detectors and X-ray polycapillary optics
    as a new approach for advanced X-Ray imaging

          CCD                              LiF                    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.
                                                                  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 X-ray micro-radiography stored in the LiF
                                                                  crystal has been read by a CLSM in fluorescence
                                                                  mode

                                                                   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.

                                                                                  2000
                                                                                  1800
                                                                                  1600
                                                                                  1400
                                                                     grey level

                                                                                  1200
                                                                                  1000
                                                                                  800
D. Hampai, et al., Europhysics                                                    600
Letters 96 (2011) 60010 p1-p4.                                                    400
                                                                                  200
                                                                                                  6.5 m
                                                                                         0   20   40   60   80   100   120

                                                                                                       m

                                                                                                                             12
                     F. Bonfigli,
                    Titolo        INFN-LNF, 10 April
                           della presentazione       2018e data
                                                - Luogo
Contact X-ray micro-radiographies
    of geological samples on LiF detectors
Sample: fragment of a magnesium-hastingsite amphibole – ideal composition NaCa2 (Mg4Fe3+) (Si6Al2) O22 (OH,O)2


Optical image under white light                                        X-ray micro-radiography stored in a LiF crystal and
illumination in transmission mode                                       read by a CLSM in fluorescence mode


                                                                                                        LiF




                                                                                                                       X-ray image on LiF
                                                                                                                       detector: high resolved
                                                                                                                       map of microinclusions


                                                              LiF

                                                                                                                                                   13
                        F. Bonfigli,
                       Titolo        INFN-LNF, 10 April
                              della presentazione       2018e data
                                                   - Luogo
D. Hampai, S.B. Dabagov, G. Della Ventura, F. Bellatreccia, M. Magi, F. Bonfigli and R. M. Montereali, Europhysics Letters 96 (2011) 60010p1-p4.
Contact X-ray micro-radiographies
      of geological samples on LiF detectors
 Sample: Cordierite section (140 m) – Silicate with ideal composition (Mg, Fe)2 Al4Si5 O18x (H2O, CO2).

 Optical image under white light                                                           X-ray micro-radiography stored in a LiF
 illumination in transmission mode                                                          crystal  and   read  by  a   CLSM   in
                                                                                            fluorescence mode



                                                                                                                                     1 – absorbing dots
                                                                                                                                     2- straight inclusions
                                                                                                                                     3 – absorbing area
                                                                                                                                     4- more trnsparent
                                                                                                                                     straight inclusions



                                                                                                          LiF




                                                                           LiF
                                                                                                                                                   14
                          F. Bonfigli,
                         Titolo        INFN-LNF, 10 April
                                della presentazione       2018e data
                                                     - Luogo                                                                                            14
D. Hampai, S.B. Dabagov, G. Della Ventura, F. Bellatreccia, M. Magi, F. Bonfigli and R. M. Montereali, Europhysics Letters 96 (2011) 60010p1-p4.
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.


                                                  Poly-capillary         LiF detector
                                                  semi-lens



                                                                                  LiF crystal placed at the semi-lens exit



                          Transformation of a divergent beam from X-ray source
                          into a parallel beam by a polycapillary lens    15
                 F. Bonfigli,
                Titolo        INFN-LNF, 10 April
                       della presentazione       2018e data
                                            - Luogo                                                                       15
Detection by LiF detectors of the transmitted
     X-rays by a policapillary semi-lens


                                                    Fluorescence image stored in a LiF detector of the
                                                    transmitted X-ray by a polycapillary semi-lens


                                                    The fluorescence image is obtained by an optical reading of LiF detector
                                                    by a confocal microscope in fluorescence mode at different
                                                    magnifications




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      D. Hampai, F. Bonfigli, S.B. Dabagov, R.M. Montereali, G. Della Ventura, F. Bellatreccia and M. Magi,
channels.                                           Nuclear Instruments & Methods In Physics Research A, Vol. 720, p. 113-115, (2013).
                                                                                                                                              16
                        F. Bonfigli,
                       Titolo        INFN-LNF, 10 April
                              della presentazione       2018e data
                                                   - Luogo
Single channel X-ray transmission of the semi-lens
stored by LiF detector




                                                    Pholominescence signal (arb. un.)
                                                                                               3000

                                                                                               2500

                                                                                               2000

                                                                                               1500

                                                                                               1000

                                                                                                       500

                                                                                                               0
                                                                                                                   0    50         100     150       200    250      300

                                                                                                                                           m


                                                                                                               3200

                                                                                                                                                    4 m




                                                                                        PL signal (arb. un.)
                                                                                                               3000



                                                                                                               2800




CCs PL signal produced by transmitted X-rays from                                                              2600
                                                                                                                  100        110         120        130    140    17 150
a single channel   of the
            Titolo della    optics - Luogo e data
                         presentazione                                                                                         17
                                                                                                                                               m
The working scheme of point scanning
  confocal microscope
                                                      PMT

The basic key to the confocal                                               Confocal               microscopy
approach is the use of spatial                                              eliminates the background
filtering techniques to eliminate                                           signal by incorporating a
out-of-focus light.
                                                                Pinhole     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
                Laser
                                                                Dicrhoic mirror


                                                                Objective



                                  Sample                         Focal plane
                                                                                                        18
                  F.F.Bonfigli,
                      Bonfigli,
                 Titolo         INFN-LNF,
                                 INFN-LNF,10
                        della presentazione10April
                                             April 2018
                                                    2018
                                              - Luogo  e data
3D reconstruction by scanning confocal
  microscope




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.

                                                                                            19
               F. Bonfigli,
              Titolo        INFN-LNF, 10 April
                     della presentazione       2018e data
                                          - Luogo
Investigation by 3D confocal fluorescence microscopy
    of coloured LiF crystals by a focused X-ray beam

                  Polycapillary lens           LiF crystal
                                                               The optical sectioning was performed by an objective 20x (N.A. 0.5).
X-ray source                                                   The samples were analysed over a Z interval of 500 μm acquiring 50
                                                               2D-images with a step size of 10 μm.


                                                         CCs produced
                                                         by X-rays




  LiF crystal




Colored volume by
                                                    Z-stack
focusing X-ray beam                                                                     Z-stack of 2D confocal fluorescence
                                                                                        images of the irradiated LiF crystal


                     F. Bonfigli,
                    Titolo        INFN-LNF, 10 April
                           della presentazione       2018e data
                                                - Luogo                                                                          20
F. Bonfigli, D. Hampai, S. B. Dabagov, R. M. Montereali, Optical Materials 58 (2016) 398-405
21
 F. Bonfigli,
Titolo        INFN-LNF, 10 April
       della presentazione       2018e data
                            - Luogo
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




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




                                                    23

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

                       Z=0                              front surface                                                                                                  Z= -500 m                                                 back surface
                                                                                                 PL signal (arb. un.)
                                          Y profile



                                                                                                                                                                                                                                                                 PL signal (arb. un.)




                                                                                                                                                                                                                Y profile
                                                                                                        1000

                                                                                                               1500

                                                                                                                                2000

                                                                                                                                       2500

                                                                                                                                              3000

                                                                                                                                                           3500
                                                                                                  500




                                                                                                                                                                                                                                                                                                 100
                                                                                                                                                                                                                                                                                                       120
                                                                                                                                                                                                                                                                                                             140
                                                                                                                                                                                                                                                                                                                         160
                                                                                                                                                                                                                                                                 20
                                                                                                                                                                                                                                                                      40
                                                                                                                                                                                                                                                                           60
                                                                                                                                                                                                                                                                                            80
                                                                                           100
                                                                                             0




                                                                                                                                                                                                                                                             0
                                                                                                                                                                                                                                                         0
                                                                                                                                               Y profile




                                                                                                                                                                                                                                                                                                             Y profile
                                                                                                                                                                                                                                                         100
                                                                                           200




                                                                                                                                                                                                                                                         200
                                                                                           300




                                                                                                                                                                                                                                                        m
                                                                                      m




                                                                                                                                                                                                                                                         300
                                                                         X profile                                                                                                                                                      X profile
                                                                                           400




                                                                                                                FWHM = 142 m




                                                                                                                                                                                                                                                                            FWHM = 130 m
                                                                                                                                                                                                                                                         400
                                                                                           500




                                                                                                                                                                                                                                                         500
                                                                                           600




                                                                                                                                                                                                                                                         600
                                                                                             Y profile – FWHM = 142 m                                                                                                                               Y profile – FWHM = 130 m
                       3500
                                                                                                                                                                                         160
                                  X profile
                       3000                                                                                                                                                                         X profile
                                                                                     X profile – FWHM = 145 m                                                                           140
                                                                                                                                                                                                                                                    X profile – FWHM = 122 m




                                                                                                                                                                  PL signal (arb. un.)
PL signal (arb. un.)




                       2500                                                                                                                                                              120

                       2000                                                                                                                                                              100
                                                                                                                                                                                          80
                       1500                                       FWHM = 145 m                                                                                                                    FWHM = 122 m
                                                                                                                                                                                          60
                       1000
                                                                                                                                                                                          40
                       500
                                                                                                                                                                                          20
                          0                                                                                                                                                                0
                              0       100             200   300   400    500   600                                                                                                             0       100      200         300   400   500   600
                                                            m                                                                                                                                                              m



                                                                                                                       Focusing angle (measured)  x) 18 mrad
                                                                                                                                                   y) 11 mrad


                                                                         F. Bonfigli,
                                                                        Titolo        INFN-LNF, 10 April
                                                                               della presentazione       2018e data
                                                                                                    - Luogo
CLSM Z distributions of CCs in a LiF crystal depth
    coloured by a X-ray beam


                           Polycapillary optics
                                                        LiF detector

    X-ray
    source


                                                       F
                                                               Z

                                                                                                45000
                                                                                                                    650
                                                                                                40000               600

    F= 32 mm           F= 36 mm            F= 40 mm            F= 44 mm                                             550
                                                                                                                    500
                                                                                                35000




                                                                                                        FWHM (m)
                                                                                                                    450



X
                                                                                                                    400
                                                                                                30000




                                                                          PL signal Intensity
                                                                                                                    350
                                                                                                                    300

                                                                                                25000               250
                                                                                                                    200
                                                                                                                       30   32   34   36   38   40   42   44   46   48

                                                                                                20000                                      F (mm)


                                                                                                15000

                                                                                                10000

                                                                                                5000

                                                                                                   0
                                                                                                                    32            34            36             38        40   42   44   46

             Y                                                                                                                                            F (mm)

                                                                                                 FWHM (F=44 mm) = 240 m focus
                                                                                                 FWHM (F=32 mm) 605 m out of
                                                                                                 focus


                                                                                                 focusing angle (x) = 15 mrad
                                                                                                 focusing                 25
                                                                                                          angle (y) = 16 mrad
                  F. Bonfigli,
                 Titolo        INFN-LNF, 10 April
                        della presentazione       2018e data
                                             - Luogo                                              25
                  Z
CLSM Z distributions of CCs in a LiF crystal depth
  coloured by a X-ray beam

                    Poly-capillary         LiF detector
                    semi-lens                                                                                                                 Polycapillary optics
                                                                                                                                                                     LiF detector
X-ray
source
                                                                                                       X-ray
                                                                                                       source




                                                                          Z                                                                                                  Z


                                                                                    LiF crystal edge
                                                                          200                                     experimental data
                                                                                                                  fitting curve
                                                PL Intensity (arb. un.)
                                                                          150


                                                                          100
                                                                                                                          LiF crystal edge

                                                                          50


                                                                           0
                                                                                0     100        200   300   400    500       600       700
                                                                                                         z (m)




                                                              Z                                                                                                          Z
  CLSM Z distributions of CCs in a LiF crystal depth of a                                                            CLSM Z distributions of CCs in a LiF crystal depth of a
  irradiated LiF crystal by a parallel X-ray beam.                                                                   irradiated LiF crystal by a focused X-ray beam.

                                                                                                                                                                          26
                   F. Bonfigli,
                  Titolo        INFN-LNF, 10 April
                         della presentazione       2018e data
                                              - Luogo
Investigation by 3D confocal fluorescence microscopy
    of coloured depth in X-ray irradiated LiF crystals

                                                                                                    Z distribution of CCS PL intensity profile
                                                                                                    along the coloured depth of LiF crystal
                                                                                                             LiF crystal edge
                                                                                                  200                                             experimental data
                                                                                                                                                  fitting curve




                                                                  PL Intensity (arb. un.)
                                                                                                  150


                                                                                                  100
                                                                                                                                                          LiF crystal edge

                                                                                                   50

                                                                                                             1/e of the maximum the
                                                                                                             exponential curve ~ 325 m
                                                                                                     0
                                                                                                         0     100        200      300     400      500       600       700
                                                                                                                                         z (m)
                                                                                                 10000

                                                                                                 1000
                                                                                                                                                              Assuming this
                                                                                                                                                              value as the X-
                                                                      Atten Length in LiF (um)
                                                                                                                       ~ 325 m
                                                                                                  100                                                         rays
                                                                                                                                                              attenuation
CLSM 2D (x,y) fluorescence images of the X-ray coloured                                            10                 fluorine K edge
                                                                                                                                                              length in LiF, a
LiF crystal together with two Z distributions visualized along                                                                                                X-ray energy of
                                                                                                    1
a constant X coordinate (X0) and along a constant Y                                                                                         ~ 8 keV           ~ 8.1 keV was
coordinate (Y0)                                                                                    0,1
                                                                                                                                                              derived.
                                                                                                  0,01                                                                        27
                     F. Bonfigli,
                    Titolo        INFN-LNF, 10 April
                           della presentazione       2018e data
                                                - Luogo                                                       100               1000          10000
                                                                                                                                E (eV)
Conclusions


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.




                                                                                           28
                  F. Bonfigli,
                 Titolo        INFN-LNF, 10 April
                        della presentazione       2018e data
                                             - Luogo           Thank you for 28your attention
LiF film deposition by thermal evaporation

                                                                                                            100
                                                                                                                                                         T
                                                                                                                80




                                                                                                      R&T (%)
                                                                                                                60

                                                        Substrate holder                                        40

                                        Oscillating quartz
                                                                                                                20
                                                                                                                                                         R
                                                                                                                 0
                                                                                                                 200     400   600   800   1000   1200       1400
                                                                                                                               Wavelength (nm)
                                         Vacuum
                                         pump



                                                              crucible
                                                                           LiF film on Si substrate
GP20 evaporation system at Photonic
Micro- and Nano-structures Laboratory      Deposition parameters
of ENEA C.R. Frascati.                     Pressure P < 10-6 mbar
                                           Evaporation rate R = 0.5-2 nm/s
                                           Total film thickness t up to 6 m                                         SEM micrograph of the surface of a
                                           Substrate temperature Ts = 30-350 °C                                      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 theTitolo
                   deposition    parameters:- T                                                        29
                         della presentazione   s , t, R
                                              Luogo   e data                      29                   29
Investigation by 3D confocal fluorescence microscopy
of coloured LiF crystals by a X-ray beam




                                                   30
      Titolo della presentazione - Luogo e data
High resolution contact X-ray microscopy on LiF read by confocal
   microscopy

Reading microscope: Confocal Laser Scanning Microscope
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)
                                         m
                                         mm
                                            
                                      50
                                      1050
                                       50



                                                                                    250 nm
The modulation is clearly seen up to a radius of about
                                                                                    Spatial resolution
90 m, which corresponds to a zone width of about 270
nm
                                                                                                                      32
                 F. Bonfigli,
                Titolo        INFN-LNF, 10 April
                       della presentazione       2018e data
                                            - Luogo
                                                                S. Almaviva et al, Applied Physics Letters 89, 054102-4 (2006).
High resolution contact X-ray microscopy on LiF read by
  Scanning Near Field Microscope

         Reading microscope: Scanning Near Field Microscope SNOM (CNR-ISM)
                                                              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.
                                                                                              75 nm
                                                                                             Spatial resolution




SNOM image of contact X-ray micro-radiography of a
                                                                                                                         33
mask stored in a LiF film
                                                                    A. Ustione, et al, Appl. Phys. Lett. 88 (2006), 141107-9.
                 F. Bonfigli,
                Titolo        INFN-LNF, 10 April
                       della presentazione       2018e data
                                            - Luogo
You can also read
Next part ... Cancel