BL4U

Commissioning of a Scanning Transmission X-ray Microscopy Beamline
T. Ohigashi1, 2, H. Arai1, Y. Inagaki1, N. Kondo1, M. Sakai1, K. Hayashi1, E. Shigemasa1, 2,A. P. Hitchcock3, N. Kosugi1, 4 and M. Katoh1, 2
1

UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585, JapanThe Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585, Japan
3
Brockhouse Institute of Materials Research, McMaster University, Hamilton, ON L8S 4M1, Canada
4
Department of Photo-Molecular Science, Institute for Molecular Science, Okazaki 444-8585, Japan2distributions of the components are clearly
distinguished as shown in Fig. 2. These analyses areperformed by using aXis2000 [2].
The commissioning of the beamline is almost
finished. The STXM system is now ready for user
operation. Currently, different kinds of measurement
methods and sample cells for in-situ observation are
underdevelopment
forvariousupcomingapplications.

Construction of a scanning transmission X-ray
microscopy (STXM) beamline, BL4U, was started inApril 2012 as part of the UVSOR-III upgrade project[1]. This beamline covers the X-ray energy range
from 100 to 700 eV. The STXM end station is used tomeasure near edge X-ray absorption fine structure(NEXAFS) spectra to analyze chemical states ofspecific elements, especially light elements, with highspatialresolution.
Toachieve
satisfactory
performance of the STXM, we need high intensity,
high photon energy resolution, and high stability ofthe beam position as well as fine coordination of thelight source, the monochromator and the STXM. We
have been developing interface software and a control
system for the complete beamline.
BL4U is equipped with an in-vacuum undulator
and a variable included angle Monk-Gillieson
mounting monochromator using a varied-line-spacing
plane grating. During monochromator commissioning,
the X-ray energy range from 270 to 640 eV wascalibrated. Then, the 9th harmonic peak of theundulator was synchronized with the X-ray energy ofthe monochromator by changing the gap width from13 to 40 mm. The energy resolution (E/'E) of themonochromator was evaluated from the absorption
spectrum of the K absorption edge of nitrogen gas.
The nitrogen gas was introduced into the STXM
chamber (~1 mbar) and the transmitted x-rays weremeasured with a photo multiplier tube. The
absorption spectrum measured with exit slits of 30 x30 m is shown in Fig. 1. From this spectrum, theresolving power was estimated to be ~6,000. On theother hand, the intensity of X-rays around the carbon
K absorption edge from 283 to 300 eV, was very low
because of carbon contamination on the mirrors. We
expect this problem will be solved by cleaning themirror chambers and recoating the mirrors.
As a test sample, printer toner particles werestudied at the oxygen K edge. Toner particles wereembedded in resin and a thin specimen was preparedwith an ultra-microtome. A stack of 78 X-ray
transmission images was acquired from 522 to 564 eV.
The exit slit was set to 30 x 30 m and the dwell timewas 3 msec for each pixel. A spectrum of eachcomponent of the specimen, matrix and resin, isextracted from the each specific part of the imagestack. By fitting these spectral data of the matrix, theresin and the wax, to the image stack, chemical

Fig. 1. 1s-S* absorption spectrum of nitrogen gas.
(a)

(b)

(c)

Fig. 2. Chemical maps of three components in a
printer tonner sample, (a) matrix, (b) resin and (c)wax. Higher concentrations of each component arebrighter. Scale bars are 1 m.
[1] T. Ohigashi, T. Araki, E. Nakamura, N. Kondo, E.
Shigemasa, N. Kosugi and M. Kato, UVSOR Activity
Report 39 (2012) 42.
[2] http://unicorn.mcmaster.ca/aXis2000.html

43

BL5B

Reflectance Measurements of Black Coatings for Stray Light Rejection
Used in Bepi Colombo Mission
K. Uji1, K. Yoshioka2, G. Murakami2 and I. Yoshikawa11Department of Earth and Planetary Science, Graduate School of Science,
The University of Tokyo, Tokyo113-0033, Japan2
Institute of Space and Astronautical Science, Sagamihara 252-5210, Japan

show low reflectivity. Especially, Sample #1 has
lower reflectivity than sample #2 at every incident
angles.
As the next step, we plan to measure thereflectivities of these black coatings at variouswavelengths.

We study the tenuous atmosphere of Mercury
through the spectroscopic observations. To date, somespecies (e.g., H, He, O, Na, Mg, K and Ca) have been
identified in the Mercury’s atmosphere. As thesespecies have many resonance scattering lines in theextreme ultraviolet (EUV) region, spectroscopic
observations will enable us deduce the source process,current environment, and evolution of the Mercury’satmosphere.
We are now developing an ultraviolet spectrometer;
PHEBUS (Probing of Hermean Exosphere by
Ultraviolet Spectroscopy) which is a part of theBepiColombo mission. From the orbit around
Mercury, PHEBUS will observe the atmosphere in
the EUV and FUV (far ultraviolet) region. In thismission, the signals from the targets are so faint thatthe stray light must be kept as low as possible. The
black coatings techniques are commonly used invarious space telescopes and optical instruments inorder to reject the stray light in the instrument.
In this experiment, we measure the reflectivities of
two types of black coatings in EUV range. As theseblack coatings have low reflectivities (less than 1 %),the intense light is needed for the accurate
measurement.
We install Indium filters on the entrance of thebeam line in order to eliminate the multi-order lines.
At first, we investigate the purity of the 83.4 nm line
through indium filters. We judge the purity fromconsistency between the wavelength characteristics ofindium filters for continuous lines at UVSOR andthose for the particular lines at the EUV facilities ofInstitute of Space and Astronautical Science (ISAS).
The latter is measured for the emission lines of theoxygen gas with the discharged light source.
Comparing the transmittances of indium filter
measured at UVSOR and at ISAS, we confirm thatthe pure 83.4 nm light is achieved at UVSOR withthe entrance filter.
With the pure 83.4 nm line, we measure thereflectivities of two black coating samples at various
incident angles (30, 40, 50, 60, 70 and 80 degrees).
One is fabricated by EBINA Co. (hereafter referred toas sample #1) and another is by ACTAR (hereafterreferred to as sample #2). These black coatings will
be used inside the spectrometer. Sample #1 is also
used in the EXCEED spectrometer on board theJAXA’s SPRINT-A mission.
The results are shown in Fig. 2 and both samples

Fig. 1. Photo of the black coating samples. Left isfabricated by EBINA and right is by ACTOR.

10-1

Sample #1
Sample #2

Reflectivity

10-210-310-410-530

40506070

Incident angle (degree)

Fig. 2. The reflectivities of the black coating samples
at 83.4 nm. Both samples show low reflectivities.

4480

BL6B

Performance Test of Infrared Microspectroscopy
Using Synchrotron Radiation at UVSOR-III
S. Kimura1,2, T. Katsumata3 and J. Koshobu3
1

UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585, Japan
School of Physical Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585,
Japan
3IR System Group, JASCO Corporation, Tokyo 192-8537, Japan2

area of the front-end part of BL6B.
To demonstrate the performance of IR-SR, IR
images of a U. S. Air Force (USAF) test target
measured with IR-SR and an internal thermal (globar)
source are shown in Fig. 2. The test target, on which a
metal pattern is formed on a quartz substrate, wasused for the evaluation of spatial resolution. The test
target was measured on the focal plane of the IR
microscope. By using IR-SR, a clear spatial image
was obtained with the instrumental spatial resolutionof 5u5 Pm2 in contrast to that of a thermal source,even though the optics in the IR-MS is aligned to theinternal source. This implies that the IR-SR is suitableto IR-MS.
The IR-MS instrument will be installed
permanently in FY2013.

Infrared (IR) synchrotron radiation (SR) has theadvantage of higher brilliance and intensity than thoseof thermal light sources such as the globar (a SiC rod
heated to ~1500 K) and the mercury lamp (adischarge lamp with mercury vapor), which utilize
the black-body radiation from a heated object [1]. IR
microspectroscopy (IR-MS) is currently one of themost common analysis methods for various materials
in many fields of science and industry. Commercial
IR microspectroscopy instruments, designed for
mid-IR spectral range with a thermal IR source, aregenerally available. However, because of the low
brilliance of the thermal light sources, the spatial
resolution cannot be the same as the diffraction limit(~ wavelength). With the use of IR-SR, one canfurther improve the spatial resolution of IR
microspectroscopy. Then, we tested that acommercial IR microspectroscopy instrument can beequipped to the IR-SR beamline, BL6B [2] andobtained the performance combined with IR-SR.
A p ho to gr a p h o f the I R-M S in str u me nt(FTIR6100+IRT7000, JASCO Corp.) installed at
BL6B is shown in Fig. 1. IR-SR was introduced toIR-MS by two plane mirrors through the atmospherefrom the free port at the downstream of aCVD-diamond window, which separates a low
vacuum area of the Fo ur ier-transfor m I R
interferometer (FTIR) from an ultra-high vacuum

Fig. 2. Obtained reflectance image of USAF test target
at the wavenumber of 4000 cm-1 using IR-SRfrom
UVSOR-III compared with an internal globarlamp(thermal light source). The objective of theIRmicroscope had a magnification of 32u. The
instrumental spatial resolution was set as 5u5 Pm2.
[1] S. Kimura and H. Okamura, J. Phys. Soc. Jpn. 82
(2013) 021004.
[2] S. Kimura, E. Nakamura, T. Nishi, Y. Sakurai, K.
Hayashi, J. Yamazaki and M. Katoh, Infrared Phys.
Tech. 49 (2006) 147.
Fig. 1. Layout of the IR microspectroscopy (IR-MS)
apparatus installed at BL6B. The infrared synchrotron
radiation (IR-SR) is introduced to the IR-MS by twoplane mirrors through the atmosphere.

45

BL7B

Development of the Cold Mirror Coating (Reflective Narrow Band Filter)
across 300 mm Diameter for Lyman-Alpha Line (121.6 nm)
N. Narukage1, R. Ishikawa2, K. Aoki2, K. Miyagawa2,
T. Kobiki2, R. Kano2, T. Bando2 and S. Tsuneta2
1

Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency,
3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210, Japan
2
National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588, Japan
Our team consisting of Japan, US, Spain, France,and Norway is developing a Chromospheric
Lyman-Alpha SpectroPolarimeter (CLASP), which isproposed to fly with a NASA sounding rocket in 2015[1]. CLASP will explore the magnetic fields in thesolar atmosphere (the upper chromosphere andtransition region) via the Hanle effect in the
Lyman-alpha (LyD) line (121.6 nm) for the first time.
This experiment requires precise spectropolarimetricobservations with a polarimetric sensitivity of < 0.1%
and a wavelength resolution of 0.01 nm.
In order to achieve the polarimetric sensitivity of <0.1%, the rejection of visible light (VL) from theinstrument is indispensable, since the total intensity inthe solar VL wavelength range is about 2105 times
larger than solar LyD line. For the VL rejection, weplan to perform the multi-layer “cold mirror coating”
on the 300 mm diameter primary mirror of theCLASP. This coating is a reflective narrow band filter
with the reflectivity of more than 50 % in the LyD
line, and less than 5 % for VL in average.
Though this coating itself is difficult to adjust thepeak wavelength and to enhance the reflectivity, theuniformity of the coating performance across the 300mm diameter area is also required for the CLASP. If
there is a large amount of non-uniformity in thereflectivity, this causes the spurious polarization. So,
we performed the development of the uniform coatingwith Acton Optics and Coatings.
Figure 1 shows the location of the 12 witness
samples deployed in the 300 mm diameter area
during the coating process. Figure 2 is theirreflectivity as a function of wavelength near the LyD
line at AOI = 2 degree measured with UVSOR BL7B.
The spatial distributions of the reflectivity at the LyD
line and the peak wavelength are summarized in theleft and right panels of Fig. 1, respectively. As a result,
the reflectivity of the developed coating is distributed
among 60%r2%.
Based on these results, we estimate how much thiscoating generates the spurious polarization. Figure 3
shows the differences in the pupil maps of the Stokes
signals for +Q input between the ideal (uniform) andreal coating cases. With these maps, we confirmed thatthe spurious polarization by this coating is ~ 0.001 %,which is 2 orders smaller than the requiredpolarimetric sensitivity of < 0.1%. Hence, weconclude that the development of the uniform enoughcoating for the CLASP is successfully completed.

Fig. 1. Location of witness samples during thecoating process and the uniformity of the coatingperformance.

Fig. 2. Measured reflectivity of 12 witness samples asa function of wavelength near the LyD line.

Fig. 3. Difference in Stokes signal pupil map for +Q
input between the case for the uniform coating andthat for the non-uniform coating.
[1] R. Kano et al., SPIE 8443 (2012) 84434F.

46

BL7B

Development of the Multi-Layer Coating for the High-Efficiency Reflective
Polarizer in Lyman-Alpha Line (121.6 nm)
N. Narukage1, S. Ishikawa2, T. Kobiki2, R. Kano2, T. Bando2 and S. Tsuneta2
1

Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku,
Sagamihara, Kanagawa 252-5210, Japan
2
National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588, Japan

Our team consisting of Japan, US, Spain, France,and Norway is developing a Chromospheric
Lyman-Alpha SpectroPolarimeter (CLASP), which is
proposed to fly with a NASA sounding rocket in 2015[1]. CLASP will explore the magnetic fields in thesolar atmosphere (the upper chromosphere andtransition region) via the Hanle effect in theLyman-alpha (LyD) line (121.6 nm) for the first time.
This experiment requires precise spectropolarimetricobservations with a polarimetric sensitivity of < 0.1%
and a wavelength resolution of 0.01 nm.
In order to achieve the polarimetric sensitivity of <0.1%, CLASP requires the high throughput as muchas possible for suppressing the photon noise. For thispurpose, we plan to apply the high-efficiency
reflective polarizer consisting of the Fused Silicasubstrate and the multi-layer coating of SiO2 andMgF2 proposed by Bridou et al. [2] as thepolarization analyzer of CLASP. This high-efficiency
reflective polarizer is theoretically predicted to have areflectivity of 58.4 % for s-polarized beam, which isabout 2.65 times higher than MgF2 plate of 22 %(This MgF2 reflectivity was measured at UVSOR
BL7B in 2009 [3].).
For the development of the high-efficiency
reflective polarizer, we fabricated three polarizers andsix witness samples with the multi-layer coating ofSiO2 and MgF2 performed by Acton Optics andCoatings, and we evaluated their performance withthe witness samples at UVSOR BL7B using ourmeasurement system shown in Fig. 1. Our system
consists of the beam splitter, beam cleaner andgoniometer. The beam splitter made of MgF2 splits
the synchrotron beam into two beams for themeasurements and for monitoring the intensity
variation of BL7B. This BL7B monitor makes theeffect of the intensity fluctuation of the synchrotron
beam on the measurements significantly small. The
beam cleaner mounted at the Brewster’s angle
eliminates the p-polarized beam from the beam of
BL7B. Then, 100% linear polarized beam can be used
for the measurements with the goniometer.
The top and bottom panels in Fig. 2 are themeasured reflectivity of 6 witness samples of thehigh-efficiency reflective polarizer for s- andp-polarized beam, respectively. We note that when wemeasure Rp and Rs, the goniometer is mounted at theconfigurations shown in Fig. 1 and rotated 90 degrees
from Fig. 1, respectively. Based on our measurements,
the polarizers have uniform performance of Rs =54.7 % and Rp = 0.3 % at their Brewster’s angle of 68
degree, which is close to the theoretical value inBridou et al. [2]. We conclude that we havesuccessfully developed the high performancereflective polarizer which has high efficiency andhigh polarization power (҂ (Rs – Rp) / (Rs + Rp)) of
98.9 %.

Fig. 1. Our measurement system.

Fig. 2. Measured reflectivity of witness samples for s(top panel) and p- (bottom panel) polarized beams.
[1] R. Kano et al., SPIE 8443 (2012) 84434F.
[2] F. Bridou et al., Applied Physics A 102 (2011)641.
[3] H. Watanabe et al., UVSOR Activity Report 37(2009) 51.

47