MIRRORCLE light source demonstrating one micron resolution andclear density mapping
H. Yamadaa, T. Hiraia, M. Moritab, D. Hasegawab, and M. Hanashimab
SLLS center, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, 525-0857, JapanbPhoton Production Laboratory Ltd. Dept. 4-2-1 Takagaichominami, Omihachiman, 523-0898, JapaaABSTRACTMIRRORCLE is a hard X-ray source, which is quite different from either X-ray tubes or synchrotron light sources (SLS).
MIRRORCLE generates high-density photons like SLS, but the source emitter size is much smaller than SLS as well astube. The x-ray angular distribution is much wider than that of SLS. Thus diagnosis of human body is possible. The Xray spectrum is polychromatic and peaking around 30-200 keV, which is higher than that of SLS. The center energy isselected by changing the target material and thickness. Because of these features imaging by MIRRORCLE is advancedby the largely magnified imaging, extremely sharp edge enhancement due to the phase contrast, and one micron order
spatial resolution without optical elements. Density mapping is demonstrated in a simple magnified imaging. By
tomography density volume mapping is obtained.
Keywords: tabletop synchrotron, hard x-ray source, phase contrast, density mapping, tomography

1. INTRODUCTIONMIRRORCLE is an x-ray source based on a low energy storage ring [1-5]. The 4 and 1-MeV MIRRORCLE’s storage
ring is now 35cm outer diameter and 8cm orbit radius as seen in Fig. 1. The 4-MeV MIRRORCLE is designed for nondestructive testing of bridges, chemical and power plants and space crafts and so on. The 1-MeV MIRRORCLE is a sizeof x-ray tube, and is useful for medical diagnosis and X-ray microscope, which is under commissioning.

35cmFig. 1. Left: The 4 MeV MIRRORCLE is made of 8 cm orbit radius normal conducting storage ring as seen in pink color.
Yoke is of 35 cm long rectangular shape. The injector is in the left behind, and pulse compressor is seen in the right.
The total weight is 1.2 t. Right: Inside of MIRRORCLE chamber. X-ray emission from a target is demonstrated.

1.1 What is MIRRORCLEMIRRORCLE is really a low energy storage ring that emits far infrared synchrotron radiation, but x-rays are generated
by a target placed in the electron orbit as seen in Fig. 1 [10-12]. The accumulated beam current reaches 4A when theinjector current is100mA. The measured beam size of the 20 MeV machine without target is around 2mm, damping time
10ms, and lifetime 1 minute. Injection is carried out at 400Hz repetition for the 4 MeV machine and 1k Hz for the 1
MeV machine. The designed X-ray density of the 20 MeV machine is 1010 photons/sec, mrad2, 0.1%BW, while thepresent value is 108 without synchrotron accelerator power. This value is comparable to that of x-ray tube as
monochromatic x-ray beams are compared, but it should be remembered that MIRRORCLE generates polychromatic Xrays. The left figure in Fig. 2 shows the brilliance that is the value divided by the target cross section 10-4 mm2 forMIRRORCLE’s. Since the angular divergence of MIRRORCLE is much wider, the total flux is much higher than that ofSLS as seen in the right figure in Fig. 2. This implies that MIRRORCLE is an excellent imaging source.

MIRRORCLESLSFig. 2 Left: MIRRORCLE’s Brilliance is compared with that of regular synchrotron light sources. Right: integrated
photon number over 2π/γ in 0.1%BW., where γ is the normalized electron energy. This is the case for 20 MeVMIRRORCLE. Currently those intensities of MIRRORCLE are one order lower.

1.2 How it’s different from conventional SR and x-ray tube
MIRRORCLE is a synchrotron based x-ray source, but there are many differences from regular SLS and x-ray tube as
summarized in Table. 1. It generates polychromatic spectrum in the range higher than 10keV up to the electron energy.
We can select the central energy by the thickness and atomic number. The emission point is defined by the cross sectionof target in the electron beam direction as about one micron. Radiation spread over the cone defined by 1/γ.

Table 1 Features of MIRRORCLE are discussed from three different aspects.
How it’s different from synchrotron light source and X-ray tube
AInje ctor
Injector

Synch
Synchrotronrotron1. Highcurrent

Orbit radius=8cm> portable source
stored beam current=4A> High power radiation source

Ｘ線
Ｘ線

BC

2. Smallemission
point1-1 0 μm target

3. Conebeam> d istance reduce s thescattering backgroun d4.
PolychromaticX-ray

High e nergy X-ray> NDT of heavy construction> Magnified imaging> Characterization of materials
by monochromatic X- ray

2. MAGINFIED IMAGING
The feature of category B in Table 1 results in the magnified imaging [6-9]. Since the image is magnified, necessary
detector pixel size is less important. For instance a hundred micron pixel detector is enough to define 5 μm object as themagnification is 20. We demonstrate how resolution is improved by the target size as seen in Fig. 3.

Fig. 3 an X-ray test chart is imaged by the different size targets and at 12 times magnification. Sizes and materials areindicated in the left. We see here that not only the space resolution but also the contrast is very much improved by thesmall target. Point and line mean point and line targets, respectively.

3. SIGNIFICANT PHASE CONTRAST APPEARS
Significant phase contrast appears as the target size is less than 25μm and the magnification is larger than 2 [6]. Edge ismore enhanced as magnification is larger as seen in Fig. 4.

Fig. 4 the left: edge of 2mm thick plastic is imaged by MIRRORCLE. In the right, projections along the line
perpendicular to the edge are shown for different magnifications. Both bright side and dark side are seen. Contrast ofthe edge becomes higher as magnification (indicated as x11 or so) is larger.

x110.5mmthick plate

A

X-ray

x11

10mmφRodA

B

B

10mm

10mm
X-ray
Babble in a water
A

X-ray

X-ray
5mmφpipe

Bx11AB

10mmFig. 5 It is interesting to see how edge effect appears in the different object shape. The left upper represents a plane plate,the left lower is babble in water, the right upper represents solid rod, and the right lower represents hollow rod.

Fig. 5 demonstrates the edge effects to the different object shapes. These examples will be useful for understanding theshape and density of organs in a body from the plane image. In the simple plane images the information of volume anddensity are presented.

4. POLYCHROMATIC X-RAY BEAM IS USEFUL
There is discussion on the usefulness of polychromatic or monochromatic beams for x-ray imaging. If we remember thehistory of camera, we know that is started with black and white. We know today every body loves color prints, because
it includes more information. Probably it is the same for x-ray imaging. If a detector distinguishes the color of x-rays
like human eyes, everybody agrees with this statement. Even though let’s, however, say that information of color is
hided in these plane pictures taken by polychromatic x-ray beam. The deflection of x-ray depends on the energy of xrays, kind of materials, thicknesses and densities. Absorption contrast image includes the information on materials,volumes and densities. If we use two algorithms for absorption and phase contrast, we should be able to distinguish thematerials, densities and volumes. Of course if we use two different targets the obtainable information will be doubled,since x-ray energies are different as seen in Table 1.
The pictures in Fig. 5 demonstrate the feeling of volume. The image of flat plate and air babble in water are so different.
Gradation in the black and white density represents the shape of object. There is a significant difference from the picture
taken by the monochromatic beam.
4.1 Complex materials are recognized
In Fig. 6 we show an x-ray image of valve made of steel. The cap is made of aluminum, and inside there is a sheet ofrubber. Apparently the light material rubber is recognized. This happens because of the polychromatic nature of beam.

RubberFig. 6 X-ray image of valve is shown. The left is 2 times magnified one. The right is 4 times magnified one. Everydetails of valve is seen in the left in which image process is applied. In the right rubber inside of aluminum cap isidentified.
4.2 Tomography of solid concrete block
In Fig. 7 we demonstrate the CT image of concrete. The size of concrete block is about 4cm. The detector used is Flat
panel (Varian Paxscan 2520, pixel size: 250μm). 5 times magnification is applied, thus we are resolving 50μm space.
Total exposure time was 2 minutes for 380 deg. We applied regular CT algorithm for absorption contrast. Concrete issupposed to be solid, but we see here complex structures. Millimeter size holes are seen many. Patterns were, however,unexpected. In the process of drying, concentration appears differently at different spot depending on conditions. Watercontents and density must be different. This must be important information to study how to make a tough concrete.
Anyway in this example we could observe mosaic density in a concrete. Polychromatic x-ray beam takes an importantrole.

X-ray CT by MIRRORCLE

Cross sectional view ofConcrete block

１23

4

56

789

１
40mm

24mm
36mm
9・MIRRORCLE-6X
target size: 50μmφ×5 magnified image
・detector：Flat panel（Varian社 Paxscan2520）
254μm/pixel

Fig. 7 Cross section of concrete block is seen at the different depth obtained by CT.

4.3 NDT by high energy flux
The available x-ray energy from MIRRORCLE is much higher compared to regular synchrotron and x-ray tube. For
heavy construction LINAC is usually used, but the resolution is less than 3mm. MIRRORCLE is the machine thatachieved the finest space resolution ever observed [13, 14]. In Fig. 8 we demonstrate iron wires through 45cm thickconcrete block. This image was taken in 6 minutes by 4MeV MIRRORCLE. In the right we demonstrate how the insideof motorcycle engine is. It should be noted that any image processes are not applied to these images. Particular image
process will improve the contrast.

12mm
9m

3m
6mm

Fig. 8 the left: stainless wires placed at the end of 45cm concrete block are clearly seen. Density of concrete is also
demonstrated. The right is the motor cycle engine. Spark plague is identified.

5. FURTHER DEVELOPMENT
MIRRORCLE generates high energy, widely spread and large x-ray flux from 1 μm order target. We can selectparticular wavelength by monochrometer. Extraction of thin fan beam is possible by MIRRORCLE. We are now
constructing such a submicron spacing collimator system shown in Fig. 9. We expect less than one micron resolution
small angle scattering combining with tomography. We will be able to extract nano-100nm particle information anddistribution in volume materials. Proteins space distribution and structure of strings, thin films are the subject to bestudied as described in Fig. 9.

We combines SAXS and fan beam CT to measuresnano to 100nm size particles and structure
Regular synchrotron beam is too narrow to see the volum e

集光系

Observable field is limited

MIRRORCLE enable the measurement of shape and structure by using
narrow collimated fan beam. Sm all angle scattering and CT is combined

CT algorithm
for SAXS

collimator

1 μm gap

試料断面1~100nmの粒 度の観測

Fig. 9 a schematic view of small angle scattering using 1μm thick fan beam. When tomography is combined we areable to seen 100nm size structure in a volume sample, such as protein.

6. SUMMARY
In this paper we have demonstrated variety of unique applications related to imaging by MIRRORCLE-type x-ray source.
Uniqueness comes from its unique x-ray characteristic; very small emission size, polychromatic spectrum, and widely
spread cone beam. Advantages of MIRRORCLE are summarized below.
1, MIRRORCLE is different from synchrotron light source or X-ray tube, thus the obtained image shows different
quality.
2. Magnified imaging presents significant phase contrast and reduced scattering background.
3. Polychromatic beam is useful to see complex material in both phase and absorption contrast.
4. Image by the polychromatic beam is quite different from one by monochromatic x-rays. More information is behind.
5. Density distribution is seen by CT. We think two algorithms for reconstruction will be useful. One for phase contrast
and the other for absorption contrast
6. MIRRORCLE is the machine which can provide a very thin fan beam. By combining small angle scattering andmicro-CT, we will be able to see nano to 100 nano level particle phenomena. Image of protein will be the next target tosee by MIRRORCLE.
7. Ten micron resolution medical imaging is now realized by MIRRORCLE
8. Non destructive testing steps into new stage with less than 1 mm resolution. Such resolution has never been reachedwith other methods.
9. Of course most important fact is its machine size. MIRRORCLE realized the small machine size as well as highquality beam which is adaptable at small laboratory, hospital and factory.

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