A new kind of hard X-ray / gamma-ray optic is proposed. This optics may be useful for collecting primary X-rays or gammarays from a point source and direct secondary hard X-rays into a given direction. The main element of the proposed optic is a multichannel collimator, which is a glass poly-capillary tube. Incident gamma-rays or hard X-rays with energy E from a point source cross the channel walls of the collimator at a given angle to channel axis and produce secondary Comptonscattered hard X-rays with energy E<sub>1</sub> < E. A small portion of the secondary, Compton-scattered hard X-rays, which are emitted in parallel to the center axis of each channel, transmit through the collimator without absorption, forming a hard Xray beam.
With emergence of focusing X-ray optics many configurations of X-ray microscope have been developed. In this paper we report on a laboratory X-ray microscope based on refractive X-ray optics and microfocus laboratory source. In our experimental setup we use parabolic Compound Refractive X-ray Lens (CRL) made of beryllium and capillary spherical CRL made of epoxy. A copper 2000 mesh grid with 13 μm period and the width of the wire of about 4-5 μm has been clearly resolved with good enough contrast in transmission full-field X-ray microscopy mode. The advantages of the two-lens design have been shown experimentally for both transmission full-field and scanning X-ray microscopes. The discussion of the optimal distances between optical elements in the X-ray microscope is presented.
A focusing test of hard x-rays has been done using spherical compound refractive lens which was composed of 123 biconcave microlenses with a size of 200 μm in diameter. Each microlens was
formed by the epoxy between two bubbles which were injected into an epoxy-filled glass capillary. The focal length of the lens was 114 mm at 8 keV. The optical simulation was completed by ray tracing by
the commercial program of ZEMAX. The estimated size of focal spot was 17.2 μm. The focusing experiment has been achieved at U7B beamline in the National Synchrotron Radiation Laboratory (NSRL) at the energy of 8 keV. The measured focal spot size (FWHM) was 33.3x65.9 μm<sup>2</sup> (VxH).
Compound refractive x-ray lens is a unique device to form image of opaque object which is
illuminated by x-rays. It is consisted of a lot number of placed in-line concave microlenses and works
like ordinary refractive lens for visual light. In contrast to other x-ray optical devices, it could achieve
satisfying resolution without complicated equipment. The spherical compound refractive x-ray lens
used in this experiment is composed of 123 biconcave microlenses of 200 μm diameter. Each microlens
was formed by the epoxy between two bubbles which were injected into an epoxy-filled glass capillary.
There are three advantages ensuring good image quality of the lens for using in hard x-rays: (1) The
epoxy (C<sub>100</sub>H<sub>200</sub>O<sub>20</sub>N, 1.08 g/cc) is composed of carbon, hydrogen and nitrogen, each of them is
characterized by a low absorption coefficient for 5-30 keV x-rays. (2) Because of the nature of physics
forming the bubble, the lens surface quality is extremely good. (3) The capillary makes sure that the
series of unit lenses are well aligned coaxially. The lens focal length is 114 mm at 8.05 keV which is
adjusted according to thick-lens analysis. X-ray images of grid mesh are compared between using a
copper anode x-ray tube without filter and a synchrotron radiation source with monochromator. It could
be found that the resolution and contrast are improved a lot by using monochromatic x-rays. The field
of view and geometrical distortion around the edges of the field of view are reduced because of using a
synchrotron radiation source. For x-ray tube as source the lens achieved a spatial resolution of 5 μm
and field of view of about 700 μm. For a synchrotron radiation source, that is 3.8 μm by 2.3 μm
resolution and field of view of about 316 μm by 128 μm.
Compound refractive lenses (CRL), consisting of a lot number in-line concave microlenses made of low-Z material were studied. Lenses with focal length 109 mm and 41 mm for 8-keV X-rays, microfocus X-ray tube and X-ray CCD camera were used in experiments. Obtained images show intensity distribution of magnified microfocus X-ray source
focal spot. Within the experiments, one lens was also used as an objective lens of the X-ray microscope, where the copper anode X-ray microfocus tube served as a source. Magnified images of gold mesh with 5 microns bars were obtained. Theoretical limits of CRL and experimental results are discussed.
A prototype x-ray imaging system was built and tested for high-resolution x-ray radiography and tomography. The
instrument consists of a microspot x-ray tube with a multilayer optic, a parabolic compound refractive lens (CRL) made
of a plastic containing only hydrogen and carbon, and an x-ray detector. A rotation stage was added for tomography.
Images were acquired of both grid meshes and biological materials, and these are compared to images achieved with
spherical lenses. We found the best image quality using the multilayer condenser with a parabolic lens, compared to
images with a spherical lens and without the multilayer optics. The resolution was measured using a 155 element
parabolic CRL and a multilayer condenser with the microspot tube. The experiment demonstrates about 1.1 μm
New projection- type X-ray microscope with a compound refractive lens as the optical element is presented. The microscope consists of an X-ray source that is 1-2 mm in diameter, compound X-ray lens and X-ray camera that are placed in-line to satisfy the lens formula. The lens forms an image of the X-ray source at camera sensitive plate. An object is placed between the X-ray source and the lens as close as possible to the source, and the camera shows a shadow image of the object. Spatial resolution of the microscope depends on the lens focal length, lens aperture and the distance from the source to the object. One to two micron resolution may be achieved by placing the object at a distance of 1-5mm from the source. The X-ray source may be designed with the target deposited on a 200-μm thick Be window, which permits the object to be placed very close to the emitting surface. The tube focal spot is equal to 1-2 mm. Results of imaging experiments with an ordinary copper anode X-ray tube and a 10-cm focal length spherical compound refractive X-ray lens are discussed.
Compound refractive X-ray lens, consisting of a lot number of placed in-line concave microlenses, is a unique device to control X-ray beams. It works like ordinary refractive lens for visual light and, in contrast to other X-ray optical devices, is useful for forming image of X-ray source. The size of the source image S1 depends on the distance a between the source and the lens and may be calculated as S1=S M, where S is source size, M- magnification. The magnification M depends on a and b as M=b/a, where b is distance from the lens to the source image. This distance b satisfies to a well-known lens formula 1/a+1/b=1/f, where f is lens focal length. This lens property may be used for forming small-sized X-ray spots at a large enough distances from the lens. Such beams are of great interest for experiments on SAXS and X-ray diffraction.
Here we report results of our first experiments in Istituto per lo Studio dei Materiali Nanostrutturati and Laboratori Nazionali di Frascati on using compound refractive X-ray lenses for forming X-ray beams.
We have fabricated and tested short focal-length compound refractive lenses for X-rays (CRLs) and considered its
application for focusing coherent beams. The lens is designed in the form of glass capillary filled by micro-air-bubbles
embedded into epoxy. The interface between the bubbles formed 90 to 196 spherical bi-concave microlenses with curvature
radius equals to the capillary one. When compared with CRLs manufactured using other methods, the micro-bubble lenses
have shorter focal lengths with higher transmission for moderate energy X-rays (e.g. 7 - 12 keV). The lenses are inexpensive
and are ideally suited for focusing X-rays generated by high power single pulsed operation coherent X-ray sources with
Source size 50-100 microns. We used beamline 2-3 at the Stanford Synchrotron Radiation Laboratory (SSRL) to measure
focal lengths between 100-150 mm and absorption apertures between 90 to 120 pm. Transmission profiles were measured
giving, for example, a peak transmission of 27 % for a 130-mm focal length CRL at 8 keV. The focal-spot sizes were also
measured yielding, for example, an elliptical spot of 5 × 14-μm<sup>2</sup> resulting from an approximate 80-fold demagnification of
the 0.44 × 1.7 mm<sup>2</sup> source.
Microcapillary lens, designed in the form of glass capillary filled by a set of concave spherical microlenses, is a novel design of the compound refractive lens for X-rays. The microlenses inside the capillary are formed by putting air bubbles into epoxy. The interface between two air bubbles has a biconcave form and may acts as a lens for X-rays. The lens for investigations was realized in the form of 200-microns in diameter glass microcapillary filled by 137 individual epoxy spherical concave lenses. The lens focal length is about 10 cm for 8-keV X-rays. Adelphi Technology, Inc. formerly tested the microcapillary lens at Stanford Synchrotron Radiation Laboratory for 7-12 keV X-rays. It was shown that the lens focuses 8-keV synchrotron radiation X-ray beam into micron-sized spot. We have studied a possibility to use the lens for imaging applications for the case when an ordinary copper-anode X-ray tube was used as a source of radiation. The image of the object was recorded by CMOS-camera. The object, lens and CMOS-camera were placed inline at a distance to one from each another satisfied to the lens formula. Results of experiments on with lens imaging of gold mesh are presented and discussed.
We have fabricated and tested short focal-length compound refractive lenses (CRLs) composed of micro-bubbles embedded in epoxy. The bubbles were formed in epoxy inside glass capillaries. The interface between the bubbles formed 90 to 196 spherical bi-concave microlenses reducing the overall focal length inversely by the number of lenses.
When compared with CRLs manufactured using other methods, the micro-bubble lenses have shorter focal lengths, better imaging, and focusing qualities with higher transmissions and gains for moderate energy x-rays (e.g. 7 - 12 keV). We used beamline 2-3 at the Stanford Synchrotron Radiation Laboratory (SSRL) to measure focal lengths between 100-150 mm and absorption apertures between 90 to 120 μm. Transmission profiles were measured giving, for example, a peak transmission of 27 % for a 130-mm focal length CRL at 8 keV. The focal-spot sizes were also measured yielding, for example, an elliptical spot of 5 x 14-μm<sup>2</sup> resulting from an approximate 80-fold demagnification of the 0.44 x 1.7 mm<sup>2</sup> source. The measured gains in intensity over that of unfocused beam were between 9 and 26. Theoretical gain calculations that include spherical aberrations show that these values are reasonable. The micro-bubble technique opens a new opportunity for designing lenses in the 8-9 keV range with focal lengths less than 30-40 mm.
Refractive microcapillary lens for hard x-rays is presented. The lens is designed as glass capillary filled by a large number of biconcave microlenses. Fabrication technique for the lens is described. It is shown that the the microlenses have a spherical shape. The spherical aberrations of the lens are calculated. The possibility of production of micrometer sized x-ray beams by using the microcapillary x-ray lens is discussed.
We developed and studied refracting microcapillary lens for x-ray photons with energy 5.4 keV. This lens is a glass capillary wiht a central channel filled with a number of concave microlenses. The lenses are made by injection compressed air into a capillary channel, previously filled by liquid polymer. The images of 20-100μm width slits are obtained. A good agreement is seen betweenthe image and slits sizes. Ray tracing calculations of iamge formation are made. Experimental and calculated results are in a good agreement.
A novel experimental method is presented for evaluating the crystal lattice imperfections using a reflection X-ray microscope (RXM). An X-ray microscope using an X-ray refractive lens is constructed on the reflected beam axis of the crystal. This method has a unique advantage that the image contrast due to the integral reflectivity variation and due to the phase-contrast of the crystal surface are easily discriminated by de-focusing technique. The sample crystals chosen were silicon circular Bragg Fresnel zone places (BFZPs). The BFZPs had circular zones on Si(111) plane with two different groove depths of 3.9 micrometers and 5.9 micrometers . The validity of the de-focusing method was proved and a clear difference of the X-ray microscope images was observed for the BFZPs with different groove depth.
Refractive microcapillary lens for hard X-rays is presented. The lens is designed as glass capillary filled by a large number of biconcave microlenses. Fabrication technique for the lens is described. It is shown that the microlenses have a spherical shape. The spherical aberrations of the lens are calculated. The possibility of production of micrometer sized X-ray beams by using the microcapillary X-ray lens is discussed.
Calculation procedures and experimental results form glancing angle x-ray fluorescence from thin films on a flat substrate are presented. A new x-ray tube unit with a super smooth-surface anode and a built-in waveguide collimator is described. The unit makes it possible to obtain narrowly- collimated beams of x-ray radiation with a microfocus line.
A new X-ray tube unit with a super smooth-surface anode and a built-in waveguide collimator is proposed. The unit makes it possible to obtain narrow-collimated beams of X-ray radiation with a line microfocus. Calculation procedure and experimental results for the glancing angle X—ray fluorescence are presented.
Keywords: X—ray tubes, X—ray waveguides, X—ray fluorescence
We have investigated the propagation of the characteristic radiation of the Mo and Re atoms through the planar X-ray waveguides. It is established that if the number of reflections in the waveguide channel is sufficiently large, it is necessary to take into account the scattering of the beam at the roughnesses of the channel walls for the description of the angle distribution of the radiation at the exist of the waveguide. One of the possible systems for scanning the objects by the X-ray beam on the base of the planar waveguides is proposed.
A study is made of transmission of straight and curved thin-film gamma-waveguides. It is shown that in curved waveguides maintaining the limited number of waveguide modes a radiation flux may be appreciably attenuated due to radiation of photons into the medium surrounding a waveguide. Measurement was made of the angular distribution of photons passed through the x-ray guide.