X-ray Gabor holography

1995 ◽  
Vol 53 ◽  
pp. 612-613
Author(s):  
Steve Lindaas ◽  
Chris Jacobsen ◽  
Alex Kalinovsky ◽  
Malcolm Howells
Keyword(s):  
Surface Relief ◽  
Biological Imaging ◽  
Specimen Preparation ◽  
X Rays ◽  
X Ray ◽  
Water Window ◽  
Biological Objects ◽  
Transmission Imaging ◽  
Atomic Force ◽  
Electron Microscopes

Soft x-ray microscopy offers an approach to transmission imaging of wet, micron-thick biological objects at a resolution superior to that of optical microscopes and with less specimen preparation/manipulation than electron microscopes. Gabor holography has unique characteristics which make it particularly well suited for certain investigations: it requires no prefocussing, it is compatible with flash x-ray sources, and it is able to use the whole footprint of multimode sources. Our method serves to refine this technique in anticipation of the development of suitable flash sources (such as x-ray lasers) and to develop cryo capabilities with which to reduce specimen damage. Our primary emphasis has been on biological imaging so we use x-rays in the water window (between the Oxygen-K and Carbon-K absorption edges) with which we record holograms in vacuum or in air.The hologram is recorded on a high resolution recording medium; our work employs the photoresist poly(methylmethacrylate) (PMMA). Following resist “development” (solvent etching), a surface relief pattern is produced which an atomic force microscope is aptly suited to image.

scholarly journals Characterization and optimization of a laser generated plasma source of soft X rays

1988 ◽  
Vol 6 (2) ◽  
pp. 225-234 ◽  
Author(s):  
A. M. Rogoyski ◽  
P. Charalambous ◽  
C. P. Hills ◽  
A. G. Michette
Keyword(s):  
Angular Distribution ◽  
Plasma Source ◽  
Biological Imaging ◽  
X Rays ◽  
Specific Interest ◽  
X Ray ◽  
Preliminary Characterization ◽  
Water Window ◽  
Monochromatic Source

An investigation into the feasibility of using a laser-generated plasma source of soft X rays as a laboratory based instrument for biological imaging and microlithography is presented. A preliminary characterization of the source has been carried out with carbon, copper and aluminum targets with specific interest in generating a monochromatic source of soft X rays in the ‘water window’. Measurements of X-ray production with respect to angular distribution, effects of cratering and different focusing conditions are reported. Initial conclusions on the optimization of the source for use in biological imaging are drawn.

X-ray Gabor holography: Recent progress

1994 ◽  
Vol 52 ◽  
pp. 72-73
Author(s):  
Steve Lindaas ◽  
Chris Jacobsen ◽  
Alex Kalinovsky ◽  
Malcolm Howells
Keyword(s):  
Numerical Aperture ◽  
Single Mode ◽  
Biological Imaging ◽  
X Rays ◽  
Reconstruction Process ◽  
X Ray ◽  
Water Window ◽  
Reconstruction Methods ◽  
Resolution Imaging ◽  
Sample Alignment

Gabor holography is well positioned to exploit flash x-ray sources, such as x-ray lasers and free electron lasers, as well as ultra-bright third generation synchrotron sources as a sub-50 nm resolution imaging technique for biological samples. Gabor holography requires no optics (except for a monochromator with λ/Δλ ~ 500) and no sample prefocusing since the image is focused in the reconstruction process. Furthermore, sample alignment is eased since the area of illumination can be quite large. In fact, Gabor holography can be used to image large fields with multimode sources with the resulting numerical aperture, and hence resolution, being limited by the size of a single mode. However, Gabor holography is not a real time technique so there is no rapid feedback to improve the immediate experiment. In addition, the resolution has been limited by shortcomings in the reconstruction methods.Our primary emphasis has been on biological imaging so we use x-rays in the water window (between the O-K and C-K absorption edges).

Studies of metaphase chromosomes in the scanning transmission x-ray microscope: Image fidelity, radiation damage and specimen preparation

1992 ◽  
Vol 50 (2) ◽  
pp. 1038-1039
Author(s):  
Shawn Williams ◽  
Xiaodong Zhang ◽  
Susan Lamm ◽  
Jack Van’t Hof
Keyword(s):  
Visible Light ◽  
Radiation Damage ◽  
Cross Section ◽  
Imaging Techniques ◽  
Dose Range ◽  
Specimen Preparation ◽  
X Rays ◽  
Metaphase Chromosomes ◽  
X Ray ◽  
Scanning Transmission

The Scanning Transmission X-ray Microscope (STXM) is well suited for investigating metaphase chromosome structure. The absorption cross-section of soft x-rays having energies between the carbon and oxygen K edges (284 - 531 eV) is 6 - 9.5 times greater for organic specimens than for water, which permits one to examine unstained, wet biological specimens with resolution superior to that attainable using visible light. The attenuation length of the x-rays is suitable for imaging micron thick specimens without sectioning. This large difference in cross-section yields good specimen contrast, so that fewer soft x-rays than electrons are required to image wet biological specimens at a given resolution. But most imaging techniques delivering better resolution than visible light produce radiation damage. Soft x-rays are known to be very effective in damaging biological specimens. The STXM is constructed to minimize specimen dose, but it is important to measure the actual damage induced as a function of dose in order to determine the dose range within which radiation damage does not compromise image quality.

An x-ray microprobe based upon a close-coupled focal-spot / glass capillary arrangement

1992 ◽  
Vol 50 (2) ◽  
pp. 1758-1759
Author(s):  
D. A. Carpenter ◽  
M. A. Taylor
Keyword(s):  
Imaging Techniques ◽  
Fluorescence Analysis ◽  
High Sensitivity ◽  
Specimen Preparation ◽  
X Rays ◽  
Glass Capillary ◽  
Close Coupling ◽  
X Ray ◽  
Point To Point ◽  
Beam Damage

The development of intense sources of x rays has led to renewed interest in the use of microbeams of x rays in x-ray fluorescence analysis. Sparks pointed out that the use of x rays as a probe offered the advantages of high sensitivity, low detection limits, low beam damage, and large penetration depths with minimal specimen preparation or perturbation. In addition, the option of air operation provided special advantages for examination of hydrated systems or for nondestructive microanalysis of large specimens.The disadvantages of synchrotron sources prompted the development of laboratory-based instrumentation with various schemes to maximize the beam flux while maintaining small point-to-point resolution. Nichols and Ryon developed a microprobe using a rotating anode source and a modified microdiffractometer. Cross and Wherry showed that by close-coupling the x-ray source, specimen, and detector, good intensities could be obtained for beam sizes between 30 and 100μm. More importantly, both groups combined specimen scanning with modern imaging techniques for rapid element mapping.

The Limits of Resolution in X-Ray Microscopy

1997 ◽  
Vol 3 (S2) ◽  
pp. 1185-1186
Author(s):  
J. Maser ◽  
C. Jacobsen ◽  
S. Spector
Keyword(s):  
Near Field ◽  
High Spectral Resolution ◽  
X Rays ◽  
Thin Specimen ◽  
Selective Labeling ◽  
X Ray ◽  
Luminescent Probes ◽  
Electron Microscopes ◽  
Good Signal ◽  
Do So

In far-field microscopes, the spatial resolution is ultimately limited by the wavelength of the radiation used. While near-field and related microscopes can improve upon this, they can only do so with thin specimen regions. Thin specimens can also be studied at atomic resolution using electron microscopes. To achieve improved resolution on micrometer-thick specimens, another alternative is to use significantly shorter photon wavelengths. We discuss here the use of soft x-rays for microscopy and their resolution limits.Image formation requires resolution and contrast. by using soft x-rays with a photon energy between the K absorption edges of carbon and oxygen, one is able to image hydrated biological specimens with high contrast. The contrast is such that no addi-tional staining is required, while efforts are also underway to utilize gold and luminescent probes for selective labeling. In addition, x-ray sources have high spectral resolution and good signal-to-background relative to electron microscopes which allows for elemental and chemical state mapping of major constituents.

Applications of a Laboratory X-ray Micropsobe to Materials Analysis

1988 ◽  
Vol 32 ◽  
pp. 115-120 ◽  
Author(s):  
D. A. Carpenter ◽  
M. A. Taylor ◽  
C. E. Holcombe
Keyword(s):  
Spatial Resolution ◽  
High Spatial Resolution ◽  
High Sensitivity ◽  
Specimen Preparation ◽  
X Rays ◽  
Glass Capillary ◽  
Materials Analysis ◽  
X Ray ◽  
Small Glass

A laboratory-based X-ray microprobe, composed of a high-brilliance microfocus X-ray tube, coupled with a small glass capillary, has been developed for materials applications. Because of total external reflectance of X rays from the smooth inside bore of the glass capillary, the microprobe has a high sensitivity as well as a high spatial resolution. The use of X rays to excite elemental fluorescence offers the advantages of good peak-to-background, the ability to operate in air, and minimal specimen preparation. In addition, the development of laboratory-based instrumentation has been of Interest recently because of greater accessibility when compared with synchrotron X-ray microprobes.

Recent Applications with the X-Ray Microscope

1957 ◽  
Vol 1 ◽  
pp. 483-494
Author(s):  
Selby E. Summers
Keyword(s):  
Resolving Power ◽  
Depth Of Field ◽  
Specimen Preparation ◽  
X Rays ◽  
Optical Instrument ◽  
X Ray ◽  
Technical Details ◽  
The Many ◽  
Preparation Techniques ◽  
Shadow Projection

AbstractThe X-ray microscope is an electrostatic optical instrument employing X-rays for shadow projection to magnify and reveal detailed internal structure of specimens opaque to light or electrons. Its many advantages — high resolving power, greater penetration, large depth of field, and stereographic presentation — make the X-ray Microscope a versatile instrument for industrial research and development. Because the instrument was recently introduced, little information is available on specimen preparation techniques, or types of specimens suitable for study. A few of the many possible applications will be discussed, as well as a brief review of the technical details of the instrument.

Improving the soft X-ray reflectivity of Cr/Ti multilayers by co-deposition of B4C

2020 ◽  
Vol 27 (6) ◽  
pp. 1614-1617
Author(s):  
Jingtao Zhu ◽  
Jiayi Zhang ◽  
Haochuan Li ◽  
Yuchun Tu ◽  
Jinwen Chen ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Normal Incidence ◽  
X Rays ◽  
Interface Quality ◽  
X Ray ◽  
Water Window ◽  
Section Electron ◽  
Biology Research ◽  
Section Electron Microscopy

The `water window', covering 2.4–4.4 nm, is an important wavelength range particularly essential to biology research. Cr/Ti multilayers are one of the promising reflecting elements in this region because the near-normal-incidence reflectivity is theoretically as high as 64% at 2.73 nm. However, due to multilayer imperfections, the reported reflectivity is lower than 3% for near-normal incidence. Here, B and C were intentionally incorporated into ultra-thin Cr/Ti soft X-ray multilayers by co-deposition of B4C at the interfaces. The effect on the multilayer structure and composition has been investigated using X-ray reflectometry, X-ray photoelectron spectroscopy, and cross-section electron microscopy. It is shown that B and C are mainly bonded to Ti sites, forming a nonstoichiometric TiB x C y composition, which hinders the interface diffusion, supresses the crystallization of the Cr/Ti multilayer and dramatically improves the interface quality of Cr/TiB x C y multilayers. As a result, the near-normal-incidence reflectivity of soft X-rays increases from 4.48% to 15.75% at a wavelength of 2.73 nm.

X-Ray Safety of Electron Microscopes

1972 ◽  
Vol 30 ◽  
pp. 414-417
Author(s):  
D. F. Parsons ◽  
V. A. Phillips ◽  
J. S. Lally
Keyword(s):  
Electron Microscope ◽  
Atomic Number ◽  
Health Hazards ◽  
X Rays ◽  
X Ray ◽  
Metal Parts ◽  
Voltage Electron ◽  
Two Factors ◽  
Electron Microscopes ◽  
Acceleration Voltage

This investigation was initiated to provide the first assessment, from the users viewpoint, of the health hazards of X-ray leakages from conventional (40-200 Kv acceleration voltage) electron microscopes. Scanning microscopes were not considered at this point.X-rays are produced in the electron microscope when the beam strikes metal parts of the instrument. The degree of X-ray leakage depends on two factors--the intensity of the X-ray source and the amount of metal shielding surrounding it. The efficiency of total (continuous and characteristic) X-ray production is approximately proportional to the atomic number of the metal and to the acceleration voltage (platinum apertures are three times as efficient as the iron of pole pieces). However, the fraction of beam striking the metal has to be taken into account and the efficiency of the shielding. The thickness (number of Half Value Layers), the effect of absorption edges on X-ray transmission, and the cracks or openings in the shielding all have to be taken into account.

Imaging of 30nm gold spheres by dark-field scanning transmission x-ray microscopy

1994 ◽  
Vol 52 ◽  
pp. 52-53
Author(s):  
Henry N. Chapman ◽  
Shawn Williams ◽  
Chris Jacobsen
Keyword(s):  
Dark Field ◽  
Important Application ◽  
X Rays ◽  
National Synchrotron Light Source ◽  
Bright Field ◽  
X Ray ◽  
Biological Objects ◽  
Scanning Transmission ◽  
Gold Labelling ◽  
Synchrotron Light

In a scanning transmission x-ray microscope (STXM), such as that operated at the beamline X-lA at the National Synchrotron Light Source, it is possible to obtain dark-field images by blocking the undeviated transmitted photons so that only x rays scattered by the specimen are detected. Although the signal that is detected in dark-field is much weaker than the conventional bright-field signal the method offers much higher contrast of small features and the possibility of detecting small features with higher signal to noise for the same incident x-ray flux. Also, the signal depends on both the amplitude and phase of the specimen, rather than just the amplitude. One important application of dark-field x-ray microscopy is the imaging of gold-labelled biological specimens. This unites the advantages of x-ray microscopy (the ability of imaging thick biological objects, low radiation dose) with those of gold labelling (specific-site or specific-protien labelling, well documented protocols).The x-ray microscope consists of the scanning transmission x-ray microscope, in which a zone-plate is used to focus monochromatic x rays to a probe, through which the sample is scanned.

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