Synchrotron radiation white beam topography with an oscillating monochromator

Drawbacks of white beam topography with synchrotron radiation, such as intense fluorescence background, thermal strain, and radiation damage, can be avoided by filtering the beam with an oscillating perfect crystal monochromator. The advantage of the white beam technique, namely the imaging of a sample of poor quality, is maintained. The image contrast is even improved due to the suppression of higher harmonics. Topographs of a LiF crystal demonstrate the feasibility of the method

Performance of an x‐ray optical time delay line with synchrotron radiation

We describe pump‐probe experiments in the x‐ray region using synchrotron radiation to supply both the pump and probe beams. The time between pump and probe is adjustable on the nanosecond time scale by means of an optical delay line operating in the x‐ray region. With the ‘‘third generation’’ sources presently under construction around the world it should be practicable to study optical excitations using similar techniques to those described here. The initial studies we describe were carried out at the National Synchrotron Light Source. A 30‐μm‐thick silicon [110] crystal was irradiated by white light from a bending magnet. The radiation passing through this sample was monochromated by two silicon [660] reflections in such a way that the monochromatic beam was directed onto the first surface of the thin crystal sample. The surface of this thin crystal was probed by recording the symmetric (220) reflexion 2.78 ns after illumination by the white beam. Techniques for overcoming the background problem resulting from scattering of the white beam by the sample crystal are discussed

High Spatial Resolution Imaging of Bone Mineral Using Computed Microtomography

RATIONALE AND OBJECTIVES. The application of various high-resolution (<100 [micro]m) imaging techniques for in vitro bone mineral analysis is explored.METHODS. The techniques of contact microradiography and microtomography, using the x-ray spectrum filtered out of synchrotron radiation (SR) and conventional staining techniques, are compared to each other by presenting a variety of different samples. The relationship between radiation exposure and spatial resolution micro-computed tomography (CT) images of a finger bone is explored. The relevant properties of SR are explained.RESULTS. In CT images, a spatial resolution of 100 [micro]m was obtained. New bone mineral induced by mechanical periosteal irritation in a rabbit tibia was quantified. In one case a microradiogram and a microtomogram of the same slice were taken for comparison. Histologic sections and miroradiograms taken from a specimen of a human femur for comparison are presented.CONCLUSIONS. Microradiography and staining techniques require rather sophisticated sample preparation; quantitative image analysis is more difficult as the resulting image must be digitized. The CT technique requires almost no sample preparation and allows for accurate bone mineral quantification. However, CT images with a resolution of several microns limit the sample size to a few mm. Micro-CT and microradiography can be performed with conventional x-ray sources, but the use of SR is of particular interest in high resolution imaging, because its white spectrum allows for optimum x-ray energy selection and its high intensity for short scan times