Huapeng Huang

Overview of polycapillary X-ray optics

Polycapillary optics are utilized in a wide variety of applications and are integral components in many state of the art instruments. Polycapillary optics operate by collecting X-rays and efficiently propagating them by total external reflection to form focused and parallel beams. We discuss the general parameters for designing these optics and provide specific examples on balancing the interrelations of beam flux, source size, focal spot-size, and beam divergence. The development of compact X-ray sources with characteristics tailored to match the requirements of polycapillary optics allows substantial reduction in size, weight, and power of complete X-ray systems. These compact systems have enabled the development of portable, remote, and in-line sensors for applications in industry, science and medicine. We present examples of the utility and potential of these optics for enhancing a wide variety of X-ray analyses.

In situ monitoring of wet granulation using online X-ray powder diffraction.

AbstractPurpose. Polymorphic transformations during the wet granulation of a metastable polymorph of flufenamic acid were monitored in situ using online X-ray powder diffraction. The resulting data were used in testing a proposed process induced transformation rate model, which allows the extent and occurrence of polymorphic transformations during wet granulation to be controlled by adjusting the granulation time. Methods. A small-scale, top mixing granulator was designed for compatibility with novel X-ray powder diffraction equipment (available from X-Ray Optical Systems of East Greenbush, NY). Results. The unique polycapillary optic and X-ray source allowed the transformation of the metastable to the stable polymorph to be followed during the granulation. Following a diffraction peak each for the metastable and stable forms demonstrated that polymorphic transformations during the wetting phase of granulation follow the trends predicted by the model. Conclusions. The advanced online monitoring may allow real-time control of the process by the adjustment of process parameters, such as granulation time, and clearly qualifies as a PAT (process analytical technology).

Convergent-beam method in macromolecular crystallography

A data-collection method for macromolecular crystals using convergent sources is described here. Because of the unique characteristics of the diffraction patterns, a software package CBMPRO has been developed specifically for processing data images collected with the convergent beam method (CBM). The resulting data sets from crystals with two different sets of unit-cell parameters are presented and compared. There is good agreement between data sets from the same type of crystals under slightly different experimental conditions and data sets collected and processed with CBM also agree well with those from conventional oscillation methods, marking an important step to establishing CBM as a viable alternate data-collection method for macromolecular crystals.

Polycapillary optics beam divergences

This paper is about the beam divergences of polycapillary optics. The definitions and measurement methods of polycapillary optics beam local divergence and global divergence are given. Factors like source spot size, optic input focal distance etc. for determining the beam local divergences are analyzed. Some simulation and experimental results for the polycapillary optics, which are used for X-ray diffraction and X-ray lithography, will also be presented.

New capabilities and applications of compact source-optic combinations

Polycapillary and doubly curved crystal x-ray optics have gained broad acceptance and are now being used in a wide variety of applications. Beginning as optics integrated into research setups, they were then used to enhance the performance of existing x-ray analytical instruments and are now widely used as essential components in x-ray spectrometers and diffractometers designed to utilize their capabilities. Development of compact x-ray sources, matched to the optic input requirements have allowed large reduction in the size, power, and weight of x-ray systems which are now resulting in development of compact x-ray instruments for portable, remote, or in-line analytical tools for new applications in industry, science, or medicine.