Engineering topics

Modi, M H

Publications and source records attributed to Modi, M H.

3 records

DOE OSTI2012

Measurement of absolute diffraction efficiency of a variable line spaced grating using reflectivity beamline

First and second order diffraction efficiency of a variable line spacing grating of average 1200 lines/mm density is measured at the reflectivity beam line of Indus-1. This grating is blazed at 3.2 deg. and has a blaze wavelength of 10 nm. The measurement has been carried out in the spectral range of 4.5 nm to 80 nm at 3o grazing angle of incidence. The maximum diffraction efficiency of the first order at {approx}10 nm has been found to be {approx} 23% and for the second order it is {approx}13%.

43 PARTICLE ACCELERATORS↗

DOE OSTI2010

Optical Design of VLS-PGM Soft X-Ray Beamline on Indus-2

The optical design of a soft x-ray beamline on the bending magnet of Indus-2 synchrotron source is presented. A Varied Line Spacing Plane Grating Monochromator (VLS-PGM) was adopted with Hettrick type optics. The VLS-PGM consists of a spherical mirror and three interchangeable gratings of line densities 1200 l/mm, 400 l/mm and 150 l/mm to efficiently cover the energy region 50-1500 eV. The VLS groove parameters were obtained by minimizing defocus aberration, coma and spherical aberration. The overall performance of the beamline was estimated by detailed raytracing calculations. The beamline design, results of the raytracing calculations and the expected performances are presented.

43 PARTICLE ACCELERATORS↗

DOE OSTI2010

X-ray Phase Contrast analysis - Digital wavefront development

Optical schemes that enable imaging of the phase shift produced by an object have become popular in the x-ray region, where phase can be the dominant contrast mechanism. The propagation-based technique consists of recording the interference pattern produced by choosing one or several sample-to-detector distances. Pioneering studies, carried out making use of synchrotron radiation, demonstrated that this technique results in a dramatic increase of image contrast and detail visibility, allowing the detection of structures invisible with conventional techniques. An experimental and theoretical study of in-line hard x-ray phase-contrast imaging had been performed. The theoretical description of the technique is based on Fresnel diffraction. As an illustration of the potential of this quantitative imaging technique, high-resolution x-ray phase contrast images of simple objects will be presented.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗