The manufacture of a very high precision x-ray collimator array for rapid tomographic energy dispersive diffraction imaging (TEDDI)

Abstract

A very high resolution x-ray collimator array has been constructed for use with tomographic energy dispersive diffraction imaging (TEDDI). The collimator consists of a 16 × 16 array of 50 µm diameter holes in a series of 0.1 mm tungsten plates aligned to a tolerance of ±2 µm. The minimum angular divergence of the transmitted x-ray beams through each transmission pathway in the collimator array has been designed to be 0.02°, which is equivalent to an energy dispersed resolution of 250 eV with an aspect ratio of 6000:1. The collimator array has been matched to the development of an energy sensitive x-ray detector array (Seller et al 1998 Proc. SPIE 3445 584–92) for TEDDI studies of materials. The very high tolerance of the aperture size and placement was achieved by utilizing high intensity femtosecond pulse duration laser machining from a diode pumped solid state laser (DPSS). Using a novel arrangement the laser acted as the principal alignment and cutting tool. The collimator transmission function has been tested using a uniform synchrotron radiation flood field. The transmission and spatial uniformity were found to be consistent with the design parameters for TEDDI applications and also as a diffracted beam collimator for monochromatic powder diffraction studies.