Use Of A C.C.D. Array In An X-Ray Pinhole Camera

Abstract

X-ray imaging adapted to the laser-matter interaction experiments consits in recording plasma images from its X-ray emission ; those phenomena have between 100 ps and some nanoseconds duration. When we only need spatial information on 1-10 keV X-ray emission, the most simple imaging device is the pinhole camera ; the two dimension image of the plasma is temporally integrated by an X-ray sensitive detector. Until now, X-ray film was used. Its operation and processing were long and tedious, so we replaced it by a television camera built around a Charge Coupled Device (C.C.D.). This camera is directly integrated in the pinhole camera. The X-ray detection is made by the silicon substrat of a C.C.D. without input window working in the vacuum of the expe-riment chamber ; a compact camera head (40 mm diameter, 120 mm length) located near the C.C.D. (1 to 2 cm) makes the charge/voltage conversion and the signal amplification. The immediate operation of images is done by an image acquisition and processing unit after digitizing the video signal on 8 bits. From measurements made on a continuous X-ray source (5,4 keV) we could point out the fact that a THOMSON-CSF THX 31135 CCD is 10 times more sensitive than the X-ray SB2 KODAK film that we use in pinhole cameras. The dynamic range measured in these conditions was about 300. The first experimental results obtained on a pulsed X-ray source are presented.