In-line phase-contrast imaging with a laser-based hard x-ray source

We demonstrate the feasibility of phase-contrast imaging with an ultrafast laser-based hard x-ray source. Hard x rays are generated during the interaction of a high-intensity femtosecond laser pulse (10 TW, 60 fs, 10 Hz) focused onto solid target in a very small spot (3 mu m diam). Such a novel x-ray source has a number of advantages over other sources previously used for phase-contrast imaging: It is very compact and much cheaper than a synchrotron, it has higher power and better x-ray spectrum control than a microfocal x-ray tube, and it has much higher repetition rate than an x-pinch source. The K alpha line at 17 keV produced using a solid Mo target, and the in-line imaging geometry have been utilized in this study. Phase-contrast images of test objects and biological samples have been realized. The characteristics of the images are the significant enhancement of interfaces due to an x-ray phase shift that reveal details that were hardly observable, or even undetectable, in absorption images and suppression of optically dense structures well defined in the absorption images. Our study indicates that the absorption and the phase-contrast images obtained with an ultrafast laser-based x-ray source provide complementary information about the imaged objects, thus enriching our arsenal of research tools for laboratory or clinic-based biomedical imaging. (c) 2005 American Institute of Physics.