K α x-ray emission characterization of 100 Hz, 15 mJ femtosecond laser system with high contrast ratio.

We report K α x-ray production with a high energy (110 mJ per pulse at 800 nm before compression/15 mJ at 400 nm after compression), high repetition rate (100 Hz), and high pulse contrast (better than 10−9 at 400 nm) laser system. To develop laser-based x-ray sources for biomedical imaging requires to use high-energy and high-power ultrafast laser system where compression is achieved under vacuum. Using this type of laser system, we demonstrate long-term stability of the x-ray yield, conversion efficiency higher than 1.5×10−5 with a Mo target, and the x-ray spot size close to the optical focal spot. This high-repetition K α x-ray source can be very useful for x-ray phase-contrast imaging. [ABSTRACT FROM AUTHOR]