When we illuminate something, we usually expect that the brighter the source we use, the brighter the resulting image will be. This rule also works for ultra-short pulses of laser light—but only up to a certain intensity. The answer to the question why an X-ray diffraction image 'darkens' at very high X-ray intensities not only deepens fundamental understanding of the light-matter interaction, but also offers a unique perspective for the production of laser pulses that have significantly shorter pulse duration than those currently available.
