Lacking either of these effects, the X-ray laser has to rely entirely on stimulation as the photons travel through the media only once. To increase the odds that any given photon causes stimulation, and to focus the output, X-ray lasers are designed to be very long and skinny. In this arrangement, most of the photons being released naturally through conventional emissions in random directions will simply exit the media. Only those photons that happen to be released traveling down the long axis of the media have a reasonable chance of stimulating another release. A suitable lasing medium would have an aspect ratio on the order of 10,000.