A method and apparatus for measuring a structure. An x-ray system and the structure are positioned relative to each other. The x-ray system comprises a gas source configured to provide a gas, a laser system configured to emit a laser beam, a steering system, and a detector. The steering system is configured to direct a first portion of the laser beam into the gas such that an electron beam is generated by the laser beam interacting with the gas and is configured to direct a second portion of the laser beam into the electron beam such that a collimated x-ray beam is formed. The detector is configured to detect the collimated x-ray beam. The collimated x-ray beam is emitted with the structure positioned relative to the x-ray system.