A system for laser shock peening includes a laser positioned to direct a laser pulse at a first side of a work piece and a coupler on a second side of the work piece. The system further includes a Doppler shift detector positioned to measure a velocity of the coupler. A method for laser shock peening includes depositing an amount of energy from a laser pulse into a first side of a work piece and transmitting a pulse having a first frequency at a second side of the work piece. The method further includes receiving a reflected pulse having a second frequency from the second side of the work piece and determining the velocity of the work piece based on the difference between the first frequency and the second frequency.