A novel force sensor based on optical beam deflection was developed to investigate the mechanical effects during the pulsed laser ablation of a metal in water at different pulsed energies from 2.4 mJ to 27.6 mJ.The detection principles of this sensor were discussed in detail.The experimental and theoretical results are shown that the target underwater is affected by a laser ablation force,two liquid-jet impacts induced by a cavitation bubble collapse near a solid boundary;with the laser incident energy increase,the amplitudes of three forces all firstly increase and then decrease during the interaction process.The liquid-jet formation and the final bubble collapse become earlier with the energy increase.Besides,the former appear earlier than the latter.The results are of value in theoretical and applied research in the laser-matter interaction water.