Zhu, W.Eckerskorn, N.Upadhya, A.Li, L.Rode, A.V.Lee, W.M.2023-05-162023-05-162016Biomedical Optics Express, 2016; 7(7):2902-29112156-70852156-7085https://hdl.handle.net/2440/138396Efficient delivery of viruses, proteins and biological macromelecules into a micrometer-sized focal spot of an XFEL beam for coherent diffraction imaging inspired new development in touch-free particle injection methods in gaseous and vacuum environments. This paper lays out our ongoing effort in constructing an all-optical particle delivery approach that uses piconewton photophoretic and femtonewton light-pressure forces to control particle delivery into the XFEL beam. We combine a spatial light modulator (SLM) and an electrically tunable lens (ETL) to construct a variable-divergence vortex beam providing dynamic and stable positioning of levitated micrometer-size particles, under normal atmospheric pressure. A sensorless wavefront correction approach is used to reduce optical aberrations to generate a high quality vortex beam for particle manipulation. As a proof of concept, stable manipulation of optically-controlled axial motion of trapped particles is demonstrated with a response time of 100ms. In addition, modulation of trapping intensity provides a measure of the mass of a single, isolated particle. The driving signal of this oscillatory motion can potentially be phase-locked to an external timing signal enabling synchronization of particle delivery into the x-ray focus with XFEL pulse train.en©2016 Optical Society of America. Open Access (CC BY 4.0)(140.7010) Laser trapping(350.4855) Optical tweezers or optical manipulationJournal article10.1364/BOE.7.0029022023-05-15640601Upadhya, A. [0000-0003-0841-303X]