A device includes a collimated light source operable to generate a collimated light source beam, which includes a beam direction. The device includes a first channel in a first plane and a second channel in a second plane different from the first plane. The second channel communicates with the first channel and includes a flow direction. The second channel is oriented to receive the collimated light source beam. The device includes a third channel in a third plane different from the second plane and communicates with the second channel. The collimated light source beam is oriented to enter a cross-section of the first channel, then to pass through the second channel, and then to enter a cross-section of the third channel such that the beam direction is opposite to the flow direction in the second channel. The device includes a focused particle stream nozzle operably connected to the first channel.