1. A pick and place machine comprising: a placement head having a nozzle for temporarily adhering a component thereto; a robotic system for generating relative movement between the placement head and a workpiece; a sensor having an illuminator disposed to direct illumination at the component, the sensor also having image acquisition system disposed to acquire a two-dimensional before-pick shadow image of the nozzle, and to acquire at least one two-dimensional after-pick shadow image of the nozzle and the component; and a processor adapted to process the before- and after-pick images to characterize a pick operation.