An imaging system, safety system or combined imaging and safety system includes a light transmitter and a corresponding receiver. Image data relating to a machine tool and/or workpiece is derived and processed to determine information regarding the tool and/or tool position and/or extent of work carried out on the workpiece. A screen, such as a shadow screen, can be used to form an image of a profile of the tool tip and end of the workpiece. Tool tip position and extent of work on the workpiece can be derived from the image. Certain aspects are directed to a safety system application for halting a machine or tool when a light beam is interrupted, and can provide progressive muting of beam interruption detection, such as by systematically disregarding or muting signals from rows of receiver array elements as the beam passes through a mute point ahead of a tool.