Image system designed to scan for security threats

An imaging system comprising:

• a transmitter
• a receiver
• an array of reflectors,
• a controller for directing the transmitter, the receiver, and the reflectors to scan an object in a volume,
• wherein the controller determines which sub-volumes of said volume the object is located within and to perform a fine scan in said sub-volumes,
• wherein the controller initially scans the volume using the transmitter, the receiver, and the reflectors to use said initial scan to decide which sub-volumes the object is located within, and to then perform the fine scan in said sub-volumes, again using said transmitter, receiver, and reflectors;
• wherein the controller compares a received signal sample magnitude from the initial scan with a threshold to make said decision;
• and
• wherein the controller directs the transmitter and the receiver to perform the initial scan with a spot size to include only one or more particular volume elements within at least some of the sub-volumes.