1. A reflect-array based threat detection system employing compressive sensing to effectively determine whether or not an object is a threat, the system comprising: (a) a first processor executing a first optimization algorithm using a plurality of samples to generate a plurality of optimized projections; (b) a library operatively coupled to the first processor, wherein the plurality of optimized projections and the plurality of samples are stored in the library, wherein the library is capable of adaptively increasing an amount of samples by adding a plurality of new measurement results to improve accuracy of threat determination accuracy; (c) a reflect-array panel emitting a synthesized radiation in a plurality of directions to scan the object, wherein the reflect-array panel comprises a first set of reflect-array elements, wherein each reflect-array element emits the plurality of optimized projections as a radiation pattern in one of the plurality of directions, wherein the synthesized radiation is a collective radiation comprising each radiation pattern emitted by each reflect-array element, wherein an illumination pattern results from the synthesized radiation reflecting off of the object; (d) one or more detectors configured to collect a plurality of measurements of the illumination pattern; and (e) a compressive sensing computer, operatively coupled to the one or more detectors, having a second processor configured to execute a compressive sensing optimization algorithm, herein referred to as a second optimization algorithm, wherein the second optimization algorithm processes the plurality of measurements and determines whether the object poses a threat using the plurality of optimized projections as bases of measurement.