Apparatus and methods of obtaining information concerning a substance (57) is provided by applying pulses (91, 92, 93) of electromagnetic energy to the substance (57) and evaluating the response of the substance to the electromagnetic energy. The pulses (91, 92, 93) generated by a source (51) are of sufficiently short duration to generate a very broad frequency band of energy. The pulsed energy is directed to the substance (57) to be processed and energy pulses (91, 92, 93) passing through the substance (57) are received (56) and analyzed (66) to determine the properties of substance (57).