1. A diagnostic field device for detecting a condition of a process conduit in an industrial process, comprising: an infrared detector comprising a plurality of pixels configured to receive infrared radiation from the process conduit and responsively provide a plurality of pixel outputs, wherein a first pixel of the plurality of pixels is configured to receive infrared radiation from a first location on the process conduit and a second pixel of the plurality of pixels is configured to receive infrared radiation from a second location on the process conduit; a memory containing thermal profile information which relates an output from the first pixel to a first temperature and relates an output from the second pixel to a second temperature; a microprocessor configured to identify a process anomaly based upon outputs from the first and second pixels and the thermal profile information; and output circuitry configured to provide a diagnostic output indicative of the identified process anomaly.