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    High speed, time-resolved, thermoreflectance imaging is a novel way to locate defects or regions of potential failures in microelectronic devices. This paper reports on our thermoreflectance technique for dynamic imaging of circuit temperature distributions. This transient imaging method is based on a precise electrical lock-in technique with image processing similar to an old fashioned animation movie. An ordinal shutter speed camera is used in conjunction with an illumination LED that is pulsed for sampling the temperature distribution. This paper presents the method and gives a description of the system hardware. A theoretical comparison to lock-in thermography, which is based on infrared emission imaging, will be given. Limitations of thermoreflectance and the driving factors for spatial and time resolution will be discussed. Finally, we highlight and provide examples of near infrared (NIR) wavelength imaging, to enable both through- silicon thermal imaging and emission imaging in the same system. The combination of these two techniques is expected to enable hotspot temperatures and any anomalous emission sites to be correlated, hopefully leading to a better understanding of the nature of the defect.