To increase inspection throughput, the field of view (FOV) of an IR camera
can be moved over the sample at a constant velocity. Throughout this
moving, a modulation (e.g. optical or electrical) can be provided to the
sample and IR images can be captured using the IR camera. Moving the FOV,
providing the modulation, and capturing the IR images can be
synchronized. The IR images can be filtered to generate the time delay
LIT, thereby providing defect identification. In one embodiment, this
filtering accounts for the number of pixels of the IR camera in a
scanning direction. For the case of optical modulation, a dark field
region can be provided for the FOV throughout the moving, thereby
providing an improved signal-to-noise ratio (SNR) during filtering.