An apparatus for processing a workpiece can be exemplarily characterized as including a processing tool having a processing region within which a workpiece can be processed, and an illumination system configured to direct detection light into the processing region. In this embodiment, detection light directable by the illumination system has a wavelength to which the workpiece is at least partially opaque. The apparatus may further include an image sensor configured to detect a characteristic of the detection light transmitted through the processing region and a chuck configured to support a workpiece such that at least a portion of the workpiece is disposable within the processing region and is illuminatable by the detection light. Methods for processing a workpiece are also disclosed.