Patent ID: 7626724

Claim:
A measurement head for facilitating detection of a visual characteristic of a target on a substrate, the measurement head comprising: a. a look-ahead sensor associated with a target tracking system; and b. a data acquisition unit; wherein the measurement head is movable relative to a substrate, thereby defining a measurement path for the measurement head, the look-ahead sensor preceding the data acquisition unit along the measurement path such that the look-ahead sensor anticipates a scan path for a component of the data acquisition unit relative to the substrate; wherein the look-ahead sensor and the target tracking system are adapted to determine a spatial characteristic of a target on the substrate when the target is at least partially within a field of view of the look-ahead sensor; wherein at least one of: (i) the scan path for the component of the data acquisition unit, and (ii) the orientation of the component of the data acquisition unit is adjusted, relative to the substrate, based on the determined spatial characteristic of the target, such that, as the measurement head advances along the measurement path, the data acquisition unit is better configured to detect a visual characteristic of the target.