Abstract: A metrology system may receive one or more first images of an overlay target on a sample from a first detector, where the overlay target includes one or more Moiré structures, which may be formed as first-layer features and second-layer features that at least partially overlap and have different pitches. In the first images, the first-layer features and the second-layer features may be unresolved, but a Moiré pitch may be resolved. The system may further receive one or more second images of the overlay target from a second detector, where at least one of the first-layer features or the second-layer features are resolved in the one or more second images. The controller may generate a metrology measurement based on the one or more first images and generate a measurement of a systematic error associated with the metrology measurement based on the one or more second images.