Laser printers with multiple laser diodes in a single diode package may have diode to diode spacing requirements critical to print quality. Standard off-the-shelf equipment is seldom designed to measure to the nanometer resolutions and linearity desired, especially if the measurements are time constrained. Therefore characterizing the linearity of the measurement system is important to the understanding of the measurement system limitations.Diode to diode spacing is a comparison of the centroids of multiple adjacent laser spots in one or more axes. It is physically possible to measure the centroid location of the spots using various methods including scanning aperture, CCD/CMOS cameras or position sensing devices. The accuracies and precisions desired for good measurements as well as for good manufacturing process capabilities are often smaller than what are easily available with these products, often by an order of magnitude.A procedure has been developed to estimate the measurement system error over a wide range of scales. It can be applied to several of the common laser spot centroid measurement devices enabling estimation of measurement resolution of the relative centroid. This method is based on an innovative technique involving controllable movement on a much larger scale.