The OptiGauge II is a highly accurate instrument for non-contact light-based thickness measurements of transparent and translucent materials. The instrument is subject to a low measurement limit of 12 microns (for glass). It means that only layers that are above this limit in thickness can be measured accurately to a precision of 0.1 microns. However, in some instances, it is possible to measure thicknesses that are below this limit. For example, it can be done when thin coatings or adhesives are applied to thicker substrates.