Controls: Location of mechanical datums, the distance between optical surfaces, or a combination of the two
Related Terms: Center Thickness (CT), Sagitta (Sag), Outside Diameter (OD), Overall Height (OAH)
Units: Linear units
Specification Must Contain: Nominal value and linear tolerance
Optimax Preferred Specification: Directly measured quantities
Reasons: Directly measured quantities offer the best chance for repeatable measurements with minimal error sources
Manufacturing Standards: MIL-STD-34, ISO 10110-1