Dimensional tolerances refer to the allowed variations in the physical dimensions, such as diameter, length, width and thickness, of a finished part. Performing dimensional measurements during part fabrication is usually relatively straightforward, and is accomplished using familiar tools such as calipers, gauges and optical comparators. ARO typically determines radius of curvature on convex or concave parts with an interferometer and a high resolution, optical encoder-based length gauge.
All ARO stock optics are toleranced so that the nominal diameter or length is the maximum value that will occur (+0.0). This ensures that the optic will always fit in a mechanical mount or holder intended for that size component.