Sphericity
Fig. 1 Principle of sphericity measurement.
Sphericity is one of the important dimensional parameters. Highly precise sphericity standard with high numerical aperture (NA)is recently required in the areas of photomasks, standard for spherical and ascpherical lenses, collimator lenses in UV and X-ray lithography, probe standard of micro CMM. We calibrate sphericity using a method of comparing two concave surfaces using three positional measurements.
Range: up to 10 µm of sphericity
| Expanded Uncertainty(k=2) | Measurement Conditions | Accreditation |
|---|---|---|
| 5.8 nm | concave surface with radius of curvature of 10 mm to 298 mm, or convex surface with radius of curvature of 5 mm to 40 mm, up to 0.66 of NA, up to 100 mm of aperture diameter |