FTA offers contact angle standards consisting of sapphire and glass lens embedded in aluminum carrier blocks. These spherical lens protrude a known height from the block and thus form a known contact angle with the block. The current design has one angle per block and two angles are available: 90 and 39.6 degrees. All have a 6mm diameter. The 90 degree standard is also useful as a 6mm magnification calibration standard.
A simple magnification standard is also available. This is a sapphire ball mounted on a post for support and handling. It has a known diameter. Even millimeter diameters are available in the range of interest for drop shape measurements.
These standards are furnished with their specified angle or diameter stated in their documentation. Formal certification by traceable measurements is also available, but at extra cost and must be specified at the time of order.
For a more complete description and reference, see Calibration Standards