Both surfaces are finished to perfect flatness and in parallel.
By observing light wave interference fringes caused by the contact surface, the degree of flatness and parallelism of the measurement surfaces of measurement instruments and certain measurement tools can be checked.
- Diameter: 30mm
- Thickness: 12mm, 12.12mm, 12.25mm, 12.37mm
- Flatness: within 0.1µm
- Parallel level: within 0.2µm