Related Terms: Form Error, Sphericity, Flatness
Units: Linear units, wavelengths or half-wavelengths (fringes)
Specification Must Contain: Value (RMS, Peak-to-Valley (P-V) or both) over an aperture
Optimax Preferred Specification: P-V surface error in fringes at HeNe
Reasons: Contributors may be directly targeted
Manufacturing Standards: ISO 10110-5, OEOSC OPI.004
![Irregularity: Interferometer Measurement](https://optimaxsi-com.dev.webhost.io/wp-content/uploads/Irregularity-Interferometric-Measurement1.png)