Reference Certification Services
An interferometer measurement always involves two surfaces: The reference surface, which is the ‘perfect’ surface, and the surface under test. The ‘optical cavity’ is a map of the variation in distance between these two surfaces, which is directly measured using the interferometer. All error is assumed to be in the test surface. However, no surface is perfect. More precise surface measurement requires subtraction of the reference surface error from the optical cavity error for an ‘absolute’ measurement of the test surface.
AMS reference certifications are performed on high quality reference optics, including Transmission Flats (TFs) or Transmission Sphere (TSs), to produce an absolute map of the reference optic. Certification services ensure that this reference optic is still within its stated specification, and are required to be performed at regular intervals to satisfy ISO 9001 quality standards.
AMS’ absolute testing methods are fully traceable per ISO 17025. Certifications on a reference optic of 1/20th wave PV are typically accurate to 1/300th wave (2nm) or better. Certificates state the measured PV and related uncertainty. A surface map of the optic is provided with every certificate.
Quantities we can certify include flatness error, spherical form error, and spherical radius of curvature.
But how does AMS quantify the error of the reference surface, absolutely? Read about a past reference certification.