Calibration of shape standards

Proposed calibration services

Measurement of roundness deviations by comparison to a reference air spindle or by mechanical comparison (maximum deviations of 50 µm and 20 µm depending on the method chosen)

• Roundness standard (standard sphere, cylinder with a flat section (flat section ≤ 30 µm), inclined cylinder, etc.)
  Paris site: Maximum height of the measured section: 100 mm

Optimal measurement uncertainty: from 0.06 to 0.20 µm, depending on the standard.

• Cylindrical or spherical shape standard (smooth ring, smooth buffer gauge, square cylinder, etc.)

Measurement range: 1 mm ≤ D ≤ 500 mm
Optimal measurement uncertainty: from 0.06 to 0.25 µm, depending on the method used (k=2).

Measurement of straightness deviations and parallelism by comparison to a reference trajectory and deviation separation technique or by mechanical comparison (maximum deviations of 10 µm and 20 µm depending on the method chosen)

• Cylindrical shape standard (smooth ring, smooth buffer gauge, etc.)
• Straightness standard (flat ruler, plate glass)
• Square cylinder

Measurement range: L ≤ 600 mm
Straightness over four 90° profiling plates / Parallelism of profiling plates taken 2 by 2
Optimal measurement uncertainty: 0.3 µm for straightness and 0.5 µm for parallelism (k=2).
Control of perpendicularity of the support surface with the profiling plates, conducted on an MMT device (excluded from COFRAC accreditation) / Optimal measurement uncertainty: 1.5µm / 100 mm (k=2).

Flatness measurement by interferometry in comparison with a reference mirror (excluded from COFRAC accreditation)

Plate glass D ≤ 60 mm
Measurement conducted on 1 or 2 surfaces.
Optimal measurement uncertainty: 0.04 µm (k=2).

Accreditation details

• COFRAC Accreditation No. 2-35 (Paris site) and No. 2-1446 (Nîmes site)

List of sites and scopes available on www.cofrac.fr

• Please feel free to also consult the BIPM website.