The laboratory develops, maintains and disseminates the unit of measurement for plane angles, the radian (rad).
Its primary activity is to ensure traceability and maximum accuracy in angle measurement for the scientific community and national industry.
To fulfil this mission, the laboratory has state-of-the-art instruments, including several reference standards. These standards are based on two main methodologies:
- The circle division: these high-precision devices, such as rotary tables and optical polygons, allow the circle to be divided into a certain number of equal parts, thus creating known reference angles.
- Trigonometric generation: this technique is suitable for generating small angles from the measurement of two lengths (the hypotenuse and one cathetus of a right-angled triangle).
The laboratory is constantly engaged in research and development activities to:
- Experiment new angle measurement techniques and devices.
- Improve the measurement uncertainty of primary and secondary standards in order to achieve the limits imposed by the best measurement and calibration capabilities (CMC).
- Reply proactively to evolving metrological needs, particularly those arising from high-tech sectors such as precision engineering, aerospace (where angular precision is crucial for navigation and positioning) and the measuring instrument industry.
In addition to maintaining the angle unit, the laboratory also provides calibration services and high-precision measurements in the field of shape geometry. In particular, it performs roundness measurements on circular samples and mechanical components.
These measurements are performed using a precision rotary table that ensures highly uniform and stable rotational movement.
The measurement is performed using a mechanical contact probe that detects the variation in the radius of the sample during its rotation. The crucial element for traceability is the interferometric calibration of the measurement system, which ensures that the probe measurements are directly traceable to the metre.
Finally, the laboratory actively participates in international measurement comparisons (Key and Supplementary Comparisons) promoted within CIPM and EURAMET, in support of CMCs.
