TUBITAK UME has measured interatomic distances with picometer (one trillionth of a meter ) and angles in 1 nanoradian steps produced by a small angle generator with picoradian sensitivity using the Differential Fabry-Perot Interferometer (DFPI) developed and improved under the scope of joint research project within the EC-funded European Metrology Research Program (EMRP)
The improved method based on the frequency measurements with DFPI benefits from its frequency based measurement advantages and the stable measurements of the highly precise angle generator and was used for the first time for nanoradian angle measurements.
Between the years 2008-2011, within the scope of the EMRP NANOTRACE Project, displacement measurements with picometre sensitivity, which has important potential applications in the nanotechnology area, were carried out using the new methodology based on beat frequency measurements. The first applications were introduced using the Differential Fabry – Perot interferometer developed for these measurements.
As a continuation of this study, under the EMRP project SIB08 “Subnano - Traceability of sub-nm Length Measurements” Project [2] coordinated by Dr. Birk Andreas of Physikalisch- Technische Bundestanstalt (PTB) and in which TUBITAK UME participated as one of the 9 international partners, work was carried out for a comparison measurement in which improved Differential Fabry Perot İnterferometer of TUBITAK UME was compared with the X-ray interferometer developed by the National Physical Laboratory (NPL) making use of the lattice spacings of the Si atoms forming the interferometer. The group of the researchers achieved picometre level accuracy of the displacements corresponding to the distances between layers of the Si atoms.
Since 2013, in the scope of the EMRP project SIB58 “Angles - Angle Measurements” coordinated by Prof. Dr. Tanfer Yandayan of TUBITAK UME with its international 16 partners; work has been carried out for high-level scientific studies and the development of new generation angle measuring equipment and angle measurement methods for technological applications [3].
1 nanoradian angular steps obtained with the precise angle generator [4] improved by TUBITAK UME in the scope of the SIB58 Angles Project were detected as a frequency change of the differential Fabry-Perot Interferometer which was improved during the SIB08 subnano Project. The frequency -based angle measurement method that was improved with joint efforts of the TUBITAK UME SIB08 subnano and SIB58 Angles projects teams seems to be important as it constitutes an alternative method for nanoradian and sub-nanoradian angle measurements. To define what these measured values means; 1 nanoradian angular value indicates that a missile sent from Edirne to Hakkari could reach the target having a flight range of 1,500 kilometers with an error of 1.5 mm, while the picoradian level measurement; symbolizes that this error of 1.5 mm to the target can be detected with a resolution of one thousandths of its value.
The information obtained and produced, such as the angular adjustment of mirrors and optics in nanoradian level used in the space work of institutions like NASA, production of the mirrors utilized for directing X-rays in accelerator centers like CERN, investigation of the material structure using gamma rays is expected to meet the demands of the nano and picoradian level angular measurements using evolving technology needs. Besides it is also expected that it will meet the top-level demands of nanoradian angle metrology reference standards for the development of new generation measurement instruments and for the improvement of existing ones.
References
1. M. Celik, R. Hamid, U. Kuetgens and A. Yacoot, Picometre displacement measurements using a differential Fabry-Perot optical interferometer and an x-ray interferometer, Meas. Sci. Technol. 23, 085901 (6pp) (2012)
2. https://www.ptb.de/emrp/subnano-home.html
3. http://www.anglemetrology.com
4. Yandayan T, Ozgur B, Karaboce N, and Yaman O, "High precision small angle generator for realization of the SI unit of plane angle and calibration of high precision aucollimators" Meas. Sci. Technol. 23 (2012), 094006 (12pp).