7.55 Photonic Pressure Measurement

The young working group 7.55 "Photonic Pressure Measurement" with its focus on research and development deals with the laser-optical measurement of density and temperature of selected gases for the determination of partial pressures and for the realization of the pressure scale in the range from high vacuum to normal pressure.

The photonic realization of the Pascal represents an innovative challenge which can currently only be implemented in cooperation. Accordingly, there is also interdepartmental and close cooperation with other working groups and departments within PTB: for example, for the pressure measurement (cooperation with 7.54 and 3.33), the thermostatization of the apparatus and temperature determination of the gases as well as the consideration of real gas effects (cooperation with 7.4), the measurement of the beat frequencies of the lasers stabilized on cavities among each other and in comparison with frequency standards, FEM simulations and optimization of the design with respect to length stability (cooperation with 4.31 and 5.2).

There is also close cooperation with other metrological institutes and universities outside the PTB, for example within the framework of the EU project: "QuantumPascal", which is coordinated by Tom Rubin:

www.ptb.de/empir2019/quantumpascal/

The density-based, photonic representation of the Pascal has the prospect of significantly lower uncertainties, especially with the introduction of the new SI. For this purpose, the focus is on the design and implementation of two measurement methods:

•     Refractive index measurement on high purity helium, argon and nitrogen for primary density or pressure measurements with lowest uncertainties in the range of 10 Pa to 100 kPa (fine vacuum to normal pressure).
•     Absorption measurement on carbon dioxide, water vapor and other gases in the range from 1 mPa to 10 Pa (high vacuum to fine vacuum) for the determination of partial and absolute pressures.

The team of WG 7.55 'Photonic Pressure Measurement'

Dr. Tom Rubin (Head of group)

André Kussicke (PHD student with focus: absorption spectroscopy)

Patrick Asbahr (PHD student with focus: refractometry)

Sandra Lukanek (former member)

Selected Publications:

• JOUSTEN, Karl, et al. Perspectives for a new realization of the pascal by optical methods. Metrologia, 2017, 54. Jg., Nr. 6, S. S146. https://iopscience.iop.org/article/10.1088/1681-7575/aa8a4d/pdf
  
  
• AVDIAJ, Sefer, et al. Note: Diffusion constant and solubility of helium in ULE glass at 23° C. The Journal of chemical physics, 2018, 148. Jg., Nr. 11, S. 116101. https://aip.scitation.org/doi/full/10.1063/1.5019015

Selected Innovations:

• Optische Langwegzelle mit minimiertem Strahlversatz: https://patents.google.com/patent/DE102016102431B3/de
  
  
• Optische Langwegzelle mit deutlich erhöhter Weglänge (Rubin-Zelle): https://patents.google.com/patent/DE102016102430B3/de