A new Ultra Precision Interferometer for absolute length measurements down to cryogenic temperatures

A new Ultra Precision Interferometer (UPI) was built at Physikalisch-Technische Bundesanstalt. As its precursor, the precision interferometer, it was designed for highly precise absolute length measurements of prismatic bodies, e.g. gauge blocks, under well-defined temperature conditions and pressure, making use of phase stepping imaging interferometry. The UPI enables a number of enhanced features, e.g. it is designed for a much better lateral resolution and better temperature stability. In addition to the original concept, the UPI is equipped with an external measurement pathway (EMP) in which a prismatic body can be placed alternatively. The temperature of the EMP can be controlled in a much wider range compared to the temperature of the interferometer's main chamber. An appropriate cryostat system, a precision temperature measurement system and improved imaging interferometry were established to permit absolute length measurements down to cryogenic temperature, demonstrated for the first time ever. Results of such measurements are important for studying thermal expansion of materials from room temperature towards less than 10 K.

[1]  René Schödel,et al.  Highest-accuracy interferometer alignment by retroreflection scanning. , 2004, Applied optics.

[2]  Arnold Nicolaus,et al.  Phase-stepping interferometry: methods for reducing errors caused by camera nonlinearities. , 2002, Applied optics.

[3]  R. Schoedel.  Accurate extraction of thermal expansion coefficients and their uncertainties from high precision interferometric length measurements , 2005, SPIE Optics + Photonics.

[4]  René Schödel,et al.  Ultra-high accuracy thermal expansion measurements with PTB's precision interferometer , 2008 .

[5]  J. Stone,et al.  Using helium as a standard of refractive index: correcting errors in a gas refractometer , 2004 .

[6]  Andrew S. Brown,et al.  Gravimetric methods for the preparation of standard gas mixtures , 2011 .

[7]  George K. Burgess,et al.  The international temperature scale , 1928 .

[8]  H. Preston‐Thomas,et al.  The International Temperature Scale of 1990 (ITS-90) , 1990 .

[9]  C. Gaiser,et al.  Temperature-measurement errors with capsule-type resistance thermometers , 2013 .

[10]  S. Tang.  Self-calibrating five-frame algorithm for phase-shifting interferometry , 1996, Optics & Photonics.

[11]  Rene Schoedel,et al.  Methods to recognize the sample position for most precise interferometric length measurements , 2004, SPIE Optics + Photonics.

[12]  Bernd Fellmuth,et al.  Primary Dielectric-Constant Gas Thermometry in the Range from 2.4 K to 26 K at PTB , 2008 .

[13]  J. Olsen,et al.  The effect of intermolecular interactions on the electric properties of helium and argon. II. The dielectric, refractivity, Kerr, and hyperpolarizability second virial coefficients , 1999 .

[14]  G. Thummes,et al.  DAMPING OF INTRINSIC TEMPERATURE OSCILLATIONS IN A 4 K PULSE TUBE COOLER BY MEANS OF RARE EARTH PLATES , 2008 .

[15]  Naofumi Yamada,et al.  Ultra-precise thermal expansion measurements of ceramic and steel gauge blocks with an interferometric dilatometer , 2000 .

[16]  M. Stock.  Watt balance experiments for the determination of the Planck constant and the redefinition of the kilogram , 2013 .

[17]  Rene Schoedel,et al.  Precise interferometric measurements at single-crystal silicon yielding thermal expansion coefficients from 12° to 28°C and compressibility , 2001, Lasers in Metrology and Art Conservation.

[18]  R. Schödel,et al.  High accuracy measurements of long-term stability of material with PTB's Precision Interferometer , 2009, Other Conferences.

[19]  A. Boccara,et al.  A common path interferometer for testing the optical thickness of possibly birefringent transparent substrates , 2001 .

[20]  R. Hellmann,et al.  Ab initio potential energy curve for the helium atom pair and thermophysical properties of the dilute helium gas. II. Thermophysical standard values for low-density helium , 2007 .

[21]  R. W. Evans,et al.  A review of measurement techniques for the thermal expansion coefficient of metals and alloys at elevated temperatures , 2001 .

[22]  G Galzerano,et al.  International comparison of two iodine-stabilized frequency-doubled Nd:YAG lasers at λ = 532 nm , 2000 .