Optical interferometry at ultra low temperatures

P. J. Hakonen*, H. Alles, A. V. Babkin, J. P. Ruutu

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

6 Citations (Scopus)


We have developed optical, interferometric methods for investigations of interfaces at ultra low temperatures. In our scheme conventional optical windows are avoided: laser illumination (He-Ne) is guided into the cryostat via a single-mode optical fiber and images are taken using a CCD sensor mounted inside the 4-K vacuum can. A real-time video camera has been successfully used in investigations of superfluid3He down to 0.6 mK whereas a slow-scan camera has been employed for optimal contrast in low-intensity imaging of liquid/solid interfaces (reflection coefficient ∼10-6). The investigated topics include (1) superfluid3He surface in rotation and during rapid deceleration, (2) hydrodynamics of thin superfluid3He layers, (3) superfluid/solid interface in4He, and (4) wetting of superfluid4He by normal3He in phase separated mixtures. A vertical resolution of 10 nm and even below has been achieved in these studies.

Original languageEnglish
Pages (from-to)41-47
Number of pages7
JournalJournal of Low Temperature Physics
Issue number1
Publication statusPublished - Oct 1995
MoE publication typeA1 Journal article-refereed


  • 07.60.Ly
  • 67.50.Fi
  • 67.60.Fp
  • 67.80.-s


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