Hook Interferometry Using a Single Plate Interferometer
The hook method of Roschdestvensky1 has been used in the past to study the anomalous dispersion of gases and has recently received much attention as a tool to measure the Nf values of a variety of gases in conjunction with the shock tube2 . The method is generally more accurate than other methods3 and may also be used when the line in question is substantially broadened. The method is in fact self-calibrating, but it entails the complexity of an interferometer. Most of the recent work has been done using a Mach-Zehnder interferometer. This instrument allows considerable freedom in adjustments, such as fringe spacing and fringe orientation, and also allows a wide beam separation. Of these advantages only the wide beam separation can be important in the hook method; the fringe orientation, by contrast, is always fixed in this application and the fringe spacing is largely, but not solely, determined by the order of the fringes being observed, i.e., by the difference in optical path in the two legs of the interferometer. This path difference, which is purposely introduced by inserting a parallel plate in one leg, is the essential difference of the hook method of Roschdestvensky and the method by Puccianti. As a result of the additional path the fringes are inclined in the spectrum.
KeywordsPath Difference Test Beam Anomalous Dispersion Lithium Fluoride Fringe Spacing
Unable to display preview. Download preview PDF.
- 2.Yu. A. Dunaev, G. K. Tumakaev and A. M. Shukhtin, Soviet Phys.—Tech. Phys. 6, 815 (1962).Google Scholar