A simple wavemeter with crossed dispersion

A simple wavemeter has been developed by crossing the dispersions of a conventional monochromator and a Fabry-Perot interferometer. The interference pattern is scanned by a linear image sensor and processed by a microcomputer to determine the wavelength of cw laser sources with a better than 0.02 Å accuracy even when the sources have more than one spectral peak.     

Isotopic Analysis by Optical Spectroscopy

The paper describes different methods of isotopic analysis for hydrogen, nitrogen, and oxygen. In the cases of the hydrogen and the oxygen, a light source with high frequency excitation and a Fabry-Perot spectrometer with photoelectric recording were employed. For the nitrogen we used a Zeiss Q-24-spectrograph, or a Zeiss SPM-2 monochromator, converted by us to photoelectric automatic recording instruments. In the last case the method teas extended for determining the nitrogen isotopic concentration in nitric oxide gas.     

Comparative study of multilayers used in monochromators for synchrotron‐based coherent hard X‐ray imaging

A systematic study is presented in which multilayers of different composition (W/Si, Mo/Si, Pd/B₄C), periodicity (from 2.5 to 5.5 nm) and number of layers have been characterized. In particular, the intrinsic quality (roughness and reflectivity) as well as the performance (homogeneity and coherence of the outgoing beam) as a monochromator for synchrotron radiation hard X‐ray micro‐imaging are investigated. The results indicate that the material composition is the dominating factor for the performance. By helping scientists and engineers specify the design parameters of multilayer monochromators, these results can contribute to a better exploitation of the advantages of multilayer monochromators over crystal‐based devices; i.e. larger spectral bandwidth and high photon flux density, which are particularly useful for synchrotron‐based micro‐radiography and ‐tomography.     

Walsh’s contributions to molecular spectroscopy and its instrumentation

Alan Walsh made major contributions to molecular spectroscopy and its instrumentation, particularly with his invention of the multiple monochromator, which greatly improved the performance of infrared spectrometers.