Hook method: improvement and simplification of the experimental setup

Abstract

The conventional experimental setup used to measure anomalous dispersion by the hook method has been modified by replacing the spectrograph by a single grating in combination with a camera. The grating is used for diffraction angles close to pi/2 rad, and the focal distance for projection of the hook spectrum is 4 m. The high dispersion thus obtained (typically 200 mm/nm) considerably facilitates the use of the hook method for diagnostic purposes. Further, it is demonstrated that, for such large diffraction angles, a focusing element after diffraction at the grating can be avoided without losing too much sharpness in the hook spectrum.