A prototype for piston sensing by the dispersed speckle method

Abstract
We describe a prototype instrument built to validate the principle of the dispersed speckle method (Borkowski et al. 2002; Borkowski et al. 2004). This prototype, still under test, is a spectrograph where the multiple pupil, highly reduced in size, replaces the slit. An array of optical wedges is added near the grating to separate the spectra from each speckle. The fabrication and properties will be explained.