This paper deals with the quality of diffraction gratings. Diffraction gratings are widely used in many optical devices and an accuracy of those devices depends on the quality of used diffraction gratings. Our work performs a theoretical analysis of an influence of the change of diffraction grating constant on properties of the diffraction grating. and Článek se zabývá analýzou kvality difrakčních mřížek. Difrakční mřížky jsou často používané v různých měřicích optických zařízeních, přičemž přesnost těchto zařízení závisí na kvalitě použité difrakční mřížky. V této práci je analyzován vliv změny mřížkové konstanty na optické vlastnosti difrakční mřížky.
High resolution {OV5) two-dimensional spectra performed with the Multichannel Soustractive Double Pass (MSDP) spectrograph of the Pie du Midi Observatory, were analysed. An adapted image processing provides two-dimensional intensity and velocity maps of the solar granulation at two intensity levels of the photospheric line NaD2, filtered for the 5 min oscillations. An inspection of such
maps confirms that the bright granules at the continuum level are well correlated witli rising material as well as the dark intergranular spaces with falling material, and that the velocity fluctuations
penetrate much high into the photosphere than the intensity fluctuations. The one-dimensional power spectrum has a slope close to - 5/3, characteristic of a turbulent medium, in the size range
of the granulation. It is suggested that the convectivc energy is supplied by the mesogranulation and the supergranulation; this energy is then cascading toward the smaller scales through the granulation, which thus appears to be turbulent.