You can use the diffraction pattern of the slicer to determine its output slit
width. The distance h between the two first minima (either side of the
central maximum) is inversely proportional to the slit width sw
where h is measured in mm and sw in microns; 0.632815 is the wavelength of the laser in microns. The distance between the alignment plate on the slit--end of the UHRF cross--disperser assembly and the slit itself is 1220 mm.