Linear dispersion, therefore, varies directly with cos beta, and inversely with the exit path length, L B , order, k, and groove density, n. Lambda n . In order to monitor only light at 800 nm, filters must be used to eliminate the higher orders. First order wavelengths between 200 and 380 nm may be monitored without filters because wavelengths below 190 nm are absorbed by air. If, however, the instrument is evacuated or N 2 purged, higher order filters would again be required.
Resolution is then the ability of the instrument to separate adjacent spectral lines.
Two peaks are considered resolved if the distance between them is such that the maximum of one falls on the first minimum of the other. This is called the Rayleigh criterion. See Section 2 for further discussion. The concentration of a limited region of the spectrum into any order other than the zero order. Blazed gratings are manufactured to produce maximum efficiency at designated wavelengths.