![]() ![]() For zero order, m = 0, the angles of incidence and diffraction are equal but have opposite signs. It is essential, however, that the user understands the significance of the grating order integer, m. ![]() Thus, the grating angles are accurately translated into the wavelength axis that is presented in a normal spectral scan. The Analyzer is programmed to calibrate itself via the insertion of a NIST traceable rare-earth standard filter mounted on the filter wheel. A spectrum is recorded by rotating the grating and measuring the intensity of the light impinging on the detector. The light is dispersed onto the output module fiber array by the grating, where it is directed to the detector module. White light enters the monochromator through an entrance fiber in the multiplexer housing. This equation describes how white light is dispersed into its fundamental wavelengths (e.g., color for visible light). ![]() Φ = the angle of the diffracted light (also measured from the grating perpendicular) Θ = the angle of the incident light (measured from the perpendicular to the grating) The operation of the grating is defined by the grating equation:ĭ = the grating constant (lines per millimeter) Let us review a few of these facts, as they are important to the correct operation of the Analyzer. How gratings work is described in all good introductory college physics textbooks. (This surface is very delicate and should never be touched or cleaned.) As such, a grating is one of the most precise objects ever made. A diffraction grating is essentially an aluminum-coated mirror with thousands of parallel and equally spaced grooves etched into its surface. The basic optical element of the Analyzer is a plane (flat) diffraction grating. ![]()
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