Dispersive methods

This chapter discusses dispersive means of obtaining spectral resolution in spectrophotometry. These methods are used to spatially disperse or separate the various wavelengths of optical electromagnetic radiation to enable analysis of material properties in wavelength bandwidths that are appropriate to the material, the material property, and the material application under consideration. The two predominant spectrometer types are based upon gratings or prisms to physically separate the different wavelengths of the radiation. We discuss characteristics of each spectrometer type that result in their particular advantages and disadvantages. Important characteristics include the spectral range, spectral bandpass, spectral resolution, system aperture, and system throughput. The effects of imperfections in ideal spectrometers, such as wavelength error, stray light, and polarization effects, will be considered. Issues important to the choice of radiation sources will be discussed. Some characteristics of radiation detectors, such as linearity and noise, will be discussed. The techniques that are used to identify the presence and effects of these spectrometer properties will be discussed, as well as methods that are used to mitigate and/or quantify their effect upon the validity and accuracy of our measured results.Peer reviewed: YesNRC publication: Ye