Monochromatic images

P. J. Galley, J. A. Horner and G. M. Hieftje, Automated simplex optimisation for monochromatic imaging inductively coupled plasma atomic emission spectroscopy, Spectrochim. Acta, Part B, 50(1), 1995, 87-107. 170. L. M. Cabezon, M. Caballero, J. M. Diaz, R. Cela and J. A. Perez-Bustamante, Multielemental separation and determination of some heavy metals (copper, cobalt, cadmium and nickel) in tap water and high salinity media by CGA (colloidal gas aphron)-coflotation, Analusis, 19(4), 1991, 123-127. 

OPTICAL EMISSION SPECTROCHEMICAL ANALYSIS. In this analytical technique, an optical device is used to analyze radiation from electrically excited sample atoms. The analyzing device provides monochromatic images whose intensities are measured and related to the concentration of the elements within the sample that produces the specific radiation measured. The technique is precise and rapid, and adaptable to solid, powder, or liquid samples. 

Emission spectrography includes an excitation source (in this instance a direct-current arc), an optical unit using a dispersion system to provide monochromatic images of the input slit on its focal surface, and a detection system (in this instance, a photographic emulsion). 

Mountings with a concave grating are also used. Here the radius of the grating determines the so-called Rowland circle. In the direction of dispersion the spectral lines are focussed on the Rowland circle and are monochromatic images of the... 

The source is thus transformed into an luminous object of linear profile of which the optical system of the instrument gives as many defined images — the lines — as there are different wavelengths in the source. Each line corresponds to an almost monochromatic image of the entrance slit of the spectrophotometer. A single element can generate more than 2000 lines. 

P. J. Galley, J. A. Horner and G. M. Hieftje, Automated simplex optimisation for monochromatic imaging inductively coupled plasma atomic emission speetroscopy, Spectrochim. Acta B, 1995, 50(1), 87-107. 

Fig. 2.7 Image of a fraction of the Rosette nebula obtained at far infrared wavelengths with the Herschel telescope. The colours correspond to the three monochromatic images that have been combined, with blue coding for the shortest wave- length (60 pm) and red for the longest wavelength (500 pm) [45]. Regions with the warmest dust appear in blue while the cold dust regions, further away from the heating sources, appear in red...

We scan the telescope normal to the spectrograph slit, and record separate frames from each position of the telescope. Each frame has as axes wavelength and one spatial coordinate the stack of successive frames provides the second spatial coordinate and thus generates a data cube (strictly, cuboid). From that cube we extract monochromatic images. Continuum subtraction is effected by differendng nei bouring wavelengths. We refer to this technique as ima g spectroscopy. 

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