This document explains the network formula, separation of a doublet by a network, and the principle of interferometric nulling for extinction of radiation from a star.
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Principle of Interferometric Cancellation
Networks Galore !
Principle of Interferometric Cancellation
Networks Galore !
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[...] In reporting in the formula of the networks we obtain: . Finally . According to the previous formula, we get: . One can therefore determine the wavelength of a radiation by measuring the minimum deviation. One varies the angle of incidence and measures the refracted angle until finding the minimum deviation. The interest of such a method is to be able to determine very precisely the wavelength. It just suffices to know the step of the network as well as the order . [...]
[...] The total step difference in so it is: . (assuming a phase shift of in ) By similarity with the calculations of question of the previous part, we have . The star and the point are located at a distance considered as infinite by telescopes, we can therefore say that they form two coherent sources between them. On can therefore directly sum the intensities coming from the two elements of the system {Star + The intensity received in is maximum for , i.e i.e . [...]
[...] Principle of Interferometric Nulling Extinction of radiation from the star On a the following relationships: , and . Assuming that and therefore that on deduce that the angles and are very small: and so and . The phase shift of introduces an additional phase difference equal to half a wavelength: . From where . On note et the light vibrations in complex notation of rays from and , with the phase shift between the two waves. The total resulting wave is , what sounds in real notation: The total luminous intensity is given by: Or , so . [...]
[...] At order one has : We can separate the sodium doublet at order 2. Realization of a monochromator The grid step is worth . On has the following diffraction relation: . The minimum angle to pass through the opening is given by: . The maximum angle is given by: . On a alors and . Application numérique : et . Minimum deviation of a network The deviation passes through a minimum when d'where et donc . According to the network formula . On différencie this expression: so it is so it . [...]
