Enea-comitato Nazionale Per La Ricerca E Lo Sviluppo Dell'energia

Elia Palange

Gianemilio Salvetti

Giampiero Giuliani

Errico Armandillo

An apodizing filter is disclosed comprising two solid bodies of transparent material the first of which is struck by the incident light while the second receives the light from the first. The second body has a curve surface approaching the first body at a distance therefrom not greater than some wavelengths of the incident light. The plane tangent to the curve surface of the second body at the point of minimum distance from the first one forms with the direction of the incident light an angle greater than the limit angle of the total reflection related to the first body with respect to the medium in which the filter is sunk. The indexes of refraction of the two materials of which the two bodies are made are such that the light incidence on said tangent plane is lower than the limit angle of the total reflection. The combination is disclosed of the apoditic filter according to this invention with a mirror and an example is given of the filter application to a laser cavity.

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Rome, Italy

Elia Palange