| 摘要 |
PROBLEM TO BE SOLVED: To produce fluoride thin coating good in safety, convenience and environmental properties and small in coating loss in a low wavelength region by evaporating fluorine compds. in a vacuum atmosphere to form coating on a substrate, furthermore thermally decomposing the fluorides of transition elements in the process of the coating formation and feeding fluorine thereto. SOLUTION: In a vacuum chamber 1, a substrate 6 loaded onto a rotatable and revolvable substrate holder 7 is heated at about 200 to 400 deg.C by a heater 9 for substrate heating. On the other hand, As fluorine compds. stored into resistance heating vessels 2 and 3 of an evaporating source, e.g. MgF2 4 and GdF3 5 are heated to evaporate. This evaporated and scattered fluorine compds. are controlled by a sticking preventing board 8 for shielding and are deposited on the substrate 6 to form fluoride thin coating. At this time, in the process of the coating formation, the fluorides of transition elements such as MnF3 11 or the like are thermally decomposed to feed fluorine thereto from a fluorine feeding source 10 provided with a temp. controlling mechanism. In this way, the defect of fluorine is prevented to obtain the optical thin coating composed of fluoride thin coating small in coating loss in a wavelength region ofλ=400 nm.
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