The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 30, 1987
Filed:
Sep. 17, 1985
Michel Letellier, Paris, FR;
D.M.E., Paris, FR;
Abstract
A process for the deposition, on an optical substrate, of an antireflection coating capable of being engraved. In the process, metal is evaporated in a reactive atmosphere within the enclosure of an evaporator under vacuum and then deposited on the substrate. Previously cleaned substrates are disposed within the enclosure, which is then evacuated until a pressure of at most 1.5 .mu.Pa (10.sup.-8 torr) is obtained. Pure oxygen is injected at a regulated throughput in such a manner that the pressure is within the range of from 2 to 4 mPa, preferably 3 mPa (2.times.10.sup.-5 torr). A heated boat which is disposed within the enclosure and contains chromium is unmasked. The chromium evaporates at a temperature such that a coating of chromium oxide grows in thickness on the substrates at a rate of 0.1 to 0.5 nm per second, preferably 0.2 nm per second. The boat is masked when the coating of chromium oxide has reached a thickness corresponding to the first extinction in specular reflection at substantially normal incidence. The rate of growth is controlled with reference to the resonance drift of a quartz resonator which is also subjected to the deposit of chromium oxide. The extinction is monitored in white light at 3400.degree. K. on a control substrate which has previously been metallized.