Patent ID: 7311938

Claim:
A method for making optical lenses having an anti-reflection (AR) coating comprising the steps of: supplying one or more optical lens and an optical reference lens; positioning the lens and the optical reference lens in a vacuum deposition chamber in the same coating plane, the vacuum deposition chamber having an optical monitor communicating with the optical reference lens; providing in the chamber at least one source of a high index of refraction AR coating composition and at least one low index of refraction AR coating composition; applying a layer of the high index of refraction composition on the lens until the desired optical thickness coating is obtained as determined by the optical monitor; applying a layer of the low index of refraction composition on the lens until the desired optical thickness coating is obtained as determined by the optical monitor; and repeating alternately the high index layer application step and the low index layer application step until the desired AR coating is applied; wherein the optical monitor comprises means for directing an on/off beam of light into the chamber at the optical reference lens and a light detector at the end of the optical monitor which is programmed so that the light beam it receives during the off period is noise which is subtracted from the light beam it receives when the light beam is on wherein only the light to be measured is measured and ambient light is not measured, measuring the reflected light from the reference lens at a particular frequency and using this measurement to determine when the desired optical coating thickness is achieved.