Method and apparatus for measuring optical extinction in a thin film during its deposition
OwnerGeorge Dubéinventor
Life of this patent
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Abstract
A method of measuring the extinction of light in a coating including the steps of: directing a light beam to a substrate to be coated at an angle of incidence for which the beam undergoes nominal total internal reflection; depositing a coating on the substrate such that the light beam will be waveguided in the coating thus reducing internal reflection for a period of deposition time; measuring a reduction of the internal reflection during deposition; and calculating an extinction value of the light beam in the deposited layer corresponding to the measured drop in internal reflection.
Claims16
A method of measuring the extinction of light in a coating as it is being deposited, comprising the steps of:
- depositing at least one pair of thin film layers comprising a first layer and a second layer with refractive index at least 0.10 lower than the refractive index of the first layer, each layer within any pair having optical thickness between about 1.4 and 2.5 quarter wavelengths, and
- sending at least one nominally collimated probe light beam from a substrate side of a substrate surface to be coated such that the beam encounters that surface at an angle of incidence for which the beam undergoes nominal total internal reflection prior to the deposition of the coating to be studied and such that the probe beam will, at a certain layer thickness less than the intended final thickness, be waveguided in that layer thus reducing the internal reflection for some limited period of deposition, and
- measuring any reduction(s) of the internal reflection during the deposition and calculating the extinction(s) in that deposited waveguiding layer that correspond(s) to the measured drop(s) in internal reflection.
A method of measuring the extinction of light in a coating comprising the steps of:
- directing a light beam to a substrate to be coated at an angle of incidence for which the beam undergoes nominal total internal reflection;
- depositing an enhancement coating on the substrate such that the light beam will be waveguided in the next coating deposited thus reducing internal reflection for a period of deposition time;
- measuring a reduction of the internal reflection during deposition;
- calculating an extinction value of the light beam in the deposited layer corresponding to the measured drop in internal reflection, and
- wherein the enhancement coating comprises at least one pair of layers comprising of a first layer and a second layer with refractive index at least 0.10 lower than the refractive index of the first layer, each layer within any pair having an optical thickness between about 1.4 and about 2.5 quarter wavelengths.
A method of measuring the extinction of light in a coating during its deposition comprising the steps of:
- depositing an enhancement coating on a substrate such that an increased fraction of a probe light beam will be coupled into a waveguide in a next layer to be deposited before that layer reaches its final thickness thus reducing internal reflection of a probe beam for a period of deposition time;
- directing a nominally collimated probe light beam to this enhancement coated substrate at an angle of incidence for which the beam undergoes nominal total internal reflection;
- measuring a reduction of the internal reflection during deposition;
- calculating an extinction value of the light beam in the deposited layer corresponding to the measured drop in internal reflection;
- and
- wherein the enhancement coating comprises at least one pair of layers comprising of a first layer and a second layer with refractive index at least 0.10 lower than the refractive index of the first layer, each layer within any pair having an optical thickness between about 1.4 and about 2.5 quarter wavelengths.
Dependencies are inferred from the claim text.