Coating processes – Measuring – testing – or indicating – Thickness or uniformity of thickness determined
Patent
1980-02-26
1981-09-29
Hoffman, James R.
Coating processes
Measuring, testing, or indicating
Thickness or uniformity of thickness determined
65 311, 427 8, 427163, G03C 1702, G02B 110, G02B 514
Patent
active
042923417
ABSTRACT:
The refractive index profile of an optical fiber preform is controlled during manufacture by illuminating the gaseous precursor being fed to the preform substrate tube with ultraviolet radiation, measuring the intensity of either the uv that traverses the gas or the induced fluorescence, comparing this measurement with a reference signal, generating an error signal, in response to this comparison, and controlling composition of the gaseous precursor in response to said error signal. A similar technique can be used to control the thickness and refractive index of each layer deposited upon the substrate tube by forming an x-ray shadowgraph of the layers as they are deposited and comparing the shadowgraph characteristics with appropriate reference signals to form a second set of error signals. The latter are then used to fine tune the fabrication process. The invention can also be employed in conjunction with the vapor axial deposition method of fabricating preforms.
REFERENCES:
patent: 3373278 (1968-03-01), Cilyo
patent: 3654109 (1972-04-01), Hohl et al.
patent: 4161656 (1979-07-01), Marcuse et al.
patent: 4217027 (1980-08-01), MacChesney et al.
Takahashi et al., "Applicative Investigation of X-Ray Non-Destructive Inspection Technique for Measurement of Core Diameters and Germanium Doping Concentration Profiles of Optical Fiber Preforms", Proc. Opt. Comm. Conf. Amsterdam, Sep. 17, 1979, pp. 14.41 to 14.44.
Marcuse Dietrich
Presby Herman M.
Bell Telephone Laboratories Incorporated
Hoffman James R.
Sherman Sylvan
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