Optical thickness rate monitor

Claim 2

In an optical thickness rate monitor for use with a vaccuum chamber having an evaporation source therein providing a vapor stream for measuring the rate of deposition of material on an article while in the vacuum chamber, means forming an aperture having one side exposed to the vapor stream from said evaporation source, an elongate transparent element spaced from the article disposed on one side of the aperture opposite the side exposed to the evaporation source, means for progressively advancing the elongate element past the aperture so that successive portions of the elongate element are coated with material from said vapor stream at the same time that material is being deposited on the article, means for supplying a beam of radiation to the element so that the radiation is affected by the material deposited on the element from the vapor stream and means for determining the manner in which the radiation is affected by the material deposited on the element to determine the rate of deposition of the coating material solely by determination of optical properties of the coating material.

Claim 3

A monitor as in claim 1 together with means connected to said means for determining any changes in the material and adapted to be connected to the evaporation source for controlling the rate of evaporation from the evaporation source.

Claim 4

A monitor as in claim 1 together with means for causing the beam of radiation to sweep in a direction parallel to the direction of movement of the element.

Claim 5

A monitor as in claim 1 wherein one side of the elongate element is exposed to the vapor stream from the evaporation source and wherein the beam of radiation is directed to the other side of the elongate element.

Claim 6

A monitor as in claim 4 together with means for preventing coating material from being deposited on the elongate element during the time that the beam of radiation is being directed onto the elongate element.

Claim 7

A monitor as in claim 1 together with a supply reel and a take-up reel, said elongate element being wound on said supply reel and take-up reels, capstan means for continuously advancing the elongate element, and means for driving said supply reel and said take-up reels so that said elongate element is continuously maintained under tension.

Claim 8

A monitor as in claim 6 together with means for driving said capstan at a predetermined rate of speed.

Claim 9

In an optical thickness rate monitor for use with a vacuum chamber having an evaporation source therein providing a vapor stream, means forming an aperture having one side exposed to the vapor stream from said evaporation source, an elongate element disposed on one side of the aperture opposite the side exposed to the evaporation source, means for progressively advancing the elongate element past the aperture so that progressive portions of the elongate element are coated with material from said vapor streams, first source for supplying a beam of radiation to the element so that the radiation is affected by the material deposited on the element from the vapor stream, means for determining the manner in which the radiation is affected by the material deposited on the element, means for chopping said beam of radiation at a predetermined frequency, means for forming said beam of radiation into spaced parallel sample and reference beams, means for directing the sample and reference beams onto the elongate element, means for receiving the sample and reference beams after they have been affected by the coating material on the elongate element and for combining the same into a single beam, means for comparing the sample and reference beams for supplying an error signal, and means utilizing the error signal to control the rate of evaporation from said source.

Claim 10

In an optical thickness rate monitor for use with a vacuum chamber having an evaporation source therein providing a vapor stream, means forming an aperture having one side exposed to the vapor stream from said evaporation source, an elongate element disposed on one side of the aperture opposite the side exposed to the evaporation source, means for progressively advancing the elongate element past the aperture so that progressive portions of the elongate element are coated with material from said vapor streams, first source for supplying a beam of radiation to the element so that the radiation is affected by the material deposited on the element from the vapor stream, means for determining the manner in which the radiation is affected by the material deposited on the element, means for chopping said beam of radiation at a predetermined frequency, means for forming said beam of radiation into spaced parallel sample and reference beams, means for directing the sample and reference beams onto the elongate element, means for receiving the sample and reference beams after they have been affected by the coating material on the elongate element and for combining the same into a single beam, means for comparing the sample and reference beams for supplying an error signal, and means utilizing the error signal to control the rate of evaporation from said source.

Claim 11

A monitor as in claim 8 together with means mounted in said sample and reference beams to cause said sample and reference beams to sweep said elongate element in the direction of movement of the elongate element.

Claim 12

A monitor as in claim 9 wherein said means in said sample and reference beams includes a prism assembly having first and second prisms, each of the prisms having a plurality of faces and means for rotating said prisms in said sample and reference beams.

Claim 13

A monitor as in claim 10 wherein said prism assembly consists of a housing with said first and second prisms mounted in said housing, said housing having spaced slots formed therein in two separate rows with said rows being in alignment with said first and second prisms, said slots in each of said rows being positioned so that when one of the beams is passing through one of said prisms, the other of said beams cannot pass through the oher of said prisms.

Claim 14

A monitor as in claim 10 together with first and second chopper discs, one of said chopper discs being disposed on one side of said aperture and the other of said chopper discs being disposed on the other side of said aperture, said chopper discs being positioned so that one chopper disc operates out of phase with the other chopper disc, said chopper discs having the same number of openings as the number of faces on said prisms, and means for rotating said chopper discs in unison with the rotation of said prisms.

Claim 15

A monitor as in claim 12 wherein said means for rotating said prisms and said means for rotating said first and second chopper discs includes servo means.

Claim 16

A monitor as in claim 12 wherein said means connected to said error signal includes a source of power supply connected to the evaporation source, an evaporation rate controller connected to said power supply, an adjustable reference for said evaporation rate controller and means connecting said error signal into said evaporation rate controller.

Claim 17

A monitor as in claim 14 wherein said means responsive to said error signal includes a power supply for said first source of radiation, an adjustable reference for said power supply and means connecting said error signal to said power supply.

Claim 18

A monitor as in claim 12 together with an additional source of radiation, a chopper mounted on said prisms and rotatble with said prisms, said chopper having a number of openings therein corresponding to the number of faces on each of said prisms, means for detecting radiation from said additional source of radiation and means connected to said detector means for supplying an error signal to control the intensity of radiation from said first source of radiation.