Apparatus and method for measuring pressures and indicating leaks with optical analysis
First Claim
1. Apparatus for deriving a partial pressure signal and for deriving a total pressure signal correlated with said partial pressure signal, comprising:
- means to ionize and to excite light emission from residual gas within said apparatus;
spectral discrimination means coupled to said light whereby a portion of said emitted light is selected for transmission by said spectral discrimination means, said portion being characteristic of a selected gas;
means responsive to the total pressure of said residual gas including electrode means for the collection of currents of said ions and first output means for indicating the magnitude of said ion currents;
means responsive to the partial pressure of a selected gas including optical detection means whereby an electrical signal responsive to the intensity of said spectrally selected portion of emitted light is derived, and second output means for indicating the magnitude of said optically detected signal; and
means responsive to the relative magnitude of said partial pressure output and said total pressure output whereby a relative magnitude signal is derived.
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Abstract
A partial pressure gauge utilizes an efficient electron collision excitation source yielding de-excitation radiation characteristic of residual gases. The intensity of a given spectral line is proportional to the partial pressure of the gas having such spectral line, and the current drawn from the excitation source provides a measure of the total pressure. A calibration technique based upon comparing the emitted light intensity with the ion currents associated with the excitation process yields an accurate measure of the relative partial pressure. Use of a filter to selectively pass radiation from a known constituent in known proportion in ambient gas provides an indication of the presence of a leak without the need for probing with a test gas. Provision for passing an evaporant stream through the excitation region permits accurate monitoring of the evaporant flux from which depostion rate is determined. In combination with techniques for achieving high differential sensitivity to iluctuations in light output from a selected spectral line, a novel leak detector is achieved. In combination with an optically dispersive element a residual gas analyzer is obtained.
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Citations
30 Claims
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1. Apparatus for deriving a partial pressure signal and for deriving a total pressure signal correlated with said partial pressure signal, comprising:
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means to ionize and to excite light emission from residual gas within said apparatus; spectral discrimination means coupled to said light whereby a portion of said emitted light is selected for transmission by said spectral discrimination means, said portion being characteristic of a selected gas; means responsive to the total pressure of said residual gas including electrode means for the collection of currents of said ions and first output means for indicating the magnitude of said ion currents; means responsive to the partial pressure of a selected gas including optical detection means whereby an electrical signal responsive to the intensity of said spectrally selected portion of emitted light is derived, and second output means for indicating the magnitude of said optically detected signal; and means responsive to the relative magnitude of said partial pressure output and said total pressure output whereby a relative magnitude signal is derived. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. Apparatus for deriving a partial pressure signal and for deriving a total pressure signal correlated with said partical pressure signal, comprising:
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means to ionize and to excite light emission from residual gas within said apparatus; spectral discrimination means coupled to said light whereby a portion of said emitted light is selected for transmission by said spectral discrimination means, said portion being characteristic of a selected gas; means responsive to the total pressure of said residual gas including electrode means for the collection of currents of said ions and first output means for indicating the magnitude of said ion currents; and means responsive to the partial pressure of a selected gas including optical detection means whereby an electrical signal responsive to the intensity of said spectrally selected portion of emitted light is derived, and second output means for indicating the magnitude of said optically detected signal.
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15. A method for analyzing gas in a vacuum enclosure, comprising the steps of:
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exciting gas atoms to cause a gaseous discharge phenomena; deriving a first signal from the de-excitation of gas atoms from said gaseous discharge representative of the partial pressure of a selected gas in said enclosure; deriving a second signal proportional to said step of exciting gas atoms said second signal representative of the total pressure in said enclosure, whereby said second signal is causatively related to said gaseous discharge and said first and second signals are causally correlated; and comparing said first and second signals to obtain the relative magnitude thereof. - View Dependent Claims (16)
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17. Apparatus for deriving and interrelating a partial pressure signal and a total pressure signal comprising:
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means to excite light emitting quantum levels of quantum systems of gas within said apparatus, said means generating a signal indicative of the extent of said excitation; spectral discrimination means coupled to said light whereby a portion of said emitted light is selected for transmission by said spectral discrimination means, said portion being characteristic of a selected gas; means indicative of the total pressure of said gas to provide a signal representative of said total pressure and first output means for indicating the magnitude of said total pressure signal said means responsive to said signal generated by said light exciting means; means responsive to the partial pressure of a selected gas including optical detection means whereby a signal responsive to the intensity of said spectrally selected portion of emitted light is derived, and second output means for indicating the magnitude of said optically detected signal; and means responsive to the relative magnitude of said partial pressure output and said total pressure output whereby a relative magnitude signal is derived.
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18. Apparatus for deriving and interrelating a partial pressure signal and a total pressure signal comprising:
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means to excite light emitting quantum levels of quantum systems of gas within said apparatus, said means generating a signal indicative of the extent of said excitation; spectral discrimination means coupled to said light whereby a portion of said emitted light is selected for transmission by said spectral discrimination means, said portion being characteristic of a selected gas; means indicative of the total pressure of said gas to provide a signal representative of said total pressure, said means responsive to said signal generated by said light exciting means; means responsive to the partial pressure of a selected gas including optical detection means whereby a signal responsive to the intensity of said spectrally selected portion of emitted light is derived; means responsive to the relative magnitude of said partial pressure output and said total pressure output whereby a relative magnitude signal is derived; indicating means for indicating the magnitude of a selected one of said total pressure signal, partial pressure signal or relative magnitude signal; and switching means for selectably connected one of said signals to said indicating means.
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19. Apparatus for deriving a partial pressure signal, a total pressure signal, relationship of said total pressure signal with said partial pressure signal comprising:
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means to ionize and to excite light emission from residual gas within said apparatus, a portion of said quantum systems being ionized by said excitation means; spectral discrimination means coupled to said light whereby a portion of said emitted light is selected for transmission by said spectral discrimination means, said portion being characteristic of a selected gas; means responsive to the total pressure of said residual gas including electrode means for the collection of currents of said ions; means responsive to the partial pressure of a selected gas including optical detection means whereby an electrical signal responsive to the intensity of said spectrally selected portion of emitted light is derived; switching means for selecting one of said total pressure signal, said partial pressure signal or said relative magnitude signal; and output means for indicating the magnitude of said selected signal. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification