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US3902809A Expired / Lapsed US ⏱️ 0.0 years remaining

Apparatus with multipurpose sample cavity for emissivity and absorptivity measurements

Assignee: ELSCINT IMAGING Inc
•
Filing: 1973-11-30
•
Granted: 1975-09-02
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Expires: 1993-11-30
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Abstract

Abstract An apparatus for measuring emissivity and/or absorptivity of a sample in a highly reflective, spherical sample cavity in a sample chamber or holder. The sample chamber is provided therein with a modulation hole exposed to constant external temperature, the apparatus including modulating means for periodically opening and closing the modulation hole, thereby periodically spoiling the quality factor Q of the cavity. For emissivity measurements, a signal, modulated by the modulating means, emanates from the cavity through a small signal hole for detection by an external detection means, a large portion of the energy exiting through the signal hole. The sample chamber is split into two parts which are separable to open the sample cavity for insertion of a heated sample from an external heating means, the sample chamber normally being isolated from the heating means by a movable shielding means. For absorptivity measurements, or for heating the sample, radiant energy is directed into the cavity through an input hole spaced from the modulation and signal holes, an external detecting means, such as a spectroscopic detecting means, measuring the sample temperature through the signal hole. For either the emissivity or the absorptivity mode, the apparatus is enclosed in an evacuated housing having air lock means through which the sample may be inserted and removed. The sample chamber may be maintained at a desired low temperature by thermally connecting the two halves thereof to a container of liquid nitrogen. With the foregoing construction, the apparatus of the invention provides a high signal-to-noise ratio and thermal problems are solved by setting the temperature of the sample externally of the cavity. The device measures smaller values of emissivity and absorptivity (which are not independent) than previously possible, and makes these measurements over a large range of wavelength and temperature. A method of measuring absorption coefficients Beta <10 4cm 1 is provided. Such low values cannot be measured in conventional transmission spectrometers, and are difficult in conventional laser calorimeters.

Inventors

  • 👤 Marshall S Sparks

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-01 01:14
CPC Classifications
G; G01; G01J; G01J5/00; G01J5/02; G01J5/08; G01J5/0803; G01J5/0805

Claims Analysis

Total Claims: 20
Claim 1
Independent Claim 64 words
In an apparatus for measuring radiant characteristics of a sample, the combination of: a. a sample chamber having therein a sample cavity and spaced holes which communicate with said cavity and one of which is a modulation hole; and b. means for modulating the optical characteristics of said cavity, comprising means for periodically opening and closing said modulation hole to a constant reference temperature.
Claim 2
Dependent Claim 64 words
In an apparatus for measuring radiant characteristics of a sample, the combination of: a. a sample chamber having therein a sample cavity and spaced holes which communicate with said cavity and one of which is a modulation hole; and b. means for modulating the optical characteristics of said cavity, comprising means for periodically opening and closing said modulation hole to a constant reference temperature.
Claim 3
Dependent Claim 57 words
In an apparatus for measuring radiant characteristics of a sample, the combination of: a. a sample chamber having therein a sample cavity and a modulation hole which communicates with said cavity; and b. means for modulating the optical characteristics of said cavity, comprisinG means for periodically opening and closing said modulation hole to a constant reference temperature.
Claim 4
Dependent Claim 57 words
In an apparatus for measuring radiant characteristics of a sample, the combination of: a. a sample chamber having therein a sample cavity and a modulation hole which communicates with said cavity; and b. means for modulating the optical characteristics of said cavity, comprisinG means for periodically opening and closing said modulation hole to a constant reference temperature.
Claim 5
Dependent Claim 12 words
An apparatus according to claim 2 wherein said cavity is substantially spherical.
Claim 6
Dependent Claim 17 words
An apparatus as defined in claim 2 including means for heating the sample externally of said cavity.
Claim 7
Dependent Claim 20 words
An apparatus as defined in claim 2 including means for heating the sample by directing radiant energy into said cavity.
Claim 8
Dependent Claim 79 words
In an apparatus for measuring radiant characteristics of a sample, the combination of: a. a sample chamber having therein a sample cavity and spaced signal and modulation holes which communicate with said cavity; means for modulating the optical characteristics of said cavity, comprising means for periodically opening and closing said modulation hole to a constant reference temperature to modulate a signal emanating from said cavity through said signal hole; and c. signal detecting means for detecting the modulated signal.
Claim 9
Dependent Claim 79 words
In an apparatus for measuring radiant characteristics of a sample, the combination of: a. a sample chamber having therein a sample cavity and spaced signal and modulation holes which communicate with said cavity; means for modulating the optical characteristics of said cavity, comprising means for periodically opening and closing said modulation hole to a constant reference temperature to modulate a signal emanating from said cavity through said signal hole; and c. signal detecting means for detecting the modulated signal.
Claim 10
Dependent Claim 48 words
An apparatus as defined in claim 6 wherein said chamber is openable, said apparatus further including: a. means for heating a sample externally of said chamber; b. means for opening said chamber; and c. means for inserting the heated sample into said cavity upon opening of said chamber.
Claim 11
Dependent Claim 19 words
An apparatus as set forth in claim 7 including movable means for shielding said chamber from said heating means.
Claim 12
Dependent Claim 47 words
An apparatus according to claim 8 including: a. an evacuated housing containing said chamber, said heating means and said shielding means; and b. air lock means on said housing through which a sample may be inserted into and removed from said housing with a minimum vacuum loss.
Claim 13
Dependent Claim 17 words
An apparatus as defined by claim 9 including a liquid gas container thermally connected to said chamber.
Claim 14
Dependent Claim 51 words
An apparatus as set forth in claim 6 wherein one of said holes is an input hole, said apparatus further including: a. means for directing radiant energy into said cavity through said input hole; and b. temperature detecting means for detecting the temperature of the sample through one of said holes.
Claim 15
Independent Claim 25 words
A method of modulating a radiant signal emanating from a sample in a sample cavity, comprising periodically opening said cavity to a constant reference temperature.
Claim 16
Independent Claim 25 words
A method of modulating a radiant signal emanating from a sample in a sample cavity, comprising periodically opening said cavity to a constant reference temperature.
Claim 17
Independent Claim 37 words
A method of modulating a radiant signal emanating from a sample in a sample cavity, comprising periodically opening said cavity, at a point spaced from the point of exit of said signal, to a constant reference temperature.
Claim 18
Independent Claim 37 words
A method of modulating a radiant signal emanating from a sample in a sample cavity, comprising periodically opening said cavity, at a point spaced from the point of exit of said signal, to a constant reference temperature.
Claim 19
Dependent Claim 63 words
In an apparatus for measuring radiant characteristics of a sample, the combination of: a. a sample chamber having therein a sample cavity and a signal hole which communicates with said cavity; and b. modulating means for modulating the optical properties of said cavity comprising means for periodically opening said cavity to a constant reference temperature at a point spaced from said signal hole.
Claim 20
Dependent Claim 63 words
In an apparatus for measuring radiant characteristics of a sample, the combination of: a. a sample chamber having therein a sample cavity and a signal hole which communicates with said cavity; and b. modulating means for modulating the optical properties of said cavity comprising means for periodically opening said cavity to a constant reference temperature at a point spaced from said signal hole.

References Cited (Backward Citations)

US2792484A Cited
US3749495A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1978-09-01 1979-03-03 1979-09-02 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1982-09-01 1983-03-03 1983-09-02 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1986-09-01 1987-03-03 1987-09-02 $7700.00 Window Closed / Lapsed

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