Temperature controlled detectors for infrared-type gas analyzers

• US 5,153,436 A
• Filed: 04/16/1991
• Issued: 10/06/1992
• Est. Priority Date: 05/23/1990
• Status: Expired due to Term

• Current Assignee: NTC Technology, Inc. (Dixtal Medical, Inc.)
• Original Assignee: NTC Technology, Inc. (Dixtal Medical, Inc.)
• Inventors: Labuda, Lawrence L., Apperson, Jerry R., Knodle, Daniel W., Russell, James T., Bang, Gary M.
• Primary Examiner(s): FIELDS, CAROLYN
• Application Number:
  US07/686,139
• Time in Patent Office: 539 Days
• Field of Search: 250/343, 250/345, 250/346, 250/339, 250/352, 250/349, 250/238
• US Class Current: 250/345
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 3/36 Investigating two or more bands of a spectrum by separate detectors
• CPC Class Codes: G01N 21/3504 for analysing gases, e.g. multi-gas analysis

Abstract

A detector unit which is capable of outputting electrical signals proportional in magnitude to the intensity of that energy in a beam thereof which lies in two different wavelength bands. A beam splitter directs energy in those bands from the entire compass of the beam to a data detector and a reference detector, and bandpass filters and optical traps in front of those detectors ensure that only energy in the selected bands and from the beam reach them. The detectors are mounted in precisely aligned relationship with each other and the beam splitter on, and are electrically isolated from, a monolithic, conductive, isothermal support which allows them to be maintained at the same, selected temperature by a system including data and reference detector heaters and a temperature responsive controller.

Claims

1. A system for detecting electromagnetic radiation which comprises:

a housing;

reference and data detectors;

detector supporting means for so supporting said detectors in said housing that said detectors can be maintained at the same, selected temperature, said detector supporting means comprising a monolithic, isothermal member fabricated of a material having a high coefficient of thermal conductivity; and

reference and data detector heaters mounted to the detector supporting means in conductive heat transfer relationship to said detector supporting means for heating said reference and data detectors, respectively;

wherein

the reference and data heaters are so mounted to the detector supporting means adjacent to their respective detectors that heat is directed from the reference and data detector heaters past the reference and data detectors to a given measurement point.

2. A detector system as defined in claim 1 which also includes

control means for regulating the flow of current through said heaters, said control means comprising a temperature responsive, current flow limiter in conductive heat transfer relationship to said detector supporting means.

3. A detector system as defined in claim 2 in which there are heater receiving recesses in the detector supporting means, said recesses being configured to complement the external configurations of the data and reference detector heaters.

4. A detector system as defined in claim 2 which comprises a power supply for making operating voltage and biasing voltage respectively available at selected, precise levels to said data and reference detector heaters and to the reference and data detectors.

5. A detector system as defined in claim 4 in which the power supply includes an inverter so connected that biasing voltages of opposite polarity are supplied to opposite sides of the reference detector and the data detector.

6. A detector system as defined in claim 2, in which the detector supporting means is dimensioned and configured to direct thermal energy omitted from the reference detector and data detector heaters first past the reference and data detectors, then past the temperature responsive, current flow limiter, and then overboard from the detector supporting means.

7. A detector system as defined in claim 2, which:

includes a beam splitting means for reflecting that energy in a beam impinging thereon and above a designated wavelength onto one of the detectors and for transmitting energy of a shorter wavelength from the same compass of the beam to the other of the detectors, said beam splitting means being supported from the detector supporting means midway between, and in mirror image relationship to, the reference and data detectors;

wherein

the beam splitting means has front and back sides and a generally parallelepidedal configuration; and

the longitudinal axes of the detector heaters and the temperature responsive current limiter and the plane of symmetry between the sides of the beam splitter are in the same plane.

8. A detector system as defined in claim 1

in which the detector heaters are mounted in said detector suppporting means in conductive heat transfer relationship to the supporting means and in equidistantly spaced relationship to the reference and data detectors;

and

control means for so regulating the flow of current through the detector heaters as to keep the detectors at the desired temperature, said control means comprising a temperature responsive current flow limiter in conductive heat flow relationship to the detector supporting means and in equidistantly spaced relationship to the reference and data detectors.

9. A detector system as defined in claim 1 which includes a beam splitting means for reflecting that energy in a beam impinging thereon and above a designated wavelength onto one of the detectors and for transmitting energy of a shorter wavelength from the same compass of the beam to the other of the detectors, said beam splitting means being supported from the detector supporting means midway between, and in mirror image relationship to, the reference and data detectors.

10. A detector system as defined in claim 1:

which includes a beam splitting device for respectively reflecting and transmitting that electromagnetic energy in a beam reaching the system which is above and below a selected wavelength to the data detector and the reference detector; and

wherein said detector supporting means has therein recesses opening onto the face of the supporting means in which the reference and data detectors are so installed that the surfaces of the detectors are exposed, are at equal distances from any given point through the midplane of the beam splitter, and are disposed at equal angles to the beam splitter.

11. A detector system as defined in claim 10 in which:

the reference and data detectors have electrically conductive electrodes on their exposed surfaces;

the detector supporting means has recesses in which the detectors are installed; and

the edges of the detector receiving recesses are spaced from said surfaces to prevent shorting between the detectors and the detector supporting means.

12. A detector system as defined in claim 1:

in which said housing has therein an aperture via which a beam of electromagnetic energy can pass to the interior of the housing; and

said system also includes light trap means in said housing for keeping electromagnetic energy other than that making up a particular beam from reaching said reference and data detectors.

13. A detector system as defined in claim 12 in which:

said detector supporting means has first and second detector receiving recesses which open onto an exterior surface of the supporting means;

said reference detector and said data detector are respectively seated in said first and second recesses; and

said light trap means comprises means extending toward the axis of symmetry of the beam from said housing on those sides of the detector receiving apertures facing that aperture in the housing via which the beam of electromagnetic energy is admitted to interior of the housing.

14. A detector system as defined in claim 12:

which has a beam splitter for reflecting that electromagnetic energy in said beam which is above a selected wavelength toward one of said detectors and for transmitting the remainder of the energy making up said beam to the other of the detectors, said beam splitter having a parallelepipedal configuration and being supported at one edge thereof from said detector supporting means; and

said light trap means being configured and dimensioned to support the opposite edge of the beam splitter.

15. A system for detecting electromagnetic radiation which comprises:

a housing;

reference and data detectors;

detector supporting means for so supporting said detectors in said housing that said detectors can be maintained at the same, selected temperature, said detector supporting means comprising a monolithic, isothermal member fabricated of a material having a high coefficient of thermal conductivity;

heating means for heating the reference and data detectors including;

(a) reference and data detector heaters supported from, and in conductive heat transfer relationship to, said detector supporting means; and

(b) control means for regulating the flow of current through said heaters, said control means comprising a temperature responsive, current flow limiter in conductive heat transfer relationship to said supporting means;

wherein

the detector supporting means is dimensioned and configured to direct thermal energy emitted from the reference detector and data detector heaters first past the reference and data detectors, then past the temperature responsive, current flow limiter, and then overboard from the detector supporting means.

16. A system for detecting electromagnetic radiation which comprises:

a housing;

reference and data detectors;

detector supporting means for so supporting said detectors in said housing that said detectors can be maintained at the same, selected temperature, said detector supporting means comprising a monolithic, isothermal member fabricated of a material having a high coeficient of thermal conductivity;

heating means for heating the reference and data detectors including;

(a) reference and data detector heaters supported from, and in conductive heat transfer relationship to, said detector supporting means;

(b) control means for regulating the flow of current through said heaters, said control means comprising a temperature responsive, current flow limiter in conductive heat transfer relationship to said supporting means; and

(c) a power supply for making operating voltage and biasing voltage respectively available at selected, precise levels to said detector heaters and to the reference and data detectors, the power supply including an inverter so connected that biasing voltages of opposite polarity are supplied to opposite sides of the reference detector and the data detector.