Infrared radiation source

• US 3,875,413 A
• Filed: 10/09/1973
• Issued: 04/01/1975
• Est. Priority Date: 10/09/1973
• Status: Expired due to Term

• Current Assignee: John A. Bridgham
• Original Assignee: John A. Bridgham
• Inventors: Bridgham, John A.
• Primary Examiner(s): Lawrence, James W.
• Assistant Examiner(s): Church, C. E.
• Application Number:
  US05/404,845
• Time in Patent Office: 539 Days
• Field of Search: 250/503,504,492,493 219/354,553 350/164
• US Class Current: 250/492.1
• CPC Class Codes: G01J 3/108 for measurement in the infrared range
• CPC Class Codes: H05B 2203/011 Heaters using laterally extending conductive material as connecting means
• CPC Class Codes: H05B 2203/013 Heaters using resistive films or coatings
• CPC Class Codes: H05B 2203/017 Manufacturing methods or apparatus for heaters
• CPC Class Codes: H05B 2203/032 Heaters specially adapted for heating by radiation heating
• CPC Class Codes: H05B 3/00 Ohmic-resistance heating
• CPC Class Codes: H05B 3/009 heating devices not specially adapted for a particular application
• CPC Class Codes: H05B 3/26 heating conductor mounted on insulating base for transparent areas H05B3/84, H05B3/86

Abstract

A source of infrared radiation is provided which includes a thin film resistive heater of high emissivity evaporated onto a substrate. The thin film heater is positioned between a pair of thin metal elements on the substrate. The resulting structure provides a well-defined, mechanically stable source. In one embodiment of the invention, the resistive element is coated with an antireflecting layer to enhance its emissivity.

Claims

1. An infrared radiation source comprising:

a substrate;

a pair of metal strips of emissivity less than about 0.2 in the infrared region positioned on one side of the substrate;

a thin film resistive heater of emissivity greater than about 0.5 in the infrared region positioned on the substrate in between the pair of metal strips to serve as a radiation source area bounded by the metal strips; and

input and output leads electrically interconnected with the pair of metal strips for conducting an electrical current through the source.

2. An infrared radiation source as in claim 1 wherein the thin film resistive heater comprises a layer of Cr3Si deposited onto the substrate.

3. An infrared radiation source as in claim 2 wherein the substrate material is selected from the group consisting of sapphire and Y2O3 and quartz.

4. An infrared radiation source as in claim 2 including an antireflecting layer on the Cr3Si layer for increasing the effective emissivity of the heater.

5. An infrared radiation source as in claim 4 wherein the antireflecting layer is of TiO2.

6. An infrared radiation source as in claim 5 including another metal strip on another side of the substrate opposite the side on which the resistive heater is deposited, for preventing spurious radiation from said other side of the substrate.

7. An infrared radiation source as in claim 6 wherein the substrate is mounted in a housing including a base and a reflecting surface mounted on the base, the reflecting surface for reflecting and focusing infrared radiation from the thin film resistive heater.

8. An infrared radiation source as in claim 7 wherein:

the housing is of a circular cross section;

the reflecting surface is an eliptical mirror; and

the substrate and thin film resistive heater are mounted in spaced relation with the reflecting surface.

9. An infrared radiation source as in claim 7 wherein:

the housing is of a circular cross section;

the reflecting surface is a parabolic mirror; and

the substrate and the thin film resistive heater are mounted in spaced relation with the reflecting surface.