Explosion-proof thermal imaging system

Patent metadata

Field	Value
Publication number	US-10873686-B2
Application number	US-201514755107-A
Country	US
Kind code	B2
Filing date	Jun 30, 2015
Priority date	Jun 30, 2015
Publication date	Dec 22, 2020
Grant date	Dec 22, 2020

Abstract

A thermal imaging system is provided. The thermal imaging system includes an explosion-proof housing with an optical window configured to contain an explosive pressure. The optical window allows electromagnetic thermal energy to pass. A thermal imaging sensor is disposed within the explosion-proof housing. Thermal imaging electronics are coupled to the thermal imaging sensor and configured to provide at least one thermal image based on a signal from the thermal imaging sensor. A lens assembly is disposed at least in front of the optical window external to the explosion-proof housing. A composite optical window for thermal imaging is also provided. In another embodiment, a thermal imaging system includes an explosion-proof housing having an optical window configured to contain an explosive pressure. An infrared (IR) camera is disposed within the explosion-proof housing. A reflector reflects electromagnetic thermal energy to the IR camera, but prevent an object from impacting the optical window.

First claim

What is claimed is:

1. A thermal imaging system comprising:
a metallic explosion-proof housing including an optical window, wherein the explosion-proof housing complies with at least one explosion-proof rating, the optical window allowing electromagnetic thermal energy to pass through;
a thermal imaging sensor disposed within the explosion-proof housing;
thermal imaging electronics coupled to the thermal imaging sensor and configured to provide at least one thermal image based on a signal from the thermal imaging sensor;
at least one lens disposed at least in front of the optical window and external to the explosion-proof housing; and
wherein the IR transparent optical window is formed of an IR transparent, impact resistant layer comprised of a first material sandwiched between a first and a second IR transparent layer comprised of a second material.

2. The thermal imaging system of claim 1 , wherein the at least one lens includes a first and second lens disposed in front of the IR transparent optical window, wherein the first lens is external to the explosion proof housing.

3. The thermal imaging system of claim 2 , wherein the at least one lens further includes a third lens disposed within the explosion-proof housing and configured to focus the electromagnetic thermal energy on the thermal imaging sensor.

4. The thermal imaging system of claim 1 , wherein the IR transparent optical window comprises of zinc selenide.

5. The thermal imaging system of claim 1 , wherein the lens assembly includes a housing having a diameter less than 1 inch.

6. The thermal imaging system of claim 1 , wherein the thermal imaging electronics are disposed within the explosion-proof housing.

7. The thermal imaging system of claim 4 , wherein the thermal imaging sensor obtains the at least one thermal image substantially completely through a reflector, wherein the reflector is disposed to prevent an object from impacting the optical window.

8. The thermal imaging system of claim 1 wherein the at least one lens comprises a lens assembly, the lens assembly comprising:
a first forward-facing convex lens disposed in front of the optical window and external to the explosion-proof housing;
a second forward-facing convex lens disposed behind the first lens and in front of the optical window;
a third forward-facing convex lens disposed behind the optical window and within the explosion-proof housing; and
a fourth rearward-facing convex lens disposed behind the third lens and within the explosion-proof housing.

9. The thermal imaging system of claim 7 wherein the reflector is external to the explosion-proof housing.

10. The thermal imaging system of claim 9 wherein the reflector comprises a parabolic mirror.

11. The thermal imaging system of claim 10 wherein the reflector is within a point of view of the thermal imaging sensor and reflects light, received from a surface outside of the point of view of the thermal imaging sensor, towards the thermal imaging sensor.

12. The thermal imaging system of claim 1 and further comprising a shroud disposed in front of the IR transparent optical window and having a diameter of less than 1 inch.

13. The thermal imaging system of claim 6 , wherein the electronics are further configured to detect damage to the at least one lens based on the at least one thermal image.

14. The thermal imaging system of claim 13 , wherein the electronics are further configured to generate an alert based on the detection of damage to the at least one lens.

15. The thermal imaging system of claim 1 , wherein the first material comprises polyamide.

16. The thermal imaging system of claim 15 , wherein the second material comprises zinc selenide.

17. A composite optical window for thermal imaging, the composite optical window including:
a first layer of material that passes thermal imaging electromagnetic radiation, but is subject to fracture;
a second layer of material that passes thermal imaging electromagnetic radiation, but is also subject to fracture; and
an IR-transparent, impact resistant, layer disposed between the first and second layers and, wherein each of the first and second layers contain an explosive pressure in accordance with at least one explosion-proof rating; and
wherein each layer of the composite optical window is composed of only IR transparent materials.

18. The composite optical window of claim 17 , wherein the first and second layers are formed of zinc selenide.

19. The composite optical window of claim 18 , wherein the IR-transparent impact resistant layer comprises polyamide.

20. The composite optical window of claim 17 wherein the first layer is disposed in front of both the IR-transparent impact resistant layer and the second layer and can absorb a force from an impact of an object, such that the IR-transparent impact resistant layer can maintain a pressure bearing seal of an interior of an explosion proof housing in which the composite optical window is disposed, wherein the force being exerted upon impact by the object is at least 4 joules.

Assignees

• Rosemount Inc
• Rosmeount Inc

Inventors

• Rud Jason H
• Kitzman Andrew J
• Kienitz Sascha Ulrich
• Kienitz Ulrich
• Gentz Johannes

Classifications

• G01J5/048 Primary

  Protective parts · CPC title

• H04N23/51 Primary

  Housings · CPC title

• H04N23/555

  for picking-up images in sites, inaccessible due to their dimensions or hazardous conditions, e.g. endoscopes or borescopes · CPC title

• G01J5/0816

  using attenuators · CPC title

• G01J5/0808

  Convex mirrors · CPC title