Mm-wave terrestrial imager

• US 20040130311A1
• Filed: 10/24/2003
• Published: 07/08/2004
• Est. Priority Date: 04/28/2001
• Status: Active Grant

• Current Assignee: Qinetiq Limited (QinetiQ Group PLC)
• Original Assignee: Qinetiq Limited (QinetiQ Group PLC)
• Inventors: Rees, Huw D, Humphreys, Richard G, Satchell, Julian S
• Granted Patent: US 7,532,917 B2
• Time in Patent Office: Days
• US Class Current: 324/76.11
• CPC Class Codes: G01J 2005/0077 Imaging
• CPC Class Codes: G01J 5/046 Materials; Selection of thermal materials
• CPC Class Codes: G01J 5/06 Arrangements for eliminating effects of disturbing radiation; Arrangements for compensating changes in sensitivity for adjusting of solid angle of collected radiation G01J5/07; means for wavelength selection G01J5/0801
• CPC Class Codes: G01J 5/061 by controlling the temperature of the apparatus or parts thereof, e.g. using cooling means or thermostats
• CPC Class Codes: G01J 5/08 Optical arrangements
• CPC Class Codes: G01J 5/0837 Microantennas, e.g. bow-tie
• CPC Class Codes: G01J 5/20 using resistors, thermistors or semiconductors sensitive to radiation, e.g. photoconductive devices
• CPC Class Codes: G01V 8/005 operating with millimetre waves, e.g. measuring the black losey radiation
• CPC Class Codes: H10N 69/00 Integrated devices, or assemblies of multiple devices, comprising at least one superconducting element covered by group H10N60/00

Abstract

A passive mm-wave imager comprises an optical immersion lens arrangement which is illuminated by front end optics and an array of direct detectors (12a) to (12d) located in the focal plane of the immersion lens arrangement. The detectors comprise antennae coupled high temperature superconductor weak links, in particular C-axis cross-over or step microbridges.

Claims

1. An array of sensors for receiving a focussed terrestrial mm-wave image and providing a corresponding pixel-wise set of image representative signals therefrom, said sensors being antenna coupled high temperature superconductor weak links for directly detecting incident mm-wave radiation.

2. An array according to claim 1 wherein the weak links are Josephson junctions.

3. An array according to claim 1 wherein the weak links are microbridges.

4. An array according to claim 3 wherein the microbridges are C-axis microbridges.

5. An array according to claim 4 wherein the C-axis microbridges are cross-over micro bridges.

6. An array according to claim 4 wherein the C-axis microbridges are step microbridges.

7. An array according to claim 2 wherein the Josephson junction has a barrier.

8. An array according to any preceding claim wherein the weak links are made from a high temperature superconductor RBa₂Cu₃O_x material, where R is Y or a rare earth element.

9. An array according to any preceding claim, and further comprising means for maintaining the sensors at a temperature substantially below the superconducting critical temperature T_c.

10. An array according to any preceding claim which is formed monolithically by a process of epitaxial growth and patterning.

11. An array according to any preceding claim, and further provided with means for electrically biassing the sensors.

12. An array according to any preceding claim, and further provided with means for electrically reading our the signals from the sensors.

13. A sensor element comprising an array according to any preceding claim and a lens or lens array, the sensor array being in close proximity to or in contact with the lens or lens array so that the lens or lenses act as immersion lenses.

14. An imaging arrangement comprising an array according to any one of claims 1 to 12 and imaging optics for focussing a mm-wave image on the array.

15. An imaging arrangement according to claim 14 wherein the imaging optics is or includes a lens or lens array, the sensor array being arranged or secured in close proximity to or in contact with the lens or lens array so that the lens or lenses act as immersion lenses.

16. An imaging arrangement according to claim 15 wherein the imaging optics comprises a doublet having a relatively warm high optical power lens element adjacent but spaced from said lens or lens array to which the sensor array is secured for optical immersion.

17. An imaging arrangement according to any one of claims 14 to 16 wherein a ground plane is located at the side of the integrated array remote from the immersion lens.

18. An imaging arrangement according to any one of claims 14 to 17 wherein the optical immersion lens arrangement is thermally decoupled from the detector array.