Cold shield for cryogenic camera

{
  "publication_number": "US2005078208A1",
  "country": "US",
  "kind": "A1",
  "title": "Cold shield for cryogenic camera",
  "abstract": "A cold shield of a cryogenic camera. The cold shield reflects external thermal radiation away from the cryogenic camera, so as to shield the cryogenic camera in a cryogenic temperature such that no internal thermal radiation will be generated. The cryogenic camera has a lens assembly and a focal plane array. The cold shield has an upper cold shield member for holding the lens assembly and a lower cold shield member for holding the focal plane array. The upper cold shield member fits over the lower cold shield member by contact friction, such that limited translation and rotation of the lower cold shield member relative to the upper cold shield member are allowable. Therefore, the cold shield allows a fine adjustment for aligning the lens assembly to the focal plane array.",
  "claims": [
    "1. A cold shield for shielding a cryogenic camera including a lens assembly and a focal plane array, the cold shield comprising: an upper cold shield member for holding the lens assembly; and a lower cold shield member for holding the focal plane array, wherein the upper cold shield member fits over the lower cold shield by contact friction which allows limited translation and rotation of the lower cold shield member within the upper cold shield member. 2. The cold shield of claim 1, wherein the upper cold shield member includes a lens holder for holding the lens assembly therein and a holder mount for mounting the lens holder thereon. 3. The cold shield of claim 2, wherein the holder mount includes at least one bump protruding from an interior sidewall thereof. 4. The cold shield of claim 3, wherein the bump is configured to provide the contact force between the upper cold shield member and the lower cold shield member. 5. The cold shield of claim 1, further comprising a cap adhered to the upper cold shield member for securing the lens assembly in the upper cold shield member. 6. The cold shield of claim 1, further comprising a mounting ring adhered to the lower cold shield and a mounting plate for mounting the lower cold shield and the mounting ring thereon, such that the focal plane array is secured in the lower cold shield member. 7. The cold shield of claim 1, further comprising a filling material applied between the upper cold shield member and the lower cold shield member for fixing relative positions between the upper and lower cold shield member. 8. The cold shield of claim 1, wherein the upper and lower cold shield members each comprises a window allowing imaging light incident onto the lens assembly held in the upper cold shield members and propagate towards of the focal plane array held in the lower cold shield member. 9. A cold shield, comprising: a lower cold shield member, comprising: a lower hollow cylinder with a front end covered by a plate and a rear open end terminated with a flange; and a mounting plate for connecting the rear open end of the hollow cylinder; and an upper cold shield member, comprising: an upper hollow cylinder with a front end covered by a plate and a rear open end terminated with a flange, the upper hollow cylinder being configured to fit over the lower hollow cylinder; a lens holder with a rear end mounted to a front surface of the plate and a front open end; and a cap attached to the open end of the lens holder. 10. The cold shield of claim 9, wherein the lower hollow cylinder is configured for receiving a focal plane array of a camera therein. 11. The cold shield of claim 10, wherein the lens holder is configured to receive a lens assembly of a camera therein. 12. The cold shield of claim 9, wherein the plate of the lower hollow cylinder, the plate of the upper hollow cylinder, the rear end of the lens holder and the cap each is perforated with a window. 13. The cold shield of claim 9, wherein the lower hollow cylinder has an outer diameter smaller than an inner diameter of the upper hollow cylinder. 14. The cold shield of claim 13, wherein the upper hollow cylinder further comprises at least one bump protruding inwardly from an interior sidewall thereof. 15. The cold shield of claim 14, wherein the lower hollow cylinder is frictionally engaged with the upper hollow cylinder by the bump. 16. The cold shield of claim 9, wherein the outer diameter of the lower hollow cylinder is 0.005 inches smaller than an inner diameter of the upper hollow cylinder. 17. The cold shield of claim 9, wherein the upper and lower cold shield members are made of electroformed cupper. 18. The cold shield of claim 9, wherein the upper and lower cold shield members each has a thickness less than 0.001 inches. 19. The cold shield of claim 9, wherein the upper and lower cold shield members are coated with gold. 20. The cold shield of claim 9, wherein the lower cold shield member further comprises a mounting ring as an interface to interconnect the lower hollow cylinder and the mounting plate. 21. The cold shield of claim 20, wherein the mounting ring is made of ceramic material. 22. A cryogenic camera system, comprising: a camera, comprising a lens assembly and a focal plane array; and a cold shield, comprising: a lower cold shield member for holding the focal plane array therein; and an upper cold shield member for holding the lens assembly therein, wherein the upper cold shield member fitting over the lower cold shield member in a manner that the lower cold shield member is operative to translate and rotate within the upper cold shield member. 23. The cryogenic camera system of claim 22, wherein the cold shield further comprises a cryogenic stable adhesive to adhere the lower and upper cold shield members before the cryogenic camera system is cooled down to a cryogenic temperature. 24. The cryogenic camera system of claim 22, wherein the camera further comprises a filter installed in the cold shield between the lens assembly and the focal plane array. 25. The cryogenic camera system of claim 22, wherein the camera further comprises a readout integrated circuit installed in the lower cold shield member."
  ],
  "description_excerpt": "Not Applicable\n\nNot Applicable\n\nThe present invention relates in general to a cold shield, and more particularly, to a cold shield for shielding a cryogenic camera and reducing thermal noise of images registered by the cryogenic camera.\n\nImage registration is a fundamental task required in many applications of image processing which involves taking two or more images and aligning them so as to either eliminate differences between them or highlight the salient differences for the purpose of study. To obtain sub-pixel accuracy of the registration, a well registered and stable camera configuration is required. An integrated lens has been used in the single element multiple field cameras. In the integrated lens design, the lens position is constantly referenced to the same mechanical plane referred as a focal plane for minimizing allowable movements critical to maintaining alignment. However, since the focus and alignment of the camera are sensitive to temperature, there is a demand for applying a cryogenic system to the camera to suppress the noise caused by thermal radiation.\n\nIn U.S. Pat. No. 5,479,015, a multi-image detector assembly has been disclosed. The multi-image detector assembly allows image detection occurring continuously and simultaneously so as to provide a spatially and temporally correlated set of separate images utilizing a single focal plane. However, the cryogenic application of such multi-image detector assembly was not addressed in this patent.\n\nThe cryogenic camera is typically disposed in a cryo-vacuum dewar.",
  "cpc": [
    "H04N 23/54",
    "H04N 23/52",
    "H04N 23/55"
  ],
  "ipc": [
    "H04N 5/225",
    "G01J 5/02"
  ],
  "inventors": [
    "Philip Minarik",
    "Sung-Shik Yoo"
  ],
  "filing_date": "2003-10-10",
  "publication_date": "2005-04-14",
  "priority_date": "2003-10-10",
  "application_number": "US-68307303-A",
  "family_id": "34422652",
  "cited_by_count": 11,
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  ]
}