Image gating using an array of reflective elements

{
  "publication_number": "US9835849B2",
  "country": "US",
  "kind": "B2",
  "title": "Image gating using an array of reflective elements",
  "abstract": "A device for image gating using an array of reflective elements is provided herein. The device includes an array of reflective elements, wherein each one of the reflective elements is movable within a range of a plurality of tilt positions, wherein the array is located at an image plane of the device, wherein the array is perpendicular to an optical axis of the device. The device further includes a control unit configured to control the reflective elements such that in at least some of the tilt positions, the reflective elements reflect the radiant flux at said image plane, to one or more projection planes. A gradual rotation of the reflective elements along the plurality of tilt positions result in a gradual increase or decrease in the intensity of the image reflected from the array of reflective elements while maintaining the image integrity.",
  "claims": [
    "1. A gated imaging system comprising: a pulsed light source configured to generate a light pulse; at least one sensor; a main lens configured to focus a radiant flux of electromagnetic radiation from the pulsed light source entering the lens at a focal plane of the main lens; an array of tiltable reflective elements, located at the focal plane of the main lens, wherein the tiltable reflective elements have a 1 st position and a 2 nd position, being respectively extreme tilt positions of the tiltable reflective elements; and a control unit configured to selectively set the reflective elements, in said 1 st position and said 2 nd position, at each of which the reflective elements reflect the radiant flux focused at said focal plane, to the at least one sensor via a folding mirror other than the tiltable reflective elements, wherein the control unit is synchronized with the pulsed light source such that the pulsed light source is activated when the tiltable reflective elements are in transition between the 1st and 2nd positions.",
    "2. The imaging system according to claim 1, further comprising one or more sets of field lens through which the radiant flux coming from the array of reflective elements is focused, and wherein the at least one sensor is located at a focal plane of the one or more sets of field lens.",
    "3. The imaging system according to claim 1, further comprising one or more folding elements configured to fold the radiant flux reflected from the reflective elements onto the at least one sensor.",
    "4. The imaging system according to claim 3, wherein the folding element is a beam splitter.",
    "5. The imaging system according to claim 3, wherein the folding element is a total internal reflection (TIR) prism.",
    "6. The imaging system according to claim 1, further comprising a photographic lens, wherein the array of the reflective elements is located at the focal plane of the photographic lens, and wherein the imaging system is configured to operate within an optical spectrum.",
    "7. The imaging system according to claim 1, wherein in one of the 1 st or 2 nd tilt positions, the reflective elements are co-planar."
  ],
  "description_excerpt": "1. Technical Field\n\nThe present invention relates to gated systems, and more particularly, to such systems that employ an array of reflective elements for implementing the gating.\n\n2. Discussion of Related Art\n\nActive gated systems are known in the art for achieving an enhanced image of a scene in high scattering or absorption media. Gated systems are used when there is a clear advantage for a reflective image rather than a thermal (emitted) image. Since the human eye is used to perceiving a reflected image and the human brain is accustomed to process reflected images, it is easier to interpret reflected images.\n\nThermal imagers are associated to emitted image formed by the collection of the photons emitted from the observed target. There are certain features in an image that one can observe only by using the reflected image and equally there are such that can be achieved only by using the emitted image.\n\nActive imaging benefits from a unique technological feature that enables the synchronized switching between the light source and the camera. This mode of operation is referred to as synchronized gated imaging (SGI) or burst illumination (BIL). The active imaging systems mode eliminates the reflected backscatter of near range reflectors. A reflector may be an aerosol particle or any feature located within the field of view. The SGI mode of operation enables adjustments to the illumination level at each range resulting in an effective uniform illumination regardless of the range.",
  "cpc": [
    "G02B 26/08",
    "G01S 17/107",
    "G01S 17/18",
    "G01S 17/89",
    "G01S 7/4816",
    "G02B 17/023",
    "G02B 26/0833"
  ],
  "ipc": [
    "G01S 17/18",
    "G01S 17/89",
    "G02B 26/08",
    "G01S 7/481"
  ],
  "assignees": [
    "Elbit Systems Ltd"
  ],
  "inventors": [
    "Ron Schneider",
    "Eyal Zohar"
  ],
  "filing_date": "2012-09-24",
  "publication_date": "2017-12-05",
  "grant_date": "2017-12-05",
  "priority_date": "2011-09-26",
  "application_number": "US-201213625178-A",
  "family_id": "44993305",
  "cited_by_count": 7,
  "citations": [
    "US6069352A",
    "US20050270528A1",
    "US6464633B1",
    "US7224384B1",
    "US20060060758A1",
    "US7319219B2",
    "US20090207412A1",
    "US20070058038A1",
    "US20060114543A1",
    "WO2007065153A2",
    "US20070216769A1",
    "WO2010124038A2",
    "JP2011015103A",
    "US20120228482A1"
  ]
}