Laser Scanner

{
  "publication_number": "US2018106615A1",
  "country": "US",
  "kind": "A1",
  "title": "Laser Scanner",
  "abstract": "A laser scanner includes a distance measuring unit which has a light emitting element for emitting a distance measuring light, a distance measuring light projecting unit, a light receiving unit and a photodetector for producing a light receiving signal, and which performs a distance measurement based on the light receiving signal, an optical axis deflecting unit provided on a distance measuring optical axis and for deflecting the distance measuring optical axis, a projecting direction detecting unit for detecting a deflection angle of the distance measuring optical axis and a control component for controlling the optical axis deflecting unit and the distance measuring unit, wherein the optical axis deflecting unit comprises a pair of optical prisms capable of rotating and motors for rotating the optical prisms, and wherein the control component is configured to control the optical axis deflecting unit, scan the distance measuring light and acquire scanning data under scanning conditions corresponding to a measurement range.",
  "claims": [
    "1. A laser scanner comprising: a distance measuring unit which has a light emitting element for emitting a distance measuring light, a distance measuring light projecting unit for projecting said distance measuring light, a light receiving unit for receiving a reflected distance measuring light and a photodetector for receiving said reflected distance measuring light and producing alight receiving signal, and which performs a distance measurement of an object to be measured based on said light receiving signal from said photodetector, an optical axis deflecting unit provided on a distance measuring optical axis and for deflecting said distance measuring optical axis, a projecting direction detecting unit for detecting a deflection angle of said distance measuring optical axis and a control component for controlling a deflecting operation of said optical axis deflecting unit and a distance measuring operation of said distance measuring unit, wherein said optical axis deflecting unit comprises a pair of optical prisms capable of rotating with said distance measuring optical axis as a center and motors which individually and independently rotate said optical prisms, and wherein said control component is configured to control a deflection by said optical axis deflecting unit by controlling rotating directions, rotating speeds, and a rotation ratio of said pair of optical prisms, scan said distance measuring light within a measurement range as set, and acquire scanning data under scanning conditions corresponding to said measurement range. 2. The laser scanner according to claim 1, wherein said control component performs an entire scanning of a measurement range by rotating said two optical prisms over a total circumference in a predetermined relationship. 3. The laser scanner according to claim r 2, wherein a local measurement range is set within the measurement range, said control component individually rotates said two optical prisms in predetermined deflection angle ranges, integrally rotates said two optical prisms at a predetermined angle, and performs a local scanning within said local measurement range. 4. The laser scanner according to claim 3, wherein said control component sets a scanning density corresponding to a circumstance of the object to be measured in said local measurement range. 5. The laser scanner according to claim 3, further comprising an image pick up unit with an image pickup optical axis parallel to said distance measuring optical axis which is not deflected by said optical axis deflecting unit and an image processing component, wherein said image processing component performs an edge extraction processing from an image acquired by said image pickup unit, and said control component sets said local measurement range so as to include an extracted edge. 6. The laser scanner according to claim 1, further comprising an image pickup unit with an image pickup optical axis parallel to said distance measuring optical axis which is not deflected by said optical axis deflecting unit, wherein an image acquisition by said image pickup unit is synchronized with a scanning. 7. The laser scanner according to claim 3, wherein the scanning density in said local scanning is higher than the scanning density of said entire scanning. 8. The laser scanner according to claim 1, wherein said scanning data includes distance data and reflected light amount data, and said control component is configured to prepare a distance image with a display corresponding to a distance based on said distance data or a distance image with a gray-scale display based on said reflected light amount data. 9. The laser scanner according to claim 6, wherein said control component is configured to acquire a first image in synchronization with said entire scanning, a second image in synchronization with said local scanning, and combine a result of said entire scanning with a result of said local scanning by an image matching between said first image and said second image. 10. The laser scanning according to claim 5, wherein said control component is configured to perform said local scanning to a plurality of said local measurement range within said measurement range, and correct the image acquired by said image pickup unit based on the result of said local scanning as obtained. 11. The laser scanner according to claim 3, wherein said local scanning is performed at a measuring pitch which is smaller than a beam diameter of said distance measuring light and at which beam spots are overlapped on each other. 12. The laser scanner according to claim 4, wherein the scanning density in said local scanning is higher than the scanning density of said entire scanning. 13. The laser scanner according to claim 5, wherein the scanning density in said local scanning is higher than the scanning density of said entire scanning. 14. The laser scanner according to claim 4, wherein said local scanning is performed at a measuring pitch which is smaller than a beam diameter of said distance measuring light and at which beam spots are overlapped on each other. 15. The laser scanner according to claim 5, wherein said local scanning is performed at a measuring pitch which is smaller than a beam diameter of said distance measuring light and at which beam spots are overlapped on each other. 16. The laser scanner according to claim 7, wherein said local scanning is performed at a measuring pitch which is smaller than a beam diameter of said distance measuring light and at which beam spots are overlapped on each other. 17. The laser scanner according to claim 10, wherein said local scanning is performed at a measuring pitch which is smaller than a beam diameter of said distance measuring light and at which beam spots are overlapped on each other. 18. The laser scanner according to claim 12, wherein said local scanning is performed at a measuring pitch which is smaller than a beam diameter of said distance measuring light and at which beam spots are overlapped on each other. 19. The laser scanner according to claim 13, wherein said local scanning is performed at a measuring pitch which is smaller than a beam diameter of said distance measuring light and at which beam spots are overlapped on each other."
  ],
  "description_excerpt": "The present invention relates to a laser scanner which acquires point cloud data.\n\nIn recent years, in a field of a civil engineering and an architecture, a laser scanner which acquires point cloud data is used as a device which performs a distance measurement and a shape measurement.\n\nIn a conventional laser scanner, when a scanning area is set in advance and scanning conditions (for instance, a scanning speed and a light emission frequency) are once set, the scanning area is entirely scanned under the scanning conditions as set.\n\nOn the other hand, in a case where an object to be measured has a monotonous shape, a scanning density (the number of measuring point data per unit area) (a point cloud density) may be practically low. Alternatively, in a case where the object to be measured has a complicated shape, a higher point cloud density is better. Therefore, the point cloud density is set under the most demanded scanning conditions. Therefore, even a portion with a monotonous shape (e.g., a wall surface of a building) must be scanned in high density, and an enormous amount of scanning data must be acquired, which is not practical and economical.\n\nIt is an object of the present invention to provide a laser scanner which can change a scanning density corresponding to a measuring portion.",
  "cpc": [
    "G01C 15/002",
    "G01C 3/08",
    "G01S 17/42",
    "G01S 17/89",
    "G01S 7/4817",
    "G01S 7/497",
    "G06T 5/50"
  ],
  "ipc": [
    "G01C 15/00",
    "G01C 3/08",
    "G01S 17/42",
    "G01S 17/89",
    "G01S 7/481",
    "G01S 7/497",
    "G06T 5/50"
  ],
  "assignees": [
    "Topcon Corp"
  ],
  "inventors": [
    "Fumio Ohtomo",
    "Kaoru Kumagai"
  ],
  "filing_date": "2017-10-16",
  "publication_date": "2018-04-19",
  "priority_date": "2016-10-17",
  "application_number": "US-201715784563-A",
  "family_id": "61902864",
  "cited_by_count": 23
}