Structured light sensing for 3D sensing
Apparatus for structured light scanning. The structured light includes one or more projected lines or other patterns. At least two independent emitters emit light for each projected line or pattern. Typically the at least two independent emitters are arranged in a row. The apparatus also includes a pattern generator for causing light from respective emitters of a given row to overlap along a pattern axis to form a projected pattern.
1. An apparatus comprising:
an array of emitters arranged in a plurality of rows, the plurality of rows including a first row that includes at least two independent emitters that are mutually incoherent and a second row that includes at least two independent emitters that are mutually incoherent; and
a pattern generator for causing light from the at least two independent emitters of the first row to overlap to form a first part of a projected pattern and light from the at least two independent emitters of the second row to overlap to form a second part of the projected pattern,
wherein the first part of the projected pattern and the second part of the projected pattern do not overlap, wherein the mutual incoherence of the at least two independent emitters in the first row reduce speckle noise in the first part of the projected pattern, and wherein the mutual incoherence of the at least two independent emitters in the second row reduce speckle noise in the second part of the projected pattern.
2. The apparatus of claim 1 , wherein the projected pattern comprises a plurality of projected lines, wherein the first part of the projected pattern is a first line of the projected lines, and wherein the second part of the projected pattern is a second line of the projected lines.
3. The apparatus of claim 2 , wherein a spacing between the plurality of rows and a focal length of a collimating lens are predetermined to define an angular spread between the projected lines of the projected pattern.
4. The apparatus of claim 3 , wherein the angular spread between the projected lines of the projected pattern is constant for neighboring projected lines of the projected pattern.
5. The apparatus of claim 1 , wherein the first row and the second row include different numbers of operational emitters so that the first part of the projected pattern has a different level of intensity than the second part of the projected pattern.
6. The apparatus of claim 1 , wherein the first row and the second row include an equal number of emitters, and wherein predetermined emitters in the second row are switched off so that the first part of the projected pattern has a higher level of intensity than the second part of the projected pattern.
7. The apparatus of claim 1 , wherein the first row and the second row include different numbers of emitters.
8. The apparatus of claim 7 , wherein emitters in the first row have an equal separation distance as emitters in the second row, and wherein the first row and the second row have different lengths.
9. The apparatus of claim 7 , wherein emitters in the first row have a different separation distance than emitters in the second row.
10. The apparatus of claim 1 , further comprising a diffraction element configured to duplicate a block of the projected pattern to fill a field of view.
11. The apparatus of claim 1 , wherein the array of emitters comprises one member of the group comprising: a laser bar and a vertical cavity surface emitting laser (VCSEL) array.
12. A method comprising:
emitting light from independent coherent light emitters arranged in a plurality of rows, the plurality of rows including a first row that includes at least two independent emitters that are mutually incoherent and a second row that includes at least two independent emitters that are mutually incoherent; and
causing light from the at least two independent emitters of the first row to overlap to form a first line of a plurality of projected lines and causing light from the at least two independent emitters of the second row to overlap to form a second line of the plurality of projected lines,
wherein the first line and the second line do not overlap, wherein the mutual incoherence of the at least two independent emitters in the first row reduce speckle noise in the first line, and wherein the mutual incoherence of the at least two independent emitters in the second row reduce speckle noise in the second line.
13. The method of claim 12 , further comprising collimating light of a given row in an axis perpendicular to an axis of the row.
14. The method of claim 12 , wherein a spacing between the plurality of rows and a focal length of a collimating lens are predetermined to define an angular spread between the projected lines of the projected pattern.
15. The method of claim 14 , wherein the angular spread between the projected lines of the projected pattern is constant for neighboring projected lines of the projected pattern.
16. The method of claim 12 , wherein the first row and the second row include different numbers of operational emitters so that the first part of the projected pattern has a different level of intensity than the second part of the projected pattern.
17. The method of claim 12 , wherein the first row and the second row include an equal number of emitters, and wherein predetermined emitters in the second row are switched off so that the first part of the projected pattern has a higher level of intensity than the second part of the projected pattern.
18. The method of claim 12 , wherein the first row and the second row include different numbers of emitters.
19. The method of claim 18 , wherein emitters in the first row have a different separation distance than emitters in the second row.
20. An apparatus comprising:
an array of emitters arranged in a plurality of rows, the plurality of rows including a first row that includes at least two independent emitters that are mutually incoherent and a second row that includes at least two independent emitters that are mutually incoherent; and
a pattern generator for causing light from the at least two independent emitters of the first row to overlap to form a first line of a plurality of projected lines and light from the at least two independent emitters of the second row to overlap to form a second line of the plurality of lines,
wherein the first line and the second line do not overlap, wherein the mutual incoherence of the at least two independent emitters in the first row reduce speckle noise in the first line, and wherein the mutual incoherence of the at least two independent emitters in the second row reduce speckle noise in the second line.