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 for projected structured light, using at least one projected pattern, the 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 the plurality of rows including variable numbers of operational emitters per row; 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 the 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 and the mutual incoherence of the at least two independent emitters in the first row and the mutual incoherence of the at least two independent emitters in the second row reduce speckle noise in the first part of the projected pattern and the second part of the projected pattern, respectively, and the variable numbers of operational emitters per row provide different levels of intensity per projected line of the projected pattern.
2. The apparatus according to claim 1 , wherein the at least two independent emitters in the first row comprise a row or column of an overall pattern.
3. The apparatus according to claim 2 , wherein the at least two independent emitters in the first row emit light that overlaps to form a sub-pattern and the overall pattern comprises a plurality of sub-patterns.
4. The apparatus according to claim 1 , wherein the plurality of rows are provided with an equal number of emitters, of which predetermined emitters in predetermined rows are switched off to provide a lower level of light intensity.
5. The apparatus according to claim 1 , wherein the plurality of rows are provided with different numbers of emitters respectively.
6. The apparatus according to claim 5 , wherein the different number of emitters is provided by setting respective rows to different lengths and retaining a fixed distance between emitters.
7. The apparatus according to claim 5 , wherein the different number of emitters is provided by providing a different distance between emitters in respective rows of the plurality of rows.
8. The apparatus according to claim 1 , further comprising a diffraction element configured to duplicate a block of the projected pattern to fill a field of view.
9. The apparatus according to claim 1 , wherein a spacing between the rows and a focal length of a collimating lens is predetermined to define an angular spread between lines of the projected pattern.
10. The apparatus according to claim 9 , wherein the angular spread between the lines of the projected pattern is constant for all neighboring lines of the projected pattern.
11. The apparatus according to claim 1 , wherein the array of emitters comprises one member of the group consisting of a laser bar and a vertical cavity surface emitting laser array.
12. A method for structured light projection, the structured light comprising a plurality of projected lines, the 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 the plurality of rows including variable numbers of operational emitters per row; and
causing light from the at least two independent emitters of the first row to overlap to form a first line of the projected lines and light from the at least two independent emitters of the second row to overlap to form a second line of the projected lines
wherein the first line and the second line do not overlap and the mutual incoherence of the at least two independent emitters in the first row and the mutual incoherence of the at least two independent emitters in the second row reduce speckle noise in the first line and the second line, respectively, and the variable numbers of operational emitters per row provide different levels of intensity per projected line of the plurality of projected lines.
13. The method of claim 12 , further comprising collimating light of a given row in an axis perpendicular to the axis of the row.
14. The method of claim 12 , further comprising duplicating a block, the block comprising a plurality of the projected lines, one or more times to fill a field of view.
15. The method of claim 12 , comprising fixing a spacing between adjacent rows of the plurality of rows and a focal length of a collimating lens to define an angular spread between the projected lines.
16. The method of claim 15 , comprising defining the angular spread between the projected lines to be constant between all neighboring projected lines.
17. An apparatus for projected structured light using a plurality of projected lines, the 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 the plurality of rows including variable numbers of operational emitters per row; 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 the plurality of lines pattern 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 and the mutual incoherence of the at least two independent emitters in the first row and the mutual incoherence of the at least two independent emitters in the second row reduce speckle noise in the first line and the second line, respectively, and the variable numbers of operational emitters per row provide different levels of intensity per projected line of the plurality of projected lines.