Eye safe lidar system with variable resolution multi-beam scanning
A LIDAR system may have a laser emission unit configured to generate a plurality of laser beams. The LIDAR system may also have an optical system configured to transmit the plurality of laser beams from the laser emission unit to a common scanning unit. The common scanning unit may be configured to project the plurality of laser beams towards a first set of spaced apart locations of a field of view of the LIDAR system. The first set of spaced apart locations may be associated with a first plurality of parallel scan lines traversing the field of view. The common scanning unit may also be configured to simultaneously scan the field of view along the first plurality of scan lines by sequentially illuminating non-contiguous segments in a first set of non-contiguous segments of the field of view positioned along the first plurality of scan lines.
1 . A LIDAR system, comprising:
a laser emission unit configured to generate a first plurality of laser beams;
a common scanning unit; and
an optical system configured to transmit the first plurality of laser beams received from the laser emission unit towards the common scanning unit,
wherein the common scanning unit is configured to simultaneously scan the first plurality of laser beams over a field of view of the LIDAR system along a second plurality of parallel scan lines traversing the field of view in a first direction, including at least first and second groups of the scan lines, such that the scan lines in the first group of the parallel scan lines are separated from one another along a second direction, perpendicular to the first direction, by the scan lines in at least the second group of the parallel scan lines,
wherein each of the scan lines is divided into multiple sets of non-contiguous segments, including at least first and second sets, such that the segments of each scan line in the first set of the non-contiguous segments are separated from one another along the first direction by the segments in at least the second set of the non-contiguous segments, and
wherein the common scanning unit is further configured to simultaneously scan the field of view along the first group of the scan lines followed by simultaneously scanning the field of view along the second group of the scan lines and within each of the scan lines sequentially illuminating the noncontiguous segments in the first set of the non-contiguous segments along the scan lines followed by illuminating the non-contiguous segments in the second set of the non-contiguous segments along the scan lines so that the illuminated non-contiguous segments are separated from one another along both the first and second directions.
2 . The LIDAR system of claim 1 , wherein each non-contiguous segment in the second set of non-contiguous segments is contiguous with a non-contiguous segment in the first set of non-contiguous segments.
3 . The LIDAR system of claim 2 , wherein the common scanning unit is further configured to
initiate sequential illumination of the non-contiguous segments in the first set of non-contiguous segments at a first time, and
initiate sequential illumination of the non-contiguous segments in the second set of non-contiguous segments at a second time, wherein the second time is after the first time, and
wherein a difference between the first time and the second time corresponds to an elapsed time period for sequentially illuminating all the non-contiguous segments in the first set of non-contiguous segments.
4 . The LIDAR system of claim 1 , wherein the common scanning unit is further configured to sequentially illuminate the non-contiguous segments in both the first set of non-contiguous segments and the second set of non-contiguous segments in a same direction from a minimum to a maximum extent of the field of view.
5 . The LIDAR system of claim 1 , wherein the common scanning unit is further configured to
sequentially illuminate the non-contiguous segments in the first set of non-contiguous segments in a forward direction from a minimum to a maximum extent of the field of view, and
sequentially illuminate the non-contiguous segments in the second set of non-contiguous segments in a backward direction opposite to the forward direction.
6 . The LIDAR system of claim 1 , wherein a displacement between the first group of the parallel scan lines and the second group of the parallel scan lines is a fraction of a size of a field-of-view pixel.
7 . The LIDAR system of claim 1 , wherein the common scanning unit is further configured to simultaneously scan the field of view along the second group of the parallel scan lines by illuminating the non-contiguous segments of the field of view positioned along the second group of the parallel scan lines.
8 . The LIDAR system of claim 1 , wherein the common scanning unit is further configured to simultaneously scan the field of view along the second group of the parallel scan lines by sequentially illuminating a third set of non-contiguous segments of the field of view positioned along the second group of the parallel scan lines in a scanning direction from a minimum to a maximum extent of the field of view.
9 . The LIDAR system of claim 8 , wherein the third set of non-contiguous segments of the field of view are offset in the scanning direction relative to the first set of non-contiguous segments of the field of view.
10 . The LIDAR system of claim 1 , wherein at least one scan line of the second group of the parallel scan lines is spatially located between two scan lines included in the first group of the parallel scan lines.
11 . The LIDAR system of claim 1 wherein none of the second group of the parallel scan lines is spatially located between scan lines of the first group of the parallel scan lines.
12 . The LIDAR system of claim 1 wherein the second group of the parallel scan lines overlap with the first group of the parallel scan lines.
13 . The LIDAR system of claim 12 , wherein an amount of overlap between the first group of the parallel scan lines and the second group of the parallel scan lines is higher in a region of interest of the field of view as compared to other regions of the field of view.
14 . The LIDAR system of claim 1 , wherein the common scanning unit is configured perform a first number of scans of the first group of the parallel scan lines in a region of interest and a second number of scans of the first group of the parallel scan lines in other regions such that the first number is greater than the second number.
15 . The LIDAR system of claim 1 , wherein a third plurality of the non-contiguous segments are positioned along the first group of the parallel scan lines, and the common scanning unit is configured to scan the field of view along the first group of the parallel scan lines by illuminating all the segments of the third plurality that are located in a region of interest and by illuminating some of the segments of the third plurality that are located in other regions outside the region of interest.
16 . The LIDAR system of claim 1 , wherein the non-contiguous segments in the first set of non-contiguous segments are separated by regions having a size that is a multiple of a size of a field-of-view pixel.
17 . The LIDAR system of claim 1 , wherein the common scanning unit includes a single biaxial scanning mirror upon which the first plurality of laser beams are made incident.
18 . The LIDAR system of claim 17 , wherein the biaxial scanning mirror is rotatable in two axes, the two axes including a tilt axis and a scanning axis.
19 . The LIDAR system of claim 17 , wherein
rotation of the biaxial scanning mirror about the scanning axis causes movement of the first plurality of laser beams along the first group of the parallel scan lines traversing the field of view of the LIDAR system, and
rotation of the biaxial scanning mirror about the tilt axis causes displacement of the first plurality of laser beams from a first set of locations associated with the first group of the parallel scan lines to a second set of locations associated with the second group of the parallel scan lines.
20 . The LIDAR system of claim 1 , wherein the common scanning unit includes one of a biaxial scanner, a combination of a single axis mirror and a polygon, or a single axis scanner mounted on a rotating element.
21 . The LIDAR system of claim 1 , wherein the common scanning unit includes a first single axis scanning mirror and a second single axis scanning mirror, and wherein the first plurality of laser beams are made incident upon the first single axis scanning mirror before proceeding to the second single axis scanning mirror.
22 . The LIDAR system of claim 21 , wherein
the first single axis scanning mirror is configured to rotate about a scanning axis to cause movement of the first plurality of laser beams along the first plurality of scan lines traversing the field of view of the LIDAR system, and
the first single axis scanning mirror is configured to rotate about a tilt axis to cause displacement of the first plurality of laser beams from a first set of locations associated with the first group of the parallel scan lines to second set of locations associated with the second group of the parallel scan lines.
23 . The LIDAR system of claim 1 , wherein sequentially illuminating non-contiguous segments in the first set of non-contiguous segments includes:
illuminating a first non-contiguous segment of the first set of non-contiguous segments using a first pulse at a first time;
illuminating a second non-contiguous segment of the first set of non-contiguous segments using a second pulse at a second time after the first time; and
illuminating a third non-contiguous segment of the field of view positioned between the first non-contiguous segment and the second non-contiguous segment, using a third pulse at a time between the first time and the second time.
24 . The LIDAR system of claim 23 , wherein the third pulse has an energy level between 10 to 200 times less than an energy level of the first pulse or the second pulse.
25 . The LIDAR system of claim 23 , wherein a width of the third pulse is lower than a width of the first pulse or the second pulse.
26 . The LIDAR system of claim 23 , wherein a height of the third pulse is lower than a height of the first pulse or the second pulse.
27 . The LIDAR system of claim 23 , wherein the third pulse is emitted after the first time after a delay of at least a time of flight associated with the first pulse or the second pulse.
28 . A method of operating a LIDAR system, comprising:
generating, using a laser emission unit, a first plurality of laser beams;
transmitting, using an optical system, the first plurality of laser beams received from the laser emission unit towards a common scanning unit;
projecting, using the common scanning unit, the first plurality of laser beams over a field of view of the LIDAR system along a second plurality of parallel scan lines traversing the field of view in a first direction, including at least first and second groups of the scan lines, such that the scan lines in the first group of the parallel scan lines are separated from one another along a second direction, perpendicular to the first direction by the scan lines in at least the second group of the parallel scan lines,
wherein each of the scan lines is divided into multiple sets of non-contiguous segments, including at least first and second sets, such that the segments of each scan line in the first set of the non-contiguous segments are separated from one another along the first direction by the segments in at least the second set of the non-contiguous segments; and
simultaneously scanning, using the common scanning unit, the field of view along the first group of the scan lines followed by simultaneously scanning the field of view along the second group of the scan lines and within each of the scan lines sequentially illuminating the noncontiguous segments in the first set of the non-contiguous segments along the scan lines followed by illuminating the non-contiguous segments in the second set of the non-contiguous segments along the scan lines so that the illuminated non-contiguous segments are separated from one another along both the first and second directions.