Lidar system and method
A Lidar system may comprise a rotor and a stator. The rotor is configured to rotate with respect to the stator. The rotor comprises at least one supporting body and a plurality of light sources disposed on the at least one supporting body, the plurality of light sources configured to emit a plurality of first light beams. The plurality of light beams are non-uniformly distributed along a vertical direction in a vertical field of view of the Lidar system.
1. A Lidar system, comprising:
a rotor;
a stator;
a converging lens; and
an optical splitting apparatus, wherein:
the rotor is configured to rotate with respect to the stator;
the rotor comprises at least one supporting body and a plurality of light sources disposed on the at least one supporting body, the plurality of light sources configured to emit a plurality of first light beams;
the plurality of first light beams are non-uniformly distributed along a vertical direction in a vertical field of view of the Lidar system;
the converging lens is configured to converge the first light beams to the optical splitting apparatus;
the first light beams are parallel to each other;
a distance from the optical splitting apparatus to a focal plane of the converging lens is less than half of a focal depth of the converging lens; and
the optical splitting apparatus is configured to split each of the first light beams into a plurality of second light beams with different propagation directions, wherein the second light beams are non-uniformly distributed along the vertical direction in the vertical field of view of the Lidar system.
2. The Lidar system according to claim 1 , wherein the at least one supporting body comprise a plurality of the supporting bodies disposed non-uniformly along the vertical direction in the vertical field of view of the Lidar system, causing the plurality of first light beams to non-uniformly distribute along the vertical direction in the vertical field of view of the Lidar system.
3. The Lidar system according to claim 2 , wherein:
the plurality of light sources comprise one or more lasers disposed on each of the supporting bodies; and
a concentration of the lasers first increases and then decreases along a vertical direction from a highest laser to a lowest laser of the lasers.
4. The Lidar system according to claim 1 , wherein:
the non-uniform distribution of the plurality of first light beams along the vertical direction comprises a sparser concentration of the first light beams at each of two ends of the vertical field of view of the Lidar system and a denser concentration of the first light beams towards center of the vertical field of view of the Lidar system.
5. The Lidar system according to claim 1 , wherein the optical splitting apparatus comprises at least one of a grating, an optical fiber beam splitter, a plane diffraction grating, a blazed grating, or a lens combination.
6. The Lidar system according to claim 5 , wherein the grating comprises a Dammann grating.
7. The Lidar system according to claim 1 , wherein:
the optical splitting apparatus comprises an m by 1 one-dimensional grating configured to rotate about an axis normal to the grating for less than:
arccos
(
d
sin
α
m
λ
)
the grating has a grating period d;
the first light beams have a wavelength λ;
a number of the second light beams is m; and
a preset field of view of the second light beams is a.
8. The Lidar system according to claim 7 , wherein:
the grating period d is between 47 μm and 57 μm; and
the wavelength λ is between 895 nm and 915 nm.
9. The Lidar system according to claim 1 , wherein:
the optical splitting apparatus comprises a m by n two-dimensional grating configured to rotate about an axis normal to a plane of the grating for an angle between:
0.9
arctan
(
arcsin
(
λ
d
1
)
m
×
arcsin
[
λ
d
2
]
)
and
1.1
arctan
(
arcsin
(
λ
d
1
)
m
×
arcsin
[
λ
d
2
]
)
the two-dimensional grating has a period d 1 along one dimension and another period d 2 along the other dimension;
the first light beams have a wavelength λ;
m is a number of the second light beams in the d 1 direction; and
n is a number of the second light beams in the d 2 direction.
10. The Lidar system according to claim 9 , wherein:
the period d 1 is between 47 μm and 57 μm;
the period d 2 is between 47 μm and 57 μm; and
the wavelength λ is between 895 nm and 915 nm.
11. The Lidar system according to claim 1 , wherein the first light beams propagate in different directions.
12. The Lidar system according to claim 11 , wherein each two of the first light beams intersect.
13. A Lidar system, comprising:
a rotor;
a stator;
an optical splitting apparatus; and
a scanning device, wherein:
the rotor is configured to rotate with respect to the stator;
the rotor comprises at least one supporting body and a plurality of light sources disposed on the at least one supporting body, the plurality of light sources configured to emit a plurality of first light beams;
the plurality of first light beams are non-uniformly distributed along a vertical direction in a vertical field of view of the Lidar system;
the optical splitting apparatus is configured to split each of the first light beams into a plurality of second light beams with different propagation directions, wherein the second light beams are non-uniformly distributed along the vertical direction in the vertical field of view of the Lidar system;
the scanning device is configured to rotate about a vibration rotating shaft;
the scanning device comprises a first reflecting surface configured to reflect the second light beams out of the Lidar system during the rotation of the scanning device; and
an angle between the vibration rotating shaft and a normal line of the first reflecting surface is larger than zero.
14. The Lidar system according to claim 13 , wherein:
the optical splitting apparatus comprises a one-dimensional grating;
the second light beams reaching the first reflecting surface are in a propagation plane;
the first reflecting surface and the propagation plane have an intersecting line; and
an angle between the vibration rotating shaft and the intersecting line is larger than 0 degrees.
15. The Lidar system according to claim 13 , further comprising a scanning rotating shaft intersected with a propagation direction of the first light beams, wherein an angle between the vibration rotating shaft and the scanning rotating shaft is larger than 0 degrees.
16. The Lidar system according to claim 13 , further comprising:
a collimating lens configured to collimate the second light beams to progagate in parallel directions; and
a focusing lens configured to converge the collimated second light beams to the first reflecting surface of the scanning device.
17. The Lidar system according to claim 13 , further comprising a semi-transparent mirror and a receiving device, wherein:
at least a portion of the second light beams passes through the optical splitting apparatus and the semi-transparent mirror to reach a first reflecting surface of the scanning device;
at least a portion of the second light beams reflected by the first reflecting surface is reflected back to the first reflecting surface as echo beams; and
the semi-transparent mirror comprises a second reflecting surface configured to reflect the echo light beams reflected by the first reflecting surface into the receiving device.
18. The Lidar system according to claim 17 , further comprising a receiving converging lens, wherein:
the receiving converging lens is configured to converge the echo light beams reflected by the semi-transparent mirror into the receiving device; and
a distance between the receiving device and a focal point of the receiving converging lens is smaller than half of a focal depth of the receiving converging lens.
19. The Lidar system according to claim 13 , wherein the at least one supporting body comprise a plurality of the supporting bodies disposed non-uniformly along the vertical direction in the vertical field of view of the Lidar system, causing the plurality of first light beams to non-uniformly distribute along the vertical direction in the vertical field of view of the Lidar system.
20. The Lidar system according to claim 19 , wherein:
the plurality of light sources comprise one or more lasers disposed on each of the supporting bodies; and
a concentration of the lasers first increases and then decreases along a vertical direction from a highest laser to a lowest laser of the lasers.