Apparatuses for scanning a lidar system in two dimensions
A scanning lidar system includes a fixed frame, a first platform, and a first electro-optic assembly. The first electro-optic assembly includes a first laser source and a first photodetector mounted on the first platform. The scanning lidar system further includes a first flexure assembly flexibly coupling the first platform to the fixed frame, and a drive mechanism configured to scan the first platform with respect to the fixed frame in two dimensions in a plane substantially perpendicular to an optical axis of the lidar system. The scanning lidar system further includes a controller coupled to the drive mechanism. The controller is configured to cause the drive mechanism to scan the first platform in a first direction with a first frequency and in a second direction with a second frequency. The second frequency is similar but not identical to the first frequency.
1. A scanning lidar system comprising:
a fixed frame;
a first platform;
a first electro-optic assembly including a first laser source and a first photodetector mounted on the first platform;
a first flexure assembly flexibly coupling the first platform to the fixed frame;
a drive mechanism configured to, via the first flexure assembly, translate the first platform with respect to the fixed frame in two dimensions in a plane substantially perpendicular to an optical axis of the scanning lidar system; and
a controller coupled to the drive mechanism, the controller configured to cause the drive mechanism to translate the first platform in a first direction with a first frequency and in a second direction with a second frequency, the second frequency being different from the first frequency.
2. The scanning lidar system of claim 1 wherein the second frequency differs from the first frequency such that a trajectory of the first electro-optic assembly follows a Lissajous figure.
3. The scanning lidar system of claim 1 wherein a ratio of the first frequency and the second frequency ranges from about 0.5 to about 2.0.
4. The scanning lidar system of claim 1 wherein the first flexure assembly comprises four springs, each of the four springs connecting a respective corner of the first platform to the fixed frame.
5. The scanning lidar system of claim 4 wherein each of the four springs comprises a flexible rod having a first resonance frequency in the first direction and a second resonance frequency in the second direction, and wherein the first frequency is substantially equal to the first resonance frequency, and the second frequency is substantially equal to the second resonance frequency.
6. The scanning lidar system of claim 1 wherein the first flexure assembly comprises a first spring and a second spring, the first spring connecting a first lateral side of the first platform to the fixed frame, and the second spring connecting a second lateral side opposite to the first lateral side to the fixed frame.
7. The scanning lidar system of claim 1 wherein the drive mechanism is mechanically coupled to the first platform for translating the first platform.
8. The scanning lidar system of claim 7 wherein the drive mechanism comprises a voice coil motor that is mounted on the first platform.
9. The scanning lidar system of claim 1 further comprising:
a second platform; and
a second flexure assembly flexibly coupling the second platform to the fixed frame;
wherein the drive mechanism is mechanically coupled to the second platform such that, as the first platform is translated, the second platform moves in a direction opposite to a direction of motion of the first platform.
10. The scanning lidar system of claim 9 further comprising:
a second electro-optic assembly including a second laser source and a second photodetector mounted on the second platform.
11. The scanning lidar system of claim 9 wherein:
the drive mechanism comprises a voice coil motor that is mounted on the second platform.
12. A resonator structure for operating a two-dimensional scanning lidar system, the resonator structure comprising:
a fixed frame;
a first platform for carrying a first electro-optic assembly of the scanning lidar system, the first electro-optic assembly including a first laser source and a first photodetector; and
a first set of springs flexibly coupling the first platform to the fixed frame, the first set of springs configured to be flexed in two orthogonal directions so as to translate the first platform in the two orthogonal directions in a plane substantially perpendicular to an optical axis of the scanning lidar system, wherein the first set of springs has a first resonance frequency in a first direction of the two orthogonal directions and a second resonance frequency in a second direction of the two orthogonal directions, the second resonance frequency being different from the first resonance frequency.
13. The resonator structure of claim 12 wherein the first set of springs comprises four rod springs, each of the four rod springs connecting a respective corner of the first platform to the fixed frame.
14. The resonator structure of claim 13 wherein each of the four rod springs comprises a rod having an oval cross-section, or a rectangular cross-section, or a rectangular cross-section with rounded corners.
15. The resonator structure of claim 13 wherein each of the four rod springs is connected to the first platform via a flexible member.
16. The resonator structure of claim 12 wherein each of the first set of springs comprises a leaf spring.
17. The resonator structure of claim 12 further comprising:
a second platform; and
a second set of springs flexibly coupling the second platform to the fixed frame, the second set of springs configured to be flexed in the two orthogonal directions so as to translate the second platform in the two orthogonal directions, wherein a direction of motion of the second platform opposes a direction of motion of the first platform.
18. The resonator structure of claim 17 wherein the second platform carries a counter weight such that a momentum of the second platform substantially cancels a momentum of the first platform.