Systems and methods for occlusion detection

1. A system comprising:

a primary reflective surface;

a rotatable mirror configured to rotate about a rotational axis, wherein the rotatable mirror comprises a plurality of secondary reflective surfaces;

an optical element; and

a camera, wherein the camera is configured to focus on the optical element to capture at least one image of the optical element by way of the primary reflective surface and at least one secondary reflective surface of the rotatable mirror.

2. The system of claim 1 , further comprising a controller having at least one processor and a memory, wherein the at least one processor executes program instructions stored in the memory so as to carry out operations, the operations comprising:

causing the rotatable mirror to rotate about the rotational axis; and

causing the camera to capture a plurality of images of the optical element by way of the primary reflective surface and at least one secondary reflective surface of the rotatable mirror, wherein each image of the plurality of images is captured at a corresponding mirror angle of the at least one secondary reflective surface.

3. The system of claim 2 , further comprising an illuminator, wherein the operations further comprise:

while causing the camera to capture the plurality of images, causing the illuminator to emit light in a stroboscopic manner so as to illuminate the optical element by way of the primary reflective surface and the rotatable mirror.

4. The system of claim 3 , determining an aggregate image of the optical element based on the plurality of images and the corresponding mirror angles of the at least one secondary reflective surface.

5. The system of claim 3 , wherein the operations further comprise:

determining, based on an aggregate image, that at least one occlusion object is present on the optical element.

6. The system of claim 1 further comprising an illuminator configured to emit light to illuminate the optical element by way of the primary reflective surface and the rotatable mirror.

7. The system of claim 6 , wherein the illuminator comprises an infrared light-emitting diode (LED).

8. The system of claim 1 , wherein the primary reflective surface comprises a rectangular mirror.

9. The system of claim 8 , wherein the primary reflective surface comprises an aspect ratio of at least 8:1.

10. The system of claim 8 , wherein a long axis of the primary reflective surface is disposed substantially parallel to the rotational axis.

11. The system of claim 1 , wherein camera comprises a fixed focal length lens configured to focus on the optical element by way of the primary reflective surface and the at least one secondary reflective surface.

12. The system of claim 1 , wherein the camera comprises a fixed focal length lens configured to focus the camera on the optical element.

13. The system of claim 1 , wherein a shape of the rotatable mirror comprises at least one of: a rectangular prism or a triangular prism.

14. A light detection and ranging (lidar) system comprising:

a transmitter;

a receiver;

an optical element;

a rotatable mirror configured to rotate about a rotational axis, wherein the rotatable mirror comprises a plurality of secondary reflective surfaces;

a camera, wherein the camera is configured to focus on the optical element to capture at least one image of the optical element by way of at least one secondary reflective surface of the rotatable mirror; and

a controller having at least one processor and a memory, wherein the at least one processor executes program instructions stored in the memory so as to carry out operations, the operations comprising:

causing the rotatable mirror to rotate about the rotational axis; and

causing the camera to capture a plurality of images of the optical element by way of at least one secondary reflective surface of the rotatable mirror, wherein each image of the plurality of images is captured at a corresponding mirror angle of the at least one secondary reflective surface.

15. The lidar system of claim 14 , determining an aggregate image of the optical element based on the plurality of images and the corresponding mirror angles of the at least one secondary reflective surface.

16. The lidar system of claim 14 , wherein the operations further comprise:

determining, based on an aggregate image, that at least one occlusion object is present on the optical element.

17. A method comprising:

causing a rotatable mirror to rotate about a rotational axis, wherein the rotatable mirror comprises a plurality of secondary reflective surfaces; and

causing a camera, which is focused on an optical element, to capture a plurality of images of the optical element by way of at least one secondary reflective surface of the rotatable mirror, wherein each image of the plurality of images is captured at a corresponding mirror angle of the at least one secondary reflective surface.

18. The method of claim 17 further comprising:

determining an aggregate image of the optical element based on the plurality of images and the corresponding mirror angles of the at least one secondary reflective surface.

19. The method of claim 17 , further comprising:

determining, based on an aggregate image, that at least one occlusion object is present on the optical element.

20. The method of claim 17 , further comprising:

while causing the camera to capture the plurality of images, causing an illuminator to emit light in a stroboscopic manner so as to illuminate the optical element by way of a primary reflective surface and the rotatable mirror.