Sensor airflow apparatus

1. An apparatus comprising:

a housing defining a chamber and including a panel including an aperture;

a sensor fixed inside the chamber and having a field of view through a lens and the aperture;

an annular disc attached to the sensor concentrically around the lens and including a radially outer edge contactlessly exposed to the chamber; and

at least three vanes extending from the disc to the panel and arranged radially asymmetrically around the disc, the vanes positioned to direct airflow from the chamber across the lens.

2. The apparatus of claim 1 , wherein the vanes define a plurality of first openings positioned to direct airflow from the chamber in substantially a same first direction across the lens, and a second opening positioned to direct airflow from the chamber across the lens in a second direction transverse to the first direction.

3. The apparatus of claim 2 , wherein the vanes are positioned to block airflow from the chamber through the aperture except through the first openings and the second opening.

4. The apparatus of claim 2 , wherein the second direction is at an acute angle with the first direction.

5. The apparatus of claim 2 , wherein the plurality of first openings includes at least three first openings.

6. The apparatus of claim 2 , wherein the aperture includes a circular portion substantially centered on the lens and an extension portion.

7. The apparatus of claim 6 , wherein the extension portion extends in the first direction from the circular portion.

8. The apparatus of claim 1 , wherein the vanes include first vanes arranged radially symmetrically for at least 270° around the disc.

9. The apparatus of claim 8 , wherein the first vanes are each elongated in a radial and circumferential direction.

10. The apparatus of claim 8 , wherein the vanes include second vanes arranged around a remainder of the disc radially asymmetrically with the first vanes.

11. The apparatus of claim 10 , wherein the second vanes are elongated in a radial direction.

12. The apparatus of claim 1 , wherein the disc includes a radially inner surface at which the disc is attached to the sensor.

13. The apparatus of claim 12 , wherein the disc includes a front surface sloping away from the panel from the radially inner surface to the radially outer edge.

14. The apparatus of claim 12 , wherein the disc includes a back surface facing away from the panel and extending from the radially inner surface to the radially outer edge, wherein the back surface is contactlessly exposed to the chamber.

15. The apparatus of claim 1 , further comprising a pressure source positioned to raise a pressure of the chamber above an atmospheric pressure.

16. The apparatus of claim 15 , wherein the pressure source is a blower.

17. The apparatus of claim 1 , wherein the lens is convex.

18. The apparatus of claim 1 , wherein the panel has a cylindrical shape.

19. The apparatus of claim 1 , wherein the sensor is a first sensor, the aperture is a first aperture, the lens is a first lens, the apparatus further comprising a second sensor fixed inside the chamber, wherein the panel includes a second aperture, and the second sensor includes a second lens defining a field of view oriented through the second aperture.

20. The apparatus of claim 19 , wherein the disc is a first disc, the radially outer edge is a first radially outer edge, and the vanes are first vanes, the apparatus further comprising an annular second disc attached to the second sensor concentrically around the second lens and including a second radially outer edge contactlessly exposed to the chamber, and at least three second vanes extending from the second disc to the panel and arranged radially asymmetrically around the second disc.