Illuminator obstruction detection to identify an obstruction on an optical window

1. A system, comprising:

an optical window;

an illuminator and a first light sensor deployed on a same side of the optical window;

a second light sensor on another side of the optical window; and

a computer including a processor and memory, the memory including instructions such that the processor is programmed to identify an obstruction on the optical window upon the first light sensor reporting first data from the illuminator that is above an expected threshold, the expected threshold based on second data from the second light sensor.

2. The system of claim 1 , wherein the processor is further programmed to:

receive third data from the first light sensor when the illuminator is not emitting light; and

determine the expected threshold based on the third data.

3. The system of claim 1 , wherein the first light sensor is one selected from a group of an LED and a photodiode.

4. The system of claim 1 , wherein the second light sensor is a camera.

5. The system of claim 1 , wherein the processor is further programmed to:

receive temperature data specifying a temperature of the first light sensor; and

adjust the first data based on the temperature data.

6. The system of claim 1 , wherein the processor is further programmed to:

receive calibration data from the first light sensor when the optical window is determined not be to be obstructed; and

determine the expected threshold based on the calibration data.

7. The system of claim 1 , wherein the first light sensor is a photodiode and the first data specifies at least one of a group including a current through the photodiode and a voltage across the photodiode.

8. The system of claim 1 , wherein the first light sensor is an LED and the first data specifies at least one of a group including a current through the LED and a voltage across the LED.

9. The system of claim 1 , wherein the first light sensor and the illuminator are a same element.

10. The system of claim 9 , wherein the processor is further programmed to:

switch the illuminator into a mode to not emit light;

receive third data from the illuminator;

switch the illuminator into a mode to emit light; and

receive the first data from the illuminator.

11. A system, comprising:

an optical window on a vehicle;

a light sensor deployed on a first side of the optical window;

a computer including a processor and memory, the memory including instructions such that the processor is programmed to:

determine a threshold based on an estimated intensity of light arriving at a second side of the optical window from a light source; and

detect an obstruction on the optical window upon the light sensor reporting first data from the light source that is below the threshold.

12. The system of claim 11 , wherein the processor is further programmed to:

estimate the intensity of light arriving based on a type and location of the light source on the second side of the optical window.

13. The system of claim 12 , wherein the processor is further programmed to:

determine the type of the light source based on image data received from a sensor on the second side of the optical window.

14. The system of claim 12 , wherein the processor is further programmed to:

determine the location of the light source based on image data received from the second side of the optical window.

15. The system of claim 11 , wherein the processor is further programmed to:

determine the threshold based on an intensity of light received from a sensor on the second side of the optical window.

16. The system of claim 11 , wherein the processor is further programmed to:

activate an illuminator deployed on the first side of the optical window; and

detect the obstruction on the optical window upon the light sensor reporting second data that exceeds first data by a second threshold.

17. The system of claim 16 , wherein the processor is further programmed to:

determine the second threshold based on an intensity of light received from a sensor on the second side of the optical window.

18. The system of claim 17 , wherein the sensor on the second side of the optical window is a camera.

19. The system of claim 16 , wherein the processor is further programmed to:

estimate an expected intensity of light received from a sensor on the second side of the optical window based on a type and location of an object proximate to the vehicle; and

detect the obstruction on the optical window upon the sensor on the second side of the optical window reporting data below the threshold.

20. The system of claim 11 , wherein the first light sensor is a photodiode.