Road surface state detection apparatus and road surface state notification apparatus

A road surface state detection apparatus comprising:

• a light emitter;
• an optical sensor provided on a side of a vehicle;
• and
• an electronic control unit configured to determine a state of a road surface, wherein while the vehicle is stopped,
• the light emitter is configured to project an image with visible light on the road surface below the side of the vehicle,
• the optical sensor configured to receive reflected light from the projected image, and
• the electronic control unit is configured to determine the state of the road surface based on the reflected light, from the projected image, received by the optical sensor, and
• while the vehicle is running,
• the light emitter is configured to project invisible light in lieu of the visible light, and
• the optical sensor is configured to receive reflected light of the invisible light projected on the road surface, and
• the electronic control unit is configured to determine the state of the road surface based on an amount of the reflected light, of the invisible light, received by the optical sensor.