Is the Logitech G502 Hero wheel scroll affected but sunlight hitting it?

I have a Logitech G502 Hero and I noticed that the scrolling does not perform well when the sun is hitting the mouse.

I read that the sensor is a diode. I am not an expert in the field. However, is it possible that the sun blocks the sensor from functioning correctly? If so can someone explain why?

You are correct, the scroll wheel uses an optical encoder, which works by shining infrared light from an LED source and receiving it back at the sensor. The light is interrupted by some kind of spokes etc on the scroll wheel, and these interruptions in the light allow it to count how far the scroll wheel has rotated. Unfortunately the sun is also a bright source of infrared and can interfere with that.

I can confirm this also happens with the G604 mouse (why I am searching the topic right now) which uses a similar optical encoder as the G502 in the scroll wheel.

These Logitech mice also have a similar infrared LED sensor on the bottom. Try turning the mouse upside down in the sunlight and you will see the pointer go crazy!