Why is the lens of the Xiaomi Smart Projector L1 dirty?

If the lens of the Xiaomi Smart Projector L1 is dirty, please refer to the following details:
1. Please determine whether the dirt is inside or outside the lens. If the dirt is outside the lens, please wipe the lens with a cloth gently to make sure the outside of the lens is clean (Do not touch the lens with your fingers. Fingerprints will be left on the lens, but it will not affect normal use.);
2. After wiping the lens clean, if the dirtiness still exists after turning off the projector, please take the relevant pictures and submit the feedback;
3. The dirt you see is caused by the reflection of fine particles in the air after being illuminated by strong light. This is a normal phenomenon and will not affect the viewing of the screen. You can use it normally. In addition, please do not look directly at the light source for a long time, as it will damage your eyes.