How should I clean the lens?

See below.

Cleaning the Lens

Clean the projector's lens periodically, or whenever you notice dust or smudges on the surface.
• To remove dust or smudges, gently wipe the lens with lens-cleaning paper.
• To remove stubborn smudges, moisten a soft, lint-free cloth with lens cleaner and gently wipe the lens. Do not spray any liquid directly on the lens.

  Warning: Do not use a lens cleaner that contains flammable gas. The high heat generated by the projector lamp may cause a fire.

  Caution:
  Do not use glass cleaner or any harsh materials to clean the lens and do not subject the lens to any impacts; you may damage it. Do not use canned air, or the gases may leave a residue. Avoid touching the lens with your bare hands to prevent fingerprints on or damage to the lens surface.