The optics glass is located behind the disposable tip.
Regularly inspect the optics glass for contamination, residue, fingerprints, or streaking, and clean whenever necessary.
Clean the optics glass using a damp, lint-free cloth and wipe it dry with a second lint -free cloth. Make sure no residue remains on the optics glass. Never use strong cleaners or abrasives as they can damage the anti-reflective and anti-fog coating.