Described herein is a method of depositing a conformal, optically transparent coating onto a surface of one or more internal components that are enclosed within an assembled device including an optical encoder using a non-line-of-sight deposition process without altering a structure of the assembled device or impacting functionality of the assembled device. Also described is an assembled device including an optical encoder, where one or more internal components enclosed within the optical encoder and a coating deposited onto a surface of the internal components, where the coating is a conformal, optically transparent coating that is resistant to corrosion by at least one of fluorine-, chlorine-, sulfur-, hydrogen-, bromine-, or nitrogen-based acids and that does not negatively impact functionality of the internal components.