Cleaning optical lenses
In general, it is blown first, then brushed, and then wiped. Blowing is the act of blowing off the attachments on the surface of the lens with a blower (or earwash ball). But you can't blow the air directly with your mouth. If it cannot be blown away, it can be gently brushed off with a clean specialty cleaning brush. If dirt still remains on the surface of the lens after the above two methods, wipe it gently with lens cleaning paper lightly dipped in xylene.
If you find the lens is moldy and fogged up, you can wipe it with lens cleaning paper dipped in a mixture of absolute alcohol and ether. However, the liquid should not be too much and the exposure time should be short to prevent it from penetrating into the lens and causing corrosion.
Oil lenses should be wiped in a timely manner after each use. First wipe once or twice with dry lens tissue to remove most of the middle oil, then wipe twice with xylene-dampened lens tissue, and finally wipe once with dry lens tissue.

Camera lenses, microscopes, optical instruments, measuring and analysis instruments