Micron Optics - Nikon Microscope Systems for New Jersey and Puerto Rico
CLEANING A NIKON MICROSCOPE LENS
Cleaning a Nikon microscope lens can be easy or difficult, depending on the type of contaminant. It is also easy to leave smears on the lens in the attempt if you're not very careful. Much of the information below is outlined in the book “Video Microscopy”, by Shinya Inoue of Woods Hole Marine Biological Laboratory.
First inspect the lens surface under bright light to be sure that cleaning is needed. You can remove and invert a microscope eyepiece to act as magnifying glass. A properly clean optical surface should have the purplish hue of its antireflection coating, and should have no oil, grease or other contaminants on it.
Cleaning loose dust
If it's just specks of air-born dust, you may be able to blow them off with canned air. But first make sure that no liquid propellant is released from the aerosol can. You may also try a small camel’s hair brush (from an art supply store or camera store.) and attempting to gently brush the lens clean.
Cleaning clinging dust, finger prints, water marks, solvent residue
Use the moisture from your breath (which is distilled water) and crumpled microscope soft lens tissue. Do not use Kimwipes or facial tissue as they leave lots of particulate matter behind and can actually damage the lens. Clean the contaminant off the lens using a spiral pattern starting from the center of the lens and moving to the outside. Only use the lens tissue once, and avoid getting your finger oil on the face of the lens paper you are using for cleaning, as this will always leave streaks when you are done. You can use different clean virgin areas of the same tissue.
Immersion oil and tougher dirt
Wet the lens paper with a drop of full strength solvent* and slowly draw the paper across the lens surface. Never excessively soak the lens with strong solvent as this could damage the optical cements holding the lenses together.
If this doesn’t work wrap lens tissue around the non-cotton end of a wooden applicator stick. You usually have to sharpen the stick so that it fits into the concave lens openings of higher NA objectives. Wet the lens paper with solvent and clean the lens in a spiral motion form the middle to the edge. Immediately discard and replace the used tissue so that you are always cleaning with a new virgin surface.
You will often be left with solvent residue on the lens that should be cleaned with your breathe, as described above.
Water or glycerin Immersion objectives or salt crystals
Clean as above with distilled water
*For infrequent cleaning we like the solvents in the following order at 100% strength… Ether, benzene, xylene, methanol, ethanol, acetone. For very frequent cleaning such as is done in a Hematology lab use a milder commercially available microscope lens cleaner which is often an equal mixture of methyl alcohol:acetone:water or ammonia:water. Be aware that solvents are extremely flammable and typically carcinogenic.
A covered microscope requires cleaning less often.
Micron Optics, 240 Cedar Knolls Road , Cedar Knolls, NJ 07927