Ensure Optical Performance with Clean Immersion Oil

Objectives are precise pieces of microscope equipment and must be cleaned to guarantee optimal optical performance. In spite of this, lab technicians and researchers frequently forget to clean their immersion oil objective lenses and end up encountering some sticky results.

This article provides six of the best tips and techniques to properly clean oil off your objective lens.

1. After Use, Clean Off the Oil Immediately

It is not only hard to remove dried oil from an objective lens, but this sticky substance can easily trap dirt, dust, fingerprints, and other contaminating particles. A small amount of trapped dust can affect image quality and result in optical errors such as shade or fog. Over time, the dried oil can also cause deterioration of the objective lens.

Image Credit: Olympus Life Science Solutions

For this reason, it is recommended to clean immersion oil off your objectives immediately after using it. The oil will be easy to remove when it is still wet.

By adhering to this best practice each time, it ensures that the microscope system is prepared for the next technician to use. If not, the technician may inadvertently contaminate samples and other objectives with the oil residue. They also won’t need to waste energy removing the dried immersion oil and will complete their observations on time.

2. Use the Eyepiece to Inspect Any Dust on the Objective

Image Credit: Olympus Life Science Solutions

It can be hard to see any dust on the lens as objective lenses are normally extremely small. Fortunately, there is a trick that can be employed to overcome this issue. Remove the eyepiece from the microscope and raise it up to the objective lens. Now by looking through the eyepiece any dust you need to clean will be magnified. Otherwise, if you have one on hand, you can use a loupe.

Occasionally, an objective is too firmly fixed on the microscope to remove for cleaning and inspection. In this case, move the objective to an angle where the lens can be easily cleaned.

3. Remove Any Dust or Dirt with a Blower

Once the lens has been inspected, start the cleaning process. To begin with, without touching the objective lens, use a blower to remove any dust or particles.

4. Fold a Piece of Lens Paper to Create a Point

Now fetch a new piece of lens paper and fold it to make a point. Keep in mind, depending on the size of the objective, the way the lens paper is folded will vary.

For bigger objectives, wrap the lens paper around your finger. This will enable the entire lens surface to be easily wiped. This folding technique can be completed in four quick steps, as demonstrated in the following image:

Image Credit: Olympus Life Science Solutions

A great deal of objectives are fairly small, so they may be too tiny to use a finger to wipe the lens surface. In this case, simply make a triangle with the lens paper to create a point.

Don’t forget to always use lens paper instead of facial tissues or lab tissues. Consumer tissues contain coarse, loose, fibers that can scratch the lens surface or break off and stay on the lens.

5. Soak the Lens Paper in a Suitable Solvent

For the next step, soak the lens paper in an appropriate solvent that can dissolve the oil and clean the lens without damaging it. Anhydrous alcohol is recommended, a commercially available lens cleaning solution, or blended alcohol.

Bear in mind, these cleaning solutions are flammable so you must handle them with caution. To minimize any risks, turn off your microscope and any lab equipment in the area, and make sure the room is well-ventilated.

6. Wipe From the Center to the Outside in a Spiral Pattern

Now, using the soaked lens paper, wipe the lens from the center to the outside in a spiral pattern. This wiping technique will move any dust or dirt to the edges.

To check your work, use the loupe or eyepiece to search for any remnants. If any residue of immersion oil remains, fold and soak a new piece of lens paper and wipe again. Repeat these steps until the objective lens has been totally cleaned.

Image Credit: Olympus Life Science Solutions

One brilliant aspect of the spiral wiping technique is that it can be used to clean different optical surfaces, like a camera lens, condenser lens, or glass plate. If the surface is too big to be wiped with a finger, then simply hold the lens paper on the surface while rotating the object by touching only the periphery.

The image below illustrates how to clean a glass plate using this technique.

Image Credit: Olympus Life Science Solutions

One final note: After cleaning any optical microscope accessory, check each time for any leftover dust or oil using a loupe or eyepiece to ensure that it’s clean. Then reattach the cleaned component on your microscope straight away in order to keep the system organized.

The Importance of Keeping Your Objective Lens Clean and Oil Free

In a lab it is easy to get distracted as there are meetings to attend and samples to prepare. But stepping away from a busy schedule to clean oil off your objective lenses can safeguard good image quality and help avoid costly replacement of equipment.


Produced from materials originally authored by Takeo Ogama from Microscope Cameras.

This information has been sourced, reviewed and adapted from materials provided by Olympus Life Science

For more information on this source, please visit Olympus Life Science


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