Cleaning of Optical Components
Note: You follow this advice
at your own risk.
All optical elements are
delicate and should be handled as carefully as possible. The glass
and antireflective (AR) coated surfaces will be damaged by any
contact, especially if abrasive particles have come into contact with
the surface. In most cases, it is best to leave minor debris on the surface.
Use of oil-free dry air or
nitrogen under moderate pressure is the best tool for removing
excessive debris from an optical surface. In the case that the
contamination is not dislodged by the flow of gas, please use the
following protocol for cleaning the part:
1. Clean the part using an
absorbent towel such as Kimwipes, not lens paper. Use enough
toweling so that solvents do not dissolve oils from your hands which
can make their way through the toweling onto the coated surface.
2. Wet the towel with an
anhydrous reagent grade ethanol.
3. The use of powder-free
gloves will help to keep fingerprints off the part while cleaning.
4. Drag the trailing edge
of the ethanol soaked Kimwipe across the surface of the component,
moving in a single direction. A minimal amount of pressure can be
applied while wiping. However, too much pressure will damage the component.
5. If the surface requires
additional cleaning, always switch to a new Kimwipe before repeating
The purpose of the solvent
is only to dissolve any adhesive contamination that is holding the
debris on the surface. The towel needs to absorb both the excessive
solvent and entrap the debris so that it can be removed from the
surface. Surface coatings on interference filters and dichroics are
typically less hard than the substrate. It is reasonable to expect
that any cleaning will degrade the surface at an atomic level.
Consideration should be given as to whether the contamination in
question is more significant to the application than the damage that
may result from cleaning the surface. In many cases, the AR coatings
that are provided to give maximum light transmission amplify the
appearance of contamination on the surface.