NetNotes
one needs new oil, because enough remains on the lens. We also tell them to not wipe the front lens, never ever, under no circumstances, but to just put a Kimwipe (gray box) over it and suck off the oil without moving. Repeat, until it comes off dry. Wiping metal parts is okay and sometimes required. If that is not sufficient to get a good image, something is wrong, and they should call for help.
– We put hairbands around inverted oil objectives. Not sure how much that really helps, but it visually makes a point.
– I urge users to select the objective in the soſtware, not on the touch- pad: some systems have, for example, 63x oil and glycerol, on the touchpad that cannot be distinguished.
– If DAPI is used, they are told to use this to focus. If not, any bright signal (except far-red) or the green channel, even if empty, should be used: there is usually enough background and that is where our eyes are most sensitive.
– I don’t think it is safer to use the 10x before going to the 63x on an inverted system where the oil must be in the beam path. I tell users to move the 63x up until it touches the oil on the slide with the coarse drive and only then look through the eyepiece and use fine focus to continue.
– Te AFC (automatic focus control) can cause a problem if on “hold”. We recently had a type of ibidi slide under the microscope, essentially made from optical plastic with a channel inside, and the channel on both ends will end in a large cylinder to which tubing can be connected on the top side. So, the roof of the chan- nel vanishes when the cylinder is reached. Apparently, in this case, the reflection that the AFC was using came from the roof of the channel, and when the slide was moved such that the cylinder was in the optical path, the objective suddenly jumped up several millimeters. Ouch.
– “Not covered by service contract”, if I recall, is “user inflicted damage”. Scratched objectives will be the most common incident. But overloading detectors repeatedly (can be seen in logs), spilling water in electronics, or medium into the stand, etc., also fit that description. So far, we have only had scratched objectives.
– We regularly do PSF checks on the high mag lenses. Usually, we pick up problems before users complain about bad images. Wrapping it up, I don’t think you can totally avoid objective
damage by users any other way than to not let them use the micro- scope. “Te problem with making something completely foolproof is the ingenuity of complete fools” (Douglas Adams). Best you can do is to minimize the frequency. And there I am back at the begin- ning: Save some money for it. Steffen Dietzel
lists@sdietzel.de
Oil Objective Lifetime Confocal Listserver Hi all, I’ve been told (and have read on a couple of core facility web-
sites) that oil slowly dissolves the glue in objectives. Does anyone have a rough idea of the total amount of time an oil immersion objective can have oil on it before it seeps in? Is having oil on the objective for 24 hours straight equivalent to 24 hours spread over three days? To help make this tractable, let’s assume an ideal user who cleans the objective correctly and frequently. Cheers, William Giang
wgiang@pennstatehealth.psu.edu
I have been doing microscopy for 30 years and have not per-
sonally encountered a problem with this. Years ago (late 1990s/ early 2000s) we did have this issue with one specific lens type in an inverted configuration where user application of too much oil re- sulted in oil running down the side of the cap and getting to the lens barrel and down to the lens elements, but this was unusual and very specific to the lens combined with misuse. We worry more about
2022 May •
www.microscopy-today.com
overcleaning being a problem. As discussed, a few days ago on this listserver, lenses damaged by physical impact is not uncommon. Michael Cammer
michael.cammer@
med.nyu.edu
I have only heard that immersion oil can be corrosive to the
cement/glue used for dry lenses, not for oil immersion objectives. Do you have a reference for the claim that the oil is a problem for immersion lenses? Elke Küster-Schöck
elke.kuster.hsj@ssss.gouv.qc.ca
Here are two different sources: 1. Microcourses video (https://
youtu.be/c58P4Zt9xX0?t=384): “As objectives age, it does become more likely that oil will seep through the cement and accumulate under the lens. However, it can be accelerated by using solvents too oſten to clean the lens”. 2. Duke light microscopy core website (
https://microscopy.duke.edu/guides/clean-objective): “It is impor- tant to remove the oil aſter use (oil traps dirt and slowly dissolves the glue in objectives)”. Tanks Michael and Elke for your responses. William Giang
wgiang@pennstatehealth.psu.edu
What they said. I only have 24 years, but it’s the cleaning re-
agents, not the immersion solutions. Some immersion media will cause cancer, but that’s for another thread. Oil can drip down the inner barrel, and that can wreak havoc over time, but that has noth- ing to do with the seals. Gary Laevsky
glaevsky.lists@
gmail.com
Since it’s our website at Duke that was referenced, I thought I
should clarify and offer one experience. I agree that it is the solvents that are used to clean oil objectives that can partially dissolve the cement holding in the front lens and may cause oil to seep in under the front lens. I will update our website to reflect this information more clearly. What is described in the Microcourse youtube descrip- tion is exactly what I have seen in some circumstances (and what I’ve been taught/told by other microscopy experts). (Tanks for alerting me to this). We had one 40x oil objective get oil under the front lens and we returned it to the manufacturer for repair. I cannot say for sure how old the objective was because the confocal system predated my time at Duke, but I think the system was approximately 6-7 years old in 2018 when we sent the objective back for repair. In all my years of experience, I have sent back 2 objectives to the manu- facturer for repair and received the objective back in good working order. We do not want our users to clean objectives and ask them to contact our LMCF staff members to help them. For instance, we do not want users taking the objectives off the turret. We ask users to carefully remove excess oil when they have completed their micro- scope session which included using an oil immersion lens. Of note, when I was reading the information on a couple of manufacturer’s websites, it was noted that some dry objectives are not sealed to pre- vent seeping of oil into/under the lens, so it may not be that dry objective cement degrades more, just that the lens is not fully sealed to prevent oil seepage. Tanks for bringing this information to light. Lisa Cameron
lisa.cameron@
duke.edu
I’ve been watching this thread and thought this comment
would be beneficial. When I was a much younger guy, employed by a then-Zeiss franchise in Maryland covering the central east coast, I oſten came across objectives that were only partially wiped off or partially cleaned. Tis resulted in a thin layer of oil remaining on the objective that would easily oxidize, especially overnight! Tis thin oxidized layer had an irregular refractive index. Ten, when additional oil was added for imaging, you can imagine what happened to the image. I found the best way to clean them was to, aſter removing the bulk of the visible oil,
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