Best Way To Clean Microscope Lens

[bostonman]

I have a microscope and the right side is a bit blurry.

I removed the eyepiece and cleaned both sides of the lens with a soft cloth (the type for eyeglasses and TVs), but seems like some grime is around the parameter too because I see a slight halo. After I tried rubbing alcohol on a q-tip and then cleaned/dried with the same soft cloth, but it didn't seem to get much better.

Also, I'm thinking it may be the lens inside on the bottom, but, I'm concerned it will be worse if I attempt to clean it; assuming I can reach the bottom side.

[loki42]

Ultrasonic is pretty amazing for glasses assume it might be for this too?

[jpanhalt]

As for ultrasonic cleaning, most lenses in microscopes (objective and oculars) have multiple elements.  Ultrasonic might get cleaning fluid where you don't want it to be.

We just used a few drops of liquid detergent in water and lens paper for our microscope lenses.*  Dawn was preferred at the time, but it fragrance now gets to me.  I use a fragrance-free laundry detergent.  We rarely, if ever disassembled an objective.  If needed, that was handled by the manufacturer or service tech. 


*Edit: It was very dilute.  Like 1 drop in a few ounces of water.  The ratio wasn't measured, but the water did not feel soapy slick.

[coppice]

As for ultrasonic cleaning, most lenses in microscopes (objective and oculars) have multiple elements.  Ultrasonic might get cleaning fluid where you don't want it to be.

We just used a few drops of liquid detergent in water and lens paper for our microscope lenses.  Dawn was preferred at the time, but it fragrance now gets to me.  I use a fragrance-free laundry detergent.  We rarely, if ever disassembled an objective.  If needed, that was handled by the manufacturer or service tech.

One drop of detergent. Only ever one drop for something the size of a lens...... unless that lens is a really large celestial telescope mirror.

[bostonman]

I'm assuming the lens isn't scratched as in someone used abrasive material to clean the lenses (I got this from my old company) because it would be more of a haze.

The lenses were quite dirty when I first got the scope. The solder fumes and stuff must have taken a toll on the underside.

The eyepieces come out (I have tape around them so they don't fall and break) but most likely dipping them in water/detergent may cause water to seep in areas I don't want.

I don't know if the alcohol gets around the parameter causing dirt like haze or if it needs a good cleaning. Since I cleaned the eyepieces and the bottom side, the only part left is the inner side of the bottom lenses which is hard to reach. I'm only guessing that maybe they are dirty and the reflection is appearing as if the smudges are on the eyepieces. I fear leaving streaks or moving around dirt making it worse.

[jfiresto]

I have a microscope and the right side is a bit blurry....

So, just to make sure, you tried swapping the left and right side eyepieces – and when you did, the blurriness changed sides?

I like to inspect and clean eyepieces under the microscope. With off-axis illumination and a high magnification, you can focus on and inspect the surfaces of the individual lens elements – especially so in stereo.

What is the magnification and field number on the eyepieces? If you only have a pair of, say, 10X/20 eyepieces, this could be a good excuse to get some nicer, wider field, high eyepoint eyepieces and have an extra pair for cleaning the other. I picked up some competent Chinese made, 10X/23 eyepieces for my father which were around $50 or so.

[bostonman]

So, just to make sure, you tried swapping the left and right side eyepieces – and when you did, the blurriness changed sides?

It's the silly questions that are the most useful. Actually, I didn't think to do that, I don't know why, but will.

The microscope itself doesn't have a model or company name, but I'll check the eye pieces (and swap them) to check the magnification.

The blurriness is extremely faint. It's clear enough that I need to focus on the quality of magnification to realize one side is blurry, but, once noticed, it's annoying.

[jpanhalt]

I would stick with water and detergent.  Alcohol(s) can damage some coatings.  If you absolutely need to use an organic solvent, I would start with VM&P Naphtha.  Diethyl ether is great for fats and oils and is relatively mild, but again caution is advised.  We used it for optical cleaning non-coated  things.  As for dipping the lens in water, I wouldn't do that either.

EDIT: Another mild solvent is diacetone alcohol (https://en.wikipedia.org/wiki/Diacetone_alcohol ).  It has almost no smell.

[coppice]

I would stick with water and detergent.  Alcohol(s) can damage some coatings.  If you absolutely need to use an organic solvent, I would start with VM&P Naphtha.  Diethyl ether is great for fats and oils and is relatively mild, but again caution is advised.  We used it for optical cleaning non-coated  things.  As for dipping the lens in water, I wouldn't do that either.

EDIT: Another mild solvent is diacetone alcohol (https://en.wikipedia.org/wiki/Diacetone_alcohol ).  It has almost no smell.

Yep, stick with water and a tiny amount of mild detergent that's not bulked up with salt (quite a few are). Use distilled water if your water is hard. There isn't an organic solvent you can name that isn't going to ruin something. They are lots which are great, like isopropanol, until you find the thing you are cleaning was developed by a sadist who specifically chose a material that is not resistant to the commonly used cleaners.

[bostonman]

I apologize for the delay, but I've been busy and also kept forgetting to look into this.

Earlier I swapped lenses and it was difficult to tell whether the blurriness followed. From the looks of things, both sides have issues, but the right is worse. I turned the lenses and the blurriness didn't seem to move, and tells me the issue is internal.

I don't see a brand name anywhere and the electrical tape on the lenses is to prevent them from falling off should I invert the microscope head.

I'm uncertain how to clean the inside lenses and how many are internal. Does anyone have suggestions?

[Bud]

Your issue may be with the prisms in the optical paths, not lenses. In my stereo microscope one prism developed milky tint because the coating started to flake off. There was nothing that could be done other than to replace it.

[jfiresto]

What you have looks like a copy of an Olympus SZ-III stereo microscope. Allan Wood has instruction and service manuals for that one, here.

If you shine a penlight into the microscope, so as to shine through or reflect back, then zoom in and out, you should see the inner lens surfaces go in and out of focus and find which ones might be fogged.

Sometimes you have to try different solvents to find one that cleans an optical surface. I had a photo adapter with a fogged, internal projection lens that did not respond to isopropyl alcohol, but a drop of dishwashing liquid in 100ml of distilled water did the trick. The microscope makers usually have specific recommendations for what to use and not use. I think in the 90's, Olympus was recommending a mixture of ether and isopropanol because it evaporates so quickly and is less likely to invade the lens.

EDIT: I should add that the design of your microscope is a couple decades older.

[bostonman]

EDIT: I should add that the design of your microscope is a couple decades older.

I don't know how old, but you're correct. I've had this for about twelve-years and it was old and being thrown away at my old company. The main reason was the arm would rotate regardless of how tight the locking screws were. I disassembled it and found the internal plastic locking pieces were out of alignment.

A few years ago I did a basic cleaning and found lots of dirt; most likely from years of solder fumes.

I don't want to go too deep with this issue because it's minor, and, if I make it worse, then I'm out a microscope. Over the weekend I'll read into cleaning.

You mentioned shining a pen light into the microscope and looking in. Do you mean from the eyepiece down or bottom up, or remove the eyepiece?

[jfiresto]

Every which way, although you probably can't excite all the surfaces. What you try to do is shine the beam at an angle, so that you don't look at the beam, but rather the weaker light that scatters off the surface: either scatters onward into the optical path, or scatters backward and backtracks the path (transmitted and reflected "dark field" illumination).

I have attached an example of the former. The first shows loss of sharpness (blurriness) through a glass reticle. The second, with strong transmitted light, viewed off axis, shows the cause.

EDIT: Removing an eyepiece and shining a light into the tube works well for me. If I then peer into the objective from an angle, so that the beam does not blind me, I can count a vertical column of perhaps 7 to 8 dust layers between the bottommost and topmost lens surfaces. Scattered dust is generally not a problem. Film layers, however, kill the contrast and resolution.

[bostonman]

What you have looks like a copy of an Olympus SZ-III stereo microscope. Allan Wood has instruction and service manuals for that one, here.

Glancing at the service manual, looks like it's more involved to disassemble and more lenses that I thought including making sure things are aligned. I didn't realize a prism exists too, although had I given thought, I would realize it has an angle from the bottom to the eye piece.

Using a light (I don't have a pen light) didn't reveal anything obvious, so dismantling it may be too much of a gamble.

Initially I used this off and on, and, long story short, cleaned the lenses. The bottom lenses were extremely dirty if I remember correctly. My guess is the microscope has never been disassembled and cleaned, so maybe lots of solder fumes have seeped inside causing some cloudiness (assuming it isn't sealed well and fumes can seep in).

[jfiresto]

Can you really know without taking it apart? It is really hard to say from this great distance.

That appears to me to be a clone of a pretty old model so it may not have been the best when new. If it were mine, I would use it to discover what I liked and needed, while searching for something more recent that had an easier life.

[bostonman]

Can you really know without taking it apart?

You're correct; dismantling it will answer questions. I'm just afraid of messing with something that is in good shape only to break it (whether by something breaking, misaligning during reassembly, or making the smudges worse).

If I knew how many lenses are inside, then I'd at least have a better idea of what I'm getting into. I thought it was only the bottom lens and the top, then learned a prism exists (something I should have known), and then the manuals indicate several lenses are inside.

The whole idea of getting a free microscope is to not spend money on a new one. Breaking this throws out that savings if I need to buy another one.

My only issue with this scope is it didn't have a light nor can a COTS light be mounted to it since the head is tapered lacking the ability to keep a round light mounted to it.

[jfiresto]

My only issue with this scope is it didn't have a light nor can a COTS light be mounted to it since the head is tapered lacking the ability to keep a round light mounted to it.

Your picture of the microscope's "business" end shows some internal threads, probably for screwing on an auxiliary objective to scale the magnification range and working distance. The thread might be something common, perhaps M48x0.75mm, in which case you could get, say, a camera thread adapter, and fashion and glue a fixture to hold the lighting. Just an idea.

A stereo microscope is a very nice tool to have, especially as your eyes get older and don't accommodate like they used to (why I got one).