SOME ADVICE ON CARING FOR MICROSCOPES

by James McHone of Stones2Gems.  Here are a few bits of advice that during my teaching years, I provided to my students in geology courses (petrology, petrography, mineralogy). Not methodology for making observations (someone could write another guide for that), but just some basic introduction for students and beginners. Advanced users will already know this stuff and a lot more, as will you before too long.

Types of Microscopes. Even though they usually have two eyepieces, compound microscopes are not stereo microscopes. Stereo microscopes (sometimes called dissecting microscopes) are used mainly to identify and examine 3-dimensional objects such as bugs, plants, or minerals, at least by people like me. And you see them in 3-d as well, quite amazing the first time you use one. They use low magnification powers, usually less than 100x. Compound scopes usually require prepared slides or flat polished surfaces and are used in science, medical research, and education, as well as for materials analysis in industry. The view is 2-dimensional, with only a flat plane in focus, but it can be extremely clear and very highly magnified. Common powers of magnification are about 40x, 100x, 400x, and 1000x (you will probably mostly use 100x and 400x), based on four objective powers times a 10x eyepiece. No matter what type or level of microscope you have, many of the same procedures will be appropriate for using and maintaining it.

Left: Wild Heerbrugg M11 student or lab and field compound microscope, with metal hood. Center: Nikon Labophot polarizing compound scope -- a benchtop workhorse with excellent optics. Right: Olympus SZ on a boom stand, a stereo scope with many uses.

Shipping. Although some people believe that certain shipping companies are better than others about careful handling, I have not noticed much difference among them. It is wise to buy shipping insurance, if you can. Don't automatically blame the seller for damage during shipping, unless you can see that it was not well packed. As soon as it is handed over to the post office or shipping company, the seller has no more control over it than you do. Along the way to you, the box could be tossed around like a bean bag, crushed under piles of heavy packages, and dropped onto the hard floor upside down. It makes little difference that "Fragile -- Handle Carefully" was stamped all over it! Keep a camera handy when you unpack your microscope, because you will need to document any damage to the instrument, and also what the package itself looks like. Likewise, keep any shipping documents. Contact the seller and shipping company right away about any such problems.

Setting it up. If you are buying an expensive benchtop microscope from a dealer, he or she might come to your workspace to unpack and set it up for you. But most of us buy used or "generic" microscopes that will not include on-site help, or any help at all for that matter. If there is an instruction manual, it probably gives useful info on the setup, so read it first. Several websites post scans of older microscope manuals that you can access for information. If possible, devote some benchtop or table space to the microscope, so that it does not need to be moved much after it is set up. Of course, a small microscope might have its own cabinet or case, into which you can store it away. The head, eyepieces, objectives, light source, and perhaps other parts often must be assembled, but how they go together is usually self-evident, and generally no special tools are required. Thumb screws might be backed off a little, and note whether they are spring-loaded and can be pushed back when the part is inserted. This is also a good time to inspect the optical glass and inside (enclosed) areas, and to clean them if necessary (see below for cleaning advice). Don't handle a halogen bulb with bare fingers, and if that happens clean it carefully with a lens wipe. The quartz glass on these high-temp high-pressure bulbs can react with a fingerprint and fail prematurely.

Handle microscopes carefully. The good ones are all heavy, surprisingly fragile, and have movable parts that can be pushed out of proper alignment. When you rotate the nose piece (turret) to change powers, do not push on the objectives, and watch that the next one does not hit anything, such as the slide or slide holder. Anything that is meant to move should move easily (unless locked on purpose), so don't force it. Keep your fingers off all lenses and filters -- finger oils are tricky to remove but need to be, as they soon harden on the glass surfaces. Bench top or research microscopes are not meant to be moved around much (use a permanent station), but be sure they are covered when not in use. Smaller 'lab' scopes can be stored in a case or cabinet, but beware of whacking the head on corners and edges. Pick them up only by the solid frame arm, and put your other hand under the base (foot).

Names. By the way, microscope parts have human-type anatomical names, such as foot, arm, head, nose, ocular, etc. It may be amusing to compare microscope parts to your own anatomy... but let's not go there.

Learn proper methods of use, especially the condenser and diaphragm (iris) adjustments. If you don't have a teacher to help you, try a professional website such as Molecular Expressions, OlympusMicro, Nikon's MicroscopyU, or the free downloads from Zeiss microscopy. Or just google your topic. Microscopes often use a 20 watt halogen bulb (lamp) in a light source built into the base, and replacing that bulb will be cheap and easy. Many older microscopes use specialty tungsten-filament bulbs that can be hard to find, and/or expensive. With either type, if there is a diaphragm (iris) in both the field (base) lens and an adjustable condenser, you will be able to achieve 'Koehler illumination', or perfectly even lighting that is especially good for photography. But many simpler lighting systems also work well. On a really good microscope the controls and motions feel natural and smooth, and the optical views will prompt an "Oh My!," a smile, and a feeling of satisfaction that less fortunate people (those without a microscope) will just never know. 

Petrographic microscopes, my specialty, have accessories that filter the light through polarizers, a circular stage that rotates, a Bertrand lens for conoscopic views, and optical parts that are specially made to avoid adding unwanted polarization. College geology programs have full-semester courses on their proper use in studying rocks and minerals (such courses are becoming rare, however). But actually, it's not rocket science, and you can gain a good understanding of the method with the help of one of several optical mineralogy or petrography books, available through eBay. The same procedures can be used to study many biological solids and organic crystalline materials.

Olympus BH-2 BHT-P polarizing scope with a Nikon digital camera. The stage can rotate to show the birefringent colors of minerals.

High-intensity lighting can damage your microscope when left on too long, meaning more than a few hours. Light itself is not the problem, but rather infrared heat radiating from the incandescent lamp permeates the lenses and filters, causing delamination and fogging of their optical layers. The more honest sellers will report that -- look for it in descriptions. Such problems are so difficult to repair that usually replacement is necessary, and the cost of a few parts can exceed what you paid for the entire machine (old microscope parts are in more demand than old microscopes). So, turn the lighting down whenever you can, take a break and turn the lamp off every now and then so the optics can cool down, and never walk away with it still cranked up. On the other hand, lamp bulb life is shortened by lots of on-and-offs, especially turning it on with the brightness already adjusted high. Make it a habit to turn down the brightness before turning it off. If you need to leave the scope for a few minutes, turn the brightness down to a dim setting rather than off (but don't forget it).

Keep it Clean. Dirt and dust are very debilitating for a microscope, so try hard to keep it clean.  Wash your hands before using it -- so easy, yet so rarely done. Keep a dust cover on it when not in use. Dust will collect on surfaces and eventually become a tough, sticky film, all by itself. You can clean most outer non-glass surfaces with a moist (not wet) cloth or paper towel. Use something like 'Goo Gone' (a gentle citrus-oil cleaner) to remove tougher dirt and sticky residue from painted and metal surfaces. Serious grime and dried grease might require solvents containing naptha, acetone, or other nasties. These are toxic and require proper ventilation, not for use in your kitchen around family members, so for a major cleaning you should send it out to a professional. I like to apply car polish/wax to the frame, which improves the finish and makes it easier to keep clean. Many used microscopes arrive with tape, stickers, or labels on them, which you should NOT remove with metal blade! Soak them in Goo Gone, WD-40, or something similar, and gently scrape them off with a plastic blade or perhaps your fingernail. You can rub off a lot of other marks the same way, even painted numbers if you are patient. Try rubbing a cloth with a little paint thinner in it on magic marker and stubborn stains (but beware, some scope finishes can be damaged with thinner). An old toothbrush and ammonia solution work well for cleaning the serrated chrome knobs and metal parts, but take care to keep all optical and interior parts dry.

Cleaning the Lenses. Most lenses of good microscopes have special coatings on their surfaces, and they are easily scratched or scuffed. If something is in your view, try brushing or blowing off the contaminant with a soft camera lens brush and air puffer, before using more serious tools. Use an alcohol or ammonia based lens cleaning solution (something like Windex) on an approved lens cloth, lens paper, or real cotton swabs on exterior glass surfaces. Not your shirt sleeve or a paper towel! Ebay or your local camera store offer lens solutions and cloths, but do NOT start with dry lens paper or cloth on the optics. Always clean with a moist, not dry, lens cloth or cotton swab (don't pour solutions onto the lens itself) and gently wipe in a circular motion from the center outwards. Repeat, using a fresh swab or cloth each time. Examine the surface closely with a hand lens or an eyepiece used upside down. The lens and mirror surfaces on the inside of the microscope's objectives, body, oculars, and head often have softer coatings that are very easily damaged. Best to keep them clean in the first place, or use your air puffer. Otherwise, get professional help.

Repairs and Maintenance. All microscopes sometimes need adjustments to operate at their best, especially after they have been shipped or even just carried around. If you have an instruction manual for your scope, it will tell you how to make adjustments to the condenser, light source, eye pieces, diaphragms, and accessories. Lubricants on older scopes eventually dry out and cause parts to stick or gears to need excessive force (and then they break). A little tiny bit of white lithium grease might improve a sticky sliding surface, as in a dovetail. Normally, light household oil is not what you want to use, as it will not provide the right feel, it attracts dirt, and it soon dries up. To fix serious sticking, dirt and old grease must be removed with those volatile solvents, so again, consider professional help.

Making repairs is a story too big for this short guide. The wise thing, of course, would be to contact your nearest microscope sales and service dealer. It might not even be very expensive, and they will have the special tools and jigs (and know-how) that are needed. But if cheap yet bold (i.e. foolhardy) genes run in your family (as in many of us scotch-irish types), you might wish to take it apart and see if you can at least improve it. You MUST have proper tools. I have a little kit called Wilha Master Technicians Micro Bit Set that I bought from a major internet small-tools company, as well as a Nye Hobbyist Lubricant Kit. Both have been excellent investments. You will also need standard tools such as metric hex wrenches, tweezers, needle-nose pliers, screwdrivers, spanners, rubber gripper, etc. Use a clear, well-lit table or bench top, and put down a table cloth so that you can find the tiny screws and ball bearings that are sure to fall off (some will probably disappear, never to be seen again). Think twice about opening up optical parts such as eyepieces or objectives, which need to stay spotlessly clean, even cleaner than you can make them with a lens cloth. Most objectives are not actually serviceable by owners, but some larger plastic-barrel eyepieces have screw-off ends, and it might be possible to partially dismantle them for cleaning or replacing a reticle.

Don't expect to find a good how-to book or website on fixing broken microscopes -- there aren't any. So be warned: if you don't already have a "parts scope" in a box under your bench top, you might have one soon. I have several.

Electrical Danger. Most microscopes are plugged into a 115 volt 15 amp circuit, and spilling a liquid on one can cause an electrical short that severely damages the microscope, or worse -- you! I recommend using a GFCI (ground fault circuit interrupt) outlet, either built into the wall outlet or via a portable GFCI plug receptacle, available from places like Lowes or Home Depot. Also, liquids will gum up moving parts and coat optical surfaces, all of which can be difficult and expensive to fix. Sort of like a laptop computer, you need to take extra care to avoid spilling liquids onto your microscope.  James G. McHone of Stones2Gems; Geologist, PhD, CPG