A Flexible and Economical Field Microscope
Glenn Shipley * and Robert Hoelter Sibylife Laboratories , 6718 N Mozart St. , Chicago , IL 60645 *
glennshipley@gmail.com
Introduction T e problem . For any serious microscopist, there are times and places where you would like to have a fi eld microscope at your fi ngertips, but procuring one is expensive, diffi cult, or impossible. For example there are places you can go in the USA, and even in other nations on the planet, where you are not allowed to remove any materials or specimens without special permission. As unforeseen opportunities for travel arise, that permission may not be easy or quick to obtain. It would be nearly impossible for amateurs or hobbyists to get such permission and very diffi cult even for professionals or academics traveling on short notice. Examples of such sites are national parks and World Heritage Sites. Besides the problem of not being allowed to take things out, there is the problem of getting instruments in these places in the fi rst place, or negoti- ating equipment through airport security.
In this article we propose a solution to these problems: a lightweight portable fi eld kit centered on an inexpensive bright- fi eld light microscope. T ere are still a few “fi eld microscopes” around, and some very interesting new ones on the horizon (as we describe in the concluding section), but they are rare, presently unavailable, too expensive for the hobbyist or academic on a budget, or somewhat limited in accessories. Requirements for a fi eld microscope . It is useful to begin with a list of requirements or expectations anyone should have for a completely versatile, optical fi eld microscope, particularly one that does not break the personal or institutional piggy bank of traveling professionals, hobbyists, and citizen microscopists. Such a list of criteria would include: 1. Portability – it should be small and light enough to fi t in a backpack or luggage that can pass through airport security;
2. Rugged construction – preferably an all-metal body and parts;
3. Standard focus – using rack-and-pinion coarse adjustment and having some way to stop gravitational tube driſt ;
4. Standardized optics – it should take standard RMS-threaded objectives and 23 mm oculars that fi t most brightfi eld microscopes produced by major manufacturers and provide for a normal range of magnifi cation and resolution up to 600× or 800×;
5. Camera capability – it should be capable of ordinary on-site photomicroscopy to record images of non-removable or biologically fragile specimens;
6. Usable under a wide variety of light conditions – it should be able to use both on-location available light sources and small battery-powered LED light sources;
7. Illumination fl exibility – it should be capable of on-site brightfi eld, darkfi eld, Rheinberg, polarization, oblique, and epi-illumination techniques;
8. Environmental versatility – it should be able to be used on location in somewhat challenging temperature and climate conditions without worry of expensive damage or loss;
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Figure 1 : The typical shop inspection microscope. The fl ashlight on the extension arm is adjustable and both are easily removed.
doi: 10.1017/S1551929515000553
www.microscopy-today.com • 2015 July
9. Availability – it should be a basic instrument not likely to be dropped from inventory by manufacturers;
10. Age neutrality and professional fl exibility – it should be usable not only by professionals, but by amateurs and children;
11. Economy – it should not be prohibitively expensive in case of loss, theſt , or damage.
T e following sections describe a microscope that satisfi es these criteria and a set of accessories comprising a suitable fi eld kit.
Materials and Methods Shop inspection microscope . Figure 1 shows a suitable microscope manufactured and sold today as a “shop inspection microscope.” It is readily available through internet outlets for less than $100. T e example shown is a Chinese- manufactured Amscope (SKU: H100) off ered regularly on eBay, but nearly identical models are available elsewhere, for example, from PrecisionWorld and MicroscopeNet. T e rugged body is made of metal (meeting criteria #1 and #2), the only plastic part being the handle of the rack-and-pinion coarse adjustment (meeting criterion #3), and yet the overall
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