Field Microscope
of color, polarization, and light intensity combinations under fi eld conditions.
Digital camera . Although the shop inspection microscope is capable of supporting heavier cameras, adapters for mounting them would off er a challenge, and traveling light would seem to require something smaller and more portable. An Amscope MU300 3 MP digital eyepiece camera with FMA050 adapter is shown in Figure 7 . T e camera mounts in place of the eyepiece and attaches by USB to a laptop computer. T is limits portability, of course, but with current generations of laptop tablets and such, this is not a signifi cant obstacle to overcome. Example images taken with this setup are shown in Figure 8 .
Discussion
The practicing field microscopist is not completely without recourse to alternative field microscopy equipment at the present time, There are commercially manufactured microscopes currently advertised as “field microscopes,” and the patient shopper can still find an occasional “vintage” Swift FM-series field microscope for sale on eBay. In a previous article in this magazine (B. Cline et al., “Design and Validation of a Low-Cost Microscope for Diagnostics in the Developing World,” [ 2 ]), the authors propose a design for a versatile and lightweight field microscope, but to this author’s knowledge that microscope is still not commercially available. Other new developments also bear watching, such as Manu Prakash‘s amazing origami “Foldscope” (see [ 3 ] and
www.foldscope.com), which is currently undergoing beta testing but is still not generally available for sale to interested field microscopists. Other commercial field microscopes currently being sold are expensive and still require more careful handling than field conditions may allow. T e shop inspection microscope described in this article is widely and readily available right now and promises to be for some time to come. T e do-it-yourself custom stage platform can be made and assembled easily and cheaply and is quite versatile and rugged for fi eldwork. T is combination meets all the basic requirements listed at the beginning of this article. Besides fi eldwork, this microscope is an excellent intro- ductory instrument for students and hobbyists. It gives them a “hands on” sense of what is involved in a truly basic microscope with a form that is reminiscent of the original compound
microscope of Robert Hooke and other early seventeeth- and eighteenth-century microscopists. Rather than being faced with a complicated and expensive instrument, novices are quickly engaged with a simple and inexpensive one that they can handle and control, which uses standard lenses that enable them to clearly see an enormous diversity of microscopic forms. Even aſt er someone moves on to a more expensive and sophisticated professional stand, it will remain useful as a fi eld instrument or a hand-me-down fi rst microscope giſt to another beginner. T e authors have oſt en packed additional standard eye- pieces and objectives in this fi eld kit (for example, a 15× widefi eld ocular and 40× and 60× objectives), and we have sometimes found it handy to use a “divisible” 10× objective (Bausch & Lomb), where the front section of the objective unscrews to allow it to be used as a 5× hand lens. T e only limitation to this scope is that it is unsuitable for higher-power work requiring oil-immersion objectives in the 100× range, which would be diffi cult to focus without a fi ne adjustment. However the authors have used it quite eff ectively with a 60× dry objective and a 15× ocular, which approaches that level of magnifi cation (if not resolution). But other than that, the fl exibility of this stand is limited only by the microscopist’s imagination!
Conclusion
For about $100 and change, a credible fi eld microscope kit can be fashioned from easily available parts. In this article the authors have presented a fl exible and durable system using standard optical components and home-customized parts. It meets all the relevant requirements outlined at the beginning of the article. Its economy and portability recommend it for anyone with a need for doing fi eld microscopy on a limited budget.
References [1] WB Carpenter , T e Microscope and Its Revelations , 5th Edition , Lindsay and Blakiston , Philadelphia , 1875 , fi g. 32, p. 80. Various editions of this classic work are available for free on-line download from the Internet Archive website.
[2] B Cline et al ., Microscopy Today 17 ( 2009 ) 16 – 19 . [3] Microscopy Today Innovation Awards , Microscopy Today 22 ( 2014 ) 48 – 53 .
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