December 2012 - MicrobeHunter.com

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STEREOMICROSCOPYHistory of StereomicroscopyFigure 4: Bauschand Lombcomparisonmicroscope. c.1929 front view.Figure 3: AO high N.A. 0.95 APOobjective.history of instruments used to see imagesin 3D, and in particular the evolutionof stereo microscopes. However, thecoverage here has depended upon: (1)the help of technical staff still employedor retired from microscope manufacturers.It's useful to remember that someearlier microscope manufacturers are nolonger in business. Some material, evenfor manufacturers still operating, hasbeen lost over time, (2) the printedresources I had available, i.e., manufactureror reseller brochures, manuals, andbooks contemporary to the original timeof microscope manufacture, and moremodern texts, journals, on-line resources,etc., (3) the instruments in my collection,and (4) lastly but no lessimportantly the knowledge fellow microscopyenthusiasts have been kindenough to share.If you have additional information,or see any changes you feel would beappropriate, please let me know at theemail address provided at the end of thispaper. I'm pleased to consider all inputs.6 - MicrobeHunter Microscopy Magazine - December 2012
History of StereomicroscopySTEREOMICROSCOPYFigure 5: Bauschand Lombcomparisonmicroscope rightsideview.Background: The CompoundMicroscopeIn this paper the term "compoundmicroscope" is restricted to mean a standard"non stereoscopic" monocular orbinocular microscope, although moststereo microscopes are also compoundmicroscopes.Most compound microscopes, metallurgicalmicroscopes being an exception,use objectives designed forspecimens mounted on slides and enclosedunder coverslips. Objects arecommonly flattened or cut into thin sectionsso they can be viewed with transmittedlight, which passes through thesubject before it enters the objective.Conversely, stereo microscopes viewmost objects using incident light. Thatis, light is reflected from an object beforeentering the lens. Some early compoundmicroscopes are an exception.For example, Hooke's microscope of1665 used reflected light, Fig. 2.Later compound microscopes primarilyused transmitted light. For highresolution imaging it's critical to correctfor coverslip thickness. In the recentpast, top quality, and thus expensive,apochromatic (APO) lenses, e.g., Fig. 3,had correction collars to allow the necessaryoptical adjustments. The RoyalMicroscopical Society (RMS) standardizedcoverslip thickness is 0.17mm (thecurrent standard for No. 1.5 coverslips).This standardization significantly diminishedthe need for correction collarson objectives used with modern slides.However, owing to coverslip manufacturingvariations, high magnification,high N.A. objectives can still benefitfrom the presence of correction collarswhich may be needed to adjust for potentialoptical aberrations.Stereo microscopes, and comparisonmicroscopes (described in the section tofollow), have dual objectives developedfor viewing without coverslips. They'redesigned to view objects at relativelylow magnifications, typically 10x - 40x.For most stereo microscopes, workingdistance (the distance from the bottomof an objective to the in-focus areaof an object) and depth of field arerelatively large. Resolution and workingdistance typically have an inverse rela-MicrobeHunter Microscopy Magazine - December 2012 - 7
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Page 4 and 5: STEREOMICROSCOPYHistory of Stereomi
Page 26 and 27: REFERENCE PLATEDesmids26 - MicrobeH
Page 28 and 29: MEASURINGMicroscope calibration tec
Page 30 and 31: OBSERVATIONSOf computer screens and
Page 32 and 33: GALLERYEpithelial cellsMouth cells
Page 34 and 35: GALLERYVorticella sp. ciliate20x (t
Page 36 and 37: GALLERYAlgae and Radiolarian eggTop
Page 38: What’s this? Answer on page 3.38

December 2012 - MicrobeHunter.com

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