Fluorescence Spectra Viewer 

Optical Microscopy by Michael W. Davidson and Mortimer Abramowitz

This article discusses the basics of image formation, depth of field, objectives, eyepieces, condensers, contrast enhancement, and photomicrography with full-color illustrations.  

Optical Microscopy Primer from Molecular Expressions 

Interactive virtual microscopes (Java enabled) examine specimen focus, illumination intensity, magnification, and translation using 17 different microscopy techniques. 

Resolution App by Andrew L. Barlow

Available for Android and Apple Products

Link for Google Play: https://play.google.com/store/apps/details?id=com.Barlowax.resolutionfragments&hl=en

Koehler tutor App by Andrew L. Barlow

Available for Android and Apple Products

Link for Google Play: https://play.google.com/store/apps/details?id=com.barlowax.koehlertutor&hl=en