An inexpensive, simple and easy-to-use illuminator element--consisting of chromophores, particularly fluorophores, and/or light-scattering bodies in a stable, typically a polymer plastic, matrix--completely replaces an infinite set of condensers for a optical microscope, and works equally well with microscope objective lenses of any and all numerical apertures. Illuminator elements of a fluorescent type are employed in combination with a primary source of light that is external to the illuminator element itself, and that is preferably but a simple incandescent light bulb. Nonetheless to be energized with spectrally impure light, each illuminator element produces spectrally pure light(s) of a predetermined color or colors, including a pseudo-white light. Sets of illuminator elements permit the ready production of colored light(s) of any desired spectral characteristics from primary light sources that are no more sophisticated, nor any more expensive, than common electric light bulbs. An illuminator element substantially eliminates most image artifacts while supporting imaging of a quality comparable to the best images obtainable with highest quality condensers correctly matched to the numerical aperture of a microscope's objective lens. Illumination fully comparable to Koehler illumination is obtained virtually effortlessly simply by placing an illuminator element near, and normally directly upon, a specimen that is typically mounted upon a microscope slide.