Wednesday, March 07, 2007

The phase contrast microscopes are widely used for a variety of applications such as molecular and cellular biology research, clinical and medical diagnosis of health conditions, living tissue culture viewing, microbiological research, dog breeding, horse breeding, animal breeding, infertility treatments, analysis of spermatoza in semen, sperm cell motility, sperm count, sperm morphology, mold and mildew detection and abatement, mold spore count, mold spore identification, stachybotrys (toxic black mold, stack mold) treatment, aspergillus mold identification, environmental air pollution monitoring, viewing of human squamous cheek cells, dust mite control, and asbestos testing. It is a type of light microscopy that enhances contrasts of transparent and colorless objects by influencing the optical path of light. The phase contrast microscope is able to show components in a cell or bacteria, which would be very difficult to see in an ordinary light microscope. Phase contrast microscopes, or phase contrast microscopy, employ a special illumination technique known as phase contrast to improve the contrast in unstained biological samples without significantly sacrificing image resolution. Similar to darkfield illumination, phase contrast is ideal for use with transparent samples that seem to blend into a light background, and results in specimens that contrast from a darker background. The phase contrast effect is achieved by superimposing a circular phase annulus located in the sub-stage condenser with a corresponding circular phase ring located in the back focal plane of the objective lens. Specimens subjected to phase contrast illumination often appear to be surrounded by halos, and appear against a grayish background if used with plain white light, and appear against a green background if used with a green filter in the light path. Phase contrast is one of the most, if not the most, commonly used biological contrast enhancing technique today. Phase contrast microscopy can be performed on upright microscopes and inverted microscopes, and is especially useful in the study of living cells and tissues, aquatic and other microorganisms, microbiological features such as cell nuclei, glass fragments and fibers, mineral fibers such as asbestos, bacterial cultures and more.