Transmitted Light Microscopy

A conventional compound microscope is sufficient for the majority of hair work. Most observations are conducted below x40 objective magnification. In order to minimize the number of samples to prepare, hair is first mounted dry under large cover slips. Tape can be used to secure the cover slip at either end. Due to the thickness of the hair shaft and optical interference from the hair surface it may be difficult to resolve very sharp images. However, damaged fiber ends, brush breaks, tichorrhexis nodosa, bubble hair, and changes in fi ber shape such as pilitorti are all easily observed.

 Transmitted light microscopy in liquids is shown in Figures 6 and 7. Due to the difference in refractive index between dry hair, air, and glass, combined with the thickness of the sample it is difficult to see beyond the hair surface. The addition of either distilled water or immersion oil between the cover slip and slide removes most of the refractive index differences. Water is the liquid of choice, as this can be easily instilled by capillary action along the edge of a dry mount slide. Water also has little effect on the fiber should it be required for storage or further investigation. Using a liquid provides more detail of the cortex in conditions such as bubble hair or piliannulati.