 By removing the concentration dependence, the extinction coefficient (ε) can be determined as a function of wavelength.UV–visible spectroscopy of microscopic samples is done by integrating an optical microscope with UV–visible optics, white light sources, a monochromator, and a sensitive detector such as a charge-coupled device (CCD) or photomultiplier tube (PMT).As only a single optical path is available, these are single beam instruments.