The basic function of a fluorescence microscope is to irradiate the specimen with a desired and specific band of wavelengths. A fluorescence microscope uses a mercury or xenon lamp to produce ultraviolet light. The light comes into the microscope and hits a dichroic mirror. The dichroic mirror reflects the ultraviolet light up to the specimen. The ultraviolet light excites fluorescence within molecules in the specimen. The objective lens collects the fluorescent-wavelength light produced. This fluorescent light passes through the dichroic mirror and a barrier filter, making it to the eyepiece to form the image.
They are called a population, because they are the same species living in a given area. The word population means the amount of a certain species living in a certain environment.
