The light rays are organized and conducted through the instrument so the light can be polarized and redirected.
The light from the condenser (has as function concentrate light on the sample) will fill the plane of the objective and a ray of light will be project to lighten the field, basically the condenser is able to control the angle of the illumination which permits the right balance of resolution and contrast in the microscope.
The light passes through the sample and it will go to the objective where the image will be magnified. The second step it’s going to the oculars when the enlargement can be observe. This type of microscopy permits the capture of high-quality images but the most important factor it’s the illumination because permits the capture of images bright enough to be useful.