The Phase Telescope - أطلس مختبرات العرب

If the condenser annulus, positioned in the front focal plane of the substage condenser, is not in exact alignment with the fixed phase plate in the objective (that is located centrally along the microscope optical axis), the contrast effect afforded by phase contrast optical systems will be dramatically compromised. In order to ensure proper microscope operation and to maximize the phase contrast effect, the objective rear focal plane should be examined with the condenser annulus in place to ensure that the microscope is properly aligned. This task can be accomplished using either a phase telescope, which can be inserted into one of the eyepiece observation tubes (in place of a normal eyepiece), or a Bertrand lens built into the microscope binocular (or trinocular) eyepiece tube assembly.