Microscope Terms


Arm: The vertical portion of the microscope that connects the base and head.


Base: Heavy bottom that supports the microscope.


Coarse adjustment knob: Used for initial focusing on the microscope specimen.


Condenser: A small substage lens that concentrates light on the microscope specimen.


Fine adjustment knob: Used for precise focusing, once initial focusing has been done on the microscope specimen.


Head: Supports the microscope ocular lenses and the objective lens system, which is mounted on a movable nosepiece. Also called body tube.


Iris diaphragm: Used to regulate the amount of light passing through the microscope specimen


Mechanical stage: Holds the microscope slide in position for viewing, and allows precise movement of the specimen.


Microscope field: The area that is seen under a microscope. For example, at 40× magnification the diameter of the microscope field is around 5 mm, at 100× it is around 2 mm, at 400× it is around 0.5 mm, and at 1000× it is around 0.2 mm.


Nosepiece: A rotating mechanism at the bottom of the head.on the microscope, which contains three or four objective lenses.


Objective: An adjustable system of four lenses with different magnifying powers on the microscope. In our lab, the scanning lens (4×) provides 40-fold magnification, the low power lens (10×) provides 100-fold magnification, the high power lens (40×) provides 400-fold magnification, and the oil immersion lens (100×) provides 1000-fold magnification.


Ocular: The eyepiece lenses at the superior end of the head that allows observations to be made on the microscope.


Parfocal: A microscope that only needs to be focused at the low power, and all of the higher powers will either be in focus, or they will only need a fine adjustment.


Resolution: The resolving power of the microscope; the optic ability to distinguish detail, such as the ability to discriminate between two close objects.


Stage: A platform on which the microscope slide rests for viewing.


Working distance: The distance from the bottom of the objective lens to the specimen on the microscope slide.