Optical Microscope

 The calibrated eyepiece has a ruler with marking in it. 

First line up the ruler to the edge of the feature you want to measure.

Each of the markings on the ruler is 100 units. In the drawing the feature is 300

units + some amount less than 100. Use the long line that is controlled by the

knob on the calibrated eyepiece to measure the remaining length. First, turn

the knob until the line is overlapping the last ruler marking that falls on the

feature. Check the number on the knob. Turn the knob until the line is at the

edge of the object that you want to measure. Check the number again. Add or

subtract the numbers depending on the direction you turned the knob. Add this

to the measurement you took using the ruler. In this example add the number

to 300. Make a simple drawing for one of the structures and mark the important 

dimensions.

Calculation: Once you have obtained a measure for each of the features in

units, you will need to convert this measure to microns. There is a conversion

on the microscope for 20x objective 207 units = 100 microns.

Depth Measurements:  To measure depth, focus the lens on the upper surface, using the knob on the right (shown above at the base of microscope), and note the   number on the knob.  Now bring the bottom surface into focus, keeping track of the number of revolutions of the knob. Subtract/add the number on the knob acquired from focusing on the upper surface and the number on the knob for focusing on the bottom surface. Convert this number to microns and add it to the value calculated for the number of revolutions.     

Calculation:  1 revolution = 120 microns

procedure prepared by Jennifer Blain, Fall 2002; modified by La Vida Cooper, Spring 2003.