2.1.3 - Measuring objects seen with a light microscope

Question 1

What is an eyepiece graticule?

Answer 1

a measuring device, placed in the eyepiece of a microscope

acts as a ruler when you view an object

Question 2

What is a stage graticule?

Answer 2

a precise measuring device
it is a small scale that is placed on a microscope stage
used to calibrate the value of eyepiece divisions at different magnifications
only used to calibrate the eyepiece graticule

Question 3

How do you calibrate the eyepiece graticule?

Answer 3

• stage graticule placed on the microscope stage
  1. insert eyepiece graticule into the x10 eyepiece of your microscope = 100 divisions
  2. place a stage graticule on the microscope stage and bring to focus using low-power (x4). total magnification is now x40
  3. align eyepiece and stage graticule. check value of one eyepiece division
  4. in book example (pg 33) stage graticule (1mm or 1000um) corresponds to 40 eyepiece divisions
  5. each eyepiece = 1000/40um = 25um
  6. use x10 lens and focus on the stage graticule
  repeat procedure