Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Distance measurement

  1. Jun 3, 2005 #1
    How are distances on the order of microns or nanometers measured for objects like say a bacteria or a very small component of a device where distance measurement through interference of light isn't very feasible?
  2. jcsd
  3. Jun 3, 2005 #2
    relative distance or exact distance..?
    it is a lot easier to get relative distance than exact..
  4. Jun 3, 2005 #3
    Well, exact distance.
    Can't you get that by doing a series of relative measurements?

    And anyhow, how do we measure relative distances?
  5. Jun 3, 2005 #4
    Can electron microscopes help here? I know they can see stuff smaller than the wavelength of light.
  6. Jun 3, 2005 #5
    They are very expensive even if you try and make one yourself. I am sure there are other more cost effective methods.

    As for wavelength of light, that depends on what wavelength you are referring too.
  7. Jun 3, 2005 #6


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Sid, not too sure what you want to measure, but mechanical parts are often measured using something called an optical comparator. Most precision machine shops have these things, and I'm sure if its use were applicable you could use one without having to pay for its use. It only takes a few seconds to measure something with it, and you don't need any experience or special knowledge to run one. They can measure lengths down to about 0.0001" or less. Here's a link to a description: http://www.starrett.com/pages/691_optical_comparators.cfm [Broken]
    Last edited by a moderator: May 2, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook