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

Comparing Chromatic Aberration Quantitatively?

  1. Nov 18, 2015 #1
    Hi, I have 2 similar lens systems used for basic astronomy (as refracting telescopes). The first is a telephoto lens designed for a camera and the second is the main objective of an old pair of binocs paired with an eyepiece in a tube. I am suspecting the former exhibits more chromatic aberration just based on some observations of the moon and bright stars.

    I was wondering if there is an experimental setup I could perform, even crudely, on my workbench tabletop that would allow me to compare the chromatic aberrations of both systems quantitatively.
     
  2. jcsd
  3. Nov 18, 2015 #2
    If you have two different colored lasers, you can measure their refraction angles.
     
  4. Nov 19, 2015 #3

    Andy Resnick

    User Avatar
    Science Advisor
    Education Advisor
    2016 Award

    As with any optical test, the details matter: image and object distance, field height, f/#... There are two 'flavors' of chromatic aberration- transverse (or lateral) and longitudinal, and these are independent.

    Start with the standard spectral lines: 656.3, 587.6, and 486.1 nm. If you don't have access to a 'clean' spectral source, you can probably use a compact fluorescent source. Use of a broadband source (sunlight) will make the measurement more difficult.

    The simplest measurement is a 'star test': image a point source and compare the locations of the image at different colors: transverse chromatic will shift the image from side to side, while longitudinal will shift the focal plane along the optical axis. Note that typical chromatic aberrations in a reasonably corrected lens will give displacements on the order of microns. Imaging the 'star' at different field heights and stop sizes will characterize the system.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Comparing Chromatic Aberration Quantitatively?
  1. Chromatic aberration (Replies: 1)

  2. Chromatic dispersion (Replies: 1)

Loading...