Comparing Chromatic Aberration Quantitatively?

  • Thread starter mishima
  • Start date
  • #1
532
31
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.
 

Answers and Replies

  • #2
Khashishi
Science Advisor
2,815
493
If you have two different colored lasers, you can measure their refraction angles.
 
  • #3
Andy Resnick
Science Advisor
Education Advisor
Insights Author
7,509
2,079
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.
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.
 

Related Threads on Comparing Chromatic Aberration Quantitatively?

  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
15
Views
4K
Replies
12
Views
1K
  • Last Post
Replies
1
Views
2K
Replies
18
Views
18K
Replies
5
Views
2K
Replies
3
Views
3K
Replies
41
Views
12K
Top