A case-study in confusion
Compare Howland aberroscope with Shack-Hartmann aberrometer
Should we use ray or wave aberrations?
Should we use Seidel, Taylor, or Zernike descriptors?
Which data-fitting method works best?
How to convert between describing systems?
How to generate and order the Zernike polynomials?
How to specify pupil center, reference axis?
How to convert between different reference axes?
How will we know if we did it right?
Notes:
To illustrate the practical problems that currently exist in our field, I will digress momentarily to present a “case study in confusion”. Last summer, Applegate and I wanted to compare results obtained with the venerable Howland crossed-cylinder aberro
Read & elaborate each question.
The last question is especially troublesome. Ray’s favorite question is “Where is the gold standard in our field? Where is the model eye with known aberrations that we can use to can calibrate our aberrometers? “
In the absence of a gold standard, Applegate built a physical model eye which I will tell you about in a moment. But first, let me give you some concrete examples of how the the problems identified on this slide can rear their ugly heads and impede progress