Getting Data#

The goodman focus value ranges from \(-2000\) to \(+2000\) the best practice (from experience) is to sample every \(200\). If you want to refine you should not go below a \(100\) step. If you already know the approximate focus value for a given setup, you don’t need to do the full range, just take enough samples so it is possible to make a fit or see the trends. At least five points.

Note

Always use the narrowest slit available

Imaging#

For imaging, an image of the slit is obtained, illuminated by an uniform light such as a quartz lamp. A special ROI is used for faster reading. This does not affect the focus of course.

(Source code, png, hires.png, pdf)