Any time you make changes to the instrument configuration the new characteristics of the instrument are updated and displayed in the text area to the right.
Some of the choices are limited by the characteristics of the instrument. It is not possible to choose a configuration that will not work on the instrument selected.
The available aperture sizes are circular with the following diameters (given in fractions of an inch): 1/8, 1/4, 3/8, 1/2, 5/8.
Other aperture shapes and sizes can be arranged but require consultation with an instrument responsible.
Report errors or make inquiries to Alan Munter, <alan.munter@nist.gov>