When the focal length is larger, the annulus and the Fourier spectrum are magnified. This is another degree of freedom to match the constraints of the detectors with the optical systems. The annulus is pixelated at the moment, both radially and angularly. We are seeking an optimal number of detector elements distributed throughout this region that minimizes the number, while maintaining the required degree of discrimination. What isn't easy is to go out and buy an array of detectors already mapped onto a semicircle.
Most arrays are linear.
We haven't decided whether we want to optically map the region in the Fourier plane into a linear array or whether we should construct an array of point detectors in a semicircular geometry ourselves. It could go either way. We haven't decided. Dr. Fiddy and Dr. Testorf are giving me a lot of suggestions and ideas. I do the calculations and the analysis.