High throughput and high resolution are not independent parameters, and optimization must be performed to define the best system. The optimization procedure must consider practical limitations. N is a combination of the finesses due to reflectivity, instrument defects and detector broadening. There are three important features to note from these equations. First, the amount of light collected decreases monotonically as the reflectivity increases.
Defects increase the interferometer halfwidth and decrease the peak transmission.
Third, if the finesses are significantly different, then the resolution is determined by the smallest finesse. A practical rule is to try to make the finesses approximately equal. The HRDI detector is a multi-channel device which has 32 channels equally spaced in wavelength. The number of channels was limited by telemetry and manufacturing capabilities. The aperture finesse is approximately the number of channels per order.