Method: each detector/ camera images an even illumination/ fluorescent source. This can be performed using the internal light sources and a fluorescent acetate slide or an etched fluorescent pattern covering the field of view (or alternatively, an external light source at objective? How to get even enough?). A minimum standard would be recording the field of view for each objective over the widest field of view.
Justification: this allows monitoring of objective quality and internal lightpath optics (eg galvo mirrors or filter cubes). Comparison of field flatness over time for each objective will identify any new aberrations in the system (eg damaged objective, light source centricity (widefield), offset galvo mirrors). The data can be used for post acquisition correction if required, and therefore improves the quantification of data from across the field of view, improving data reliability.