System and method with fiducials in non-rectilinear layouts

An array, comprising:

• a support having locations that, in an operation, receive biological samples differing from one another to respond differently in successive cycles of fluorescent imaging;
• and
• fiducial features on the support having a fluorescent material that responds in the successive cycles of fluorescent imaging, wherein the fiducial features are disposed on the support in a non-rectilinear layout, wherein the fiducial features comprise a non-closed shape.

A method, comprising:

• disposing biological samples at locations on a support, the biological samples differing from one another to respond differently in successive cycles of fluorescent imaging;
• and
• disposing fiducial features on the support, each of the fiducial features comprising a fluorescent material that responds in the successive cycles of fluorescent imaging, wherein the fiducial features are disposed on the support in a non-rectilinear layout.