System and method with reflective fiducials for locating or registering locations receiving biological samples in successive cycles of fluorescent imaging

An array, comprising:

• a support comprising a glass material, a semiconductor material, or combinations thereof, the support having locations that, in an operation, receive biological samples differing from one another to respond differently in successive cycles of fluorescent imaging;
• and
• a fiducial feature that is formed in or on the support and that is optically reflective to, during the successive cycles of fluorescent imaging, return at least a portion of an incident radiation for locating or registering the support or the locations,
• wherein the fiducial feature comprises a metallic material.

A method, comprising:

• accessing image data encoding successive images of biological samples disposed at locations on a support and of a fiducial feature formed as troughs in or as ridges on a surface of a support, the biological samples differing from one another to respond differently in successive cycles of fluorescent imaging, the fiducial feature being optically reflective to, during each of the successive cycles of fluorescent imaging, return at least a portion of an incident light away from the surface of the support for locating or registering the support or the locations;
• registering, for the successive images, the locations on the support by a reference to the fiducial feature;
• and
• processing the registered successive images to transform data derived from the registered successive images to sequence data.