Light detection device with means for tracking sample sites

An apparatus for detecting light transmitted from a sample site, the apparatus comprising:

• a stage for supporting a substrate containing the sample site;
• a detector configured to detect light;
• an optical relay structure positioned between the stage and the detector and configured to transmit light from a sensed volume to the detector;
• and
• a support structure configured to support the stage, the detector, and the optical relay structure;
• where the stage and the optical relay structure are configured to align the sample site and the sensed volume automatically and to maintain that alignment while moving the sample site relative to a fixed portion of the support structure, so that light transmitted from the sample site can be detected by the detector as the sample site is moved.

A method of detecting light transmitted from a substrate having first and second sample sites, the method comprising:

• moving the substrate in a first direction so that the first and second sample sites pass sequentially through an initiation position and a termination position;
• aligning a sensed volume with the first sample site at the initiation position and maintaining the alignment while detecting light transmitted from the sensed volume as the first sample site moves from the initiation position to the termination position;
• and
• aligning the sensed volume with the second sample site at the initiation position and maintaining the alignment while detecting light transmitted from the sensed volume as the second sample site moves from the initiation position to the termination position.