Continuous scanning optical assembly and method of use thereof

An automated sample analyzer comprising:

• a) a rotation assembly operable to start and stop continuous rotation of a substrate, the substrate having a well disposed within a perimeter of the substrate, wherein the well is configured to hold a reaction mixture including a sample and reagent;
• b) an optical assembly having an illumination source and an illumination detector,
• wherein the optical assembly is operable to irradiate the reaction mixture with light emitted from the illumination source and detect emission light from the reaction mixture via the illumination detector, and
• wherein the optical assembly is configured to generate a coincidence of the focal points of the illumination and detection light paths on a plane of rotation of the substrate;
• and
• c) a processor operable to control movement of the rotation assembly, wherein the processor includes functionality to cause the rotation assembly to continually rotate the substrate and adjust a height of the plane of rotation of the substrate relative to the focal point.