Rotatable detector

A rotatable detection unit in an instrument for supporting a cuvette tray having a plurality of samples to be evaluated by the instrument, which comprises a horizontal mount carried by said instrument, a rotatable, hollow shaft extending vertically through said mount, said hollow shaft having an axis, a circular printed circuit board fixed to one end of said shaft and rotatable therewith, a plurality of light detectors spaced equidistant adjacent the periphery of said circuit board, a hollow, metal, receptacle means having an annular groove adapted to receive the cuvette portion of the tray, said annular groove being concentric to said axis, a spacer connecting said receptacle to said circuit board for rotation therewith, a light source positioned on said axis in a plane passing through said annular groove, a plurality of light passages extending radially in said plane through said receptacle to said annular groove for illuminating a respective plurality of samples, light attenuating means for providing a substantially equal amount of light exiting each of said passages, a plurality of light pipes, each of said plurality of light pipes being adapted to conduct light received from a respective sample to a respective one of said plurality of light detectors and drive means to selectively rotate said shaft.