Patent ID: 8269193

Claim:
A handheld fluorometer, comprising: a handheld controller module comprising an elongated housing comprising a bottom surface, a controller that determines a concentration of a substance in a water sample based on a detected fluorescent emission, a display coupled to the controller for displaying the concentration, and an input interface for entering data for use by the controller; an immersible sensor head comprising a light source coupled to the controller, an emission detector coupled to the controller, and a housing comprising a proximal end and a distal end between which extends a longitudinal axis of the sensor head, the sensor head being connected to the bottom surface of the controller module at the proximal end of the sensor head housing, the sensor head housing further comprising a light source window that transmits excitation light from the light source inside the sensor head housing to an analytical area outside the sensor head housing, and an emission detector window that transmits fluorescent emissions from the analytical area to the emission detector inside the sensor head housing; a sample cup for containing the water sample; and a fastener that removably fastens the sample cup about the sensor head such that at least the light source window and the emission detector window can be immersed in the water sample contained in the sample cup, wherein the water sample occupies the analytical area.