Patent ID: 7450235

Claim:
A method for determining a condition of a fluid flow, the method comprising: directing a first optical signal to a fluid sample in a fluidic cavity in a glass block optically transparent to the first optical signal, wherein the fluidic cavity is connected in-line with the fluid flow; guiding a second optical signal from the fluidic cavity via a glass waveguide region of the glass block, the second optical signal resulting from illumination of the fluid sample with the first optical signal; capturing the second optical signal via a detector spaced from the fluidic cavity and coupled to the glass block to receive the second optical signal via the waveguide region; and, monitoring an optical property of the fluid sample based on the second optical signal to determine the condition of the fluid flow; wherein the monitoring step comprises quantitatively measuring an intensity value of the second optical signal at the detector, and wherein the glass waveguide region is positioned such that the intensity value of the second optical signal is indicative of absorption of the first optical signal in the fluid flow.