Patent ID: 7719686

Claim:
A system for measuring a property of a pressurized flowing fluid using interrogating radiation at a predetermined wavelength, the system comprising: a flow cell itself comprising: a first and a second housing member, one of the housing members having a window transparent to interrogating radiation; a substantially planar partition transparent to interrogating radiation mounted within the flow cell in spaced relationship to both the housing member having the window and to the other housing member, the partition having a first surface and a second surface thereon, the first surface of the partition confronting the window in the one housing member and the second surface of the partition confronting the other housing member, the partition being disposed such that the first surface of the partition and the window cooperate to define a cavity therebetween while the second surface of the partition and the other housing member cooperate to define a fluid sample chamber therebetween, the spacing between the partition and the window being such that radiation reflected from a fluid being interrogated in the sample chamber is able to undergo total internal reflection in the partition without evanescently coupling into the window, the partition having a maximum thickness dimension sized such that lateral propagation of radiation due to total internal reflection within the partition is minimized so that substantially all of the radiation reflected from a fluid being interrogated in the sample chamber exits the partition within a predetermined lateral distance along the plane of the partition and through the surface of the partition facing the window; a pump for pumping a fluid through the sample chamber; and a spectrophotometer operative to direct interrogating radiation toward a fluid flowing through the sample chamber and to respond to interrogating radiation reflected from a fluid to produce an electrical signal representative of a property thereof.