Method and apparatus for optical analysis of the contents of a sheathed stream

Claim 1

Apparatus for optical analysis of a sample stream including a liquid in a coaxial sheath stream liquid comprising: means defining a flow chamber having an elongated passageway portion having a forward outlet end and at a rear end of said portion a tube inlet of substantially smaller diameter than said passageway portion extending concentrically a distance forwardly into said passageway portion and terminating forwardly in a free tube end, the last-named means defining a second inlet in said passageway portion at a location a distance rearwardly from said free tube end, and the last-named means also defining a restriction with a narrow sloping approach in said passageway portion intermediate said outlet end thereof and said free tube end, the internal and external surfaces of said free tube end and the internal surface of said passageway portion being circular in cross section, means for flowing a sample stream through said tube inlet into said passageway portion, means for flowing a sheath stream into said second passageway inlet at a greater flow rate than the sample stream to entrain the latter so as to increase the velocity of the sample stream and narrow it as the streams flow toward said restriction of the passageway portion, photometric means downstream from the upstream extremity of said restriction of the passageway portion in proximity to the sheathed stream and including a light source on one side of the sheathed stream in a position to direct light onto the contents of the sample stream and a light detector externally of the sheathed stream in angular position to detect the photometric results of impingement of light on the sample stream, and means controlling the relative flow rates of said streams into said flow chamber, which controls the radius of the sample stream, so that in the area where said light is directed on the sample stream the last-named radius may be varied proportionately to the radius of the inner surface of the sheath stream for equal and opposite refraction of light at the interfaces of said sheath stream.

Claim 15

A method for optical analysis of a sample stream including a liquid in a coaxial sheath stream liquid comprising: providing means defining an elongated passageway portion of circular cross section in a flow chamber which portion has at one end thereof a circular restriction; flowing a first laminar liquid stream into said passageway portion in a direction toward said restriction; concurrently flowing in the same direction a slower moving liquid stream of cylindrical cross section and of a substantially smaller diameter than said first stream, containing a sample, into the first stream concentrically so that the latter sheaths and entrains the second stream, accelerating and narrowing it as the streams approach said restriction in a concentric relation to one another; directing an impinging light beam of a photometer, in a direction transversely of the aforementioned direction of flow, onto the sample-containing stream for photometric analysis of the sample by a light detector of the photometer, downstream from the upstream extremity of said restriction; and controlling the relative flow rates of the streams into said passageway portion, which controls the radius of the second or sample stream, so that in the area where said light beam impinges said sample stream the last-named radius may be varied proportionately to the radius of the inner surface of the sheath stream for equal and opposite refraction of light at the interfaces of the sheath stream.

Claim 16

A method for optical analysis of a sample stream including a liquid in a coaxial sheath stream liquid comprising: providing means defining an elongated passageway portion of circular cross section in a flow chamber which portion has at one end thereof a circular restriction; flowing a first laminar liquid stream into said passageway portion in a direction toward said restriction; concurrently flowing in the same direction a slower moving liquid stream of cylindrical cross section and of a substantially smaller diameter than said first stream, containing a sample, into the first stream concentrically so that the latter sheaths and entrains the second stream, accelerating and narrowing it as the streams approach said restriction in a concentric relation to one another; directing an impinging light beam of a photometer, in a direction transversely of the aforementioned direction of flow, onto the sample-containing stream for photometric analysis of the sample by a light detector of the photometer, downstream from the upstream extremity of said restriction; and controlling the relative flow rates of the streams into said passageway portion, which controls the radius of the second or sample stream, so that in the area where said light beam impinges said sample stream the last-named radius may be varied proportionately to the radius of the inner surface of the sheath stream for equal and opposite refraction of light at the interfaces of the sheath stream.