Flow cell and optical system for analyzing fluid

Abstract

A flow cell analyzes a fluid sample. A flow cell body contains a reference material and includes at least one hollow chamber to contain the fluid sample. Opposing surfaces of the flow cell body each have at least one transparent portion thereof. An optical path for light traversing through the flow cell body is defined in part by the transparent portions. A switching mechanism adjusts the amount of the reference material in the optical path to effect switching of the flow cell between a reference measurement state and a fluid sample measurement state. The reference measurement state corresponds to a first light intensity measurement and the fluid sample measurement state corresponds to a second light intensity measurement.

1 . A flow cell for analyzing a fluid sample, comprising:
 a first hollow chamber for containing a reference fluid, the first hollow chamber including opposing first and second transparent surfaces;   a second hollow chamber for containing the fluid sample, the second hollow chamber including opposing first and second transparent surfaces; and   a switching mechanism operative to move the first and second hollow chambers so as to alternately position the transparent surfaces of the first hollow chamber and the transparent surfaces of the second hollow chamber in a light path between a light source and a light detector to effect switching of the flow cell between a reference measurement state corresponding to a measurement associated with light traversing through the first hollow chamber, and a fluid sample measurement state corresponding to a measurement associated with light traversing through the second hollow chamber.   
     
     
         2 . The flow cell of  claim 1 , wherein the switching mechanism is configured to translationally move the hollow chambers to effect switching between the states. 
     
     
         3 . The flow cell of  claim 1 , wherein the hollow chambers are moved jointly by the switching mechanism. 
     
     
         4 . The flow cell of  claim 1 , wherein when in the reference measurement state, light emitted by the light source passes at least through the first transparent surface of the first hollow chamber, the reference fluid, and the second transparent surface of the first hollow chamber, prior to reaching the light detector. 
     
     
         5 . The flow cell of  claim 1 , wherein when in the fluid sample measurement state, light emitted by the light source passes at least through the first transparent surface of the second hollow chamber, the fluid sample, and the second transparent surface of the second hollow chamber, prior to reaching the light detector. 
     
     
         6 . The flow cell of  claim 1 , further comprising a static lens arrangement including at least a first lens and a second lens that define an optical path, and wherein when the flow cell is in the reference measurement state, the transparent surfaces of the first hollow chamber are deployed in the optical path, and wherein when the flow cell is in the fluid sample measurement state, the transparent surfaces of the second hollow chamber are deployed in the optical path. 
     
     
         7 . The flow cell of  claim 6 , wherein when the flow cell is in the reference measurement state, light emitted by the light source passes at least through the first lens, the first transparent surface of the first hollow chamber, the reference fluid, the second transparent surface of the first hollow chamber, and the second lens, prior to reaching the light detector. 
     
     
         8 . The flow cell of  claim 6 , wherein when the flow cell is in the fluid sample measurement state, light emitted by the light source passes at least through the first lens, the first transparent surface of the second hollow chamber, the fluid sample, the second transparent surface of the second hollow chamber, and the second lens, prior to reaching the light detector. 
     
     
         9 . The flow cell of  claim 1 , wherein when the flow cell is in the reference measurement state, the second hollow chamber is positioned out of the light path between the light source and the light detector such that substantially none of the light emitted by the light source reaches the light detector. 
     
     
         10 . The flow cell of  claim 1 , wherein when the flow cell is in the fluid sample measurement state, the first hollow chamber is positioned out of the light path between the light source and the light detector such that substantially none of the light emitted by the light source reaches the light detector. 
     
     
         11 . The flow cell of  claim 1 , wherein the measurement associated with light traversing through the first hollow chamber and the measurement associated with light traversing through the second hollow chamber are light intensity measurements. 
     
     
         12 . The flow cell of  claim 1 , wherein the reference fluid is air. 
     
     
         13 . The flow cell of  claim 1 , wherein the reference fluid is deionized water. 
     
     
         14 . A flow cell for analyzing a fluid sample, comprising:
 a flow cell body including a hollow chamber for containing the fluid sample, the hollow chamber including a first surface and a second surface, the first surface fixed at a first end of the hollow chamber, and the second surface moveable relative to first surface; and   a switching mechanism operative to move the second surface relative to the first surface so as to adjust an amount of the fluid sample, present in a light path extending through the hollow chamber, between at least a first fluid sample amount and a second fluid sample amount to effect switching of the flow cell between:
 a reference measurement state corresponding to a measurement associated with light traversing the hollow chamber, via the light path, through the first fluid sample amount, and 
 a fluid sample measurement state corresponding to a measurement associated with light traversing the hollow chamber, via the light path, through the second fluid sample amount. 
   
     
     
         15 . The flow cell of  claim 14 , wherein the first and second surfaces are transparent surfaces, and wherein the light path is defined in part by the first and second transparent surfaces. 
     
     
         16 . The flow cell of  claim 14 , wherein the amount of the fluid sample in the light path corresponds to an amount of the fluid sample between the first and second surfaces. 
     
     
         17 . The flow cell of  claim 14 , wherein the second surface is linearly moveable relative to the first surface. 
     
     
         18 . The flow cell of  claim 14 , wherein movement of the second surface relative to the first surface effects a distance between the first and second surfaces, and wherein the distance is variable over a range of distances between a first distance and a second distance. 
     
     
         19 . The flow cell of  claim 14 , wherein the first and second surfaces are substantially parallel to each other. 
     
     
         20 . The flow cell of  claim 14 , wherein when the flow cell is in the fluid sample measurement state the first and second surfaces are separated by a first distance, and wherein when the flow cell is in the fluid sample measurement state the first and second surfaces are separated by a second distance that is less than the first distance.