Patent ID: 7724356

Claim:
An apparatus for measuring a differential refractive index having a flow cell deflecting a measurement beam in accordance with the refractive index difference between a reference liquid and a sample liquid for measuring the change of the deflection angle on the basis of the refractive index difference of the measurement beam transmitted between the reference liquid and the sample liquid, wherein the flow cell comprises three independent chambers including a first chamber, a second chamber adjacent to the first chamber and a third chamber adjacent to the second chamber, and the measurement beam is irradiated on the flow cell so as to sequentially transmit these three chambers in a state in which the reference liquid flows or is sealed in the first and third chambers and in a state in which the sample liquid flows or is sealed in the second chamber; wherein the apparatus further comprises a flow passage which allow the reference liquid to flow from the first chamber to the third chamber; wherein the apparatus further comprises a first sealing plate forming the flow passages and a first block, wherein the first sealing plate is sandwiched between the first block and the flow cell; wherein the flow cell further comprises: a first inflow port allowing the reference liquid to flow into the first chamber, a first outflow port allowing the reference liquid to flow out from the first chamber, a second inflow port allowing the sample liquid to flow into the second chamber, a second outflow port allowing the sample liquid to flow out from the second chamber, a third inflow port allowing the reference liquid to flow into the third chamber, and a third outflow port allowing the reference liquid to flow out from the third chamber, wherein the first sealing plate comprises a reference-side inflow hole and a reference-side outflow hole in positions corresponding to the first inflow port and the third outflow port, the first block comprises a reference-side inflow passage and a reference-side outflow passage at positions corresponding to the reference-side inflow hole and the reference-side outflow hole, and the flow passage is formed between the first outflow port and the third inflow port; and wherein the apparatus further comprises: a second sealing plate having a sample-side inflow hole and a sample-side outflow hole at positions corresponding to the second inflow port and the second outflow port, and a second block having a sample-side inflow passage and a sample-side outflow passage in positions corresponding to the sample-side inflow hole and the sample-side outflow hole, wherein the second sealing plate is sandwiched between the second block and the flow cell.