(12) United States Patent ao) Patent No.: us 6,549,276 Bi
Longtin (45) Date of Patent: Apr. 15,2003
(54) METHOD AND APPARATUS FOR OPTICAL MEASUREMENT OF CONCENTRATION AND TEMPERATURE OF LIQUIDS
(75) Inventor: Jon P. Longtin, East Setauket, NY (US)
(73) Assignee: Research Foundation of State
University of New York, Stony Brook,
NY (US)
( * ) Notice: Subject to any disclaimer, the term ol this patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days.
(21) Appl. No.: 09/830,735
(22) PCT Filed: Oct. 30, 1998
(86) PCT No.: PCT/US98/23179
§ 371 (c)(1),
(2), (4) Date: Jul. 9, 2001
(87) PCT Pub. No.: WO00/26665 PCT Pub. Date: May 11, 2000
(51) Int. CI.7 G01N 21/41
(52) U.S. CI 356/128; 356/134
(58) Field of Search 356/128, 134,
356/335, 336, 337, 338, 341, 343, 388,
394
(56) References Cited
U.S. PATENT DOCUMENTS
4,907,884 A * 3/1990 Philips et al 356/336
Disclosed are a method and an apparatus for precision optical measurement ol solute concentration and temperature ol a transparent liquid. The apparatus includes a vessel (12) which contains a sample ol liquid (14), the refractive index ol which is to be determined, a light source (22) and a beam position sensor (30). The vessel (12) has an entrance side and an exit side, with a known angular relationship therebetween, and is situated in a known ambient The light source (22) is located so as to cause a beam ol light to impinge on the entrance side at an angle with respect to a normal to an outer surface ol the entrance side, to pass through the liquid (14), and to then pass through the exit side, from which it exits at an angle with respect to a normal to an outer surface ol the exit side. The beam position sensor (30) provides data lor determining the exit angle thereby permitting the refractive index ol the liquid to be determined, based on the angles.
23 Claims, 4 Drawing Sheets
