Optical transducers based on liquid crystalline phases

US6137576A · kind A · utility

Assignee

• Merck Patent GmbH · DE

Inventors

• Detlef Pauluth · Ober-Ramstadt, DE
• Joachim Krause · Dieburg, DE
• Gunter Gauglitz · Tübingen, DE
• Bernd Drapp · Reutlingen, DE

Key dates

• Filing date: Jul 28, 1998
• Grant date: Oct 24, 2000
• Expiry date: Jul 28, 2018

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N21/45
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Optical transducers for measuring a contaminant in a gas are disclosed, whereby said contaminant interacts with a liquid crystalline phase as a sensing element in a flow cell. According to the invention nematic crystalline phases on a orientation layer are used. Means are provided to measure or to detect changes of the refractive index of said liquid crystalline phase caused by interaction of said contaminant with said liquid crystalline phase. In preferred embodiments the means for measuring or for detecting the refractive index is a Mach-Zehnder interferometer, a grating coupler, or a device for e.g. visual detection, whereby the flow cell is placed between two linearly polarizing filters, and whereby the two axis of polarization are crossed. Furthermore optical transducers are disclosed, which contain an isotropic dopant in a liquid crystalline phase. Also disclosed is the use of these optical transducers for detecting or measuring contaminants in gases using an optical transducer according to the invention.