Optical detector for air in fluid line the same

US5672887A · kind A · utility

Inventors

• Benjamin G. Shaw · San Francisco, US
• Tony Lillios · Palo Alto, US

Key dates

• Filing date: Aug 28, 1996
• Grant date: Sep 30, 1997
• Expiry date: Aug 28, 2016

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N2021/0364
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Ambiguity, in readings from an optical bubble detector used with tubing, can be reduced by shaping the tubing into the shape of a prism, so that when different contents of the tubing have differing indices of refraction, there is a clear difference in the exit angle of the light beam leaving the tube. A triangular prism shape is preferred for the compressed tubing. The optical bubble detector features an optics block formed with a V-shaped recess, and a clamp block. The optics block and clamp block cooperatively press or "sandwich" the flexible tubing into the V-shaped recess and deform it into a triangular prismatic cross-section. A generally U-shaped optical interrupter element, containing a photoemitter and a photosensor, fits into the optics block in such a manner that a light beam is directed radially into the triangular tubing section. The clamp block "windows" the transmitted and received light from the optical interrupter, to allow only a thin channel of light to be transmitted; this minimizes optical noise during measurement. When saline is located in the tubing, the light follows a fairly straight path through the optics block and tubing. However, when air is in the tubin…