Intra-liquid optical measuring sensor and contamination preventing method

An intra-liquid optical measuring sensor adapted for measuring a property of a liquid, said sensor comprising an optical fiber having a core and a cladding, said sensor also comprising a capillary pipe having a liquid substance inside an inner diameter portion of said pipe, said inner diameter portion having a diameter that is at least equal to an outer diameter of said core and within a range within which said liquid substance can be held by surface tension of an inner surface of said pipe and pressure of said liquid whose property is to be measured by said sensor, said liquid substance having a light transmitting property, said pipe being attached to an end of said optical fiber such that the inner diameter portion of said pipe is disposed continuously to said end of said fiber so as to form a liquid core containing said liquid substance, said liquid core being in communication with said liquid whose property is to be measured by said sensor.

A contamination preventing method for an intra-liquid optical measuring sensor adapted for measuring a property of a liquid, said sensor including an optical fiber, said method comprising:

• providing a core of said optical fiber with a liquid portion composed of a liquid substance;
• and
• directly contacting a contacting portion of said liquid portion with said liquid whose property is to be measured by said sensor, said liquid substance in said liquid portion being in communication with said liquid whose property is to be measured by said sensor and acting to reduce deposition onto said contacting portion of contaminant substances from said liquid whose property is to be measured.