Fluid flowmeter having an optical fiber sensing element

An optical flowmeter for monitoring the rate of fluid flow in a channel, said flowmeter comprising:

• first flexible light transmitting means, a first end of said first light transmitting means suspended from support means, and the seconc end of said first light transmitting means positioned in said channel and adapted to oscillate in response to the fluid flow,
• light source means positioned to supply incident light signals to the suspended first end of said first light transmitting means,
• second light transmitting means, a first end of said second light transmitting means suspended from said support means, and the second end of said second light transmitting means positioned in said channel and in proximity to the second end of said first light transmitting means in order to permit optical coupling therebetween, and
• optical detector means positioned to receive output light signals from the suspended first end of said second light transmitting means, the output light signals being supplied to said suspended first end from the oscillatory second end of said first light transmitting means and the second end of said second light transmitting means,
• the frequency of oscillation of the second end of said first light transmitting means and the optical characteristics of the corresponding output light signals supplied therefrom providing an indication of the rate of fluid flow in the channel.

An optical flowmeter for measuring the rate of fluid flow through a channel, said flowmeter comprising:

• a first light transmitting optical fiber, a first end of said optical fiber being positioned in said channel, so as to be caused to oscillate in response to fluid flowing therepast,
• light source means for supplying incident light signals to the oscillating first end of said optical fiber, and
• optical detector means to receive output light signals that are supplied thereto from the first end of said optical fiber,
• said optical detector means including first means by which to measure the frequency of the output light signals and second means by which to measure the intensity of the output light signals, the frequency and intensity of the output light signals being indicative of the rate of fluid flow through said channel.