Optical process for non-intrusive measurement of the temperature of a flowing liquid using the fluorescence induced by a laser beam in a measured volume of liquid

摘要

A single temperature sensitive fluorescent tracer is used with two spectral detection windows on the same tracer. The single reception area has a holographic filter (6) and a separation assembly (4) dividing the optical signal into two (5a,b). Each measuring route has a filter giving a measuring window, an amplifier (9a,b) converting the light signals to electrical signals and a computer (11) Preferred Features: The tracer used is Rhodamine B (C28H31ClN2O3). The ratio between the intensity measurement of the fluorescence of the two signals received in the two windows is: Rf = (If1/If2) = Ke ( beta 1 - beta 2)/T. The apparatus constant K is determined by a simple calibration at a known temperature To, giving Ln (Rf/Rfo) = ( beta 1 - beta 2)/(1/T 1/To) where Rfo is the ratio at temperature To. The filter forming the measuring window can be an interference filter, a pass-band, high pass or low pass filter. In particular, the first signal passes through a, interference pass-band filter (7) with band size DELTA lambda 1 centred on a wavelength lambda 1 of about 530 nm and the second signal passes through a high pass filter (8) with a threshold wavelength lambda 2 of about 590 nm.