PROCEDURE MEASURING FLOW VELOCITY OF LIQUID OR GAS Russian patent published in 2003 - IPC

FIELD: measurement of physical quantities. SUBSTANCE: salient feature of proposed procedure measuring flow velocity of liquid or gas based on registration of difference frequency of two coherent light waves propagating in opposite directions and passed through liquid or gas flow mentioned above is that this liquid or gas flow fills flow- type dish which opposite edges carry thin partially transmitting layer with thickness under λ/2 and reflection mirror. Angle ϕ included between plane of thin partially transmitting layer and plane of reflection mirror is found from relation sinϕ = λ/2dn where λ is length of light wave; d is period of interference bands; n is refractive index of liquid or gas filling flow-type dish. Difference frequency of two coherent light waves is recorded by means of periodic system containing photocells. Technical result lies in possibility of measurement of flow velocity of liquid or gas with registration of difference frequency under 0.1 Hz which can find use in measurement of low flow velocities of pure liquids or gases. EFFECT: measurement of low flow velocities of pure liquids or gases. 1 dwg