LIQUID LEVEL HEIGHT-MEASURING APPARATUS

摘要

A liquid level height-measuring apparatus comprises a light wave generator (203a, 203b) for generating distance-measuring light waves modulated at a predetermined modulation frequency; an objective optical system (101) for irradiating the distance-measuring light waves upon the surface (S) of a liquid level to be distance-measured and collecting the light waves reflected from the surface; a light receiving system (30) for receiving the reflected light waves; and a light wave transmission piping member (102) for optically connecting the light wave generator (203a, 203b) with the objective optical system (101), while optically connecting the objective optical system (101) to the light receiving means (30). The height of the liquid level is measured on the basis of the distance-measuring light waves and the reflected ones. The light wave generator (203a, 203b) is adapted to generate two kinds of distance-measuring light waves for measuring the height of the liquid level and the length of the light wave transmission piping member (102), both kinds of the light waves being different from each other in terms of the wavelength.