公开(公告)号：US4938590A

公开(公告)日：1990-07-03

申请号：US230552

申请日：1988-08-10

Applicant: Sadao Ishida

Inventor： Sadao Ishida

IPC: G01F23/30 ,  F17C13/02 ,  G01F23/292 ,  G01F23/68

CPC classification number: F17C13/021 ,  G01F23/292 ,  G01F23/686 ,  F17C2201/0109 ,  F17C2201/0128 ,  F17C2201/032 ,  F17C2201/035 ,  F17C2221/014 ,  F17C2221/035 ,  F17C2221/037 ,  F17C2223/0153 ,  F17C2223/033 ,  F17C2250/0417

Abstract: An fiber optic liquid level indicator with a floating reflector includes a reference scale provided with a reflector disposed in an upper space above the liquid level within a pressure vessel so that a reference distance usable to correct error due to pressure can be calculated on the basis of travel time of a laser beam pulse emitted from a laser generator and reflected from the reference scale reflector through an optical guide and lens. A beam change-over switch is used to selectively guide a laser beam pulse to either the floating reflector or to the reference scale reflector so that pulse travel time can be determined.