Patent ID: 7082828

Claim:
Liquid level measurement apparatus for liquid in a holder and comprising: a holder for containing liquid; a vertical pipe secured to said holder, said pipe being arranged for at least partial submersion in said liquid; a target in said pipe and arranged to rise and fall in synchronism with rise and fall of the surface of liquid in said holder; a laser for transmitting signals longitudinally in the pipe to impinge on said target in the pipe to be reflected by said target back to said laser; a computer coupled to said laser to compare time of transmission of said signals by said laser, with time of reception by said laser of said signals reflected back by said target, and determine the level of the surface of said liquid in said holder; a signal transmission tube coupled to said laser for said signals transmitted by said laser into said pipe; said pipe having a receiver arranged to receive said transmission tube for providing a passageway for signals produced by said laser, from said laser through said pipe to said target and for return of said laser signals reflected by said target, from said target to said laser; said signal transmission tube and said receiver are configured to mate for establishing collinear axes of said transmission tube and said pipe for transmission of signals produced by said laser on said axis, from said laser to said target; and said transmission tube and said receiver are configured to mate by sliding said tube and said receiver together.