Method and apparatus for checking continuity of optic transmission

DETAILED DESCRIPTION The present invention is directed at an apparatus for and a method of detecting whether or not a fiber optic link is established for enabling transmission of information between a transmitter and a receiver by employing a power level which is less than that required by the transmitter for transmitting the information.
One aspect of the invention resides in an apparatus for and method of checking continuity of optic transmission, which includes a transmitter for transmitting information optically, a receiver for receiving the transmitted information and a detector for detecting an enabling of the transmission of information between the transmitter and the receiver.
Transmission of a test signal is effected from the transmitter to the receiver at a power level which is lower than that required for transmitting the information.
It is an object of the present invention to monitor whether a fiber optic link is open or closed between a transmitter and receiver by sending out a test signal at a lower power level than required to transmit the information.
The lightwave output through the fiber optic link is thereby restricted at least until successful receipt of the test signal is detected.
This precautionary step substantially prevents the danger that careless or uninformed personnel may suffer eye damage from the lightwave output where the fiber optic link is open.
It is another object to provide an indication or warning to supervisory personnel when no useful information can be transmitted through the fiber optic link.
It is another object of this invention that the information source (as laser diode) lightwave output be restricted until a "link closed" signal is received, so as to substantially prevent eye damage potential to careless or uninformed personnel.
It is a further object of this invention that the "link open/link closed" monitor system provide signals to supervisory personnel, with the "link open" signal being an alarm to indicate that no useful information can be transmitted over the link