In order to provide a low noise laser beam, a noise reducing feedback network
is provided which creates a noise reducing signal and provides that signal to the
laser itself. In order to produce the noise reducing signal, the operation of the
laser is monitored and the feedback signal is a direct result of this monitoring.
Monitoring is accomplished by a fast-forward sense detector, which receives a portion
of the laser beam from the operating laser. The output from this fast-forward sense
detector is provided to an amplifier which inverts and amplifies the signal. A
noise reduction feedback network then receives the amplified signal, appropriately
filters this signal, and provides it to the laser itself so as to reduce noise
in the laser-beam for the frequency band of importance for reading the recorded
data from the optical medium. The noise reduction feedback signal further has sufficiently
high impedance so as to not disturb the traditional CW operation of the laser and
to avoid interference with the traditional RF modulation of the laser.
