Method and apparatus for internal monitoring and control of reflectors in an optical switch

A diagnostic device in an optical switch having an array of optical input fibers configured to carry input light beams;

• an array of output fibers;
• at least one switching element having a reflector array with a plurality of movable mirrors, each movable mirror adjustable to a plurality of positions, suitable for reflecting selected input light beams received from selected input fibers into selected output fibers enabling the switching of each input light beam along a signal path to one of a plurality of output fibers as an output beam;
• the diagnostic device comprising:
• an illumination source for directing at least one monitor light beam onto the movable mirrors of the reflector array;
• a photoimager arranged to receive monitor light beams reflected from the movable mirrors of the reflector array to provide two-dimensional information concerning the position of the movable mirrors, with each movable mirror of the reflector array reflecting light onto a different two-dimensional position on the photoimager depending on which one of the plurality of positions each mirror currently occupies;
• and
• a controller for adjusting the position of the movable mirrors of the reflector array according to light received at the photoimager.

A method for detecting whether movable mirrors in an optical switch have a desired orientation, the optical switch having an array of optical input fibers configured to carry input light beams;

• an array of output fibers;
• at least one switching element having a reflector array with a plurality of movable mirrors, each movable mirror adjustable to a plurality of positions, suitable for reflecting selected input light beams received from selected input fibers into selected output fibers enabling the switching of each input light beam along a signal path to one of a plurality of output fibers as an output beam, the method comprising the steps of:
• directing at least one light beam onto movable mirrors of a reflector array in an optical switch;
• receiving at least one light beam reflected from the movable mirrors of the reflector array such that the light beam can form an optical image of the at least one reflected beam;
• detecting the two-dimensional position of the at least one reflected light beam;
• comparing the two-dimensional position of the reflected light beam with a desired two-dimensional position that corresponds to that of a movable mirror having the desired orientation;
• and
• determining whether the movable mirror is positioned having the desired orientation.