OPTICAL EDGE SENSORS FOR LARGE APERATURE SEGMENTED ARRAYS

A METHOD TO ACCURATELY AND RAPIDLY MEASURE PISTON AND TILT BETWEEN SMALL SEGMENTS OF A LARGE APERATURE TELESCOPE BY AN ACTIVELY MODE-LOCKED SEMICONDUCTOR LASER DIODE IS PRESENTED. THE SIZE OF THESE SEGMENTS APPROXIMATES THAT OF A DISTURBANCE COHERENCE DIMENSION ASOCIATED WITH THE WAVELENGTH OF INTEREST. SUCH SENSORS ARE CRITICAL TO STATES-OF-THE-ART ADOPTIVE OPTICS SENSING, ACTUATION, AND CONTROL TECHNIQUES WHICH CAN LEAD TO LOW COST FABRICATION METHODS OVER A LARGE SCALE. THE SPECIFIC INNOVATION PROPOSED IS THE USE OF A SEMICONDUCTOR LASER THAT CAN BE MODULATED BY AN EXTERNAL CAVITY TO CHANGE THRESHOLD CURRENT LEVELS AND EVANESCENT SCATTERING. PHASE I WILL DEVELOP A BREADBOARD MODEL.