Analog-to-digital conversion using diffractive optics

Summary form only given. An analog electric (current or voltage) signal to be converted is fed to a multi-electrode, wavelength tunable diode laser, the output wavelength of which is uniquely determined by the signal. A microscope lens makes the Gaussian laser output beam converge weakly. The laser beam impinges on a blazed grating, the beam diffracted from it falling upon one in an array of diffractive elements. The widths of the array elements are approximately the same as the diameter of the focused beam incident on them. The diffractive array elements are designed to fan out beams into individual spot patterns. The maximum number of spots in a pattern, n, equals the number of bits the analog signal is to be resolved into. All the fanout array elements produce spots at the same fixed locations, where n individual detectors are positioned. Through this arrangement, a particular analog electric signal amplitude is first converted into a unique wavelength, a fact which makes the laser beam strike a particular diffractive element in the array. The array element in turn produces a unique spot pattern (bit-code) on the detectors, which are read out in parallel