Abstract: Apparatus and methods for noninvasive spectroscopic measurement of an analyte in a subject that have been optimized for producing uniform and repeatable tissue modulation across test subjects and for the same test subject on different occasions are provided. The apparatus comprises an ergonomically shaped grip that substantially conforms to a subject's hand; a surface for placement of at least one of the subject's fingertips upon grasping the grip; and an optically transparent aperture, or a plurality of apertures, disposed within the surface. A modification to the surface of the apparatus adjacent to the aperture that is detectable via the tactile sense of the subject can be added to provide tactile feedback to the subject to guide correct placement of the fingertip over the aperture. The apparatus and methods can also incorporate feedback methods to guide and optimize placement and conditions of the fingertip to further improve accuracy of measurements.

Abstract: Apparatus and method for high-speed analog-to-digital conversion employs photonic circuits with variable light-absorption. A coherent light source is clocked to produce a stream of coherent light pulses onto which is modulated an analog signal to be converted to digital form. An optical splitter divides the stream of pulses into a number of streams that is proportional to the resolution sought. A passive photonic quantizer absorbs, to a predetermined degree, the light energy of the incident pulse streams. The output of a fully absorbed pulse does not trigger a comparator. Pulse streams of sufficient intensity pass through the light absorbers, and their output does trigger the comparator. The output state of the comparators may be read into a digital memory to form a digital word that represents the analog signal during any discrete clock interval. Most of the elements of the apparatus can be fabricated on a substrate of photonic semiconducting material.