A blood measurement system comprises an array of laser diodes, to generate light to penetrate tissue comprising skin, having one or more wavelengths, including a near-infrared wavelength, and Bragg reflector(s). At least one of the laser diodes to pulse at a pulse repetition rate between 1-100 megahertz. A detection system to measure blood in veins based at least in part on near-infrared diffuse reflection from the skin, the detection system comprising a photo-detector and a lens system coupled to the photo-detector, wherein the photo-detector is coupled to analog-to-digital converter(s) and a processor, and configured to measure absorption of hemoglobin in the near-infrared wavelength between 700-1300 nanometers, differentiate between regions in the skin with and without distinct veins, and implement pattern matching and a threshold function to correlate detected blood concentrations with a library of known concentrations to determine overlap.
