US Patent 8470605 Optical reader for reading encoded microparticles

An optical reader for reading encoded microparticles. Each microparticle has an elongated body with an optically detectable code that extends along a longitudinal axis of the corresponding elongated body. The reader includes a plate that has a plurality of channels. The channels are configured to receive and align the microparticles so that the codes of the microparticles are in a common fixed orientation relative to each other. The reader also includes an illumination source for illuminating the microparticles on the plate. The codes in the microparticles reflect a portion of incident light and permit a portion of the incident light to pass through the microparticles thereby providing an output signal indicative of the code. The reader also includes a detection device that is configured to capture the output signal provided by the microparticles.