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We are gradually entering the world of picooptics, initiated by developing new holographic facility for fabrication of large-sized grating with picometer measurement techniques. Picometer measurement is at first developed based on the simple two-beam interference, i.e., holography, combined with laser interferometer as a measurement standard. Normally, a laser interferometer could provide nanometer resolution. If we measure over 1000 periods of a high-density grating with nanometer resolution, then for one single period, the resolution might be obtained at picometer resolution. Since we can modulate the holography by changing the angle of two beams slightly, then its period can be measured at picometer accuracy. The difference between two slightly-changed periods can be controlled in picometer accuracy and used as a picometer measurement tool. This means we have the key to open the door of picooptics. Weak chaos principle is realized as one basic characteristics of picometer optical measurement, which is similar but different from the well-known Heisenberg uncertain measurement principle. Picometer measurement is illustrated based on using holographic techniques. Picooptics holography, attosecond (femtosecond) pico-holography and relativistic optics at attosecond time scale and picometer spatial scale are anticipated in the future.
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