A new pseudorandom, two-track encoding procedure for absolute-type shaft encoders with any number of disc sectors has been developed. For n-bit resolution the new method requires only n + m reading heads, where 2m-1 &...
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A new pseudorandom, two-track encoding procedure for absolute-type shaft encoders with any number of disc sectors has been developed. For n-bit resolution the new method requires only n + m reading heads, where 2m-1 < n≤2m. This is notably better than the 2n–1 reading heads required by an earlier version.
Diffractive beam direction needs to be controlled agilely and precisely in beam steering and some diffraction applications. Far field fringe generation, wave front distortion correction by employing programmable diffr...
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ISBN:
(纸本)9780819468598
Diffractive beam direction needs to be controlled agilely and precisely in beam steering and some diffraction applications. Far field fringe generation, wave front distortion correction by employing programmable diffractive element is a new interesting research area. A phase-only liquid crystal spatial light modulator is used to produce arbitrary fringes expected. For the practical application, the main technology we tried includes: 1) the fast recovering speed from arbitrary fringe to the phase distribution of liquid crystal spatial light modulator, 2) the expected fringe light intensity information is delivered by phase information. The previous G-S phase recovering algorithm demands more iterative calculations, which is not suitable for real time purpose. According to the statistics of light field distribution of expected fringes, a pseudorandom phase encoding method has been used in this work. The expected fringe light intensity information is used to limit the initial value for phase recovering calculation. By this way, the iterative time has been reduced largely, and the phase recovering is optimized as well. The expected diffraction fringe can be obtained through 3-5 iterative calculations.
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