1,720,978 research outputs found
Multi-input digital frequency stabilization of monolithic lasers
No full textA digital control application for the frequency stabilization of optical frequency standards is presented. The standard employed is a monolithic neodymium in yttrium aluminum garnet laser locked to an iodine frequency reference. Traditionally, laser frequency is locked to the reference through analogue loops, which may require a lengthy set-up and a manual search for the reference to which to lock the source. Digital control avoids these steps and provides complete and robust instrument automation. The theory and results of a Digital Control Unit (DCU) designed to improve and facilitate stability set-up and performance are presented. The DCU elaborates frequency error signal between laser and reference at 10 kHz so as to co-ordinate a set of three frequency actuators (temperature servo, piezo-electric ceramics, acousto-optic modulator) capable of compensating frequency drifts below 1 part per 10^12 under normal environmental conditions
Digital control of an interferometric balance for micro-thrusters qualification
No full textThe digital control design of an interferometric balance for fine space thruster calibration is presented. The problem was suggested by new micro-thrusters generation aiming at thrusts with sub-micro-Newton resolution. The solution, the Nanobalance instrument, under development, will be employed for on ground qualifying thrust time profile and noise with sub-micro-Newton accuracy. The digital control has been designed and tested in parallel to instrument construction, through a fine numerical simulator of the instrument itself and of the environment disturbances, developed within a proprietary control design environment, ControLab. Severe simulation tests have shown that requirements are met. Next step will be Digital Control Unit interfacing to Nanobalance instrument and testing
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