Optical laser displacement sensor

As an example, consider the design of a simple conveyor mechanism, depicted in Fig. 5.3, built from multiple DEAs that will push a small cylindrical object forward. One solution is to use a central controller to coordinate the behavior of each actuator. Without feedback, the timing of actuation of each DEA would need to follow a predetermined pattern. However, as the object accelerates, or if objects with different masses or rotational inertias are transported, it would be difficult to ensure synchronized actuation in such an inflexible system. To improve flexibility, feedback from each actuator is required. Typically this would involve conventional external sensors, e.g., laser displacement sensors, LVDTs, optical encoders, or motion sensors, and the use of a centralized controller to coordinate the overall... 

In laser-optic measurement systems (such as Optalign), a combined laser source -sensor unit is placed on the reference shaft and the relative displacement vector and the alignment angle is calculated from the position of the incoming laser beam reflected by a prism unit, which is attached to the other shaft. This is an optical counterpart of the rim-and-face method. It is thus also relative, contact, manual and static in nature. 

The operation of proximity sensors can be based on a wide range of principles, including capacitance, induction, Hall and magnetic effects variable reluctance, linear variable differential transformer (LVDT), variable resistor mechanical and electromechanical limit switches optical, photoelectric, or fiber-optic sensors laser-based distance, dimension, or thickness sensors air gap sensors ultrasonic and displacement transducers. Their detection ranges vary from micrometers to meters, and their applications include the measurement of position, displacement, proximity, or operational limits in controlling moving components of valves and dampers. Either linear or angular position can be measured ... 

An attractive feature of fiber sensors is the possibility of performing in vivo tests and monitoring. Numerous fiber-optic sensors have already been described that measure physical parameters of the human body [41]. Pressure, temperature, physiological flow, strain, motion, displacement, or flow velocity can be monitored by optical methods such as variable reflection, laser Doppler velocimetry, optical holography, or diffraction. In this section the application of optosensing methods to the determination of molecular species encountered in clinical and biomedical analysis is described. 

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