The paper presents an optical method of damping vibration present in manually operated laser surgical devices. Considering the frequency range of the physiological tremor of 5-15Hz, the design of two compliant positioning mechanisms on 2 axes was made, which will have the role of supporting and moving the focusing lens of the laser device. A couple of compliant structures were subjected to static and dynamic finite element analyzes (modal analysis) to determine the displacement-force characteristic and resonant frequencies, eliminating the risk of operating in the frequency band of physiological tremor. Finally, the structures were teste in laboratory for final experimental results.
As tremor is a condition which occurs in all individuals, its effects can have a big impact on person’s everyday life. If we are considering professionals who rely on manual labor to perform precise activities, tremor becomes the source of many problems. Moreover, as specific literature highlights, tremor occurs mostly at hands and fingers level. The aim of this paper is to provide an enhanced controller for a precision positioning system used in laser medical instruments. The controller shall be tuned in such way to overcome the constraints imposed by electromagnetic actuators, yet providing high precision positioning, considering the application requirements (approximatively 50 µm maximum displacement).
KEYWORDS: Actuators, Mirrors, Prisms, Electromagnetism, Magnetism, Laser systems engineering, Control systems, Scanners, Chemical elements, Signal processing
The stabilization of portable laser systems is of major importance for improving performance and ensuring high mobility of devices. These systems can be grouped into two classes: resonant and non-resonant, each requiring different approaches. The article presents the conceptual and physical results of research, focused on the industrial application of a stabilization solution in the field of portable laser equipment used in the medical field. The proposed solutions to the major problems encountered are presented: mobile system motion detection and correction signal extraction, mechatronic positioning system design, feedback loop design, concept of a system performance certification stand. Aspects regarding the optimal actuation solution are discussed, comparing the piezoelectric, electrodynamic and electromagnetic ones. These are analyzed for gauge conditions imposed in terms of accuracy, range, thermal stability, the presence and size of nonlinearities and hysteresis. A major problem in these portable systems is their miniaturization. A scanning solution is presented based on the use of LIGA-Laser technology for mechanical microstructures and micromagnets, in bulk or 2D array structure manufacturing, which interact with planar coils. The solution has a practically proven improvement, not used so far in scanners, respectively a structure with two coupled degrees of freedom for each direction of movement, on the principle of dynamic absorber. The preliminary results for the numerical signal processing and the mechatronic construction of the dynamic positioning system of the entire laser assembly are also presented, as a possible option for the use of small size sources, having the advantage of an easy autofocus.
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