Mathematical model of a galvanometer-based scanner: simulations and experiments

Abstract

The paper presents an insight into our current researches on galvanometer-based scanners (GSs). A brief overview is first performed on the state-of-the-art, as well as on some of our contributions to optimize the scanning and the command functions of this most used scanning device. Considerations on the use of GSs in high-end biomedical imaging applications such as Optical Coherence Tomography (OCT) are made, with a focus towards obtaining the best possible duty cycles and artifact-free OCT images when using GSs for lateral scanning, as studied in our previous works. The scope of our present study is to obtain the mathematical model of a GS system (motor and controller included) in order to optimize the command functions of the device and to support the development of some more advanced control structures. The study is centered on the mathematical and experimental modeling of GSs. Thus, the results of an experimental identification made on a classical multi-parameter mathematical model proposed for such a system are presented. The experiments are carried out in different operating regimes, and the specific characteristic parameters of the GS are determined. Using these parameters obtained experimentally, we carry out simulations in Mathlab Simulink to validate the theoretical model. With the indentified model, an extended control solution is proposed. We point out the match between the theory and the results of the simulations and of the testing for different types of input signals, such as triangular, sinusoidal, and sawtooth with different duty cycles.

Advancements on galvanometer scanners for high-end applications

“…Some of our current and future directions of work were also pointed out, by example optimal command functions and control structures for GSs [38][39][40][41]. Other issues still have to be solved to meet the high requirements of high-end biomedical applications such as OCT: the application of 1D and 2D GSs in assemblies such as handheld scanning probes for OCT that have also been completed [43] is such a promising direction of research.…”

“…Another study [41] proposed a Model-based Predictive Control (MPC) structure to drive the GSs. The scope was to achieve either an improved precision or a higher speed.…”

Laser scanners: from industrial to biomedical applications

“…Another line of work is in the development of different control structures of the device to minimize the response time of the device or its precision [32]. The application of 1D and 2D GSs in assemblies such as handheld scanning probes for OCT have also been completed [51] and is a promising direction of research.…”

“…(1) reflective: with rotational single mirrors -monogons [1,2,6]) or polygonal mirrors (PMs) [5,[11][12][13][14][15][16][17][18] -or with oscillatory mirrors (with adjustable scan frequencies -galvanometer-based scanners (GSs) [19][20][21][22][23][24][25][26][27][28][29][30][31][32] or with higher but fixed frequencies -resonant -the latter including MEMS (Micro-Electro-Mechanical Systems);…”

Towards a research pole in photonics in Western Romania

“…Our activity, mainly focused on Optomechatronic devices and systems, is presented in detail in [6]. These research directions include: (i) Optomechanical choppers [7][8][9], for which we developed the analysis and design of classical chopper wheels with windows with linear edges [10], introduced and developed a new device, the "eclipse chopper", with wheels with windows with semi-circular edges [11], built prototypes [12], and developed a program for their design (for top-hat, Gaussian and Bessel beams), to chose the parameters of the device in order to obtain a desired profile of the output laser impulses [13]; (ii) Laser scanners: monogon [7,14,15]; polygonal [14,16], which we have analysed [17]; galvanometerbased [18,19], for which we demonstrated [20,21] the optimal scanning functions to be used (which has to be linear plus parabolic [20], not linear plus sinusoidal, as previously stated in literature [19]), and for which PG (and UG) students are working on a variety of topics including optimal control architecture [22,23] and driving algorithms; Risley prisms [24][25][26], on which student projects are studying their exact patterns [27], as well as driving solutions; (iii) Radiometry of optical systems [28], including optical attenuators [29], as well as colorimetry; (iv) Optical metrology -for industrial measurements [30], with on-going UGs projects [15,31]; (v) OCT [32,33] and related subassemblies [34,35] -including swept laser sources scanned in frequency …”