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Story of Lutronic’s innovative technology: ① Magnetic roller tracking


Consider a laser treatment delivered via a handpiece in motion over the target tissue, where the handpiece can be moved either quickly or slowly, depending on the purpose, subject, and overall conditions of the procedure, but can always deliver the correctly metered amount of laser energy per pulse, irrespective of the speed of the handpiece. In such a situation, the pulse rate of the laser beam must change corresponding to the rate at which the handpiece is moved over the target tissue to ensure accurate and consistent delivery of energy, and thus secure a safe and effective operation.

However, since 2008, the fractional type of laser beam has typically delivered a fixed number of shots per second, irrespective of the speed at which the operator moves the handpiece over the target tissue, in other words, the pulse rate is constant irrespective of the speed of the procedure. Thus, for a handpiece moved over the target tissue, rather than the conventional area by area ‘stamped’ or static delivery, the amount of laser energy delivered varied depending on the rate at which the operator passed the handpiece over the tissue. Slow handpiece motion therefore delivered a greater amount of energy (in joules per square centimeter, also known as the dose) to the tissue than when the handpiece was scanned more quickly across the tissue: Let us say for example that 10 J/cm² was the dose being delivered when the handpiece was in slow motion, the energy delivered would drop to around 5 J/cm² when the handpiece was moved at twice the speed for the same set of treatment parameters. This meant it was difficult to carry out accurate treatment in actual clinical practice: this problem has been continuously pointed out as one of the factors negatively influencing a consistent treatment effect, and even responsible for some unwanted side effects due to overexposure or underexposure.

As such, in 2008, Lutronic began to study how to uniformly deliver the dose with a pulsed laser beam from a handpiece kept in motion across tissue, termed the dynamic mode, regardless of the speed at which the handpiece was moved across the target tissue. Of course, it would be incorrect to suggest that no technology existed at that time which could control laser beam irradiation in proportion to the speed of a handpiece, but it required a special sensor to ‘feel’ the speed of the handpiece, called an accelerometer, which needed to be connected between the handpiece and the control electronics to sense the rate of handpiece inertia, or motion, and this necessitated a larger size for system consoles as well as increased expense to cover the cost of the extra technology. Therefore, Lutronic sought to solve these problems through a novel approach.


While investigating a variety of methods, Lutronic began to develop interest in rotary encoders. A rotary encoder is a device that detects the speed of rotation and direction of, for example, any axle, or the shaft of a motor. This technology is widely used in any equipment where the rotation speed and direction need to be electronically monitored, such as in the automotive industry, detecting and controlling the speeds at which elevators and conveyor belts move, and in similar industrial equipment. Among these rotary encoders, what Lutronic was particularly interested in was a rotary magnetic encoder that was small and inexpensive, and characterized by the motion and detection of magnetic north and south poles positioned diametrically opposite around a wheel.


The principle of the rotary magnetic encoder is as follows and is illustrated below:

1. When a magnet has north and south poles, a constant magnetic field automatically forms between these poles: This occurs naturally, for example between the north and south poles of our planet Earth. The strength of this field is measurable, so consider a magnet set into a wheel with the north and south poles opposite each other as usual. The strength of this field can be detected by a stationary magnetic sensor at any point surrounding the wheel.

2. As the wheel rotates, the magnet obviously rotates with it, taking its constant magnetic field with it as it does so. The degree and speed of rotation of the wheel can thus be calculated by the increase or reduction in the strength of the magnetic field as detected by the stationary sensor.

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Lutronic has incorporated these rotary magnetic encoders into a small roller. Thus, the magnetic encoder measures the number of times the roller turns, and the laser beam is activated only when a certain number of turns are made irrespective of the speed. This allows uniform irradiation of the target tissue with the same J/cm² regardless of the speed of the roller across the tissue. Furthermore, by leveraging a smaller and less expensive magnetic encoder, we have developed a smaller device with the technology much more competitive in price (around 1% of existing ones). This is Lutronic’s very own ‘magnetic roller tracking’ technology.



This technology has actually been commercialized, and has been incorporated as part of the precise control system in Lutronic's LASEMD. Through the development of the 'magnetic roller tracking' technology, it has become possible for the practitioners to deliver a uniform amount of laser energy, in other words, a uniform treatment dose, when the system is used in dynamic mode in absolute real time and completely independent of the speed at which the handpiece and roller are moved across the target tissue. Patients being treated with LASEMD can therefore be confident in receiving treatment of consistent quality.


In total accord with its dual commitment both to practitioners and their patients, Lutronic has always devoted itself to achieving more convenient procedures from the standpoint of the practitioners combined with safer and more accurate procedures from the perspective of the patients. Lutronic is creating the future for laser medical devices through development of technology for people, not just for patents.