The Origins of the Laser MicroJet®
This is the story of how Bernold Richerzhagen, Synova’s founder, succeeded in his vision of combining light and water to develop a new hybrid technology capable of achieving higher quality and accuracy than existing cutting technologies.
Initially, assigned to a project to develop a transmission system for a laser dental tool, Richerzhagen opted for a solution, in which the laser is guided by total internal reflection within a water jet. His approach differed fundamentally from either high-pressure water jet cutting or conventional laser machining. While the low water pressure in his process is insufficient to cut through metal, it is laser energy that melts and vaporizes it. The guiding of laser in a water jet promised to result in simultaneous cooling with virtually no resulting heat damage to the material. At that point of time, there was neither a working solution nor a commercial product of a water jet guided laser. Thus, Richerzhagen was breaking new ground.
Richerzhagen spent several years in conducting practical experiments and theoretical simulations before he succeeded in building a prototype that proved his theory. In his first laboratory model, the laser beam damaged components. Eventually he established the cause. Heat from laser pulses was increasing water temperature and changing its refractive index. This, in turn, disturbed total internal reflection of the beam. He carried out intensive research to obtain accurate data on the relationship between water temperature and change in its refractive index. These results were published in prestigious journals.
Based on his findings, he designed a modified prototype that consisted of a disc-type water chamber with a highly dynamic flow, just contrary to what literature recommended. By controlling the flow, it was possible to avoid any turbulences even with a very short chamber needed to avoid the thermal effects. He successfully combined a laser with a low-pressure hair-thin water jet. There was total internal reflection of the laser beam within the water jet in a manner like a conventional optical fibre. A notable scientific achievement, he was the first man in history to do so. He patented his invention in 1994 and this technology is now marketed under the trademark: Laser MicroJet® (LMJ).
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