The invention relates to a fixing device for orthopedic applications, in which at least one coupling member is mounted in the connecting rod of, or the guiding rod for, the clamping members, intended for receiving orthopedic pins, which coupling member can be brought into a rigid or a flexible coupling position. The methods are based on the correction of a digital image representation by means of a bias field. The optical switch is capable of directing a first portion of the light to continue along the first optical path, and directing a second portion of the light along a second optical path. This configuration on the polyhedral structure forms a potential barrier for repelling the ions from each of the regular polygonal surfaces and containing them in the trap. Since the ignition timing of the internal combustion engine can be easily monitored, maintenance can be carried out to the internal combustion engine and an ignition device to realize a necessary operating performance of the internal combustion engine. The contact pin is capable of movement above the platform at a distance which is equal to the sum of a thickness of the workpiece and a desired tolerance of the planeness, wherein if the planeness of the workpiece between the contact pin and the platform is out of tolerance, the testing circuit is closed, conducting power to the indicator, which will then indicate that the workpiece is ineligible.