[Automatic ultramicrotome drive for routine medical histology with the electron microscope].

In modern ultramicrotomes the thermic advance system has been replaced by a mechanical one. Earlier, conventional DC-voltage motors were used, but recently the step motor has become popular. In connection with such motors, the application of digital control elements is facilitated, thus increasing precision significantly. A further step towards improving the precision of the advance system is the application of microprocessors as intelligent and interacting control elements. The microprocessor can not only take over the function sensors, the function of regulation. This paper describes a working concept whereby the advance system does not, as usual, work freely, but in connection with a sensor which measures the advance, and first after a positive data comparison over the microprocessor, allows the cutting movement. The concept is not limited to ultramicrotomes but can also be applied to mechanical rotation microtomes.