A scanning device for biological slides is provided, which can be operated in an interactive routine mode as well as in an unsupervised high speed automatic mode. In the first case, typical components, which the pathologist is used to operating manually, such as the microscope, the stage and the focus, and which have to be motorized for the automatic unsupervised system mode, are configured to simulate manual use, operation, and response. A non-interlaced area scan camera supports the interactive selection and acquisition of individual images in the manual mode, as well as the continuous high-speed scan motion for the rare event detection and virtual slide scan applications of the system. Due to the particular requirements to accommodate both operational modes, methods are described for constructing the virtual slide out of image tiles with varying overlap areas in the x- and y-directions.