A PORTABLE MOTORIZED XY-TILTING STAGE

In Knappertsbusch (2002) a simple universal stage was applied to generate movie sequences from microfossils in reflected light at varying X- and Y-tilt angles. The mechanics allows for tilt not less than about 3 intervals between adjacent positions, which, however, must be performed manually, and which is not very precise. Here, a revised, coaxial gearing geometry is presented, and the stage is equipped with two programmable Vexta stepper motors from Oriental Motor GmbH. More precise tilting of specimens in X and Y directions is now possible at intervals of 1.8 or more from one image position to the next (see Figure 5). Motorizing the stage enables the user to repeat imaging at sequences of angular tilt with high precision and guarantees good reproducibility of the results.

The XY-tilting stage can be operated in two alternative ways: In the first modus the stage is directly connected to SK1 port of the internal OASIS-4i four axis controller, which is needed for the vertical (Z) focus control of the binocular microscope in AutoMontage. The OASIS-4i controller is a PCI compliant plug-in board from Objective Imaging that provides control of up to four micro-stepping motors. By using the OASIS-4i controller the motors of the xy-tilting stage can be accessed via the OASIS.EXE program. This is a PC standalone application supplied by Objective Imaging together with the board. This method requires alternating between the AutoMontage and OASIS.EXE programs because the Z-stepper (which drives the motorized focus of the binocular) and the X, Y-tilting stage access the same hardware and cannot run simultaneously without a major reprogramming of AutoMontage (see Appendix).

In the second modus, the stage is connected to an external device, which we designed and manufactured (Figure 6), and uses SG8030JY controllers from Vexta (available from Oriental Motor GmbH). In this modus the OASIS-4i plug-in board is only needed if the operator decides to use AutoMontage as the imaging software (e.g., for automated focus (Z)-control of the binocular microscope). A logic switchboard is connected to the external controller allowing to select four programs for each axis: Forward and backward movement, fast (=several steps) and slow motion (=1 step). The angular increments for both tilting axes can be programmed separately. Motion of the stage is triggered manually by pushing a button for either the X or the Y direction. This design makes the stage easily portable, so that it can be used under any binocular microscope without being dependent on any specialized computer hardware.