Focus drives & controllers for motorised Z focus systems

Select ProScan III when the system needs more than basic XY/Z motion, encoder options, programmable TTL I/O or future expansion. Its base unit accommodates a three-axis stage-and-focus arrangement, and the controller can support up to nine axes, including six configurable OEM axes, with ancillary sections added for further functions. OptiScan ES11 is the simpler choice when control is limited to the X, Y and Z axes and there is no requirement to add illumination or sample-handling functions through the same controller. In practice, define the full hardware list first, including focus feedback, filter wheels, shutters and triggers. This prevents the selection of a controller that cannot accommodate a later imaging sequence.

The ProScan III specification gives a minimum Z command step of 0.002 µm and typical repeatability below 1 µm for focus and stage systems. The 0.002 µm figure is the smallest commanded increment, not a guarantee that the specimen plane will move or settle with 2 nm absolute accuracy. Mechanical coupling, focus gear ratio, backlash, load, microscope construction and encoder arrangement determine the movement achieved in the completed system. For quantitative Z-stack or metrology work, verify performance on the assembled microscope using the intended objective, travel range and motion profile. Command resolution, repeatability and metric accuracy should be treated as separate acceptance criteria.

Specify encoded focus when the mechanical Z position cannot be inferred reliably from motor rotation alone, particularly with indirect couplings, backlash-prone mechanisms or long time-lapse runs. ProScan III supports encoder feedback on motor axes and can use closed-loop control to monitor whether the requested position has been reached. This improves confidence in mechanical return-to-position performance, but it does not directly measure optical sharpness at the sample. Thermal movement of the specimen, objective or microscope structure can still shift the best-focus plane even when the encoder reports the same Z coordinate. If optical focus must be maintained, combine suitable Z feedback with an autofocus strategy and validate the interaction between both control loops.

The PS3H122R is fitted to the microscope fine-focus mechanism with a model-specific sleeve or direct-coupling kit, so the microscope interface must be identified before ordering. Some configurations motorise only the fine-focus knob and leave coarse focus manual, while a direct coupling can reduce compliance where the microscope supports it. Focus hardware connects to the controller’s 15-way FOCUS port; on an H31ZFE configuration, the combined FOCUS/FILTER 1 connection is used. Power must be switched off before any focus, stage, encoder or joystick cable is attached or removed. After power-up, supported accessories are detected and configured, but travel direction, limits and the safe Z range should still be checked before installing a valuable objective or sample.

Both controller families support computer control through USB or RS232, while ProScan III adds an SDK, ASCII command access and programmable TTL I/O. Its serial protocol uses an 8-bit word, one stop bit, no parity and no handshake, with supported rates of 9,600, 19,200, 38,400 and 115,200 baud. The four programmable TTL inputs and outputs can coordinate stage or focus actions with cameras, shutters and other external equipment. For deterministic acquisition, decide whether the controlling event should originate in the imaging software, the controller or an external trigger device. Bench-test command completion, trigger polarity and timing margins because serial command latency and mechanical settling are separate from the electrical trigger transition.

Use CS200Z when the operator needs a dedicated physical control for the Z axis, particularly during specimen search, focus setup or manual scanning. The separate CS200XY and CS200Z units can be used individually or together, allowing one hand to position the stage while the other adjusts focus. A side-mounted speed-control button changes the response range, helping the same control cover coarse approach and finer adjustment. TS200 is more suitable when the operator also needs a touchscreen interface for system-wide control and parameter configuration. For workstation design, choose between tactile control and touchscreen operation according to glove use, available bench space and how frequently settings must be changed.

ProScan III is designed to start with a three-axis stage-and-focus system and accept ancillary sections for filter wheels, shutters or configurable OEM axes. The published architecture supports up to nine axes, six of which can be assigned to OEM functions, and more than one ancillary box may be added where the configuration requires it. The main controller is a 177 × 177 × 177 mm cube weighing 3 kg, while an ancillary section adds 59 mm and weighs 1 kg. OptiScan ES11 should instead be treated as a defined XY/Z controller rather than an expansion platform. Reserve enclosure space, connector access and cable bend radius during system design, especially where the controller will sit under shelving or inside an instrument frame.