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Microscope Focus Drive

Focus drive

Focus Drive is a microscope attachment that provides high resolution movement of fine focus by driving it with a step motor and at the same time retains manual movement of the coarse focus. The Focus Drive can be used as a part of an automated microscope system with a variety of commercial step motor controllers, including TOFRA Motor Controller Units.

These Z-stacks of DNA probe images were acquired using a TOFRA Focus Drive and a TOFRA Motor Controller Unit.

The Focus Drive consists of a step motor, connected directly to the fine focus shaft of the microscope via a flexible coupling, and of an adapter that fits over the coarse focus knob of the microscope. The use of a high torsion stiffness flexible coupling ensures virtually no backlash in the drive and at the same time does not require very accurate attachment of the adapter. This results in low cost and easy installation.

Focus Drive Specifications

Range of travel Entire vertical range of the microscope
Step size 1 um with full step controller, down to 0.01 um with microstep controller (depends on controller)
Backlash in the drive 0.125 um. (Not to confuse with backlash in the microscope focus system)
Motor 2 phase, 1.8 degrees per step, 1.1A/phase
Mounting No modification of the microscope is required

Ordering information for focus drives

Part number


Price (US$)

001-01 Focus Drive for Olympus BH-2 (mounting instructions) 750.
001-02 Focus Drive for Nikon Optiphot-1 750.
001-03 Focus Drive for Nikon Optiphot-2 750.
001-04 Focus Drive for Zeiss AxioSkop 1 (mounting instructions) 750.
001-05 Focus Drive for Olympus BX40/BX50/BX60/AX70/IX50/IX70 or Olympus SZX12/16 with FOF 750.
001-06 Focus Drive for Leica DML 750.
001-07 Focus Drive for Nikon Eclipse-800 (mounting instructions) 750.
001-08 Focus Drive for Nikon Microphot SA 750.
001-09 Focus Drive for Nikon Eclipse-400/600 (mounting instructions) 750.
001-10 Focus Drive for Zeiss AxioPlan/Phot-2 750.
001-12 Focus Drive for Zeiss AxioPlan/Phot-1 750.
001-13 Focus Drive for Zeiss AxioSkop 2 (mounting instructions) 750.
001-14 Focus Drive for Leica DMR 750.
001-15 Focus Drive for Olympus BX41/BX51/BX61/IX71 (mounting instructions) 750.
001-17 Focus Drive for Nikon TE300 and TE200 750.
001-18 Focus Drive for Nikon TE2000 and Ti (mounting instructions) 750.
001-19 Focus Drive for Leitz Diaplan 750.
001-20 Focus Drive for Nikon 80i (mounting instructions) 750.
001-21 Focus Drive for Leica DM 4000/5000 (mounting instructions) 750.
001-22 Focus Drive for Nikon 50i (see mounting instructions for Nikon 80i) 750.
001-23 Focus Drive for Motic BA400/450 and AE30/31 (mounting instructions) 750.
001-24 Focus Drive for Zeiss Axiovert 135 (mounting instructions) 750.
001-25 Focus Drive for Zeiss Axiovert 200 750.
001-26 Focus Drive for Breukhoven Inverted 750.
001-27 Focus Drive for Zeiss Photomicroscope 750.
001-28 Focus Drive for Nikon Optiphot 200 750.
001-29 Focus Drive for Zeiss Axiovert 40 750.
001-30 Focus Drive for Zeiss Invertoscope D 750.
001-31 Focus Drive for Leitz Orthoplan (mounting instructions) 750.
001-32 Focus Drive for Lumascope 500; may be environmentally sealed for use in incubators 750. (*)
001-33 Focus Drive for Zeiss AxioScope.A1 (mounting instructions) 750.

Specifications and prices are subject to change without notice. Delivery 4-6 weeks ARO.

(*) for the environmentally sealed version add $200.

Auxiliary devices: Switchstick and Focus Limits

Focus Switchstick is an assembly of switches. A motor controller can interpret the switch combinations as direction and speed. This allows a very intuitive interface - coarse (fast speed) and fine (slow speed) focusing. Exact values of slow and fast speed may be changed by computer depending on magnification. Focus Switchstick allows to control focus with or without a computer.

Focus limits is a safety device, it is used to limit focus travel to the safe range. Focus limits is an assembly of two optical switches and a flag. Position of optical switches is adjustable and is set so that objective is prevented from crashing into the slide. Switch assembly is mounted on the microscope column and flag is mounted on the stage support block. Focus limits fulfill the safety function only when focus is driven by the motor. If the coarse focus knob is turned manually, focus limits will not block the travel.

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