The Harmonic Drive Gear Box
Extremely high Reduction Ratio Capabilities Combined with very Accurate Motion
All Axioplan 2 with motorized focus have the Harmonic Drive Gear Box™ system. From the figure you will see that the drive has essentially three parts. A full 360º rotation of the wave generator (1) results in displacement of two teeth on the flexspine (3) in relation to the circular spine (2). This outstanding transmission ration directly impacts the high resolution of the focusing drive. Rotating the focusing knob, rotates an encoder disc. The encoder measures the amount of rotation of the focusing knob by counting the number of lines printed on the encoder disc as they pass through the encoder. This information is sent to the focus motor controller. Together with the programmed focusing sensitivity this information is translated into a movement command for the DC focus motor. Voltage is applied to the focus motor and the motor starts to move. Attached to the shaft of the focus motor is another encoder, which feeds back information to the focus motor controller telling it the actual position of the motor. Once the focus motor reaches its destination, the focus motor controller switches off the voltage to the focus motor, and the movement stops.
This makes it possible to have 40 different resolution levels in total which one can choose from to select the focusing sensitivity for a specific objective. Individual adjustment for an objective can be achieved by the user. Therefore smooth and precise movement of the focusing drive is guaranteed. The coarse focus is set to be five times of the fine focus which is programmed as a default but it can be also adjusted to the factors 1x to 40x.
Resolution: 25 nm Minimum Step Size
Reproducibility: 100 nm
Reversing Backlash: 300 nm