7
HighSpeed-Galvo-driver
MicroAmp
Tuning and adjustment
Introduction
The MicroAmp is currently the smallest and fastest scanamp for CTI´s 6800 or 6210s on the
world market. It´s new technology allows to scan up to 60k with selected galvanometers, at a
reduced scanangle of 4° optical. But even at large angles, the scanrate is increased.
The standard delivery package contains driver and input cable. The driver is presetted to CTI
6800 galvos, but has to be retuned slightly before first use. This can be done by using the
three adjustment trimmers on the drivecard.
The cable
High speed galvanometers demand for special cables, which are shielded and separated
between motor and position detector. Cable lenghts up to 100cm are allowed. We recommend
a cable lenght of maximum 50cm.
Power source
Power source is slightly critical and has strong influence on speed and quality of the complete
scanner system. Even if a standard transformer with a bridge and caps will do, MediaLas
recommends a stabilized or switched power supply. The MicroAmp is able to run b/-
20VDC to +/-30VDC, at 1.5A each. The speed between 20V and 30V is different, especially
at small step angles. While MediaLas uses mainly 30V switching power supplies, a small
speed decrease at +/-24V will be discovered, but at the same time, power dissipation is
decreasing, combined with much less heat.
If you use transformer and bridge, then make sure to have minimum 10,000 uF caps per
voltage, better 40,000 uF, parallel with a 100uF for fast peaks. Do not use extra capacitors at
switching power supplies.
Polaritiy of connecting power to the driver is important. No warranty if connected
incorrect.
The measuring procedure
The MicroAmp was measured with CT6800HP, make 1999, passice cooled. Laboratory
power supply, room temperature. Windows PC with LD Pro, 12/30k ILDA testframe. Later
we did some measurements with 6210s, connector style, passive cooled. The speed differed
from what we measured with the 6800s. Mainly this was caused by the mirrors and the
different connector, which has a slightly higher resistance than the 6800 connector. We then
changed to the older suttering style 6210s and found a speed increase at small step angles.
