Connecting 15-mm Thorlabs galvos (QS15X)

Power supply

:warning: The default Thorlabs power supply for QS15X is a bulky and heavy linear PSU. This PSU has bare terminals sticking out, including live wires (110/220V). Make sure to follow safety rules and preferably talk to electrical engineer if you use it. Improper wiring and terminals isolation can lead to short-circuit and fire.

:bulb: The PSU for older galvo models GPS011-EC/US gives enough voltage and power (+/-15V, 3A) and is nicely packed in a 2-output enclosure.

:wrench: Other power supplies can be used, if they provide voltage between $\pm$ 15V to $\pm$ 24V DC and current 3-4 A. Linear power supplies are preferred over switching ones, because they provide more stable voltage (less noise).

AO command and power cables

Cables purchased after August 2023

Since Aug 2023 Thorlabs sells command and power cable kit CBLS3P for the QS15 galvos. The kit cables have BNC connector and GPS011 power connector respectively, so no need to solder the connectors anymore.

Cables purchased before August 2023

The QS15X command cable has 3 terminals (+CMD, GNA, -CMD). In our case, the AO command is single-ended (+/-CMD, GND), so -CMD (Pin3) must be grounded.

R77 jumper

In our project, the AO command is single-ended (+/-CMD, GND), so the R77 jumper on servo board must be shorted with a soldering iron, according to the board manual.

:warning: The R77 jumper is very small, be careful when applying soldering bridge so you don't damage nearby components.

:warning: Each galvo comes with its matched servo board (with identical serial number). Mixing galvos/servo boards with different SN will affect galvo accuracy and performance. If in doubt, double-check SN written on the galvo vs the servo board.

Servo board heat sinks

Servo boards MUST be mounted on adequate heat sinks for proper heat dissipation. Their location should be away from optical path, ideally at the backplane of the system, so they do not heat up the optical components (which can lead to misalignment).

Config file

:warning: Maximal input voltage for these galvos is 5V. Make sure galvo settings in mesoSPIM config file do not exceed this value, otherwise the servo board can be damaged.