elliptec

Python interface to Thorlabs Elliptec motorized mounts

Purpose

This project allows for easy control of Thorlabs Elliptec motorized mounts in Python, using their documented serial commands. It also affords some conveniences, such as:

• Detect the module type, scaling factor, etc., during initialization
• Perform frequency calibration and homing of the motors automatically
• Monitor the replies from modules, retry commands if necessary and correct for known communication bugs
• Keep track of per-module offsets, e.g. to rotate relative to a calibrated angle for a waveplate

Getting started

from elliptec import Elliptec

# Open controller at this serial address, communicate with modules at
# the hexadecimal addresses 0, 1, and 2 (for A-F use capital letters)
e = Elliptec('/dev/ttyUSB0', ['0', '1', '2'])

# Let's assume we have three waveplates, each with a fast axis at a known
# offset angle from the motor's zero position of 13, 42, and 7 degrees,
# respectively. Relative to these positions, we want to move to (0, 90, 22.5)

# We can move one-by-one:
e.moveabsolute('0', 13 + 0)
e.moveabsolute('1', 42 + 90)
e.moveabsolute('2', 7 + 22.5)

# Or, we can use the convenience setcal() and calmove() methods:
e.setcal(['0', '1', '2'], [13, 42, 7])
e.calmove(['0', '1', '2'], [0, 90, 22.5])

# Since we're using all the modules initialized above, we can omit addresses:
e.setcal([13, 42, 7])
e.calmove([0, 90, 22.5])

# Now it's easy to go to another position without carrying the offsets:
e.calmove([0, 45, -22.5])

# We're done here!
e.close()

Installing / Developing

This project is currently not packaged on PyPI. The easiest way to install is to clone the repo and install the local version in editable mode with pip:

git clone https://git.sr.ht/~rwp/elliptec
cd elliptec
pip3 install -e .

Now, any changes you make locally will automatically be applied in your scripts. To update to a newer version, use git to pull changes as usual into your local repo.

Scope

Contributors currently have only used this to control the ELL14 rotation mount, ELL17 and ELL20 linear stages, and the ELL6 indexed filter stage. Not all commands are currently implemented but we have not found them necessary in practical use.

Contributions

Patches and comments are welcome, especially if you have another model not listed above (even if it is just to confirm everything works).