Bris-ECT

A Python library for standardisation of Handyscope and translation stages. This has currently been tested with handyscopes HS3 and HS5, and with Zaber linear stages (X-LSM200A-E03) which have firmware v6. Minor changes will need to be made regarding the velocity of stages if firmware v7 is used. Tested with Handyscope drivers v8.1.9. Developed with Python v3.10.

Setup

To get started, a valid Python installation is required. We advise that you create a new environment to install brisect to.

• Install mamba-forge to your device.
• Create a new environment from the Miniforge Prompt: mamba create -n bris-ect
• Activate the environment: mamba activate bris-ect
• Download the brisect-x.x-py3-non-any.whl file to a location on your device - note that the file you download will have a release version rather than x.x.
• In the Miniforge console, change to the directory in which you saved the *.whl file.
• Install the file: python -m pip install brisect-x.x-py3-non-any.whl. Change x.x to the version number you downloaded.

Note that you may wish to install an IDE as well: brisect has been developed with Spyder (mamba install spyder). Others exist but your mileage may vary.

You may need to install the correct drivers to connect to the Zaber linear stage: see the USB drivers page to install. TiePie driver v10 doesn't work with python-libtiepie, use v8.1.9 instead. An .exe is available in .\drivers.

If you are developing changes to this package, make a fork of this repo on GitHub, and clone it to your device. Make changes there, and then make a pull request when significant changes are made.

Usage

See the examples folder for examples of how to use this package. If you have any problems or wish to request / add new features, please raise an issue on GitHub.

examples\ect-smart-scan.py can either be run from an IDE or from the command line. To use from the command line, make a custom <filename>.yml file with properties filled out as found in the example in this repo.
To run from an IDE, the yaml_filename variable on line 33 must be changed. To run from the command line, make sure that the mamba environment is activated and run python ect-smart-scan.py <filename>.yml. The script will execute, saving a png of the measured RMS values in the output directory.

To do list:

• Zaber motion package:

  • Investigate how to make two devices move at once. Make a complicated trajectory using both.
    • Write equivalent for move_relative(x, v) function. In firmware >= v7 it takes velocity, in v6 it doesn't.
      • Wrapper function sets velocity first, then moves. On shutdown, reset the velocity to original.
    • Work out if streaming is feasible to reduce stop/start jerky motion when drawing out arcs.
      • Not a priority as we can just move with right angles right now. Shelf it for now.
  • Feed in a trajectory from external file.
    • Use yaml to do it.
    • (01/03/23) ect-smart-scan.py is now trying to work it out smartly - don't need to feed in trajectory externally.
    • Make an example script which moves along an arbitrary path which is provided externally.
  • Offline usage (function zaber_motion.Library.enable_device_db_store() updates from the internet. Alternative behaviour if offline.)

• Handyscope package:

  • Work out why Python cannot communicate with Handyscopes
    • Current python-libtiepie version does not work with most recent drivers - use v8.1.9
  • Acquire magnitude and phase when processing.
  • Read in data in real time (or as close as possible).
  • Pass in and measure arbitrary signals.
    • Multiplexed signals have default behaviour.
    • Method in Handyscope class to write any arbitrary signal. This is also accessible from Handyscope.gen.set_data().
      • May automate chirps and bandwidths later.
  • Processing output data to meaningful form.
    • RMS, frequency spectrum data.

• Feedback loop (ect-smart-scan.py):

  • Determine geometry of the part being inspected.
    • Coarse scan of entire domain with zaber.
    • In first instance, fit a box to metallic region.
    • More clever prediction of geometry from resulting map.
      • Snake around the full space until geometry found. At which point trace the edges of the geometry.
      • Trace the geometry: move back and forth over edge of geometry until a corner found. Use value of RMS to determine whether to turn left or right, and scan the next edge. Detect when the probe has returned to the start position.
  • Coarse scan of part for defects.
    • Look for deviations from pristine material.
      • Can implement by reusing the sweep for the geometry.
      • When scanning off and on the part, work out whether we are closer to one RMS or the other (i.e. vacuum vs part).
  • For RMS voltage: correct for vertical liftoff of probe.
    • In first instance treat it as linear V = ax + by + c
    • Are there any non-linear effects in liftoff? May need to add other effects.
    • Decision to move away from liftoff correction in post processing. Will instead try to correct mechanically with spring pushing coil down, and levelling the part as much as possible.
  • For phase: compare phase difference of input signal to output signal.
    • Check how good our generated input signal is, vs channel measurement on handyscope
      • Signal looks very good, small amount of noise but not awful.
        There is a phase difference from the generation depending on when generator started and stopped - will be necessary to measure the generated signal on the handyscope to compare to the output from the coil.

• Miscellaneous:

  • Select a more appropriate capacitor.
  • Select a more appropriate frequency.
  • Run program from command line, return all useful analysis as plots or print to screen.
  • GUI?
    • What would be needed from a GUI? All the inputs, plus a window for where the scan goes?