Magnetic Field Sweep and Spatial Mapping Automation

Author: Serdar (adjusted by Lukas and Ryan)
Last Updated: April 2025
Filename: Mag_Field_Sweep_2024_10_21.py

Overview

This script automates spectral acquisition in a magneto-optical experiment using:

• LightField for spectrometer control (Princeton Instruments)
• AMC Positioner for precise spatial scanning
• Attocube APS100 power supplies for magnetic field control

It enables:

• Magnetic field sweeps along selected axes
• Spatial scans across X-Y positions
• B-field vector rotations with spectral capture
• Live spectrum acquisition and intensity mapping

Features

• 2D Spatial Scan: Raster-scan across a surface using AMC positioners, capturing spectra at each coordinate.
• Magnetic Field Sweep: Vary B-fields in controlled steps along x/y/z, measure spectra at each step.
• Field Rotation: Circular B-field rotation (in-plane) with angle-defined steps.
• Automated File Handling: Acquires .spe files, extracts and saves intensity/wavelengths, deletes intermediates.
• Flexible Configuration: Resolution, range, exposure, filters, filenames and scan directions are all customizable.

Prerequisites

Hardware

• AMC100/AMC300 positioner
• Attocube APS100 single/dual-channel magnet power supplies
• Spectrometer compatible with Princeton Instruments LightField

Software & Libraries

• Python 3.8+
• Packages: pyvisa, numpy, matplotlib, pandas, clr, spe2py, spe_loader, AMC module
• .NET integration via pythonnet
• LightField SDK: Princeton Instruments (with DLLs loaded via clr)

Note: Ensure LIGHTFIELD_ROOT environment variable is set.

Setup

1. Install dependencies

   pip install pyvisa pandas numpy matplotlib pythonnet
   

2. Ensure required DLLs are present in:

   C:\Program Files\Princeton Instruments\LightField\
   

3. Set up device IPs

   IP_AMC100 = "192.168.71.100"  # or AMC300
   

4. Edit scan parameters in main block:

   range_x = 20000
   range_y = 20000
   resolution = 1000  # nanometers
   
   set_llim_bval = -0.3
   set_ulim_bval = 0.3
   set_res_bval = 0.003  # Tesla
   

Main Functions

move_scan_xy(range_x, range_y, resolution, Settings, baseFileName)

Performs a 2D XY raster scan of the probe. Acquires spectra and saves results.

sweep_b_val(instr, min_bval, max_bval, res, axis, Settings, base_file_name)

Sweeps magnetic field (in T) along the specified axis, collecting spectra at each field.

ramp_b_val(instr, bval, magnet_coil)

Smooth ramping of B-field to target value.

b_field_rotation(instr1, instr2, Babs, startangle, endangle, step, Settings)

Rotates the in-plane magnetic field by vector combination of Bx and By components.

File Saving

• .txt: Intensity data and wavelength arrays saved to timestamped folders
• Folder names include experiment metadata
• .spe files are deleted after processing to conserve space

Usage Example

To sweep B-field along the Y-axis:

sweep_b_val(
    instr=powerbox_singlesupply,
    min_bval=-0.3,
    max_bval=0.3,
    res=0.003,
    magnet_coil='y-axis',
    Settings='experiment_config',
    base_file_name='scan_name',
    zerowhenfin_bool=True,
    reversescan_bool=False,
    loopscan_bool=True
)

Notes

• Always close power supply connections with .close()
• Make sure .spe files are not locked by LightField before running
• The AMC section is currently commented — uncomment if positioner control is needed
• Ensure experiment.Load(...) points to the correct .lfe config

Troubleshooting

• DLL loading issues? Confirm path via sys.path.append(...) and DLL names.
• Communication errors? Check serial port resource names via pyvisa.ResourceManager().list_resources()
• No spectra saved? Ensure LightField is licensed and experiment file is valid.

License

Internal use only – please contact the authors before distribution or reuse.