QHOT 1.4.4

Holographic optical trapping instrument control

QHOT

QHOT is a Python framework for holographic optical trapping — controlling spatial light modulators (SLMs) to create, move, and reconfigure optical traps in real time using a live camera feed.

Features

• Real-time hologram computation (CGH) with GPU-optional acceleration
• Interactive trap manipulation via camera overlay
• Modular trap types: single tweezers, vortex beams, ring traps, arrays, and dot-matrix text patterns
• Interactive display filter pipeline (smoothing, edge detection, RGB selection, sample-hold)
• Configuration save/restore via TOML
• Full unit-test suite (1400+ tests)

Requirements

• Python 3.10+
• PyQt5 ≥ 5.15
• pyqtgraph ≥ 0.13
• numpy ≥ 1.24
• scipy ≥ 1.10
• tomlkit ≥ 0.11
• QVideo ≥ 3.2.3

Installation

pip install QHOT

Or for development:

git clone https://github.com/davidgrier/QHOT.git
cd QHOT
pip install -e .

Usage

qhot

Or from Python:

from QHOT.qhot import main
main()

Trap types

Class	Description
QTweezer	Single Gaussian tweezer
QVortex	Laguerre-Gaussian vortex beam
QRingTrap	Ring-shaped optical trap
QTrapArray	Rectangular grid of tweezers with optional mask and position jitter
QLetterArray	Single dot-matrix character (A-Z, a-z, 0-9) rendered as tweezers
QTextArray	String of QLetterArray characters

Project structure

QHOT/
├── qhot.py          — Main application window
├── QHOT.ui          — Qt Designer UI layout
├── lib/              — Core library (SLM, CGH, trap infrastructure)
│   ├── QSLM.py
│   ├── QHOTScreen.py
│   ├── QSaveFile.py
│   ├── holograms/    — Hologram computation
│   └── traps/        — Trap base classes and overlay
├── traps/            — Concrete trap implementations
└── tests/            — Unit tests

References

• E. R. Dufresne and D. G. Grier, "Optical tweezer arrays and optical substrates created with diffractive optics," Rev. Sci. Instrum. 69, 1974 (1998). https://doi.org/10.1063/1.1148883
• J. E. Curtis, B. A. Koss, and D. G. Grier, "Dynamic holographic optical tweezers," Opt. Commun. 207, 169 (2002). https://doi.org/10.1016/S0030-4018(02)01524-9
• D. G. Grier, "A revolution in optical manipulation," Nature 424, 810 (2003). https://doi.org/10.1038/nature01935

Acknowledgments

This project is maintained with support from the National Science Foundation of the United States under Award Number DMR-2428983.

License

See LICENSE.