The rapid evolution of the electronics industry, driven by Moore's law and the proliferation of integrated circuits, has led to significant advancements in modern society, including the Internet, wireless communication, and artificial intelligence (AI). Central to this progress is optical lithography, a critical technology in semiconductor manufacturing that accounts for approximately 30% to 40% of production costs. As semiconductor nodes shrink and transistor numbers increase, optical lithography becomes increasingly vital in current integrated circuit (IC) fabrication technology. This repo introduces an open-source differentiable lithography imaging framework that leverages the principles of differentiable programming and the computational power of GPUs to enhance the precision of lithography modeling and simplify the optimization of resolution enhancement techniques (RETs). The framework models the core components of lithography as differentiable segments, allowing for the implementation of standard scalar imaging models, including the Abbe and Hopkins models, as well as their approximation models.
This repo is still under construction. 🚧
# clone project
git clone https://github.com/TorchOPC/TorchLitho
cd TorchLitho
# [OPTIONAL] create conda environment
conda create -n myenv python=3.11
conda activate myenv
# install pytorch according to instructions
# https://pytorch.org/get-started/
# install requirements
pip install -r requirements.txt
Using Conda
# clone project
git clone https://github.com/TorchOPC/TorchLitho
cd TorchLitho
# create conda environment and install dependencies
conda env create -f environment.yaml -n myenv
# activate conda environment
conda activate myenv
Train model with default configuration
# Test the imaging
cd src/models/litho
python ImagingModel.py
Train model with chosen experiment configuration from configs/experiment/
python src/train.py experiment=experiment_name.yaml
You can override any parameter from command line like this
python src/train.py trainer.max_epochs=20 data.batch_size=64
@inproceedings{SPIE24_difflitho,
title = {Open-Source Differentiable Lithography Imaging Framework},
author = {Chen, Guojin and Geng, Hao and Yu, Bei and Pan, David Z.},
booktitle = {Advanced Lithography + Patterning},
organization = {International Society for Optics and Photonics},
publisher = {SPIE},
year = {2024},
month = {3},
}
Guojin Chen, Hao Geng, Bei Yu, David Z. Pan, “Open-Source Differentiable Lithography Imaging Framework”, SPIE Advanced Lithography + Patterning, San Jose, Feb. 25–29, 2024. (paper) (slides)
Guojin Chen, Hongquan He, Peng Xu, Hao Geng, Bei Yu, “Efficient Bilevel Source Mask Optimization”, ACM/IEEE Design Automation Conference (DAC), San Francisco, Jun. 23–27, 2024.
Guojin Chen, Zixiao Wang, Bei Yu, David Z. Pan, Martin D.F. Wong, “Ultra-Fast Source Mask Optimization via Conditional Discrete Diffusion”, accepted by IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems (TCAD).
@ARTICLE{DiffSMO-chen-2024,
author={Chen, Guojin and Wang, Zixiao and Yu, Bei and Pan, David Z. and Wong, Martin D.F.},
journal={IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems},
title={Ultra-Fast Source Mask Optimization via Conditional Discrete Diffusion},
year={2024},
volume={},
number={},
pages={1-1},
keywords={Optimization;Lithography;Lighting;Integrated circuits;Graphics processing units;Optical imaging;Resists},
doi={10.1109/TCAD.2024.3361400}
}
**Why you might want to use it:**
✅ Save on boilerplate
Easily add new models, datasets, tasks, experiments, and train on different accelerators, like multi-GPU, TPU or SLURM clusters.
✅ Education
Thoroughly commented. You can use this repo as a learning resource.
✅ Reusability
Collection of useful MLOps tools, configs, and code snippets. You can use this repo as a reference for various utilities.
Pytorch - PyTorch is a machine learning framework based on the Torch library, used for applications such as computer vision and natural language processing, originally developed by Meta AI and now part of the Linux Foundation umbrella.
PyTorch Lightning - a lightweight PyTorch wrapper for high-performance AI research. Think of it as a framework for organizing your PyTorch code.
Hydra - a framework for elegantly configuring complex applications. The key feature is the ability to dynamically create a hierarchical configuration by composition and override it through config files and the command line.
The directory structure of new project looks like this:
├── .github <- Github Actions workflows
│
├── configs <- Hydra configs
│ ├── callbacks <- Callbacks configs
│ ├── data <- Data configs
│ ├── debug <- Debugging configs
│ ├── experiment <- Experiment configs
│ ├── extras <- Extra utilities configs
│ ├── hparams_search <- Hyperparameter search configs
│ ├── hydra <- Hydra configs
│ ├── local <- Local configs
│ ├── logger <- Logger configs
│ ├── model <- Model configs
│ ├── paths <- Project paths configs
│ ├── trainer <- Trainer configs
│ │
│ ├── eval.yaml <- Main config for evaluation
│ └── train.yaml <- Main config for training
│
├── data <- Project data
│
├── logs <- Logs generated by hydra and lightning loggers
│
├── notebooks <- Jupyter notebooks. Naming convention is a number (for ordering),
│ the creator's initials, and a short `-` delimited description,
│ e.g. `1.0-jqp-initial-data-exploration.ipynb`.
│
├── scripts <- Shell scripts
│
├── src <- Source code
│ ├── data <- Data scripts
│ ├── models <- Model scripts
│ ├──├── litho <- lithography model scripts.
│ ├── utils <- Utility scripts
│ │
│ ├── eval.py <- Run evaluation
│ └── train.py <- Run training
│
├── tests <- Tests of any kind
│
├── .env.example <- Example of file for storing private environment variables
├── .gitignore <- List of files ignored by git
├── .pre-commit-config.yaml <- Configuration of pre-commit hooks for code formatting
├── .project-root <- File for inferring the position of project root directory
├── environment.yaml <- File for installing conda environment
├── Makefile <- Makefile with commands like `make train` or `make test`
├── pyproject.toml <- Configuration options for testing and linting
├── requirements.txt <- File for installing python dependencies
├── setup.py <- File for installing project as a package
└── README.md
Override any config parameter from command line
python train.py trainer.max_epochs=20 model.optimizer.lr=1e-4
Note: You can also add new parameters with
+
sign.
python train.py +model.new_param="owo"
Train on CPU, GPU, multi-GPU and TPU
# train on CPU
python train.py trainer=cpu
# train on 1 GPU
python train.py trainer=gpu
# train on TPU
python train.py +trainer.tpu_cores=8
# train with DDP (Distributed Data Parallel) (4 GPUs)
python train.py trainer=ddp trainer.devices=4
# train with DDP (Distributed Data Parallel) (8 GPUs, 2 nodes)
python train.py trainer=ddp trainer.devices=4 trainer.num_nodes=2
# simulate DDP on CPU processes
python train.py trainer=ddp_sim trainer.devices=2
# accelerate training on mac
python train.py trainer=mps
Warning: Currently there are problems with DDP mode, read this issue to learn more.
Train with mixed precision
# train with pytorch native automatic mixed precision (AMP)
python train.py trainer=gpu +trainer.precision=16
Train model with any logger available in PyTorch Lightning, like W&B or Tensorboard
# set project and entity names in `configs/logger/wandb`
wandb:
project: "your_project_name"
entity: "your_wandb_team_name"
# train model with Weights&Biases (link to wandb dashboard should appear in the terminal)
python train.py logger=wandb
Note: Lightning provides convenient integrations with most popular logging frameworks. Learn more here.
Note: Using wandb requires you to setup account first. After that just complete the config as below.
Note: Click here to see example wandb dashboard generated with this template.
Train model with chosen experiment config
python train.py experiment=example
Note: Experiment configs are placed in configs/experiment/.
Attach some callbacks to run
python train.py callbacks=default
Note: Callbacks can be used for things such as as model checkpointing, early stopping and many more.
Note: Callbacks configs are placed in configs/callbacks/.
Use different tricks available in Pytorch Lightning
# gradient clipping may be enabled to avoid exploding gradients
python train.py +trainer.gradient_clip_val=0.5
# run validation loop 4 times during a training epoch
python train.py +trainer.val_check_interval=0.25
# accumulate gradients
python train.py +trainer.accumulate_grad_batches=10
# terminate training after 12 hours
python train.py +trainer.max_time="00:12:00:00"
Note: PyTorch Lightning provides about 40+ useful trainer flags.
Easily debug
# runs 1 epoch in default debugging mode
# changes logging directory to `logs/debugs/...`
# sets level of all command line loggers to 'DEBUG'
# enforces debug-friendly configuration
python train.py debug=default
# run 1 train, val and test loop, using only 1 batch
python train.py debug=fdr
# print execution time profiling
python train.py debug=profiler
# try overfitting to 1 batch
python train.py debug=overfit
# raise exception if there are any numerical anomalies in tensors, like NaN or +/-inf
python train.py +trainer.detect_anomaly=true
# use only 20% of the data
python train.py +trainer.limit_train_batches=0.2 \
+trainer.limit_val_batches=0.2 +trainer.limit_test_batches=0.2
Note: Visit configs/debug/ for different debugging configs.
Resume training from checkpoint
python train.py ckpt_path="/path/to/ckpt/name.ckpt"
Note: Checkpoint can be either path or URL.
Note: Currently loading ckpt doesn't resume logger experiment, but it will be supported in future Lightning release.
Evaluate checkpoint on test dataset
python eval.py ckpt_path="/path/to/ckpt/name.ckpt"
Note: Checkpoint can be either path or URL.
Create a sweep over hyperparameters
# this will run 6 experiments one after the other,
# each with different combination of batch_size and learning rate
python train.py -m data.batch_size=32,64,128 model.lr=0.001,0.0005
Note: Hydra composes configs lazily at job launch time. If you change code or configs after launching a job/sweep, the final composed configs might be impacted.
Create a sweep over hyperparameters with Optuna
# this will run hyperparameter search defined in `configs/hparams_search/mnist_optuna.yaml`
# over chosen experiment config
python train.py -m hparams_search=mnist_optuna experiment=example
Note: Using Optuna Sweeper doesn't require you to add any boilerplate to your code, everything is defined in a single config file.
Warning: Optuna sweeps are not failure-resistant (if one job crashes then the whole sweep crashes).
Execute all experiments from folder
python train.py -m 'experiment=glob(*)'
Note: Hydra provides special syntax for controlling behavior of multiruns. Learn more here. The command above executes all experiments from configs/experiment/.
Execute run for multiple different seeds
python train.py -m seed=1,2,3,4,5 trainer.deterministic=True logger=csv tags=["benchmark"]
Note:
trainer.deterministic=True
makes pytorch more deterministic but impacts the performance.
Execute sweep on a remote AWS cluster
Note: This should be achievable with simple config using Ray AWS launcher for Hydra. Example is not implemented in this template.
Use Hydra tab completion
Note: Hydra allows you to autocomplete config argument overrides in shell as you write them, by pressing
tab
key. Read the docs.
Apply pre-commit hooks
pre-commit run -a
Note: Apply pre-commit hooks to do things like auto-formatting code and configs, performing code analysis or removing output from jupyter notebooks. See # Best Practices for more.
Update pre-commit hook versions in .pre-commit-config.yaml
with:
pre-commit autoupdate
Run tests
# run all tests
pytest
# run tests from specific file
pytest tests/test_train.py
# run all tests except the ones marked as slow
pytest -k "not slow"
Use tags
Each experiment should be tagged in order to easily filter them across files or in logger UI:
python train.py tags=["mnist","experiment_X"]
Note: You might need to escape the bracket characters in your shell with
python train.py tags=\["mnist","experiment_X"\]
.
If no tags are provided, you will be asked to input them from command line:
>>> python train.py tags=[]
[2022-07-11 15:40:09,358][src.utils.utils][INFO] - Enforcing tags! <cfg.extras.enforce_tags=True>
[2022-07-11 15:40:09,359][src.utils.rich_utils][WARNING] - No tags provided in config. Prompting user to input tags...
Enter a list of comma separated tags (dev):
If no tags are provided for multirun, an error will be raised:
>>> python train.py -m +x=1,2,3 tags=[]
ValueError: Specify tags before launching a multirun!
Note: Appending lists from command line is currently not supported in hydra :(
Suggestions for improvements are always welcome!
Location: configs/train.yaml
Main project config contains default training configuration.
It determines how config is composed when simply executing command python train.py
.
Show main project config
# order of defaults determines the order in which configs override each other
defaults:
- _self_
- data: mnist.yaml
- model: mnist.yaml
- callbacks: default.yaml
- logger: null # set logger here or use command line (e.g. `python train.py logger=csv`)
- trainer: default.yaml
- paths: default.yaml
- extras: default.yaml
- hydra: default.yaml
# experiment configs allow for version control of specific hyperparameters
# e.g. best hyperparameters for given model and datamodule
- experiment: null
# config for hyperparameter optimization
- hparams_search: null
# optional local config for machine/user specific settings
# it's optional since it doesn't need to exist and is excluded from version control
- optional local: default.yaml
# debugging config (enable through command line, e.g. `python train.py debug=default)
- debug: null
# task name, determines output directory path
task_name: "train"
# tags to help you identify your experiments
# you can overwrite this in experiment configs
# overwrite from command line with `python train.py tags="[first_tag, second_tag]"`
# appending lists from command line is currently not supported :(
# https://github.com/facebookresearch/hydra/issues/1547
tags: ["dev"]
# set False to skip model training
train: True
# evaluate on test set, using best model weights achieved during training
# lightning chooses best weights based on the metric specified in checkpoint callback
test: True
# simply provide checkpoint path to resume training
ckpt_path: null
# seed for random number generators in pytorch, numpy and python.random
seed: null
Location: configs/experiment
Experiment configs allow you to overwrite parameters from main config.
For example, you can use them to version control best hyperparameters for each combination of model and dataset.
Show example experiment config
# @package _global_
# to execute this experiment run:
# python train.py experiment=example
defaults:
- override /data: mnist.yaml
- override /model: mnist.yaml
- override /callbacks: default.yaml
- override /trainer: default.yaml
# all parameters below will be merged with parameters from default configurations set above
# this allows you to overwrite only specified parameters
tags: ["mnist", "simple_dense_net"]
seed: 12345
trainer:
min_epochs: 10
max_epochs: 10
gradient_clip_val: 0.5
model:
optimizer:
lr: 0.002
net:
lin1_size: 128
lin2_size: 256
lin3_size: 64
data:
batch_size: 64
logger:
wandb:
tags: ${tags}
group: "mnist"
Basic workflow
- Write your PyTorch Lightning module (see models/mnist_module.py for example)
- Write your PyTorch Lightning datamodule (see data/mnist_datamodule.py for example)
- Write your experiment config, containing paths to model and datamodule
- Run training with chosen experiment config:
python src/train.py experiment=experiment_name.yaml
Experiment design
Say you want to execute many runs to plot how accuracy changes in respect to batch size.
-
Execute the runs with some config parameter that allows you to identify them easily, like tags:
python train.py -m logger=csv data.batch_size=16,32,64,128 tags=["batch_size_exp"]
-
Write a script or notebook that searches over the
logs/
folder and retrieves csv logs from runs containing given tags in config. Plot the results.
Hydra creates new output directory for every executed run.
Default logging structure:
├── logs
│ ├── task_name
│ │ ├── runs # Logs generated by single runs
│ │ │ ├── YYYY-MM-DD_HH-MM-SS # Datetime of the run
│ │ │ │ ├── .hydra # Hydra logs
│ │ │ │ ├── csv # Csv logs
│ │ │ │ ├── wandb # Weights&Biases logs
│ │ │ │ ├── checkpoints # Training checkpoints
│ │ │ │ └── ... # Any other thing saved during training
│ │ │ └── ...
│ │ │
│ │ └── multiruns # Logs generated by multiruns
│ │ ├── YYYY-MM-DD_HH-MM-SS # Datetime of the multirun
│ │ │ ├──1 # Multirun job number
│ │ │ ├──2
│ │ │ └── ...
│ │ └── ...
│ │
│ └── debugs # Logs generated when debugging config is attached
│ └── ...
You can change this structure by modifying paths in hydra configuration.
PyTorch Lightning supports many popular logging frameworks: Weights&Biases, Neptune, Comet, MLFlow, Tensorboard.
These tools help you keep track of hyperparameters and output metrics and allow you to compare and visualize results. To use one of them simply complete its configuration in configs/logger and run:
python train.py logger=logger_name
You can use many of them at once (see configs/logger/many_loggers.yaml for example).
You can also write your own logger.
Lightning provides convenient method for logging custom metrics from inside LightningModule. Read the docs or take a look at MNIST example.
Template comes with generic tests implemented with pytest
.
# run all tests
pytest
# run tests from specific file
pytest tests/test_train.py
# run all tests except the ones marked as slow
pytest -k "not slow"
Most of the implemented tests don't check for any specific output - they exist to simply verify that executing some commands doesn't end up in throwing exceptions. You can execute them once in a while to speed up the development.
Currently, the tests cover cases like:
- running 1 train, val and test step
- running 1 epoch on 1% of data, saving ckpt and resuming for the second epoch
- running 2 epochs on 1% of data, with DDP simulated on CPU
And many others. You should be able to modify them easily for your use case.
There is also @RunIf
decorator implemented, that allows you to run tests only if certain conditions are met, e.g. GPU is available or system is not windows. See the examples.
Show example hyperparameter search config
# @package _global_
defaults:
- override /hydra/sweeper: optuna
# choose metric which will be optimized by Optuna
# make sure this is the correct name of some metric logged in lightning module!
optimized_metric: "val/acc_best"
# here we define Optuna hyperparameter search
# it optimizes for value returned from function with @hydra.main decorator
hydra:
sweeper:
_target_: hydra_plugins.hydra_optuna_sweeper.optuna_sweeper.OptunaSweeper
# 'minimize' or 'maximize' the objective
direction: maximize
# total number of runs that will be executed
n_trials: 20
# choose Optuna hyperparameter sampler
# docs: https://optuna.readthedocs.io/en/stable/reference/samplers.html
sampler:
_target_: optuna.samplers.TPESampler
seed: 1234
n_startup_trials: 10 # number of random sampling runs before optimization starts
# define hyperparameter search space
params:
model.optimizer.lr: interval(0.0001, 0.1)
data.batch_size: choice(32, 64, 128, 256)
model.net.lin1_size: choice(64, 128, 256)
model.net.lin2_size: choice(64, 128, 256)
model.net.lin3_size: choice(32, 64, 128, 256)
Next, execute it with: python train.py -m hparams_search=mnist_optuna
Using this approach doesn't require adding any boilerplate to code, everything is defined in a single config file. The only necessary thing is to return the optimized metric value from the launch file.
You can use different optimization frameworks integrated with Hydra, like Optuna, Ax or Nevergrad.
The optimization_results.yaml
will be available under logs/task_name/multirun
folder.
This approach doesn't support resuming interrupted search and advanced techniques like prunning - for more sophisticated search and workflows, you should probably write a dedicated optimization task (without multirun feature).
.github/workflows/test.yaml
: running all tests with pytest.github/workflows/code-quality-main.yaml
: running pre-commits on main branch for all files.github/workflows/code-quality-pr.yaml
: running pre-commits on pull requests for modified files only
# ./src/train.py
datamodule = hydra.utils.instantiate(config.data)
model = hydra.utils.instantiate(config.model, some_param=datamodule.some_param)
Note: Not a very robust solution, since it assumes all your datamodules have
some_param
attribute available.
Similarly, you can pass a whole datamodule config as an init parameter:
# ./src/train.py
model = hydra.utils.instantiate(config.model, dm_conf=config.data, _recursive_=False)
You can also pass a datamodule config parameter to your model through variable interpolation:
# ./configs/model/my_model.yaml
_target_: src.models.my_module.MyLitModule
lr: 0.01
some_param: ${data.some_param}
Another approach is to access datamodule in LightningModule directly through Trainer:
# ./src/models/mnist_module.py
def on_train_start(self):
self.some_param = self.trainer.datamodule.some_param
Note: This only works after the training starts since otherwise trainer won't be yet available in LightningModule.
Use Miniconda
It's usually unnecessary to install full anaconda environment, miniconda should be enough (weights around 80MB).
Big advantage of conda is that it allows for installing packages without requiring certain compilers or libraries to be available in the system (since it installs precompiled binaries), so it often makes it easier to install some dependencies e.g. cudatoolkit for GPU support.
It also allows you to access your environments globally which might be more convenient than creating new local environment for every project.
Example installation:
wget https://repo.anaconda.com/miniconda/Miniconda3-latest-Linux-x86_64.sh
bash Miniconda3-latest-Linux-x86_64.sh
Update conda:
conda update -n base -c defaults conda
Create new conda environment:
conda create -n myenv python=3.10
conda activate myenv
Use automatic code formatting
Use pre-commit hooks to standardize code formatting of your project and save mental energy.
Simply install pre-commit package with:
pip install pre-commit
Next, install hooks from .pre-commit-config.yaml:
pre-commit install
After that your code will be automatically reformatted on every new commit.
To reformat all files in the project use command:
pre-commit run -a
To update hook versions in .pre-commit-config.yaml use:
pre-commit autoupdate
Set private environment variables in .env file
System specific variables (e.g. absolute paths to datasets) should not be under version control or it will result in conflict between different users. Your private keys also shouldn't be versioned since you don't want them to be leaked.
Template contains .env.example
file, which serves as an example. Create a new file called .env
(this name is excluded from version control in .gitignore).
You should use it for storing environment variables like this:
MY_VAR=/home/user/my_system_path
All variables from .env
are loaded in train.py
automatically.
Hydra allows you to reference any env variable in .yaml
configs like this:
path_to_data: ${oc.env:MY_VAR}
Name metrics using '/' character
Depending on which logger you're using, it's often useful to define metric name with /
character:
self.log("train/loss", loss)
This way loggers will treat your metrics as belonging to different sections, which helps to get them organised in UI.
Use torchmetrics
Use official torchmetrics library to ensure proper calculation of metrics. This is especially important for multi-GPU training!
For example, instead of calculating accuracy by yourself, you should use the provided Accuracy
class like this:
from torchmetrics.classification.accuracy import Accuracy
class LitModel(LightningModule):
def __init__(self)
self.train_acc = Accuracy()
self.val_acc = Accuracy()
def training_step(self, batch, batch_idx):
...
acc = self.train_acc(predictions, targets)
self.log("train/acc", acc)
...
def validation_step(self, batch, batch_idx):
...
acc = self.val_acc(predictions, targets)
self.log("val/acc", acc)
...
Make sure to use different metric instance for each step to ensure proper value reduction over all GPU processes.
Torchmetrics provides metrics for most use cases, like F1 score or confusion matrix. Read documentation for more.
Follow PyTorch Lightning style guide
The style guide is available here.
-
Be explicit in your init. Try to define all the relevant defaults so that the user doesn’t have to guess. Provide type hints. This way your module is reusable across projects!
class LitModel(LightningModule): def __init__(self, layer_size: int = 256, lr: float = 0.001):
-
Preserve the recommended method order.
class LitModel(LightningModule): def __init__(): ... def forward(): ... def training_step(): ... def training_step_end(): ... def on_train_epoch_end(): ... def validation_step(): ... def validation_step_end(): ... def on_validation_epoch_end(): ... def test_step(): ... def test_step_end(): ... def on_test_epoch_end(): ... def configure_optimizers(): ... def any_extra_hook(): ...
Version control your data and models with DVC
Use DVC to version control big files, like your data or trained ML models.
To initialize the dvc repository:
dvc init
To start tracking a file or directory, use dvc add
:
dvc add data/MNIST
DVC stores information about the added file (or a directory) in a special .dvc file named data/MNIST.dvc, a small text file with a human-readable format. This file can be easily versioned like source code with Git, as a placeholder for the original data:
git add data/MNIST.dvc data/.gitignore
git commit -m "Add raw data"
Support installing project as a package
It allows other people to easily use your modules in their own projects.
Change name of the src
folder to your project name and complete the setup.py
file.
Now your project can be installed from local files:
pip install -e .
Or directly from git repository:
pip install git+git://github.com/YourGithubName/your-repo-name.git --upgrade
So any file can be easily imported into any other file like so:
from project_name.models.mnist_module import MNISTLitModule
from project_name.data.mnist_datamodule import MNISTDataModule
Keep local configs out of code versioning
Some configurations are user/machine/installation specific (e.g. configuration of local cluster, or harddrive paths on a specific machine). For such scenarios, a file configs/local/default.yaml can be created which is automatically loaded but not tracked by Git.
For example, you can use it for a SLURM cluster config:
# @package _global_
defaults:
- override /hydra/launcher@_here_: submitit_slurm
data_dir: /mnt/scratch/data/
hydra:
launcher:
timeout_min: 1440
gpus_per_task: 1
gres: gpu:1
job:
env_set:
MY_VAR: /home/user/my/system/path
MY_KEY: asdgjhawi8y23ihsghsueity23ihwd
OPC : OpenILT
TorchLitho is licensed under the GPL3.0 License.