Optical-trap force transducer that operates by direct measurement of light momentum.

@article{Smith2003OpticaltrapFT,
  title={Optical-trap force transducer that operates by direct measurement of light momentum.},
  author={Steven B Smith and Yujia Cui and C. Bustamante},
  journal={Methods in enzymology},
  year={2003},
  volume={361},
  pages={134-62}
}