Razer is bringing the opto-mechanical switches first introduced on the new Huntsman gaming keyboard to its gaming laptop models. For now, the low profile optical laptop keyboard is only available on the Blade 15 Advanced laptop, but Razer will add this feature to other 2020 models. The optical switches make use of an infrared light beam that allows for faster actuation and inputs.
https://www.notebookcheck.net/Razer-showcases-the-world-s-first-optical-laptop-keyboard.439756.0.html