https://people.uncw.edu/hermanr/labs/Phys2/optics.htm
https://play.google.com/store/apps/details?id=com.shakti.rayoptics
https://ricktu288.github.io/ray-optics/
https://www.physicsclassroom.com/Physics-Interactives/Refraction-and-Lens...
https://www.physics-chemistry-interactive-flash-animation.com/optics_inte...