Most people have probably experienced the motion aftereffect without knowing that there is a name for it. This effect was described in the early 19th century by R. Addams who found that he could get a strong motion aftereffect by staring at a waterfall for several seconds then shifting his gaze to something else. The red arrow is the object, while the gray arrow is the virtual image that results after the rays have passed through the lens. The applet also displays two focus shown as blue dots. Diverging Mirror - This applet shows the basics of the Convex Mirror.
Source code is available.
It draws the Gaussian beam as it propagates through this system. At each optical element it reports the Gaussian beam propagation parameters. These optical components can be adjusted. This applet illustrates a rainbow. This applet demonstrates the transmission of a wave through dense media - reflection and refraction.