Why is the dot not round?Updated 3 days ago

The functionality of the dot projection is based on the principle of total reflection. As with any reflection, it can be influenced by certain factors. Key among these are specific light sources that can cause disruptive secondary reflections which make the dot seem to appear not to be perfectly circular. These disruptive light sources can include the sun positioned low and obliquely from the front.
Another significant influencing factor is the human eye. Our eyes tend not to recognise dot-shaped light sources as such, particularly when a certain light intensity is exceeded. This phenomenon can be observed well with a burning candle. When looking directly at the flame, a jagged corona appears around it. This effect is solely a result of how the eye processes the image.
Vision impairments, especially astigmatism, can also cause dot-shaped light sources to appear irregular or jagged. Such visual impairments might not necessarily affect daily visual tasks and often go unnoticed. When looking at a dot-shaped light source, it may then appear jagged, usually on one side.