What is a Virtual Object in Graphical Ray Tracing?

• A virtual object is simply the object on the wrong side (right side) of the lens.

Radius v/s Clear Semi-Diameter in Zemax OpticStudio

- In Zemax, Radius defines how curved is the lens surface. This value is 'infinity' for a flat surface.

- Whereas the Clear Semi-Diameter defines how big is the optic/lens. Its is the vertical distance from the optic axis to the periphery. Because for radius values very large, we cannot have a camera infinitely tall!