Consists of a robust light box in matt black finish with a 12 V 24 W axial filament lamp with flexible leads. One end of the box takes a cylindrical convex lens in an adjustable sliding mount to enable production of convergent, parallel or divergent beams. The other end of the box has a triple aperture system for colour mixing experiments. The two side apertures are provided with hinged mirrors. All apertures are provided with vertical channels to hold slit plates and/ or colour filters.