light source can be kept stationary throughout the observations. This heliodon is an accurate instrument that can make rapid and simple adjustments. And the requirement of providing a precisely located light source is not necessary. In the 1990s, modern heliodons with quicker simulations and a greater level of accuracy were invented. EPFL Solar Energy and Building Physics Laboratory LESO-PB in Lausanne designed a robotic heliodon to simulate direct light. This heliodon is combined with a sky scanning simulator (artificial sky) to predict the light distribution in a building over the entire year. The device can reproduce direct light at any location on earth. After the 2000s, Prof. Norbert Lechner, an architect, LEED AP and an expert in energy responsive architecture has invented a manual Sun Emulator Heliodon. He invented heliodons which were much easier to evaluate daylight simulation than the previous models. The Sun Emulator Heliodon can precisely show all solar responsive design principles and strategies. Although the device can hold only small architectural scale models, it is a great instrument for teaching solar geometry. This heliodon was manufactured by High Precision Devices and now an alternative device is Orchard Heliodon produced by betanit.com, with the approval of the inventor of the Sun Emulator Heliodon. Since 2004, the Italian company betanit.com is developing various heliodons designed by architect Giulio M. Podesta for use in daylighting laboratories of universities and architectural firms. The architect designed the Orchard Heliodon with similar features to the Sun Emulator heliodon (developed by Norbert Lechner). For more precise simulations, Orange Heliodon, an easy to use robotic heliodon with a fixed light source was designed and was launched in the market in 2007. Moreover, the Orange Heliodon was used at Politecnico di Milano in the architectural design laboratory of the BEST department. It used a computerized and automatic heliodon to reproduce the sunshade. Furthermore, the architect designed Tulip Heliodon, a robotic heliodon with a fixed light source that is often merged with full dome artificial sky for collaborative design and presentation used for daylight studies. Kwok Pun Cheung, a professor and researcher at the Department of Architecture in Hong Kong University developed various heliodons. Cheung developed a simple tabletop heliodon and multi-lamp heliodon for use in architectural schools. Moreover, a tabletop heliodon with a moving light source was developed for architect offices. A patented portable direct sunlight light-duty universal heliodon set up on a camera tripod was