Recreating natural light in the lab

Light and luminous colour have a decisive effect on our health and well-being. The human organism has adapted to natural light over the course of several millennia. Today, however, people spend most of their time inside buildings with artificial light and are thus exposed to lighting circumstances they are not equipped to handle.

LED and OLED lighting technologies can create dynamic lighting sources generating a large number of light spectra that can emulate natural light. This light has a positive effect on our performance and ability to concentrate and is more comfortable for users than static artificial lighting.

In the Light Fusion Lab at Fraunhofer Institute for Industrial Engineering IAO in Stuttgart, researchers are working to optimize artificial lighting and make it as close to natural light as possible.

Researchers have investigated how artificial lighting affects people when it changes during the course of the day, the way light circumstances under the open sky change. "Dynamic light is like music for the eyes: Sometimes in particular situations we need relaxing music, sometimes we need more stirring music and sometimes we need no music at all in order to be positively stimulated," says Oliver Stefani, designer and engineer at Fraunhofer IAO.

Fraunhofer IAO has established the Light Fusion Lab, a development and testing laboratory where light researchers investigate the effects of light on people. The research results are used to derive recommendations for healthy lighting and optimum working conditions.

One of the Light Fusion Lab's developments is the Virtual Sky, the prototype of a sky simulation. A 34 square meter light surface containing 34,560 light-emitting diodes simulates the rhythm of daylight and passing clouds against a blue sky.

A matt white diffusor film located approximately 30 centimeters under the LEDs ensures that a homogenously luminous surface appears instead of perceptible individual points of light.

The researchers use red, blue, green and white LEDs in order to achieve the desired light spectrum. This combination is capable of realizing over 16 million colors.

Light's colour components control the body's day and night rhythms. In the morning the blue component in light is high, creating a cool white light with a stimulating and performance-enhancing effect on the human organism.

As the day goes on, the rate of the blue light component drops and by the evening the light changes to a warm white light with a high ratio of red light. This causes the body to produce the hormone melatonin, making us tired. During the less sunlit times of the year this can become quite a problem for people who spend the entire day in artificially lit rooms. Lack of sufficient daylight can make people tired and depressive.

In the Light Fusion Lab, researchers design and develop innovative light technologies for the workplace as well as display and interaction systems for future work environments.

The researchers advise lighting solution manufacturers and users on planning and realisation topics. The Light Fusion Lab provides workstations and tools for simulatiing and prototyping optical and electronic systems including all the necessary software components. Its high-quality photometric technologies enable reference measurements for optical characterization and quality evaluation of various lights and lamps.

Model workstations for user studies can be flexibly adapted as necessary to suit the study design in question.