An Illumination device includes light emitting devices and an optical system for collimating light emitted by the light emitting devices. A first group of the light emitting devices are arranged in a first array having first gaps, and a first optical system is arranged near the first group of light emitting devices. At least one second group of the light emitting devices are arranged in a second array, and the second array has second gaps. The second optical system is arranged near the second group of light emitting devices. The first and second optical systems are arranged so that, in a distance from the illumination device, light emitted by the first group of light emitting devices, collimated by the first optical system, and light emitted by the second group of light emitting devices, collimated by the second optical system, are superimposed to form a gap-free illumination field.