1. A projection device ( 600 ) for generation of three-dimensional images, wherein said device generates three-dimensional images in at least two colors, wherein said at least two colors comprise a first basic color and a second basic color distinct from said first basic color, wherein said first basic color and said second basic color are selected from the group consisting of three basic colors, wherein said three basic colors are red, green and blue, wherein said projection device comprises a) a first display ( 681 ) generating two-dimensional images in said first basic color, b) a second display ( 682 ) generating two-dimensional images in said second basic color, c) at least one mirror ( 640 ), the focal length of which is wavelength-sensitive, and thus can be a tunable focal length being tuned by variation of the wavelength of light, wherein said first display ( 681 ) and said at least one mirror ( 640 ) generates a first virtual image at a first plane, such that at least two wavelengths in said first basic color range are used, such that said first virtual image is generated at different depths, such that the sequence of said first virtual images is synchronized with the variation of said wavelength-sensitive focal length of said at least one mirror ( 640 ), such that a complete first three-dimensional virtual image ( 671 ) in a first basic color is formed in front of a face of an observer, such that the eyes of the observer receive said complete three-dimensional image in said first basic color, wherein said second display ( 682 ) and said at least one mirror ( 640 ) generates a second virtual image at a second plane, such that at least two wavelengths in said second basic color range are used, such that said second virtual image is generated at different depths, such that the sequence of said second virtual images is synchronized with the variation of said wavelength-sensitive focal length of said at least one mirror ( 640 ), such that a complete second three-dimensional virtual image ( 672 ) in a second basic color is formed in front of a face of an observer, such that the eyes of the observer receive said complete three-dimensional image in said second basic color, wherein said first three-dimensional virtual image in said first basic color and said second three-dimensional virtual image in said second basic color generate an image perceived by an observer as a colored three-dimensional image.