Image generation unit and method to use an image generation unit

An image generation unit for projecting an image at a projection screen comprising:

• an illumination unit configured to generate a plurality of coherent sub-beams and to illuminate an image modulator, the illumination unit including a light source;
• a projection lens configured to superimpose each of the coherent sub-beams onto the projection screen plane, an optical set-up configured to introduce angles between each two of the sub-beams, which are chosen to produce uncorrelated speckle patterns in the projection screen plane, resulting in an interference speckle pattern;
• and
• a phase modulator including a liquid crystal cell configured to change its directory profile in a lateral manner, thereby able to change the phase of light of each sub-beam individually and to change its directory profile in a temporal manner individually for each sub-beam such that a resulting interference speckle pattern in the image plane changes and is uncorrelated from previous interference speckle patterns and the change is so fast, that during an integration time of a detector, speckle contrast of a resulting time-averaged interference speckle pattern is reduced compared with a not time-averaged interference speckle pattern.