Zero order blocking and diverging for holographic imaging

A method for directing non-modulated light from a Spatial Light Modulator (SLM) and allowing through modulated light for producing an interference based holographic image, the method comprising:

• illuminating the SLM with coherent light, thereby producing a mix of light modulated by the SLM and light not modulated by the SLM;
• and
• projecting the mix of the modulated light and the not modulated light along an optical axis onto a volume grating;
• wherein
• the volume grating directs the not modulated light away from the holographic image and allows through modulated light for producing the holographic image;
• the volume grating is arranged to diffract Zero Order Diffraction light at an angle larger than a maximal diffraction angle of the SLM relative to the optical axis;
• the volume grating comprises an interference pattern of a first plane wave interfering with a second plane wave which has passed through an optical element in a shape of a conic solid;
• and
• a head angle β of the optical element in a shape of a conic solid is larger than
• β
• =
• π
• -
• 2
• *
• θ
• d
• n
• -
• 1
• where n is a refractive index of the optical element.