US 12,422,779 B2
Optical assembly and method for reducing zero-order light in a holographic display
Alfred James Newman, London (GB); and Andrzej Kaczorowski, London (GB)
Assigned to VividQ Limited, London (GB)
Filed by VividQ Limited, London (GB)
Filed on Jun. 27, 2022, as Appl. No. 17/850,740.
Application 17/850,740 is a continuation of application No. PCT/EP2021/051566, filed on Jan. 25, 2021.
Claims priority of application No. 2001289 (GB), filed on Jan. 30, 2020.
Prior Publication US 2022/0326655 A1, Oct. 13, 2022
Int. Cl. G03H 1/22 (2006.01); G02B 27/01 (2006.01)
CPC G03H 1/2205 (2013.01) [G02B 27/0172 (2013.01); G02B 2027/0145 (2013.01); G02B 2027/0174 (2013.01); G02B 2027/0178 (2013.01); G03H 2001/2231 (2013.01); G03H 1/2286 (2013.01); G03H 2222/13 (2013.01); G03H 2223/12 (2013.01); G03H 2223/22 (2013.01); G03H 2225/32 (2013.01); G03H 2225/52 (2013.01); G03H 2227/03 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A holographic display comprising an optical assembly, the optical assembly comprising:
a light source;
a light-modulation element arranged to be illuminated off-axis by a light beam and configured to modulate the incident light, the light-modulation element comprising an array of pixels and being arranged to generate a replay image and a zero-order light beam;
a focusing system arranged after the light-modulation element and configured to focus modulated light from the light-modulation element and the zero-order light beam;
a light remover positioned after the focusing system configured to remove the zero-order light beam from the light focused by the focusing system;
a terminal optical element for directing modulated light from which the zero-order light has been removed by the light remover from the optical assembly;
a collimator illuminated by a light beam from the light source to cause the light beam to converge; and
a beam splitter configured to receive light from the collimator and reflect the received light onto the light-modulation element;
wherein:
an optical axis of the collimator is out of alignment with an optical axis of the beam splitter;
the optical axis of the collimator is arranged at an angle with respect to the optical axis of the beam splitter such that a centre of the beam of light from the collimator hits the light-modulation element off-axis and in the centre of the light-modulation element;
the angle is substantially equal to the value of the shortest wavelength of light in the light beam divided by twice the value of a pixel pitch of the array of pixels;
all optical elements located after the light-modulation element, including the focusing system, are centred on a centre of the field of view of the replay image;
the focusing system is configured to focus the zero-order light from the light-modulation element in a first plane different from a second plane which is the plane of focus of parallel light of the replay image, and
the light remover is configured to remove the zero-order light in the first plane.