US 12,443,139 B2
Method for a holographic projector
Rory Cooney, Milton Keynes (GB)
Assigned to Dualitas Ltd, Milton Keynes (GB)
Filed by Dualitas Ltd, Milton Keynes (GB)
Filed on Nov. 10, 2023, as Appl. No. 18/506,355.
Application 18/506,355 is a continuation of application No. 16/752,002, filed on Jan. 24, 2020, granted, now 11,815,855.
Claims priority of application No. 1901025 (GB), filed on Jan. 25, 2019.
Prior Publication US 2024/0152093 A1, May 9, 2024
This patent is subject to a terminal disclaimer.
Int. Cl. G03H 1/04 (2006.01); G03H 1/00 (2006.01); G03H 1/24 (2006.01)
CPC G03H 1/0406 (2013.01) [G03H 1/0005 (2013.01); G03H 1/24 (2013.01)] 25 Claims
OG exemplary drawing
 
1. A method of detecting a wavelength property of the light output from the light source in a holographic projection system, the method comprising:
displaying a diffractive pattern comprising a computer-generated hologram on a spatial light modulator;
receiving, at the spatial light modulator, light having a wavelength from the light source at a spatial light modulator;
spatially modulating the received light in accordance with the displayed diffractive pattern comprising the computer-generated hologram to form an image at a display plane, the image comprising
a primary image region comprising information for a user,
a first control image region, and
a second control image region spaced apart from the first control image region, wherein positions of the first and second control image regions are dependent on the diffractive pattern and the wavelength;
detecting light travelling to or from the first control image region and, separately, detecting light travelling to or from the second control image region;
receiving a first signal representative of a position and/or a size of the first control image region based on the detection of light travelling to or from the first control image region, and receiving a second signal representative of a position and/or a size of the second control image region based on the detection of light travelling to or from the second first control image region; and
determining from the first signal and the second signal a wavelength property of the light output from the light source, the wavelength property being
a wavelength of the light output from the light source, based on the first signal and the second signal, or
a change over time in a wavelength of the light output from the light source based on a change of the first signal and the second signal.