Method for a holographic projector
AssigneeDualitas Ltd
InventorRory Cooney
Life of this patent
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Abstract
A projection system that facilitates the use of in-situ detection of a change in wavelength, thereby enabling appropriate compensation or corrections to be applied on the fly to improve the quality of the image in the primary image region. In-situ detection in this manner can allow wavelength changes due to both temperature fluctuations and hardware variations to be compensated for simultaneously, thereby reducing the time and expense for end of line hardware testing, and removing the need to perform in-situ mapping of the wavelength as a function of temperature. In this way, the quality of the image provided to a user can be improved in a simpler, more efficient manner.
Claims25
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.
A method of adjusting an optical 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
- based on characteristics of the first signal and of the second signal that are wavelength-dependent, adjusting one or more of the wavelength of the light output by the light source and the computer-generated hologram to compensate for a shift in the wavelength of the light output by the light source.
Dependencies are inferred from the claim text.