Demodulation and phase estimation of two-dimensional patterns
AssigneeCanon Kabushiki Kaisha
InventorsKieran Gerard Larkin, Michael Alexander Oldfield, Donald James Bone
Life of this patent
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Abstract
A method (100) of demodulating a real two-dimensional pattern (110) is disclosed. The method (100) estimates (120, 130) a quadrature two-dimensional pattern from the real two-dimensional pattern (110) using a smooth phase only transform having an anti-symmetric phase, such as a spiral phase filter (140). A demodulated image is created by combining (180) the real two-dimensional pattern (110) and the estimated quadrature two-dimensional pattern.
Claims17
A method of demodulating a real two-dimensional pattern, the method comprising the steps of:
- estimating a quadrature two-dimensional pattern from said real two-dimensional pattern using a smooth phase only transform having an anti-symmetric phase;
- and
- creating a demodulated image by combining said real two-dimensional pattern and said estimated quadrature two-dimensional pattern.
Apparatus for demodulating a real two-dimensional pattern, the apparatus comprising:
- means for estimating a quadrature two-dimensional pattern from said real two-dimensional pattern using a smooth phase only transform having an anti-symmetric phase;
- and
- means for creating a demodulated image by combining said real two-dimensional pattern and said estimated quadrature two-dimensional pattern.
Apparatus for calculating a quadrature conjugate of a real two-dimensional code pattern, the apparatus comprising:
- a first spatial light modulator for modulating coherent light to produce said real two-dimensional pattern;
- a first lens for Fourier transformation of said real two-dimensional pattern to produce a first Fourier transformed image;
- a second spatial light modulator or spiral phase plate for phase modulating said first Fourier transformed image to produce a phase modulated image;
- a second lens for Fourier transformation of said phase modulated image to produce a second Fourier transformed image;
- a third spatial light modulator or spiral phase plate for phase modulating said second Fourier transformed image to produce said conjugate of said real two-dimensional pattern;
- and
- an image sensor for capturing said conjugate of said real two-dimensional pattern.
A method of demodulating a real two-dimensional pattern, the method comprising the steps of:
- estimating a quadrature two-dimensional pattern from said real two-dimensional pattern using a two-dimensional spiral phase filter;
- and
- creating a demodulated image by combining said real two-dimensional pattern and said estimated quadrature two-dimensional pattern.
Dependencies are inferred from the claim text.