Patent ID: 8659810

Claim:
A method for reconstructing an image of an object represented by a digital hologram, the method comprising: generating a measurement beam and a first reference beam; irradiating the object by the measurement beam, the measurement beam becoming an object wave by reflection with the object, and guiding the object wave to an optical sensor; guiding the first reference beam to a first mirror that reflects the first reference beam with a tilt angle so that the object wave and the first reference beam together generate a first interference pattern on the optical sensor, the first interference pattern being an off-axis interference pattern, and guiding the first reference beam reflected by the first mirror to the optical sensor; generating a second reference beam that does not interfere with the first reference beam; guiding the second reference beam to a second mirror and guiding the second reference beam reflected by the second mirror to the optical sensor so that the object wave and the second reference beam together generated a second interference pattern on the optical sensor; reading out the optical sensor and providing a digital signal representing the interference patterns generated on the optical sensor; processing the digital signal to obtain a digital hologram; subjecting the digital hologram to a Fourier transform in the spatial frequency domain to obtain a two dimensional spectrum comprising a DC-term, a first image term, a first conjugate image term, a second image term, and a second conjugate image term, the first image term and the first conjugate image term being derived from the first interference pattern, and the second image term and the second conjugate image term derived from the second interference pattern; cutting out a section of the first image term, which section is a certain region in a two dimensional spectrum derived by the Fourier transform and is overlapped with the DC-term, replacing the cut section by the corresponding section of the second image term, the corresponding section of the second image term and the cut section of the first image term including same information with regard to the object wave; and subjecting the obtained spectrum region of the first image to an inverse Fourier transform and reconstructing the image of the object represented by the digital hologram.