Apparatus for accurate reconstruction of the object wave in the off-axis digital holography

摘要

The invention provides a method and an apparatus for preparing a digital hologram representing an object (9), comprising generating a measurement beam (11) and two reference beams (10,12), irradiating the object (9) by the measurement beam and guiding the reflected measurement beam to an optical sensor (7), guiding the reference beams to mirror means (5) extending under a slanting angle and guiding the reflected beams to the sensor (7) to make the beams generate an interference pattern on the sensor, providing a digital signal representing the pattern on the sensor, processing the signal to obtain a digital hologram, subjecting the digital hologram to a Fourier transform in the spatial frequency domain to obtain a spectrum comprising a DC-term,two image terms (R1*O,R2*O), and two conjugate image terms (R1O*,R2O*), filtering the spectrum to obtain a term representing the object and replacing a section of an image term overlapped by the DC-term by the corresponding section of the other image term.