Digital holographic harmonic detection and elimination method based on spectral energy

Abstract

The invention belongs to the field of digital holography, and discloses a digital holographic harmonic detection and elimination method based on spectrum energy. The method includes six steps to complete the processing of an image with harmonic interference, which are Fourier transform of the image, search of a harmonic spectrum, readout of coordinates and a complex value of the harmonic spectrum, calculation of the frequency and interference intensity coefficient of harmonics in horizontal and vertical directions and the initial phase, construction of harmonic distribution using parameters, and image correction. The method of the invention only utilizes the energy relationship between the zero-order Fourier transform spectrum and the harmonic spectrum without the need to design a filter; the acquisition of the range of harmonics corresponding to the spectrum is not required; no impact will be exerted on the information of the original light; an inverse Fourier transform is not required on the spectrum; and after the harmonic parameters are obtained using the energy relationship, the harmonic intensity distribution is constructed, the harmonic is eliminated by direct subtraction and the calculation is simple.

Description

technical field [0001] The invention belongs to the technical field of digital holography, and in particular relates to a method for detecting and eliminating harmonics of a digital hologram based on spectrum energy. Background technique [0002] When using digital holographic technology for microscopic imaging or precision measurement, the quality of digital hologram has a great influence on the quality of restored image or measurement accuracy. The existence of laser speckle, reference light tilt, and harmonics will greatly reduce imaging quality or measurement accuracy. . Digital holography requires the interference of object light and reference light to record the interferogram. Compared with ordinary photography, more optical components are required in the recording path, such as beam splitters, beam combiners, and spatial filters. When light waves pass through these devices, phenomena such as reflection and refraction will occur on the front and rear surfaces. Light ...

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Problems solved by technology

This also leads to the third defect of the filtering method: it cannot be applied to the harmonic elimination of continuous video images

[0004] The existing hologram preprocessing technology has the disadvantages of cumbersome filter design process, high cost, and difficulty in finding the spectrum; it is difficult to determine the range of filtering; it is difficult to determine the filtering amplitude; it is easy to lose useful object-light information; The processed hologram obtained by Lie transform doubles the amount of calculation; it cannot be applied to online continuous image processing

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