Accurate carrier-removal technique based on zero padding in Fourier transform method for carrier interferogram analysis

Du, Yongzhao; Feng, Guoying; Li, Hongru; Zhou, Shouhuan

doi:10.1016/j.ijleo.2013.07.145

Cited by 26 publications

(13 citation statements)

References 26 publications

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“…The experiment selected the microhole array, phase grating, and a pair of concave and convex phase steps as samples. By comparison of the spectrum's centering judgment results between amplitude maximum and unwrapped phase maximum, the feasibility of the presented method was In 2014, Du et al [62] presented a carrier frequency elimination method based on interferogram zero padding and a fast Fourier transform. The zero padding in the spatial domain of the discretization interferogram could achieve up-sampling in the frequency domain, which provided the solution for removing the residual tilt aberration under the condition that the carrier-frequency of carrier interferogram usually were not equal to an integer multiple of the Nyquist basic frequency.…”

Section: Tilt Phase Error Compensationmentioning

confidence: 99%

Recent Progress on Aberration Compensation and Coherent Noise Suppression in Digital Holography

Liu

Wang

2018

Applied Sciences

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Digital holographic microscopy (DHM) is a topographic measurement technique that permits full-field, nondestructive, dynamic, quantitative amplitude, and phase-contrast imaging. The technique may realize the lateral resolution with submicron scale and the longitudinal resolution with subnanometer scale, respectively. Improving imaging quality has always been the research focus in DHM since it has a direct effect on the precise topographic measurement. In this paper, the recent progress on phase aberration compensation and coherent noise suppression is reviewed. Included in this review are the hologram spectrum's centering judgment methods of side band in tilt phase error compensation, the physical and numerical compensation methods in phase aberration compensation, and the single-shot digital process methods in coherent noise suppression. The summaries and analyses for these approaches can contribute to improving the imaging quality and reducing the measurement error of DHM, which will further promote the wider applications of DHM in the topographic measurement fields, such as biology and micro-electro mechanical systems.

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Section: Tilt Phase Error Compensationmentioning

confidence: 99%

Recent Progress on Aberration Compensation and Coherent Noise Suppression in Digital Holography

Liu

Wang

2018

Applied Sciences

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“…In some cases, phase unwrapping can be avoided or the phase wraps can be significantly reduced, for example, in fringe projection or off-axis holographic profilometry [12][13][14]. In these techniques, a carrier signal is included in the extracted phase information.…”

Section: Introductionmentioning

confidence: 99%

Improved Carrier Frequency-Shifting Algorithm Based on 2-FFT for Phase Wrap Reduction

Zhang

Wang

et al. 2021

Mathematical Problems in Engineering

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The number of phase wraps that result from the carrier component can be completely eliminated or reduced by first applying a fast Fourier transform (FFT) to the image and then shifting the spectrum to the origin. However, because the spectrum can only be shifted by an integer number, the phase wraps of the carrier component cannot be completely reduced. In this paper, an improved carrier frequency-shifting algorithm based on 2-FFT for phase wrap reduction is proposed which allows the spectrum to be shifted by a rational number. Firstly, the phase wraps are reduced by the conventional FFT frequency shift method. Secondly, the wrapped phase with residual carrier components is filtered and magnified sequentially; the amplified phase is transformed into the frequency domain using an FFT, and then, the wrapped phase with the residual carrier components can be further reduced by shifting the spectrum by a rational number. Simulations and experiments were conducted to validate the efficiency of the proposed method.

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“…In almost all interferometry applications, the location of the carrier peak is in the sub‐pixel. To obtain the accurate carrier peak location, the zero‐padded method has been employed but the algorithmic complexity of this approach for a

β

fold zero padded interferogram of size

A \times B

O ((), β^{2} italicAB loglog ((), β^{2} italicAB))

, hence this method is nonviable due to heavy computational load [19].…”

Section: Introductionmentioning

confidence: 99%

Multimodal biomicroscopic system for the characterization of cells with high spatial phase sensitivity and sub‐pixel accuracy

Tayal

Singh

Kaur

et al. 2021

Journal of Biophotonics

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Multimodal analysis is highly advantageous for various biomedical applications including cancer and brain studies. Simultaneous measurement of quantitative phase with sub‐pixel accuracy and fluorescence image is difficult to achieve in single measurement. Conventionally, off‐axis interferograms are analyzed using the Fourier‐transform method which limits the accuracy of the phase maps by pixel size, and usually the location of the carrier peak is in sub‐pixel. We report a multimodal microscopic system consisting of high‐resolution (HR) quantitative phase interferometer to retrieve sub‐pixel accuracy in phase imaging and an oblique‐illumination‐based fluorescence imaging system which decouples the excited light from emitted signal light to avoid saturation of the camera, both integrated into a single unit. Here, highly resolved phase maps are obtained using a two‐step process. First, using a speckle‐free illumination which offers high spatial phase sensitivity. Second, using a hamming window for accurate estimation of original signal frequency information and HR discrete Fourier transform (DFT) which offers sub‐pixel accuracy in phase measurements. HR‐DFT has computational load of O()ABβ, where A×B is the size of the interferogram and β is the upsampling factor, making system computationally more robust and efficient compared to zero‐padded FFT. The experiment is conducted on MG63 osteosarcoma and human mesenchymal stem cells (hMSCs) and their quantitative parameters are extracted with significantly improved accuracy. The average phase for MG63 cells and hMSCs, for nucleus is obtained to be 8.02 rad ± 0.80 rad and 4.29 rad ± 0.43 rad, respectively, and for cytoplasm is obtained to be 2.63 rad ± 0.96 rad and 1.73 rad ± 0.57 rad, respectively.

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Accurate carrier-removal technique based on zero padding in Fourier transform method for carrier interferogram analysis

Cited by 26 publications

References 26 publications

Recent Progress on Aberration Compensation and Coherent Noise Suppression in Digital Holography

Recent Progress on Aberration Compensation and Coherent Noise Suppression in Digital Holography

Improved Carrier Frequency-Shifting Algorithm Based on 2-FFT for Phase Wrap Reduction

Multimodal biomicroscopic system for the characterization of cells with high spatial phase sensitivity and sub‐pixel accuracy

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