Apodized coherent transfer function constraint for partially coherent Fourier ptychographic microscopy

Chen, Xiong; Zhu, Youqiang; Sun, Minglu; Li, Dayu; Mu, Quanquan; Li, Xuan

doi:10.1364/oe.27.014099

Cited by 14 publications

(5 citation statements)

References 41 publications

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“…In order to further verify the proposed method, the setup of the FPM system is built based on the commercial Olympus microscopy. The experimental results are reconstructed by three different constrains in the frequency domain, which are the B-TF, AC [22], and CTF, respectively. The experimental parameters are as follow.…”

Section: Reconstruction Results Based On B-tf As the Frequency Constr...mentioning

confidence: 99%

“…It has the advantages of both maintaining the spatial coherence and reducing the computational burden. Chen et al [22] proposed to apply the apodization CTF (AC) as the constraint on the frequency domain to reduce the wrinkle of the reconstructed image. However, this kind of triangle-apodization technique is based on the case with the large illumination area of 3 mm, and it is difficult to apply to the case with the smaller illumination area.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Improved reconstruction with Butterworth-weighted transfer function for Fourier ptychographic microscopy

Zhao

Wang

Han

et al. 2022

Holography, Diffractive Optics, and Applications XII

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Fourier ptychographic microscopy (FPM) is an effective computational imaging method that incorporates many advantages such as large field of view, high resolution, label-free, and quantitative phase-contrast imaging. Typically, an LED array is used as the illumination source. Due to the small size and narrow spectral width of the LED unit, FPM is usually treated as a coherent imaging system. However, practically, each LED unit is a spatially-extended light source with a certain emitting area, rather than an ideal point source. The ideal point source approximation will decrease the quality of the reconstructed image, to a certain extent. In this paper, the spatial coherence characteristics of FPM system based on LED illumination is analyzed, and it is found that the optical field on the object plane is partially coherent. Thus, the artifacts exist when the coherent transfer function is used as the frequency domain constraint. To address this problem, a Butterworth-weighted transfer function is proposed as the frequency domain constraint in the iterative reconstruction process. The simulation and experimental results demonstrate that this new constraint approach can not only reduce the ringing effect in low-resolution images, but also improve the reconstruction quality due to its following better the actual physical mechanism inherent in FPM. In addition, it may reduce the requirement of the spatial coherence of the illumination source, which has great significance for promoting the application of FPM.

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Section: Reconstruction Results Based On B-tf As the Frequency Constr...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Improved reconstruction with Butterworth-weighted transfer function for Fourier ptychographic microscopy

Zhao

Wang

Han

et al. 2022

Holography, Diffractive Optics, and Applications XII

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“…The diffraction limited system is a circle with an exit pupil diameter of D because it is a circular symmetri- , it means that there is no movement, and the overlapping area is 1, that is, H(0, 0) 1 = , indicating that the amplitude has not changed, the phase has not changed, and all frequency components appear on the image plane; (3) If the two circles will be completely separated, then 0 θ = , at this time, , ξ η are large enough, and there is no overlapping part between the two circles, then the overlapping area is 0, that is, H( , ) 0 ξ η = , which means that the optical transfer function is 0 outside the specified range of the cut-off frequency, and these frequency components do not appear on the image plane. This also shows that the coherent optical system has a limited passband in the frequency domain, all pass through the passband, and there is a cut-off frequency outside the passband, the transfer function changes abruptly at the cut-off frequency [13,14]. Figure 6 shows the optical transfer function diagram.…”

Section: Theoretical Analysismentioning

confidence: 88%

"The Experimental Study on Optical Transfer Function under Coherent Light Based on MATLAB Simulation"

Li¹

2022

BJSTR

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Rong Duan and XiTeng Liu. The Experimental Study on Optical Transfer Function under Coherent Light Based on MATLAB Simulation. Biomed J Sci & Tech Res 45(5)-2022. BJSTR. MS.ID.007257. The Optical Transfer Function (OTF) can transfer spectra of different frequencies.In the process of transmission, the frequency will not change, but the amplitude will decrease, and the phase will shift. Therefore, the OTF is widely used in the evaluation of system imaging quality. In this paper, the intensity distribution, the coherent transfer function, the optical transfer function and the cut-off frequency of the image are obtained by using the back of the "5-yuan'he'coin" as the object of MATLAB simulation. Finally, the experimental results are consistent with the theoretical analysis, which proves the accuracy of the MATLAB simulation measurement method. At the same time, the relevant theoretical analysis also provides an important theoretical basis for optimizing the system parameters and improving the correlation calculation of OTF. The experimental study of OTF has great potential applications in military and aerospace fields.

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“…31 In our settings, θ s = 0.03 and θ p = 0.09 and was thus within the partially coherent illumination regime, as was the case in a number of previous FPM studies that utilized millimeter-sized LEDs for the illumination. 32,33 In consideration of this partial coherence effect, we used apodized pupil constraints throughout our image reconstruction algorithm, as was suggested in ref 34.…”

Section: ■ Methodsmentioning

confidence: 99%

“…Ideally, the illumination should satisfy θ s ≪ θ p to meet the spatial coherence condition, where θ s denotes the angular extent of the illumination source and θ p denotes the NA of the imaging system . In our settings, θ s = 0.03 and θ p = 0.09 and was thus within the partially coherent illumination regime, as was the case in a number of previous FPM studies that utilized millimeter-sized LEDs for the illumination. , In consideration of this partial coherence effect, we used apodized pupil constraints throughout our image reconstruction algorithm, as was suggested in ref .…”

Section: Methodsmentioning

confidence: 99%

A Smartphone-Based Fourier Ptychographic Microscope Using the Display Screen for Illumination

et al. 2021

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We propose a smartphone-mountable computational microscope that achieves wide-field and high-resolution imaging, based on the Fourier ptychographic (FP) microscopy technique. Our device uses the smartphone’s built-in camera for microscopy imaging, the display screen for programmable illumination, and the computational power of the smartphone processors for FP image reconstruction. With a compact and lightweight optics module and a custom-built application, we can transform a regular smartphone into a high-performance microscope device with a space-bandwidth product exceeding that of regular benchtop microscopes. Our device achieves a half-pitch resolution of 870 nm over a wide field-of-view of 2.1 × 1.6 mm2 with amplitude, phase, and color imaging capabilities. We report on the design of the illumination and imaging system, our methods for fast FP reconstruction on the smartphone microscope, and the performance of the device. Using various clinical samples, we also discuss the potential of our device for clinical applications in resource-limited settings.

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Apodized coherent transfer function constraint for partially coherent Fourier ptychographic microscopy

Cited by 14 publications

References 41 publications

Improved reconstruction with Butterworth-weighted transfer function for Fourier ptychographic microscopy

Improved reconstruction with Butterworth-weighted transfer function for Fourier ptychographic microscopy

"The Experimental Study on Optical Transfer Function under Coherent Light Based on MATLAB Simulation"

A Smartphone-Based Fourier Ptychographic Microscope Using the Display Screen for Illumination

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