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Label-free imaging and identification of fast-moving cells is a very challenging task. A kind of phase flow cytometry using coherent modulation imaging was proposed to realize label-free imaging and identification on fast-moving cells with compact optical alignment and high accuracy. Phase image of cells under inspection could be computed qualitatively from their diffraction patterns at the accuracy of about 0.01 wavelength and the resolution of about 1.23 μm and the view field of 0.126 mm 2 . Since the imaging system was mainly composed by a piece of random phase plate a detector without using commonly adopted reference beam and corresponding complex optical alignment, this method has much compacter optical structure and much higher tolerance capability to environmental instability in comparison with other kinds of phase flow cytometry. Current experimental results prove it could be an efficient optical tool for label-free tumor cell detection., (© 2023 Wiley-VCH GmbH.)

Whole blood cell analysis is widely used in medical applications since its results are indicators for diagnosing a series of diseases. In this work, we report automatic whole blood cell analysis from blood smear using label-free multi-modal imaging with deep neural networks. First, a commercial microscope equipped with our developed Phase Real-time Microscope Camera (PhaseRMiC) obtains both bright-field and quantitative phase images. Then, these images are automatically processed by our designed blood smear recognition networks (BSRNet) that recognize erythrocytes, leukocytes and platelets. Finally, blood cell parameters such as counts, shapes and volumes can be extracted according to both quantitative phase images and automatic recognition results. The proposed whole blood cell analysis technique provides high-quality blood cell images and supports accurate blood cell recognition and analysis. Moreover, this approach requires rather simple and cost-effective setups as well as easy and rapid sample preparations. Therefore, this proposed method has great potential application in blood testing aiming at disease diagnostics., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Microimaging is of great significance in the biological and medical fields, since it can realize observations acting as important references for cellular research and disease diagnosis. However, traditional microscopy only offers qualitative sample contours; moreover, it is difficult to reach large-amount sample observations limited by the fixed field of view (FoV). To realize massive cellular measurements quantitatively, three designed quantitative interferometric microscopic cytometers based on the FoV scanning are introduced and compared in details in this article. These devices not only retrieve the quantitative sample phase distributions in the extended FoV, but also provide the detailed information of massive cells, such as cellular volume, area, and roundness. Considering their capabilities as quantitative imaging and large-amount sampling, it is believed that these quantitative interferometric microscopic cytometers (QIMCs) can be potentially adopted in high-throughput cell imaging and statistical analysis for both the biological and medical applications., (© 2018 Wiley Periodicals, Inc.)

A variable aperture-based ptychographical iterative engine (vaPIE) is demonstrated both numerically and experimentally to reconstruct the sample phase and amplitude rapidly. By adjusting the size of a tiny aperture under the illumination of a parallel light beam to change the illumination on the sample step by step and recording the corresponding diffraction patterns sequentially, both the sample phase and amplitude can be faithfully reconstructed with a modified ptychographical iterative engine (PIE) algorithm. Since many fewer diffraction patterns are required than in common PIE and the shape, the size, and the position of the aperture need not to be known exactly, this proposed vaPIE method remarkably reduces the data acquisition time and makes PIE less dependent on the mechanical accuracy of the translation stage; therefore, the proposed technique can be potentially applied for various scientific researches., ((2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).)

Massive image acquisition is required along the optical axis in the classical image-analysis-based autofocus method, which significantly decreases autofocus efficiency. A wavefront-sensing-based autofocus technique is proposed to increase the speed of autofocusing and obtain high localization accuracy. Intensities at different planes along the optical axis can be computed numerically after extracting the wavefront at defocus position with the help of the transport-of-intensity equation method. According to the focus criterion, the focal plane can then be determined, and after sample shifting to this plane, the in-focus image can be recorded. The proposed approach allows for fast, precise focus detection with fewer image acquisitions compared to classical image-analysis-based autofocus techniques, and it can be applied in commercial microscopes only with an extra illumination filter., ((2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).)

Based on interferometric microscopy, we develop a quantitative interferometric microscopic cytometer with expanded principal component analysis (PCA) phase retrieval method to obtain phase distributions of numerous biological samples with spatial resolution ~1.5 μm. The expanded PCA method realizes high-speed phase imaging from multiple microscopic interferograms captured by CCD camera when the biological samples are scanned in the field of view. This method is a time-domain algorithm which calculates faster than traditional frequency-domain algorithms and overcomes drawbacks induced by fast Fourier transform. The potential of this phase detecting system for studying biological systems is demonstrated with simulations and phase measurement of red blood cells in experiments. [ABSTRACT FROM AUTHOR]

Abstract: Phase distribution detection of cells and tissues is concerned since it is an important auxiliary method for observing biological samples. High speed and large amount cell detection is needed for its high detecting efficiency. In this paper, we have proposed a simple large scale biological sample phase detection device called gravity driven high throughput phase detecting cytometer based on quantitative interferometric microscopy to obtain flowing red blood cells phase. The system could realize high throughput phase detecting and statistical analysis with high detecting speed and in real time. The statistical characteristics of red blood cells could be obtained which might be helpful for biological analysis and disease detection. We believe this method is a powerful tool to quantitatively measure the phase distribution of biological samples. [Copyright &y& Elsevier]

Abstract: An improved phase retrieval method based on Hilbert transform is introduced to quantitatively calculate the phase distribution from a micro-interferometric pattern. The property of Hilbert transform, losing DC offsets and owning π/2 phase shifting, is used to remove the DC component and obtain the phase distribution from an off-axis interferogram. Compared with traditional Hilbert method, the Fourier transform is omitted that can avoid the questions of frequency leakage and improve the computational efficiency. Based on the micro-interferometric measurement, the improved method is used to retrieve the phase distribution of rabbit red blood cells. And the corresponding results show that it owns high calculation efficiency and the ability of reserving details of samples. [Copyright &y& Elsevier]

Interferometric microscopy is an important technique to obtain the phase distribution of cells and tissues. However, in practice, the absorption effect of the biological samples and non-uniformities in the beam could induce errors in solving phase distributions by traditional methods. In this paper, an improved phase retrieval method is introduced to quantitatively calculate the phase distribution of absorbing samples. The proposed method could acquire more accurate phase distributions and optical transmitted sample images physically. Comparing with conventional phase retrieval methods, the proposed method has higher accuracy and calculation efficiency. [ABSTRACT FROM AUTHOR]

Aperture-scanning Fourier ptychography is a configuration of Fourier ptychgraphy by scanning an aperture at the back focal plane of the objective lens. It has been a useful tool for measuring the complex scattering field exited from a sample. However, in this method the intensity of dark images at the charge coupled device (CCD) plane is of same order or even lower than the noise when the high frequency of the Fourier spectrum is filtered by the aperture. Therefore, the recorded dark field images suffer from low signal-to-noise ratio (SNR), which results in poor reconstruction. In this paper, we report a modified Fourier ptychographic imaging method by wavefront modulation. Instead of an aperture, a diffuser is used to modulate the spectrum in the presented method. The complex distribution of the sample and the diffuser are reconstructed simultaneously via iterative phase retrieval. Numerical simulations and proof-of-concept experiments have been carried out to demonstrate the feasibility of the presented method. [ABSTRACT FROM AUTHOR]

Phase retrieval in quantitative interferometric microscopy is a time-consuming and computationally expensive process, thus limiting the applications on cell dynamic detections. Here, we propose Fast Fourier Transform and Differential–Integral based Phase Retrieval Algorithm (FFT-DI-PRA) focusing on quantitative cell phase imaging to significantly accelerate the phase retrieval process. The proposed method first obtains the wrapped phase from a single-shot interferogram using the FFT based phase extraction method; then, its phase derivatives are computed along two orthogonal directions; finally, the unwrapped specimen phase is reconstructed by phase integration from corrected phase derivatives. Since the FFT based phase extraction method can effectively suppress the noise, the phase wraps can be easily recognized in phase derivatives avoiding the noise influences, thus supporting the rapid and accurate phase wrapping. As a perfect combination of the FFT based phase extraction and the differential–integral based phase wrapping, FFT-DI-PRA only takes ∼ 0.03 second for phase imaging from one single-shot interferogram of 512 × 512 pixels using a typical desktop; moreover, it provides high-accurate specimen phase distributions as shown here by both simulations and experiments, suggesting that FFT-DI-PRA is an effective tool used in rapid quantitative live cell phase imaging and display. [ABSTRACT FROM AUTHOR]