Quantitative Phase Imaging Techniques Research Articles

High-speed transport-of-intensity phase microscopy with an electrically tunable lens

We present a high-speed transport-of-intensity equation (TIE) quantitative phase microscopy technique, named TL-TIE, by combining an electrically tunable lens with a conventional transmission microscope. This permits the specimen at different focus position to be imaged in rapid succession, with constant magnification and no physically moving parts. The simplified image stack collection significantly reduces the acquisition time, allows for the diffraction-limited through-focus intensity stack collection at 15 frames per second, making dynamic TIE phase imaging possible. The technique is demonstrated by profiling of microlens array using optimal frequency selection scheme, and time-lapse imaging of live breast cancer cells by inversion the defocused phase optical transfer function to correct the phase blurring in traditional TIE. Experimental results illustrate its outstanding capability of the technique for quantitative phase imaging, through a simple, non-interferometric, high-speed, high-resolution, and unwrapping-free approach with prosperous applications in micro-optics, life sciences and bio-photonics.

Quantitative Phase Imaging Techniques for the Study of Cell Pathophysiology: From Principles to Applications

A cellular-level study of the pathophysiology is crucial for understanding the mechanisms behind human diseases. Recent advances in quantitative phase imaging (QPI) techniques show promises for the cellular-level understanding of the pathophysiology of diseases. To provide important insight on how the QPI techniques potentially improve the study of cell pathophysiology, here we present the principles of QPI and highlight some of the recent applications of QPI ranging from cell homeostasis to infectious diseases and cancer.

Noncontact single-pulse optical method to measure interfacial properties in intact systems

We introduce a noncontact purely optical approach to measuring the localized surface properties of an interface within a system using a single optical pressure pulse and a time-resolved digital holographic quantitative phase-imaging technique to track the propagating nanometric capillary disturbance. We demonstrate the proposed method's ability to measure the surface energy of deionized water, methanol, and chemical monolayers formed by surfactants with good agreement to published values. The development of this technique boasts immediate application to static and dynamic systems and near-future applications for living biological cell membranes.

Optical detection and measurement of living cell morphometric features with single-shot quantitative phase microscopy

We present a quadriwave lateral shearing interferometer used as a wavefront sensor and mounted on a commercial non-modified transmission white-light microscope as a quantitative phase imaging technique. The setup is designed to simultaneously make measurements with both quantitative transmission phase and fluorescence modes: phase enables enhanced contrasted visualization of the cell structure including intracellular organelles, while fluorescence allows a complete and precise identification of each component. After the characterization of the phase measurement reliability and sensitivity on calibrated samples, we use these two imaging modes to measure the characteristic optical path difference between subcellular elements (mitochondria, actin fibers, and vesicles) and cell medium, and demonstrate that phase-only information should be sufficient to identify some organelles without any labeling, like lysosomes. Proof of principle results show that the technique could be used either as a qualitative tool for the control of cells before an experiment, or for quantitative studies on morphology, behavior, and dynamics of cells or cellular components.

Derivative method for phase retrieval in off-axis quantitative phase imaging

We present a method for phase retrieval in off-axis interferometric systems. By numerically calculating the transverse 1st and 2nd order derivatives of the interferogram, we show that one can directly retrieve the quantitative phase image, without the need for Fourier or Hilbert transformations. Because of this, the method is significantly faster than the current approaches. We illustrate our method using biological specimen data from three different off-axis quantitative phase imaging techniques.

Nanoscale quantitative phase imaging using XOR-based X-ray differential interference contrast microscopy

Abstract We propose a quantitative x-ray phase imaging technique using previously demonstrated XOR objectives. The fabrication process of XOR is identical to that of a Fresnel zone-plate and as a result the same finest outermost zone width, thus spatial resolution, can be achieved. A series of phase shifts from 0 to 2 π is implemented by shifting the relative position of the grating with respect to the zone-plate. Both qualitative differential interference contrast imaging and quantitative phase reconstruction are demonstrated. We expect this high-resolution quantitative x-ray phase imaging capability to further enhance the utility of existing x-ray microscopy facilities.

Harmonically matched grating-based full-field quantitative high-resolution phase microscope for observing dynamics of transparent biological samples

We have developed a full-field high resolution quantitative phase imaging technique for observing dynamics of transparent biological samples. By using a harmonically matched diffraction grating pair (600 and 1200 lines/mm), we were able to obtain non-trivial phase difference (other than 0 degrees or 180 degrees) between the output ports of the gratings. Improving upon our previous design, our current system mitigates astigmatism artifacts and is capable of high resolution imaging. This system also employs an improved phase extraction algorithm. The system has a lateral resolution of 1.6 mum and a phase sensitivity of 62 mrad. We employed the system to acquire high resolution phase images of onion skin cells and a phase movie of amoeba proteus in motion.

Diffraction phase and fluorescence microscopy

We have developed diffraction phase and fluorescence (DPF) microscopy as a new technique for simultaneous quantitative phase imaging and epi-fluorescence investigation of live cells. The DPF instrument consists of an interference microscope, which is incorporated into a conventional inverted fluorescence microscope. The quantitative phase images are characterized by sub-nanometer optical path-length stability over periods from milliseconds to a cell lifetime. The potential of the technique for quantifying rapid nanoscale motions in live cells is demonstrated by experiments on red blood cells, while the composite phase-fluorescence imaging mode is exemplified with mitotic kidney cells.

Diffraction phase microscopy for quantifying cell structure and dynamics

We have developed diffraction phase microscopy as a new technique for quantitative phase imaging of biological structures. The method combines the principles of common path interferometry and single-shot phase imaging and is characterized by subnanometer path-length stability and millisecond-scale acquisition time. The potential of the technique for quantifying nanoscale motions in live cells is demonstrated by experiments on red blood cells.