We report the use of axicons to achieve broadband "focus-free" imaging in transmission and reflection at terahertz wavelengths. We demonstrate how the use of a broadband terahertz source improves the resolution of the imaging system, and how by using time-of-flight data the axial position and dimension of objects within the large depth of field of the axicon (160 mm) could be determined.

Magnetic resonance imaging (MRI) allows noninvasive and three-dimensional visualization of whole organisms over time, and, therefore, would be ideally suited to monitor cell trafficking in vivo. Until now, systemically injected cells had been difficult to visualize by MRI because of relatively inefficient labeling methods. We developed a novel, biocompatible, and physiologically inert nanoparti...

Imaging through thick highly scattering media (sample thickness ≫ mean free path) can realize broad applications in biomedical and industrial imaging as well as remote sensing. Here we propose a computational "All Photons Imaging" (API) framework that utilizes time-resolved measurement for imaging through thick volumetric scattering by using both early arrived (non-scattered) and diffused photo...

Focusing light through an interface leads to an aberrated intensity distribution that is highly extended with a relatively low peak intensity. We present a method, using a well-chosen annular aperture, that can greatly improve the localization of the intensity about a prescribed point on the axis. Also, the intensity at that point can be increased significantly. By continuously varying the annu...

This paper presents the use and characterization of an electrically focus tunable lens to perform axial scanning in a confocal microscope. Lateral and axial resolution are characterized over a >250 µm axial scan range. Confocal microscopy using optical axial scanning is demonstrated in epithelial tissue and compared to traditional stage scanning. By enabling rapid axial scanning, minimizing mot...

Three-dimensional imaging provides profile information not available with conventional twodimensional imaging. Many three-dimensional objects of interest are opaque to the illuminating radiation, meaning that the object exhibits surface, as opposed to volume, scattering. We investigate the use of an opacity constraint to perform three-dimensional phase retrieval. The use of an opacity constrain...

Recent advances in reproductive medicine have created a demand for more accurate and safe imaging modalities before assisted reproductive treatment(ART) (1). Gradually, the important role of three-dimensional (3D) ultrasonography in the diagnosis of uterine congenital anomalies has been proved (2-4).

An explicit procedure to construct a family of martingales generated by a process with independent increments is presented. The main tools are the polynomials that give the relationship between the moments and cumulants, and a set of martingales related to the jumps of the process called Teugels martingales.

The design and operation of a noncontact surface profilometry system based on the time-correlated single-photon-counting technique are described. This system has a robust optomechanical design and uses an eye-safe laser that makes it particularly suitable for operation in an uncontrolled industrial environment. The sensitivity of the photon-counting technique permits its use on a variety of tar...