Orthographic projection images-based photon-counted integral Fourier holography.

Unlike coherent imaging techniques, light field imaging uses incoherent (white light) illumination to generate a digital hologram of three-dimensional (3D) objects in real time. Multiple projections (or elemental images) of a 3D object are captured using a microlens array attached to a digital camera. Orthographic projection images (OPIs) can be synthesized from the recorded elemental images.

Self-written waveguides in photopolymer.

Self-written waveguide (SWW) trajectories fabricated inside a dry photopolymer bulk material, acrylamide/polyvinyl alcohol (AA/PVA), are studied. Their production using both Gaussian and Laguerre-Gauss exposing (writing) light beams, output from optical fibers, is explored. The formation of the primary and secondary eyes is also discussed.

Measuring refractive index of glass by using speckle.

A method to measure the refractive index of an optically flat, regularly shaped slab of glass using speckle correlation-based techniques is reported. The intensity of the diffraction field of the diffuser is captured by a CCD both with and without the glass present. As the position of the peak correlation coefficient is quantitatively related to the change in optical path length arising due to the presence of the glass, the refractive index of the glass can be evaluated by cross-correlating the two captured images.

Simultaneous drift, microsaccades, and ocular microtremor measurement from a single noncontact far-field optical sensor.

We report on the combined far-field measurement of the three involuntary eye movements, drift, microsaccades, and ocular microtremor (OMT), using a noncontact far-field optical method. We review the significance of the smallest and least measured, and thus least understood, of the three, OMT. Using modern digital imaging techniques, we perform detailed analysis, present experimental results, and examine the extracted parameters using a noncontact far-field sensor.

Self-written waveguides in a dry acrylamide/polyvinyl alcohol photopolymer material.

For the first time it is demonstrated that permanent optical waveguides can be self-written in a solid acrylamide/polyvinyl alcohol photopolymer material. The novel (to our knowledge) technique used to prepare the polymeric medium used is described. It is demonstrated that the resulting waveguides formed can be used to guide different wavelengths.

Calibration of a digital in-line holographic microscopy system: depth of focus and bioprocess analysis.

Digital in-line holographic microscopy (DIHM) allows access to both intensity and phase information with conventional microscopic lateral resolutions. Such imaging techniques can, however, be used to increase the depth of focus compared to conventional compound microscopes. We present a simple DIHM capable of imaging weakly scattering 10 μm diameter microspheres as well as Hs578T cells over a depth of 1 mm; i.

Lensless multispectral digital in-line holographic microscope.

An compact multispectral digital in-line holographic microscope (DIHM) is developed that emulates Gabor's original holographic principle. Using sources of varying spatial coherence (laser, LED), holographic images of objects, including optical fiber, latex microspheres, and cancer cells, are successfully captured and numerically processed. Quantitative measurement of cell locations and percentage confluence are estimated, and pseudocolor images are also presented.

Dual wavelength digital holographic Laplacian reconstruction.

Access to the spatial derivatives of an optical wave field can be used to enhance edge detection, focusing, and holographic imaging. It was recently shown that, by using digital holographic techniques, the Laplacian of an object field can be extracted. Here it is demonstrated that equivalent results can be found using two holograms captured at either two distances or with two appropriately related wavelengths.

Compact portable ocular microtremor sensor: design, development and calibration.

Ocular microtremor (OMT) is a physiological high-frequency (up to 150 Hz) low-amplitude (25-2500 nm peak-to-peak) involuntary motion of the human eye. Recent studies suggest a number of clinical applications for OMT that include monitoring the depth of anesthesia of a patient in surgery, prediction of outcome in coma, and diagnosis of brain stem death. Clinical OMT investigations to date have used mechanical piezoelectric probes or piezoelectric strain gauges that have many drawbacks which arise from the fact that the probe is in contact with the eye.

Generalized in-line digital holographic technique based on intensity measurements at two different planes.

In-line digital holography based on two-intensity measurements [Zhang Opt. Lett. 29, 1787 (2004)], is modified by introducing a pi shifting in the reference phase.