Broadband and High-Resolution Static Fourier Transform Spectrometer with Bandpass Sampling.

In this study, experimental demonstration of a static Fourier transform spectrometer (static-FTS), based on division of the spectrum into multiple narrowband signals, is presented. The bandpass sampling technique used in this novel spectrometer solves the Nyquist sampling rate limitations and enables recording of wideband spectrum in high resolution. The proposed spectrometer not only has the potential of operating in a wide spectral range, but also has a resolution potential better than 2 cm.

Real-Time and Tunable Substrate for Surface Enhanced Raman Spectroscopy by Synthesis of Copper Oxide Nanoparticles via Electrolysis.

Here we show the capability of copper oxide (CuO) nanoparticles formed on copper (Cu) electrodes by the electrolysis as a real time active substrate for surface enhanced Raman scattering (SERS). We have experimentally found that using just the ultra pure water as the electrolyte and the Cu electrodes, ions are extracted from the copper anode form copper oxide nanoparticles on the anode surface in matter of minutes. Average particle size on the anode reaches to 100 nm in ninety seconds and grows to about 300 nm in five minutes.

Three-dimensional image reconstruction of macroscopic objects from a single digital hologram using stereo disparity.

We present depth extraction of macroscopic three-dimensional (3D) objects from a single digital hologram using stereo disparity. The method does not require the phase information of the hologram but two perspectives of the scene, which are easily obtained by dividing the hologram into two parts (two apertures) before the reconstruction. Variation of the hologram division is countless since each piece of a single hologram contains all the information regarding the scene; therefore, stereo disparity can be calculated along any arbitrary direction.

A broadband configuration for static Fourier transform spectroscopy with bandpass sampling.

In this work a new broadband static Fourier transform spectrometer (static-FTS) configuration based on the division of the spectrum into multiple narrow-bands is proposed. This configuration not only decreases the spectrometer size but also allows operation in the traditional spectrometer wavelength range, namely, 400 nm-1100 nm with 1 cm or better resolution. This technique solves the Nyquist sampling rate issue and enables us to record high resolution spectrums with regular CCDs.

Digital holographic microscopy and focusing methods based on image sharpness.

Digital holographic microscope allows imaging of opaque and transparent specimens without staining. A digitally recorded hologram must be reconstructed numerically at the actual depth of the object to obtain a focused image. We have developed a high-resolution digital holographic microscope for imaging amplitude and phase objects with autofocusing capability.

Real-time, auto-focusing digital holographic microscope using graphics processors.

The most significant advantage of holographic imaging is that one does not need to do focusing alignment for the scene or objects while capturing their images. To focus on a particular object recorded in a digital hologram, a post-processing on the recorded image must be performed. This post-processing, so called the reconstruction, is essentially the calculation of wave propagation in free space.

In-line hologram reconstruction using Hartley transform.

In reconstruction of in-line recorded holograms, zero-order and conjugate images appear on the same physical location as the object image. Here we propose a method, new to our knowledge, to separate the object image from the others by using two quadrature phase-shifted holograms. The method uses the Hartley transform and a phase retrieval type of algorithm on the difference hologram.

Method to calculate the far field of three-dimensional objects for computer-generated holography.

Here, a new method for calculating the computer-generated holograms of three-dimensional (3D) objects is presented along with a review of current techniques. The method, the planar layers method (PLM), is established on the idea of representing 3D objects in discrete planar layers perpendicular to the observation plane, then calculating the total far field pattern by summing up the far field patterns of each layer. Simulation results, computational complexity, and error comparisons reveal that this new method can be used to calculate far field patterns--hence, the holograms--of computer-synthesized objects very efficiently.