Publications

A label free quantitative phase imaging method is realized in this project to enable imaging of an interface between different media. This system is based on an off-axis holographic microscope and uses a high numerical aperture (NA) microscope objective to achieve total internal reflection (TIR).

In this work we took an alternative route to these problems by combining maskless lithography with digital holography. Addition of digital holography enables the use of feedback by measuring the quantitative phase of specimen near real time and in situ nondestructively. After each near UV exposure, phase retardation map of exposed photopolymer is measured with digital holography part of the system. Any deviation from target phase is corrected by changing the pattern displayed on the mask.

Here, an integrated portable system is presented that can maintain cell cultures at desired temperature in a 3D printed enclosure while imaging them in lens free inline holographic microscopy modality. Such a system is well suited for tissue culturing and monitoring at limited resources settings.

A low cost alternative to off-the-shelf top stage incubators is realized by using 3D printing technology. A closed system is designed for keeping the inner temperature at the desired value and an ITO coated glass plate is employed as a heater. The temperature inside the incubator is stabilized by using PID (Proportional-Integral-Derivative) algorithm that is controlled via Arduino Uno microcontroller.

We present an improved prism spectrometer with high wavelength range and spectral resolution.

Refractive index tomography as an emerging technique enables the 3D morphological investigation of cells with no marker. Here, refractive index tomographic imaging of myelinating glial cells is presented.

Here it is proposed to implement an off-axis holography layout that utilizes a single wedge prism.

Digital Holographic Microscopy (DHM) yields reconstructed complex wavefields. It allows synthesizing the aperture of a virtual microscope up to 2π, offering super-resolution phase images. Live images of micro-organisms and neurons with resolution less than 100 nm are presented.

As an illustration of the resolution improvement achieved with the synthetized aperture approach, Fig. 1 shows the resolution improvement obtained on a phase image. In summary, synthetizing the spatial frequencies spectrum in the reciprocal space leads to resolution improvement.

Experiments on live myoblast cells are carried out on two different platforms; random positioning machine (RPM), a ground base microgravity simulation platform, and parabolic flight campaign (PFC), a fixed wing plane flight providing short durations of alternating gravity conditions. Results show clear perinuclear phase increase. During seconds scale microgravity exposure, measurable scale morphological modifications are observed with the accumulated effect of repetitive exposures and short breaks.

We present a new technique for coherent imaging based on digital holographic microscopy. For high-resolution tomography, the diffraction effect of the microscope objective is corrected by the system’s complex point spread function.

We propose a method to improve the spatial resolution of such coherent microscopy systems by filtering of the coherent transfer function (CTF). The 3D complex deconvolution is presented and potential applications shown.

A microscope operating in Digital Holographic Microscopy (DHM) and classical widefield epi-fluorescence microscopy in a time sequential manner is developed to study morphological alterations of mouse myoblast cells under simulated microgravity in real time.

A coherent sub-wavelength resolution in a high-NA diffraction-limited optical system is demonstrated using a transmission DHM setup. By adapting inverse deconvolution post processing to coherent illumination conditions, a complex deconvolution procedure is derived.

A dual mode microscope is developed to study morphological evolution of mouse myoblast cells under simulated microgravity in real time.

Parylene was used as the structural material due to its high thermal isolation and mismatch properties. Calculations reveal that the NETD performance of a thermo-mechanical array using Parylene can be significantly better than SiNx based designs and offer a theoretical NETD value <10mK assuming an optical readout with a high dynamic range detector array.

A novel thermo-mechanical infrared (IR) imaging array with integrated diffraction gratings for optical readout was fabricated and tested.

An uncooled thermal detector array with low NETD is designed and fabricated using MEMS bimaterial structures. A diffraction grating is embedded on the pixel membrane for sensing sub-nm mechanical deflections.

A two-wavelength readout method is developed that maintains high sensitivity while increasing the detection range from 105 nm to 1.7 um assuming sensitivity is maintained at >50% of the maximum sensitivity