Spatial-Spectral Volume Holographic Imaging System

Used for both in vivo and ex vivo medical imaging applications, this spectral-spatial volume holographic imaging system (S2-VHIS) is an optical device that eliminates the need for optical scanning. The volume holographic element maps a 4-D data set (x,y,z,l) onto a 2-D image array., allowing simultaneous imaging of multiple projections of the spatial and spectral content from different depths within biological tissue samples.

System overview

System Design

PQ-PMMA hologram preparation

PQ-PMMA is chosen due to its low light absorption over a broad spectral band, low shrinkage, low scattering, versatility and availability.  Thick samples, 1.8mm, are used to increase the angular selectivity of the hologram

 

Image Results

The image above is that of an onion skin obtained with a 5 grating multiplexed hologram at 632.8nm. The hologram was recorded at 488 nm. The FWHM for the planar grating at the center is 11 mm and for the most curved grating 46 mm.

 

The images above are of human ovary tissue obtained with a 2 grating multiplexed hologram using a 30 nm bandwidth 650 nm LED.

 

Holographic Solar Concentrator

Solar Energy is abundant and capable of providing all the world’s energy needs. However, it is still significantly more expensive than non-renewable energy alternatives. The goal of Holographic Solar Concentrator is to reduce the amount of costly photovoltaic cell material and replace with low cost holographic collectors.

Properties of a grating that can work as a concentrator

 

A prototype of Holographic Solar Concentrator

 

Normalized power generation with and without Holographix Solar Concentrator

 

Past Research

  • Parallel OCT system
    • Lina Arauz, Jose E. Castillo Aguilella and Yuan Luo 
      • Design and Processing of a High-Density Single Mode Fiber Array for Imagining and Parallel Interferometer Applications.   The final goal of this project is to create a 100 channel parallel OCT system for use in endoscopic applications.  Current research includes special single mode fibers with reduced diameter, ion-exchanged integrated devices and noise reduction.

       

  • Holographic coherent imaging systems
    • Juan Manuel Russo and Chia-Hung Chen: 

      Temperature Dependence and Characterization of gratings on PQ/PMMA holographic materials:

      • PQ (phenanthrenequinone)-doped PMMA (poly methylmethacrylate) gratings have gained attention since they are inexpensive and easy to fabricate as passive filters with specific communication operation wavelengths.  The design and fabrication of edge-illuminated reflection gratings in a photopolymer material for applications in Optical Code Division Multiple Access (OCDMA) and wavelength division multiplexing (WDM) systems is presented.  The gratings are recorded holographically on PQ-doped PMMA and used as reflection gratings operating at 1550 nm wavelengths.  The operation of the holographic filters in a fiber optics communication system is demonstrated.   The characterization of such gratings?temperature dependence is presented.  The period change of the gratings can be dynamically modified by increasing or decreasing the temperature of the device.  By being able to modify the period of the grating, the center wavelength of the filter can be tuned.  The filters are tested as transmission and reflection gratings (edge-iluminated) and the results are presented and compared to theoretical values.

 

  • Fiber optic filter design and fabrication / OCDMA / DWDM
    • Jose M. Castro and Jose E. Castillo Aguilella:
      • We theoretically demonstrate parallel anti-symmetric waveguide Bragg gratings within a two-mode waveguide.  These gratings produce a reflection with mode conversions. This is the functional equivalent of superimposed Bragg gratings in silica-on-silicon without requiring multi-level etches. Also, due to their weaker coupling constant, parallel anti-symmetric waveguide Bragg gratings have a narrower filtered spectral FWHM than conventional anti-symmetric waveguide Bragg gratings.
  • Montage Imaging Project
    • Nasrin Ghanbari and Se Hoon Lim:
      • The project goal is to make a novel camera system with a 5 mm thickness. In order to decrease the thickness the main unit of the camera is designed using a folding structure. Also, a surface relief grating is used to implement the field extender. Current research includes the fabrication of a blazed grating and verify its reliability in experimental work

     

 

  •  Optofluidics
  • In this work we are investigating techniques that incorporate fluids with special optical properties into integrated optical systems. The initial system under consideration incorporates fluids that allow tuning the wavelength selected by an optical filter. The devices are formed in a pliable polymer (PDMS) replicated from a mold made in SU8 photoresist.