Spatial-Spectral Volume Holographic Imaging

Spatial-spectral volume holographic imaging (S2-VHI) system is a novel imaging technology that can simultaneously project multiple spatial images from different depths within a tissue sample along with the spectral characteristics from these regions. This allows spectral information to be correlated to the spatial structure within the tissue sample. The system is based on highly selective volume holographic or `Bragg’ gratings used in conjunction with conventional high resolution optical imaging components. The high angular selectivity of the volume holographic grating in combination with broadband illumination is used to obtain two-dimensional image information from objects without the need for mechanical scanning (Figure 1).

The use of volume holographic gratings in imaging systems was first described in 1999. It was observed that a simple volume hologram, recorded by two plane waves, could act as a depth-selective element with background rejection properties. Therefore the volume hologram may be thought of as a component similar to a pinhole in a confocal microscope. The hologram however is much more general than a pinhole and can be configured to extract spatial as well as spectral information from an object.

The goal of this project is to build a unique and simple imaging system that combines structural and fluorescence imaging. This imaging technique could have broad applicability in medical diagnostic imaging. However, the clinical purpose of this work is to make the instrument suitable for imaging cancerous ovarian tissue by simultaneously displaying spatial tissue structure with cancer specific fluorescent markers.

In order to increase the versatility of the S2-VHI system for medical applications the ultimate goal of the project is to design and fabricate a rigid endoscope package of the S2VHI instrument. The endoscope with be designed to be capable of both backscattered and fluorescence imaging using the same source and wavelength as the free-space system.