Polymer Semiconductor Focal Volume Arrays for Advanced Multidimensional Imaging

North Carolina State University, Raleigh NC

Investigators

Abstract

Non-Technical: Consumer digital cameras form an image using inorganic materials like silicon. These materials are attractive as they are durable, efficient, and low cost. However, they only detect light in a single layer. Multi-layer structures offer significant advantages in terms of improved color reproduction, but at increased cost and reduced image resolution. In this project, we will investigate new multi-layer cameras that can offer improved color reproduction without sacrificing image resolution. The multi-layer camera concept will also be studied for capturing more than the three colors of a typical camera (red, green, and blue). This will be done by using holographic lenses and by manipulating the polarization of light as it passes through the different layers. Finally, the multi-layer detector scheme will be used to improve so called "light field" imaging, in which a single camera lens can be made to capture depth information, enabling improved "digital refocusing" capabilities. Both graduate and undergraduate student researchers will be involved in this research. The project will also facilitate outreach activities to local high school students and online tutorials will be disseminated to encourage participation from avid hobbyists and students. Technical: This project will develop the first three-dimensional (3D) volumetric imaging array by leveraging the unique advantages offered by emerging organic photovoltaic detectors. These new detector-based degrees of freedom will permit an extra dimension onto which information can be modulated, enabling more compact, robust, and capable optical imaging sensors and systems. Organic semiconductors are advantageous to realize this concept due to their ability to tune spectral response, polarization sensitivity, and transmittance, enabling detector placement arbitrarily within a lens system's focal volume. These new degrees of freedom will be used to investigate new detector capabilities, optical systems, and image processing algorithms. The objectives of this proposal are to: (1) Establish an optical model of both 2D and 3D polarization sensitive organic photodetector (P-OPD) arrays; (2) Design and fabricate proof of concept 2D and 3D P-OPD arrays and readout circuitry; (3) Create algorithms for image reconstruction and calibration; (4) Leverage the model to optimize spectral- and polarimetric- imaging array using birefringent filtering techniques; and (5) Incorporate methods to create multi-layer volumetric 3D P-OPD arrays with liquid crystal layers. Merit is found in (1) The optimization strategies and algorithms needed to design 3D volumetric arrays; (2) Use of polarized light for detector-level spectral sensitivity; (3) Establishing new calibration algorithms and image reconstruction techniques; and (4) Quantifying the multiplexing trade space that can be achieved with these 3D arrays, given conventional and emerging optical devices and lens systems. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.