James Castracane

High-resolution image intensifier development: preliminary results

The steady development of megapixel detector arrays with decreasing pixel size has improved the performance of present imaging systems. These high spatial resolution detectors have been incorporated into a variety of scientific experiments. The sensitivity of the diode arrays has allowed significant progress in instrumentation development and application. However, full application of these detectors to low light level measurements has been hampered by the lack of image intensifiers which can fully exploit the available spatial resolution of the diode arrays. Current architecture of image intensifiers allows significant room for improvement. We involved in a project to design, develop and characterize an 18 mm GEN II image intensifier with improved spatial resolution. Recent advances in microchannel plate production and fiber optic architecture have been exploited to produce a series of image intensifiers. A production run of a series of tubes with reduced cathode to MCP spacing, reduced microchannel diameter and pitch, reduced MCP to phosphor screen spacing and an integral fiber optic taper has been carried out. This intensifier output will be visually examined and coupled to a megapixel array for digital characterization. The goal is to produce a significantly higher limiting spatial resolution to allow for improved measurements in scientific, commercial and military applications. First results from this production run will be discussed and compared to physical performance models.

High-resolution interferometric imaging of stress propagation in pediatric and adult skulls

Variations based on bone growth and development make stress and fracture propagation differ greatly in pediatric skulls as compared to adult skulls. Differentiating the stress propagation between the pediatric and adult skulls can improve diagnostic prediction when presented with direct frontal impact on a pediatric skull, a fairly common occurrence in the clinical environment. Critical diagnostic information can be learned from an in depth study of stress propagation as a function of impact force at critical locations on the periorbital region of the human skull. The Division of Pediatric Otolaryngology at Albany Medical College and InterScience, Inc. are utilizing electronic speckle pattern interferometry detection (ESPI) and high resolution imaging to evaluate and compare stress propagation in pediatric and adult skulls. A dual detection ESPI system was developed which integrates a medium resolution (2/3) CCD capable of real-time image processing, with a high resolution, megapixel detector capable of limited real time acquisition and image processing in software. Options to allow for high speed detection include integrating a custom, high performance image intensifier with the megapixel detector leg to be used as a high speed gate. The dual optical layout will allow for continuous and pulsed ESPI evaluation of calibrated impacts at specific landmarks on the skull. The goal of this work is to produce a full quantitative analysis of the stress propagation in pediatric versus adult skulls for a better understanding of bone dynamics. The work presented below concentrates on the development of the dual detection ESPI system and initial results achieved with an adult cadaver skull.

Luminescence studies using high-resolution intensified digital imaging: preliminary results

The use of bio-chemiluminescence immunoassay (BL/CLI) technology for molecular and cellular characterization is rapidly evolving. The excellent selectivity of this method can be exploited to identify the presence and distribution of specific cells. Current work involves the advancement of the required methods and technologies for application to the analysis of vascular wall surfaces. In this effort, various enzyme-linked antibodies are being explored which can be directed to cell surface antigens producing a luminogenic reaction. To aid in the analysis of this light emission, a custom high resolution digital imaging system which couples a multi-megapixel CCD with a specially designed image intensifier is under development. This intensifier system has high spatial resolution and excellent sensitivity in the wavelength region of the candidate BL/CL emissions. The application of this imaging system to BL/CLI requires unique performance characteristics and specialized optical design. Component level electro-optical tests of the imaging system will be presented along with design considerations for an eventual catheter based instrument. Initial in vitro experiments focused on the performance limits of the optical system in discriminating candidate luminogenic reactions. The main objective of these tests is the identification of suitable enzyme catalyzed systems for ultimate application to in vivo vascular tissue and cell diagnosis.