Near Infrared Detector for Advanced Opthamology

DESCRIPTION (provided by applicant): Some of the most useful tools for diagnosis and understanding of blinding retinal diseases rely on the use of spectral reflectance. Improvements to these tools, especially over the past decade, have greatly advanced our ability to achieve extremely high-resolution images of the human retina. In particular, scanning laser ophthalmoscopy has proven to be an important technique for studies of microperimetry, psychophysics and visual neuroscience by imaging the cone mosaic w hile simultaneously delivering stimuli to single cones. Due to the unprecedented resolution now achieved during retinal imaging, there is an increasing need for longer wavelength light that is invisible or imperceptible to the human eye. Bounded by human e ye response and increased optical absorption, the use of wavelengths between 1000 and 1100 nm is the most suitable solution. Unfortunately, while there are several venders providing sufficient light sources across this wavelength range, there are not any s uitable photodetectors. Therefore, the goal of this proposed research effort is to develop an avalanche photodiode (APD) module with exceptional response from 80nm to 1050 nm, that wil be compatible with established scaning laser ophthalmoscopes. Our propo sed solution will use a novel fabrication process to enhance the APD's responsivity to near-infrared radiation. If successful, our research team will develop the receiver module useful for ophthalmoscopy and other health sciences. In Phase I, we will demon strate feasibility of the approach by assembling a custom near-infrared enhanced receiver APD module. This will involve APD process development and the critical design of a custom wideband amplifier circuit. The two components will be tested at RMD, compar ed with other commercial units, and deployed in a scanning laser ophthalmoscopy test fixture at the University of California, Berkeley, School of Optometry. Successful completion of the Phase I effort will form the foundation for an extensive Phase II prog ram, where we will investigate APD reliability, manufacturing and packaging concerns. In addition, our research collaborators at the University of California, Berkeley, will use early versions of the receiver to perform visual threshold testing and record retinal images with illumination wavelengths longer than presently applied. PUBLIC HEALTH RELEVANCE: Radiation Monitoring Devices, Inc. proposes to develop a receiver module with response to near- infrared radiation that is significantly higher than any cu rrently available product. This module will promote new imaging technologies and let retinal specialist utilize established diagnostic imaging instruments in a much more effective manner. In particular, much more accurate visual threshold studies in both t he healthy and diseased eye will be feasible.