A Novel Technique for 4-Dimensional Atmospheric and Oceanographic Irradiance Measurements Using 3-D Spatial Filtering

Conventional imaging systems do not have any depth-discrimination capability. No technique is currently available for atmospheric or oceanographic measurements of irradiance spatial density. Physical Optics Corporation proposes a novel 3-D spatial filtering technique which will enable a conventional imaging system to reject all the light from out-of-focus planes. The key component is a novel pixel filter (or a pixel filter array) placed at the image focal plane. The pixel filter contains a wavefront-matched filter, a microlens, and an optical fiber. It allows only the light from the in-focus region to pass. Thus the system can be used for remote 4-D measurement of irradiance spatial density without the contamination of strong background and stray light. If equipped with a pixel filter array, the system can be used for sectioning imaging of three dimensional objects without any scanning. The Phase I research effort will result in an experimental demonstration of a proof-of-concept of the pixel filter and a numerical evaluation of the performance of the pixel filter. In Phase II, a prototype instrument for the measurement of irradiance spatial density using the 3-D spatial filtering technique will be developed.