Invention:
This technology is a method for detecting refractive index variations in transparent media through passive optical imaging without the need for structured backgrounds or active illumination. This method involves use of thin films to convert angular deflections of ambient light caused by refractive index gradients into measurable intensity modulations using angularly selective optical filters. The detection of refractive index variations has a wide range of applications, from the estimation of motion and maneuvering intent of planes and drones to the analysis of atmospheric turbulence.
Background:
Detecting small-scale refractive index changes in transparent media such as air is a critical need in a variety of domains including aerospace surveillance, atmospheric sensing, non-invasive flow diagnostics, and border or perimeter monitoring. These changes are typically induced by thermal gradients, pressure variations, or aerodynamic wakes generated by moving vehicles. Current methods for detecting these refractive index variations include classical Schlieren imaging and background-oriented Schlieren imaging techniques. Schlieren imaging requires a highly collimated light source and precise geometric alignment between the light source and the imaging system, and background oriented Schlieren imaging requires a structured background with easily trackable features. These needs limit the practicality of these techniques in field environments. The technology to be licensed overcomes these limitations by providing a passive system for the detection of refractive index variations without the need for structured backgrounds or active illumination.
Applications:
- Aerospace surveillance
- Atmospheric sensing
- Defense
- Non-invasive flow diagnostics
Advantages:
- Passive – does not rely on structured backgrounds or active illumination
- Applicable in real-world outdoor environments
- Increased sensitivity
