Passive Limiter For Optical Sensor Protection

Passive broadband limiter with high response speed is a promising device used to protect optical sensor against determined attack. Lam Optics, Inc. (LOI) proposes to investigate the development of a novel optical limiter using commercially available materials. The optical limiter operates on the following principles. These are beam self-defocusing and total internal reflection induced by absorption enhanced nonlinearities, and excited-state absorption. The proposed optical limiter offers the possibility of passing low intensity light with low attenuation, but blocking transmission of high intensity laser beam. High response speed in nanoseconds, low clamped output, and high linear transmission can be achieved with this device. During Phase I effort, LOI will prove the feasibility of fabricating such a limiter by using prism arrays filled with nonlinear material. Optimum structure of the limiter and requirements of the nonlinear material and additives will be established. The interested wavelength region of the proposed project is 0.4 to 1.2 micrometer. Applications include protection of optical sensors against high energy laser, when these sensors are used in missile, CCD camera, lidar, range finder, optical power/energy meter, remote sensing system and night vision viewer. It could also be equipped for eye protection in viewing instruments such as telescope of military usage and microscope in laser surgery operations.