Protection of mid-infrared sensors against laser radiation. Preliminary report

During the 1990´s the development of airborne Directed IR Countermeasures (DIRCM) has been intensified. A major thrust in military laser research nowadays is the development of suitable lasers to replace the present IR-sources in DIRCM-systems. R&D in laser technology therefore constitutes a potential threat against IR-missiles. This report presents different technical possibilities to counter the laser-threat in the mid-IR range. FOI projects on Sensor Protection against Lasers have, during the last ten years, been focused on visible wavelengths and eye protection. Starting in 2001 the funding of activities aimed at protection against lasers in the IR-band will increase. This report will provide the basis and a starting point for this limited but purposeful three-year effort. In 2003 a protective principle for use in the IR-region will be demonstrated. The most promising protective principles seem to be: 1. Absorption due to free-carriers in semiconductors 2. Light induced phase transitions. Available information indicates that these principles have a reasonable chance of fulfilling the demands. We aim to successfully demonstrate one or both of these principles for protection in an IR-limiter during year 2003.