Laser dazzling of CMOS imaging sensors using amplitude modulated and continuous wave lasers

Sammanfattning: Protecting sensitive information is important, especially in defence applications. As cameras become more common, developing countermeasure systems that limit the information gathering capabilities of imaging sensors would be beneficial. Such a countermeasure system can be based on laser dazzling of imaging sensors, which will impair the information gathering capabilities of the sensor if the countermeasur esystem is designed correctly. In order for laser dazzling to be viable as a countermeasure in practical use cases, the dazzling effect needs to be predictable and practically achievable. An existing model predicting the dazzle effect of continuous wave laser irradiance on the front optics of imaging sensors was successfully verified. This was achieved by collecting experimental data using three complementary metal-oxide semiconductor (CMOS) imaging sensors. An amplitude modulated laser was used to dazzle an imaging sensor with the automatic gain control (AGC) and automatic exposure (AE) functions of the sensor enabled. The AGC function dynamically adjusts the image gain and the AE function dynamically adjusts the shutter speed of the sensor to optimise the settings for the given lighting conditions. The impact of the AGC and AE function corrections on the image information content was investigated for a set of lighting conditions, modulation frequencies and modulation duty cycles by collecting data with a CMOS sensor. The dazzling effect was compared to the dazzling effect when using continuous wave lasers. The analysis indicate that the amplitude modulated laser dazzling performance is subpar to the continuous wave laser dazzling performance for the tested configurations. Additionally, the predictability of the modulated laser dazzling effect is complex and depends on more parameters. A model based on this technique would also be sensitive to parameter changes. The weak predictability combined with the subpar performance compared to the continuous wave laser dazzling limits the usefulness of amplitude modulated laser dazzling in practical use cases.