White Paper: Aerospace

Laser Requirements for Time Gated Active Night Vision Imaging Systems

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In 1929, physicist Kalman Tihanyi made a significant impact on the world when he invented the world’s first night vision camera. While the original night vision imaging systems were revolutionary for their time, they suffered from many limitations ranging from sensitivity to resolution.

Over the past 90 years, night vision technology has developed into a mature and diverse industry, fueled in large part by modern semiconductor technology. These days, night vision systems are utilized in a wide range of military and commercial applications ranging from traditional night vision goggles to time-gated active surveillance. Today’s modern night vision devices come in a wide variety of forms, making use of several different base technologies.

This article starts by reviewing the fundamentals of modern night vision camera technology. Next, it goes on to discuss the differences between active and passive imaging systems. Active night vision systems can come in many different forms, depending on the goal of the particular application. While broadband emission sources are still used in some active night vision systems, the vast majority of systems utilize either superluminescent diodes (SLDs) or lasers. Both of these sources offer highly effective light generation and can be tailored to specific wavelengths of interest, depending on the needs of the system. Both lasers and SLDs are capable of producing extremely bright beams, which can easily flood an extensive area with infrared light.

Finally, the article presents a detailed exploration of the advantages and disadvantages of laser-based active imaging systems illuminating why, in some instances, lasers are the preferred illumination source despite their inherent drawbacks. While theoretically any short-pulsed infrared laser can be used for active night vision imaging, it is generally preferable to work in the near-infrared (1.5 microns in particular) because it is simultaneously eye-safe and invisible. Laser sources for active night vision systems should also be specifically designed for operation in harsh environments.

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