Laser-echo reduction method based on a multifocal lens array.

ABSTRACT

A combination of an image plane tilt method and usage of a multifocal lens array is proposed to reduce the intensity of the laser echo in surveillance and tracking imaging optical systems. The tilt of the image plane was used to reduce the energy of the laser echo, while the aberration due to the tilt of the image plane was effectively corrected by the multifocal lens array. To verify the feasibility and performance of the proposed method, an experimental setup was used, which consisted of a 2×2 lens array with a dual focal length. The experimental results showed that the measured variation law of the energy of the laser echo was consistent with the derived equation of the echo. It was demonstrated that the sharpness of the image edge increased for a tilt angle of 3° when the lens array was added. Thus, the multifocal lens array could effectively reduce the image edge blur caused by the tilted image plane.