Generation of a linear array of focal spots with prescribed characteristic using the radiation pattern from a tapered line source antenna

Abstract

We report an approach for generating a linear array of focal spots with prescribed characteristics through the use of the antenna radiation theory and time reversal technology. A virtual line source antenna with a cosine-squared tapered distribution, placed at the vicinity of the common foci of a 4π-system, is employed to obtain the required illumination in the pupil plane. The polarization direction of the generated focal spots and the alignment direction of the linear array are determined by the spatial orientation of the line source antenna. The amount of focal spots depends on the period of the amplitude distribution. The position and spacing of the focal spots are related to the length and the period of the amplitude distribution. The generated linear arrays of focal spots have potential applications in laser micromachining, optical imaging and optical micromanipulation that require multiple focal points or synchronous optical operations.