High-resolution beam steering using microlens arrays

Abstract

Imaging or beam-steering systems employing a periodic array of microlenses or micromirrors suffer from diffraction problems resulting from the destructive interference of the beam segments produced by the array. Simple formulas are derived for beam steering with segmented apertures that do not suffer from diffraction problems because of the introduction of a moving linear phase shifter such as a prescan lens before the periodic structure. The technique substantially increases the resolution of imaging systems that employ microlens arrays or micromirror arrays. Theoretical, numerical, and experimental results demonstrating the high-resolution imaging concept using microlens arrays are presented.

Two-Dimensional MEMS Stage Integrated With Microlens Arrays for Laser Beam Steering

“…Achieving a large clear optical aperture is a challenge for mirrorbased systems. High-resolution laser beam steering using one moving microlens array (MLA) and two stationary MLAs, where each is separated by one focal length, has been demonstrated by our group as well as other researchers [7]- [9]. Beam steering with single microlenses integrated into a microoptoelectromechanical system (MOEMS) has also been demonstrated [10]- [13].…”

“…With MLAs, large-angle beam steering can be achieved using in-line optics and only small lateral displacements. One major limitation is the discrete addressing problem, which can be solved by adding a millimeter-sized movable prescan lens (PSL) in the light train to continuously address any point along the scanline [7]. MLA scanning can achieve 1880 × 1880 resolvable spots with about ±50-μm mechanical deflections in each axis using 20 × 20 arrays of microlenses across a 2 mm × 2 mm clear aperture [14].…”

On liquid crystal diffractive optical elements utilizing inhomogeneous alignment

“…Several types of LC optical elements have been proposed [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. The needed spatial distribution of the LC director is achieved in the majority cases by means of an inhomogeneous electric field [1][2][3][4][5][6][7][8][9][10][11][12] or with a thickness variations [1,2,13,14].…”

“…The needed spatial distribution of the LC director is achieved in the majority cases by means of an inhomogeneous electric field [1][2][3][4][5][6][7][8][9][10][11][12] or with a thickness variations [1,2,13,14]. Adaptation of such approaches for micron-scaled systems poses technological difficulties due to that electrodes are required or due to geometrical non-uniformities.…”

P‐136: Optimization of Liquid‐Crystal Phased Arrays

“…Non-mechanical compact fast and electrically tunable optical components for controlling the direction of light propagation are highly desirable and urgently needed for many modern optical applications [1]. Liquid crystals, due to their compatibility with most optoelectronic materials and ability to be easily incorporated into other device elements, are especially attractive for beam steering [1][2][3][4][5][6][7][8][9][10][11][12]. The basic idea is to vary LC molecules (director) orientations by means of an external electric field and thereby to manipulate the direction of light propagation.…”