Lidar system with nonmechanical electrowetting-based wide-angle beam steering.

A light detection and ranging (lidar) system with ±90° of steering based on an adaptive electrowetting-based prism for nonmechanical beam steering has been demonstrated. Electrowetting-based prisms provide a transmissive, low power, and compact alternative to conventional adaptive optics as a nonmechanical beam scanner. The electrowetting prism has a steering range of ±7.8°. We demonstrate a method to amplify the scan angle to ±90° and perform a one-dimensional scan in a lidar system.

Numerical analysis of wavefront aberration correction using multielectrode electrowetting-based devices.

We present numerical simulations of multielectrode electrowetting devices used in a novel optical design to correct wavefront aberration. Our optical system consists of two multielectrode devices, preceded by a single fixed lens. The multielectrode elements function as adaptive optical devices that can be used to correct aberrations inherent in many imaging setups, biological samples, and the atmosphere. We are able to accurately simulate the liquid-liquid interface shape using computational fluid dynamics. Ray tracing analysis of these surfaces shows clear evidence of aberration correction. To demonstrate the strength of our design, we studied three different input aberrations mixtures that include astigmatism, coma, trefoil, and additional higher order aberration terms, with amplitudes as large as one wave at 633 nm.

Wide-angle nonmechanical beam steering using liquid lenses.

Nonmechanical beam steering is a rapidly growing branch of adaptive optics with applications such as light detection and ranging, imaging, optical communications, and atomic physics. Here, we present an innovative technique for one- and two-dimensional beam steering using multiple tunable liquid lenses. We use an approach in which one lens controls the spot divergence, and one to two decentered lenses act as prisms and steer the beam. Continuous 1D beam steering was demonstrated, achieving steering angles of ±39° using two tunable liquid lenses. The beam scanning angle was further enhanced to ±75° using a fisheye lens. By adding a third tunable liquid lens, we achieved 2D beam steering of ±75°. In this approach, the divergence of the scanning beam is controlled at all steering angles.

Electrowetting lenses for compensating phase and curvature distortion in arrayed laser systems.

We have demonstrated a one-dimensional array of individually addressable electrowetting tunable liquid lenses that compensate for more than one wave of phase distortion across a wavefront. We report a scheme for piston control using tunable liquid lens arrays in volume-bound cavities that alter the optical path length without affecting the wavefront curvature. Liquid lens arrays with separately tunable focus or phase control hold promise for laser communication systems and adaptive optics.

Noise removal in extended depth of field microscope images through nonlinear signal processing.

Extended depth of field (EDF) microscopy, achieved through computational optics, allows for real-time 3D imaging of live cell dynamics. EDF is achieved through a combination of point spread function engineering and digital image processing. A linear Wiener filter has been conventionally used to deconvolve the image, but it suffers from high frequency noise amplification and processing artifacts. A nonlinear processing scheme is proposed which extends the depth of field while minimizing background noise. The nonlinear filter is generated via a training algorithm and an iterative optimizer. Biological microscope images processed with the nonlinear filter show a significant improvement in image quality and signal-to-noise ratio over the conventional linear filter.

Simulation of electrowetting lens and prism arrays for wavefront compensation.

A novel application of electrowetting devices has been simulated: wavefront correction using an array of electrowetting lenses and prisms. Five waves of distortion can be corrected with Strehl ratios of 0.9 or higher, utilizing piston, tip-tilt, and curvature corrections from arrays of 19 elements and fill factors as low as 40%. Effective control of piston can be achieved by placing the liquid lens array at the focus of two microlens arrays. Seven waves of piston delay can be generated with variation in focal length between 1.5 and 500 mm.