Optimization techniques have been indispensable for designing high-performance meta-devices targeted to a wide range of applications. In fact, today optimization is no longer an afterthought and is a fundamental tool for many optical and RF designers. Still, many devices presented in recent literature do not take advantage of optimization techniques. This paper seeks to address this by presenting both an introduction to and a review of several of the most popular techniques currently used for meta-device design. Additionally, emerging techniques like topology optimization and multi-objective optimization and their context to device design are thoroughly discussed. Moreover, attention is given to future directions in meta-device optimization such as surrogate-modeling and deep learning which have the potential to disrupt the fields of optical and radio frequency (RF) inverse-design. Finally, many design examples from the literature are presented and a flow-chart that provides guidance on how best to apply these optimization algorithms to a given problem is provided for the reader.

Review of numerical optimization techniques for meta-device design [Invited]

We report a zoom microscope objective which can achieve continuous zoom change and correct the aberrations dynamically. The objective consists of three electrowetting liquid lenses and two glass lenses. The magnification is changed by applying voltages on the three electrowetting lenses. Besides, the three electrowetting liquid lenses can play a role to correct the aberrations. A digital microscope based on the proposed objective is demonstrated. We analyzed the properties of the proposed objective. In contrast to the conventional objectives, the proposed objective can be tuned from ~7.8 × to ~13.2 × continuously. For our objective, the working distance is fixed, which means no movement parts are needed to refocus or change its magnification. Moreover, the zoom objective can be dynamically optimized for a wide range of wavelength. Using such an objective, the fabrication tolerance of the optical system is larger than that of a conventional system, which can decrease the fabrication cost. The proposed zoom microscope objective cannot only take place of the conventional objective, but also has potential application in the 3D microscopy.

Zoom microscope objective using electrowetting lenses.

Adaptive neuro-fuzzy estimation of optimal lens system parameters

This paper proposes a zoom lens system based on liquid lenses. The system design consists of a fixed lens and four two-chamber liquid lenses. The chambers are filled with different liquids. The design principle is analyzed. Optimization method is used to get the optimal solution. With the solution, the proposed zoom lens system can obtain achromatic and spherical aberration corrected images in a particular zooming range, and no moving element is needed in the proposed zoom lens system. By choosing proper liquids, it can be designed to work within particular working regions with improved optical performance. We give the detailed simulation examples. The results indicate that the proposed design can help to improve the optical performances of zoom lens systems.

Zoom lens design using liquid lenses for achromatic and spherical aberration corrected target

A method of glass selection for the design of optical systems with reduced chromatic aberration is presented. This method is based on the unification of two previously published methods adding new contributions and using a multi-objective approach. This new method makes it possible to select sets of compatible glasses suitable for the design of super-apochromatic optical systems. As an example, we present the selection of compatible glasses and the effective designs for all-refractive optical systems corrected in five spectral bands, with central wavelengths going from 485 nm to 1600 nm.

Method of glass selection for color correction in optical system design

This paper proposes a method for lens system design. It consists of two main steps called Glass-Selection Step and Further-Optimization Step. We modify coordinate-wise algorithm to obtain the glass combination in Glass-Selection Step. In Further-Optimization Step, we use modified coordinate-wise algorithm combined with modified evolutionary algorithm to find out the optimal solution. We succeed in obtaining high quality design with the proposed method.

Two-step method for lens system design

We propose a 3D interaction and autostereoscopic display system that use gesture recognition, which can manipulate virtual objects in the scene directly by hand gestures and can display objects in 3D stereoscopy. The system consists of a gesture recognition and manipulation part as well as an autostereoscopic display as an interactive display part. To manipulate the 3D virtual scene, a gesture recognition algorithm is proposed, which use spatial-temporal sequences of feature vectors to match predefined gestures. To get smooth 3D visualization, we utilize the programmable graphics pipeline in graphic processing unit to accelerate data processing. We develop a prototype system for 3D virtual exhibition. The prototype system reaches frame rates of 60 fps and operates efficiently with a mean recognition accuracy of 90%.

Three-dimensional interaction and autostereoscopic display system using gesture recognition

Mutated and converged damping factors in lens system optimization to find new local minima

The invention provides a naked grating two-dimensional and three-dimensional compatible display device. The device consists of a display screen, a polarization device I, an optical rotation device and a polarization device II, wherein the polarization device I, the optical rotation device and the polarization device II are sequentially arranged before the display screen, the interval between the polarization device I and the display screen is S, the optical rotation device and the polarization device I are closely attached, and the polarization device II and the optical rotation device are closely attached. The polarization device I consists of polarization units which are arranged alternatively and have polarization characteristics, and transparent units which have no polarization characteristics. The optical rotation device comprises two layers of transparent conductive glass and rotation materials, and the optical rotation materials are arranged between the two layers of transparent conductive glass. The polarization device II is of a polarization element with even polarization characteristics.

Naked grating two-dimensional and three-dimensional compatible display device

In lens system design, Damped Least Squares method is a traditionally used local search method. In this paper we apply mutation operators to control damping factor in Damped Least Squares. We study the mutation behavior in this method when the algorithm confronts with local minima. The proposed method can go beyond local minima by taking mutation operators to control damping factor. The proposed method was successfully applied to design problems. The result indicates that the mutation operators provide an effective and rapid way to jump out of poor local minima.

Xiao-Qing Xu

Papers

Two-step method for lens system design

Three-dimensional interaction and autostereoscopic display system using gesture recognition

Mutated and converged damping factors in lens system optimization to find new local minima

Naked grating two-dimensional and three-dimensional compatible display device

Mutation operators in lens system optimization to jump out of local minima