Cheng-Mu Tsai

A study of optical design and optimization of zoom optics with liquid lenses through modified genetic algorithm

A new concept for the optimization and optical design of miniature digital zoom optics with liquid lens elements is proposed in this research. The liquid lens elements are limited to the discrete configuration in order to obtain the optimal performance for digital zoom. We propose a newly developed digital zoom layout and optimization with a modified genetic algorism (GA) method, in order to meet the demands of a certain specification. The results show that we achieve a successful optical design and the optimization of the digital zoom optics with liquid optics, whose performance is greatly improved up to 48.68%, from the standpoint of on-axis spot size.

Extended optimization of chromatic aberrations via a hybrid Taguchi–genetic algorithm for zoom optics with a diffractive optical element

In this research, we propose a new method, a hybrid Taguchi–genetic algorithm (HTGA), for optics and zoom optics with a diffractive optical element (DOE) in order to eliminate chromatic aberration more efficiently than traditional damped least squares (DLS) does. By researching and validating a set of optical designs using a DOE, we have derived an optimal theory for the specific elimination of chromatic aberrations. Following the advanced technology applied to microlenses and the etching process, precisely made microDOE elements may now be manufactured on a large scale. We adopted the genetic algorithm (GA) and incorporated the steady Taguchi method into it. Combining these two methods produced a new hybrid Taguchi–genetic algorithm (HTGA). Suitable glass combinations and best positions for the DOE, which could not be properly achieved with DLS, were carefully selected to minimize the chromatic aberration in the optical system. We used an optical system with a fixed-focus and complicated 4 × zoom optics with a DOE to compare the optimization results of traditional DLS for optics with a DOE. Experiments show that, whether the chromatic aberration was axial or longitudinal, the values of the measurements involving the chromatic aberration of the optical lens could be significantly reduced.

Demonstration of a ROADM Using Cyclic AWGs

A transparent reconfigurable optical add-drop multiplexer (ROADM) based on arrayed-waveguide gratings (AWGs) and tunable fiber Bragg gratings (FBGs) is presented in this paper. The Bragg wavelength of the FBG could be tuned within the free spectral range of the AWG to implement reconfigurable add-drop function without interfering the other wavelength channels. An experiment was demonstrated to verify the add-drop function and to evaluate the performance of the proposed ROADM. Proposed novel ROADM is flexible and scalable for the dense wavelength division multiplexing network.

Optical design of adaptive automotive headlight system with digital micro-mirror device

This paper propose an optical design of adaptive automotive headlight system with advanced light-emitting diodes (LEDs) and digital micro-mirror device (DMD). In recent days, safety of on-road drive plays the role at automotive industries so that fast response of adaptive automotive headlight system becomes a critical issue especially in mountain road drive. In order to integrate the function of low and high beam into a single headlight without sacrifice of volumetric size of whole system, a DMD is employed in this optical design. Simulation shows that new optical design not only promotes light efficiency but also reduce volumetric size. Besides, light from adaptive automotive headlight system could make the projected light much suitable for drivers according to individual drivers vision experience. Results show that volumetric size of all system might be reduced up to 30 percent but light efficiency could be promoted up to 20 percent.

Color multiplexing method to capture front and side images with a capsule endoscope

This paper proposes a capsule endoscope (CE), based on color multiplexing, to simultaneously record front and side images. Only one lens associated with an X-cube prism is employed to catch the front and side view profiles in the CE. Three color filters and polarizers are placed on three sides of an X-cube prism. When objects locate at one of the X-cubes three sides, front and side view profiles of different colors will be caught through the proposed lens and recorded at the color image sensor. The proposed color multiplexing CE (CMCE) is designed with a field of view of up to 210 deg and a 180 lp/mm resolution under f-number 2.8 and overall length 13.323 mm. A ray-tracing simulation in the CMCE with the color multiplexing mechanism verifies that the CMCE not only records the front and side view profiles at the same time, but also has great image quality at a small size.

Application of genetic algorithm on optimization of laser beam shaping.

This study proposes a newly developed optimization method for an aspherical lens system employed in a refractive laser beam shaping system, which performs transformations on laser spots such that they are transformed into flat-tops of any size. In this paper, a genetic algorithm (GA) with multipoint search is proposed as the optimization method, together with macro language in optical simulation software, in order to search for ideal and optimized parameters. In comparison to a traditional two-dimensional (2D) computational method, using the one-dimensional (1D) computation for laser beam shaping can search for the optimal solution approximately twice as fast (after experiments). The optimal results show that when the laser spot shrinks from 3 mm to 1.07 mm, 88% uniformity is achieved, and when the laser spot increases from 3 mm to 5.273 mm, 90% uniformity is achieved. The distances between the lenses for both systems described above are even smaller than the thickness for the first lens, enabling us to conclude that our design objectives of extra light and slimness in the system are achieved.

Evaluation of Geometrical Modulation Transfer Function in Optical Lens System

This paper presents ray tracing algorithms to evaluate the geometrical modulation transfer function (GMTF) of optical lens system. There are two kinds of ray tracings methods that can be applied to help simulate the point spread function (PSF) in the image plane, for example, paraxial optics and real ray tracings. The paraxial optics ray tracing is used to calculate the first-order properties such as the effective focal length (EFL) and the entrance pupil position through less cost of computation. However, the PSF could have a large tolerance by only using paraxial optics ray tracing for simulation. Some formulas for real ray tracing are applied in the sagittal and tangential line spread function (LSF). The algorithms are developed to demonstrate the simulation of LSF. Finally, the GMTF is evaluated after the fast Fourier transform (FFT) of the LSF.

A Flexible FOV Capsule Endoscope Design Based on Compound Lens

This paper proposes a capsule endoscope (CE) with a flexible large field of view (FOV) that imitates the compound eyes of insects, like those of a fly. Thirty-one ball lenses are demonstrated to cover 175° viewing area for constructing the compound lens. The ball lens used in the CE is responsible for 40° view to form the image on a curve image plane. A fiber array is applied to fit the curve image plane to improve the field curvature aberration and deliver the image into an image sensor. Such a compound lens can share image aberrations into the multiple ball lenses, keep high relative illumination (RI), and make the adjustment of the FOV possible. With a 45 × 45 fiber array, a ray tracing is simulated to verify that the proposed CE is feasible. The results show that the CE can capture 175° viewing area though the compound lens with ball-lens-based design.

Suppression of Petzval Aberration in a Projector Lens by Using Genetic Algorithm

An optical solution method with genetic algorithm (GA) is proposed as a means to minimize the Petzval field curvature aberration (Petzval FCA), which is intrinsic, but plays a significant role at improvement of projection optics. Petzval FCA is generally more sensitive to the surface curvature and refractive index, closely related to the fundamental optical layout and its physical concept. Through the proposed optimization method in this research, with crossover and mutation operations provided by the GA, the simulation results imply that 79.75% at least of the Petzval FCA of projection optics can be eliminated, which leads to better performance of projector optics, especially in 1080P and 3-D high-definition projection optics.

A study of optical design of zoom optics

This paper proposes a new zoom lens design with intermediate image. The two 3x zoom lenses are independently designed and then cascaded to a 9x zoom lens. The concept of intermediate optics is applied in this paper in order to minimize size of front diameter and overall length. The final layout shows the proposed 9x zoom lens can effectively miniature the front diameter of lens about 44.25%.