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A novel meta-heuristic approach for minimizing nonlinear constrained problems is proposed, which offers tolerance information during the search for the global optimum. The method is based on the concept of design and analysis of computer experiments combined with a novel two phase design augmentation (DACEDA), which models the entire merit space using a Gaussian process, with iteratively increased resolution around the optimum. The algorithm is introduced through a series of cases studies with increasing complexity for optimizing uniformity of a short-wave infrared (SWIR) hyperspectral imaging (HSI) illumination system (IS). The method is first demonstrated for a two-dimensional problem consisting of the positioning of analytical isotropic point sources. The method is further applied to two-dimensional (2D) and five-dimensional (5D) SWIR HSI IS versions using close- and far-field measured source models applied within the non-sequential ray-tracing software FRED, including inherent stochastic noise. The proposed method is compared to other heuristic approaches such as simplex and simulated annealing (SA). It is shown that DACEDA converges towards a minimum with 1 % improvement compared to simplex and SA, and more importantly requiring only half the number of simulations. Finally, a concurrent tolerance analysis is done within DACEDA for to the five-dimensional case such that further simulations are not required. ispartof: Optics Express vol:24 issue:26 pages:29380-29405 ispartof: location:United States status: published more...

Freeform optics are limited to design with simplified source models. With a realistic extended source, the resulting design is limited by the ability to hold the source and optic to the desired tolerances. For example, a design is made around the nominal emitter characteristics, such as an encapsulated LED die. This process is called tailoring. Positioning and spectral output can vary appreciably for these emitters. A method to design optics with extended sources with tolerances taken into account is presented. This method uses targeted ray tracing to specify particular points on optical surfaces. In the method presented here, the source is represented instead as a collection of non-ideal sources, each weighted according to the statistics of the dimensional and color variations that are expected in the source. The design is iteratively developed over its extent where each step accounts for the multitude of tolerances potential ray paths through the optics. The end result is to design optics that are tolerant to the predicted level of error, while maintaining the desired level of efficiency and distribution at the target. This method notably samples the differential etendue aspects of the source as it propagates through the system. Upon solution of the iteratively generated reflector control points, an optimization run can be performed to improve performance. We present a wall-wash example to illustrate the method. more...

Faceted reflectors are widely used for providing uniform illumination in many commercial lighting products. In this paper, some approaches of constructing faceted reflectors in commercial software are discussed. Two new methods for generating non-rotationally symmetric patterns such as square/rectangular illumination patterns using curved-faceted reflectors are proposed and also explored in commercial software. The performances of various reflectors are compared using Monte Carlo ray-tracing. more...

This past spring a new for-credit course on illumination engineering was offered at the College of Optical Sciences at The University of Arizona. This course was project based such that the students could take a concept to conclusion. The main goal of the course was to learn how to use optical design and analysis software while applying principles of optics to the design of their optical systems. Projects included source modeling, displays, daylighting, light pollution, faceted reflectors, and stray light analysis. In conjunction with the course was a weekly lecture that provided information about various aspects of the field of illumination, including units, etendue, optimization, solid-state lighting, tolerancing, litappearance modeling, and fabrication of optics. These lectures harped on the important points of conservation of etendue, source modeling and tolerancing, and that no optic can be made perfectly. Based on student reviews, future versions of this course will include more hands-on demos of illumination components and assignments. more...

Lit-appearance modeling of illumination systems is the determination of what that system looks like before costly fabrication. Methods using ray-tracing software will be presented through examples: spot projection, pupil sampling, and luminance modeling. more...

Illumination engineering is a nascent field in the broader category of optical engineering. The what, where, when, and who leads us to why illumination engineering is now a field in demand. This introductory talk to this year's Nonimaging Optics and Efficient Illumination Systems IV conference touches briefly upon the former queries. It ends with a discussion of the monetary dynamics, especially commercial products, electricity costs, and forecasts for the future. more...

Illumination engineering is the novel field of more general field of optical design and engineering. A seminar, project-based course has been started at the College of Optical Science, The Univ. of Arizona. Topics include lightpipes, sources, sampling, modeling methods, reflectors, and displays. Guest lecturers from industry provide a wealth of additional content. The goal is to education our next generation of optical designers about this intriguing, complex, yet understudied field. Other goals are to provide training in nonsequential optical design software, connections between experimental data and modeling, and the non-technical aspects of the illumination field. more...

Tolerancing of illumination systems is currently a difficult task, especially for components that are injection molded. The ISO standards are not applicable to such systems due to their innate requirements of image formation. Methods to parameterize the shape of injection-molded optical components are presented. First, a method based on experimental measurement of actual components is presented. Next, this method is extended to the Monte Carlo formation of perturbed parts based upon these measurements. Finally, a method based on the application of a bi-directional surface distribution function (BSDF), i.e., scatter profile, is based upon ray-trace results from the application of the experimental measurements. The BSDF method is fit with the ABg scatter function, applied to witness sample surfaces, and compared to the perturbation method. The utility of these two methods is presented, whereby the BSDF method is appropriate for systems with many ray-surface interactions, while the perturbation method is best suited for systems with limited ray-surface interactions. more...

Lightpipes are used to transfer light from the source to a desired target. The lightpipe shape typically conforms to the necessary path, thus bending of the lightpipe is required. A number of different methods of bending the lightpipe have been developed, from linear, discontinuous bends to smooth, common circular bends to bends that expand or contract the cross-sectional size of the lightpipe over the path. In this paper we develop a set of parameters to describe the overall shape of an in-plane lightpipe section. These parameters include the thickness, radius of bend, index of refraction, and ratios of sets of these parameters. The transfer efficiency from the source to target is used to quantify the utility of parameterized lightpipes. Etendue is used to highlight the results. More complex lightpipes, such as those with several bends along their path, can be developed from the combination of parameterized sections. Finally, this parameterization can be used to automate the development of lightpipe geometry within optical analysis and design software. more...

Illumination system optimization is in its infancy, which is attributable to its complexity. I discuss issues, including: sampling, interference, convergence, constraints, and merit function. I present examples from the illumination sector, especially lightpipes and reflectors. more...

Illumination systems suffer from a lack of optimization research. Optimization is typically done based on intuition and experience. I will review research to date, especially with respect to imaging system optimization. I will show examples with the Simplex method; highlighting the end and start games, performance increase, and convergence improvement. more...

The lightpipe is a popular illumination tool due to its flexibility and low fabrication cost in automotive illumination applications. It often has a high level of geometry complexity to satisfy stringent requirements while maintaining low cost. However, its development process, based on trial-and-error, is very cost-ineffective and time-consuming. These disadvantages are more significant when higher complexity is sought to be achieved. more...

A modified simplex optimization method is developed for the design of illumination systems. The simplex method is a judicious choice for illumination optimization because of its robustness and convergence properties. To optimize the simplex method, its four parameters are adjusted dependent on the dimensionality of the space to converge with fewer iterations. This work is presented for the end game, when the optimizer is converging on a local optimum rather than searching for it. Up to a 37% reduction in the number of computations is realized. An example using a compound parabolic concentrator is compared between the standard and the modified simplex methods, providing over 22% improvement in the end game. more...