Illumination system development using design and analysis of computer experiments

Keresztes, Janos; Ketelaere, Bart De; Audenaert, Jan; Koshel, R. John; Saeys, Wouter

doi:10.1117/12.2191082

Cited by 3 publications

(12 citation statements)

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“…Ray-tracing noise quantification One way to quantify the stochastic noise of ray-tracing simulations is to repeat them for a given configuration [21]. However, this method does not suggest how many rays should be traced, or whether the signal-to-noise ratio (SNR) is sufficient to distinguish features with low irradiance contrast.…”

Section: Ray-tracing Simulationsmentioning

confidence: 99%

“…Four DC 20-W TH spots with a correlated color temperature of 2800-K DECOSTAR-51-ALU, (OSRAM, Munich, Germany) mounted with high SWIR transmittance diffusers TSG-LEGB, (Knight Optical, Kent, UK) were considered as light sources within this design [21]. The target to be uniformly illuminated is the 300 x 0.5-mm 2 field of view of a line scan HSI system placed at a distance of 500 mm from the center of the target as depicted in Fig.…”

Section: Illumination Setup and Experimental Parametersmentioning

confidence: 99%

“…In Section 3 the analytical formulation is used to validate the convergence of the optimization method without the presence of noise. Although using a GP for tolerance analysis has been proposed in the literature [21], its accuracy has not been demonstrated because it would be computationally too expensive to verify using simulations of a large number of design points. Therefore, the proposed simplified analytical description of the case study will also be used to quantify the accuracy of the GP for tolerancing.…”

Section: Introductionmentioning

confidence: 99%

“…When the merit space is non-Gaussian or not sufficiently sampled, the optimum found from the GP can deviate slightly from the actual one. Therefore, a method was proposed to correct for this deviation by performing a simplex post-optimization from the optimum found using a DACE approach [21]. However, using methods such as simplex as a post-optimization step may still result in many additional required simulations.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the simplex method is sensitive to the selected starting point when considering non-convex problems [9]. It can handle constrained problems [20] by penalizing the merit function [9], but at the cost of slower convergence [21]. Several alternatives to the classical simplex approach have been proposed, such as fractional optimization [9], hybrid Nelder-Mead [22] or simulated annealing optimization [23].…”

Section: Introductionmentioning

confidence: 99%

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Augmented design and analysis of computer experiments: a novel tolerance embedded global optimization approach applied to SWIR hyperspectral illumination design

et al. 2016

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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.

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Section: Ray-tracing Simulationsmentioning

confidence: 99%

Section: Illumination Setup and Experimental Parametersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Augmented design and analysis of computer experiments: a novel tolerance embedded global optimization approach applied to SWIR hyperspectral illumination design

et al. 2016

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Cross-polarized VNIR hyperspectral reflectance imaging for non-destructive quality evaluation of dried banana slices, drying process monitoring and control

Trong

Dusabumuremyi

Saeys

2018

Journal of Food Engineering

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A cross-polarized freeform illumination design for glare reduction in fruit quality inspection

et al. 2015

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Common illumination systems in short wave infrared (SWIR) hyperspectral imaging (HSI) include direct or indirect tungsten halogen lights. While direct lights provide more radiation onto the samples than dome setups, thus being more energy efficient, the acquired images often suffer from specular reflections and gloss. Glare artifacts in images increase variability in the data limiting the accuracy of machine vision algorithms for defect detection and quality inspection, or even providing false positives. Although domes are known to provide a near Lambertian illumination and glare free images, glossy regions and heterogeneities may remain in the data in practice. More particularly, in the field of fruit and vegetable quality inspection, due to their waxy surface, it remains challenging to design an efficient realistic lighting system. This paper suggests a new approach to optimize the illumination of fruit and vegetables based on measurements of the bidirectional reflectance distribution function (BRDF), shape and Stokes parameters. From these measured values, a BRDF model is loaded into ray-tracing software for realistic illumination engineering in order to determine the most suitable illumination scheme. This concept is applied to apples and a cross polarizer (CP) with freeform optics (FO) optical configuration is proposed, which allows the FO to be optimized to maximize uniformity in the field of view of the imager and removes the parallel polarized gloss on the apples. The performance of this CP illumination system was determined experimentally for a set of apples. This cross polarized (CP) illumination system provided a uniformity (U) of 92% and an efficiency (ν) of 90%, while U = 87% and ν = 14% for an ideal dome configuration when illuminating a rectangular target. The simulated imaged apples with assigned optical properties performed better with CP (U=80%) than when using a dome (U=73%) by 7%. Finally, the sensitivity of the design for the light positioning and spectral tolerance are investigated.

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Illumination system development using design and analysis of computer experiments

Cited by 3 publications

References 0 publications

Augmented design and analysis of computer experiments: a novel tolerance embedded global optimization approach applied to SWIR hyperspectral illumination design

Augmented design and analysis of computer experiments: a novel tolerance embedded global optimization approach applied to SWIR hyperspectral illumination design

Cross-polarized VNIR hyperspectral reflectance imaging for non-destructive quality evaluation of dried banana slices, drying process monitoring and control

A cross-polarized freeform illumination design for glare reduction in fruit quality inspection

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