This book presents, validates and applies a fast, accurate and general measurement and modeling technique to obtain spectral near field data of LED systems for optical simulations in order to address the steadily increasing requirements of modern high quality LED systems. It requires only a minimum of goniophotometric near field measurements and no time-consuming angularly resolved spectral measurements. The obtained results can be used directly in state-of-the-art ray tracers.
2015 - now
Hyperspectral LED models for optical simulations
Precise spectral and colorimetric simulations in commercial ray tracing software require realistic light source models, which provide spectral information as a function of angle and spatial dimension. We describe and validate a general workflow to create hyperspectral LED models as a linear combination of spectral models. The workflow only requires user defined precisions and rayfiles obtained with different optical filters. The rayfiles are transformed into histogram based models, whose precision is evaluated by normalized cross-correlation values of their intensity distributions in the near-, mid- and far field. Additionally, the concept is evaluated with a spatial and spectral well defined test device.
Measurement of Angular and Spatial Resolved Spectral Rayfiles
The enhanced complexity of modern lighting systems has increased the importance of realistic light source models during the optical design process of LED-based luminaires. I. Rotscholl, Research Associate, K. Trampert, C. Neumann, I. Leopoldo Sayanca from the Karlsruhe Institute of Technology, U. Krüger and F. Schmidt from the TechnoTeam Bildverarbeitung GmbH, propose a method to enhance the often used LED light source model “rayfile” towards a “spectral rayfile”. A spectral rayfile would be a model that associates each ray with its own spectrum and therefore describes varying spectra as a function of angular direction and spatial starting position. The PMBS (physical motivated basis spectra) method is based on the assumption that each LED spectrum consists of a weighted sum of individual basis spectra, for instance those of individual semiconductors and phosphors. There is no need for any special measurement equipment but a classic nearfield goniophotometer and some off-the-shelf optical filters. This method requires at least one spectral measurement and just a minimum of goniophotometric measurements with different optical filters. Finally, the authors demonstrate the potential of this method by applying the concept on a typical LED and compare the results to the often used Blue/Yellow approach in terms of accuracy and applicability.
Photometric data for the development of lighting components
The availability of accurate photometric data is crucial for the development of lighting technology components. Especially in the course of the displacement of the classical lamps by solid-state lighting (SSL) technologies and the resulting increased range of lighting applications, the requirements for these measurement data have increased. Here, optical simulation programs based on ray tracing algorithms (Computer-Aided Lighting – CAL) open up new development processes. State-of-the-art is the use of ray files measured by camera-based near-field goniophotometers. Some of those systems also offer measurements of the luminous intensity distribution, luminous flux and goniospectrometric data in conformity with IES LM-79-08, EN 13032-4 and CIE S 025, and can thus also take over the classical measurement tasks of far-field goniophotometers. This paper illustrates applications of the data measured with near-field goniophotometers and luminance measuring cameras in the field of simulation, glare evaluation and luminaire characterization.
The best of two worlds - Combining goniophotometry and digital image processing
Zukunftssicher und korrekt Messen
Invited Paper: Recent Standardization Efforts and Measurement Procedures of German Automotive OEM and German Flat Panel Forum (DFF)
Pixel Crosstalk: A New Metric to Characterize DOI Loss Due to AG Treatments of Display Glasses
Image Blurring Induced by Scattering Anti-Glare Layers
Diskussion von systematischen Effekten beim Betrieb einer Hyperspektralkamera
Determination of tailored filter sets to create rayfiles including spatial and angular resolved spectral information
Comparison of luminous intensity distributions
Entwicklung einer Hyperspektralkamera unter Verwendung einer Filtertechnologie mit stark vom Einfallswinkel des Lichts abhängigem Transmissionsverhalten
Ist eine objektive Beschreibung der Störempfindung bei künstlicher Beleuchtung möglich?
Measurement of the Unified Glare Rating (UGR) based on using ILMD
Analysis of errors associated with photometric distance in goniophotometry
Traceability of a CCD-Camera System for High-Temperature Measurements
Medição de luminância por meio de imagens para avaliação do ofuscamento