2015 - 2019
Conoscopic measurements for displays – advantages and limitations
Non-uniformity correction in recent automotive image sticking evaluation methods
Selected Evaluations of Automotive Displays Using ILMDs
Potential of selected basic homogeneity and mura quality metrics for evaluation of black mura
Requirements on the characterization of optical display attributes for automotive applications
Spectral ray data for optical simulations
This paper summarizes selected approaches, to generate spectral ray data for different types of spectrally varying light sources including only angular variable as well as spatial and angular variable sources. This includes a description of their general ideas and applications, the required measurements, and their mathematical concepts. Finally, achieved results for an Red/Green/Blue/White-light emitting diode (RGBW-LED) system are shown. Ray tracing simulations of a spatially and angularly spectral varying LED system combined with a spectrally sensitive optical system are qualitatively and quantitatively compared to a colorimetric far-field measurement of the same system. The results demonstrate the potential and benefits of spectral ray files in general.
Uncertainty evaluation and propagation for spectral measurements
The measurement of the spectral power distribution (SPD) of a radiation source by array spectroradiometers is a technique that is widely used. In many applications, quantities that are derived from the SPD by a weighted integral over a wavelength interval are of interest. These integral quantities ought to be accompanied by a reliable uncertainty statement, for example, to assess conformity with prescribed limits or in order to judge the consistency of results obtained at different laboratories. We have developed a generally applicable Monte Carlo procedure for evaluating the uncertainty of spectral measurements. The procedure naturally accounts for correlations in the SPD which turn out to be crucial. Means are provided to handle and transfer these large-scale correlation matrices easily. The proposed approach is illustrated by the determination of the SPD of colored LEDs from array spectroradiometer measurements, together with the derived CIE 1931 color coordinates. MATLABTM software implementing the proposed analysis procedure is made available.
Advanced Optics for the Evaluation of Near-To-Eye Displays
More and more, the suppliers of near-to-eye displays (NED) are seeking cost-effective imaging luminance and color measurement solutions that are adaptable to their instrument structures. Here, the authors offer a set of formulas that determine the basic parameters of imaging luminance and radiance measurement devices and lenses for different NED-concepts.
Glare assessment for research and development of measurement methods
Glare is one of the most important parameter of lighting quality. Despite the passage of time from the beginning of glare research, no standard of conducting laboratory experiments was proposed. In the article the review of solutions related to glare assessment is presented. The method of conducting research on glare is also described. The authors pay attention to the most important aspects in the methodology of glare assessment for the experimental research on glare and glare assessment based on UGR measurements. The tests of the new algorithm for UGR calculation is presented — algorithm for precise identification and extraction of glare source area from HDR image.
Requests to Lenses in Measuring Units Evaluating Near-Eye Displays
Imaging Luminance and Color Measuring Devices (ILMD, ICMD) also called Array Detectors in combination with adapted measuring lenses provide effective one-shot solutions to evaluate modern Near-Eye Displays (NED). Basic parameters of those lenses depend on the NED-arrangements under test.
Corresponding equations are deducted. The application of two new measuring lenses shows a way to generate a series of measuring lenses.
Repeatability and Reproducibility Considerations for BlackMURA Measurements
The “Uniformity measurement standard for Displays”, which is used for automotive applications, describes precise setup and alignment procedures to ensure reproducible measurement results. However, the influences of the tested device and the ILMD are not considered in detail. This contribution shows experiments and simulations to estimate these influences as well.
Aspects of Image Sticking Evaluations Using Imaging Luminance Measurement Devices
Image Sticking is an undesired display property, which requires time-consuming and expensive testing. This study summarizes some proposed Image Sticking evaluation methods and identifies relevant differences. It derives aspects, which should be considered prior to a time-consuming and potentially irreversible Sticking Image measurement. Further, parameter analysis associated with the Imaging Luminance Measurement Device is briefly outlined.
Conformity assessment with examples for BlackMURA measurements
To decide whether a display works according to the specification it is not only necessary to take the measurement values into account. The measurement uncertainty also plays a significant role in this decision. Besides some basic knowledge about the measurement uncertainty evaluation, the paper shows the main contributions and their influences for the key values of the BlackMURA standard. Using the rules of conformity assessment, the use of tolerance intervals and acceptance intervals is explained in detail to give all parties (OEMs, manufacturer of display and measurement system manufacturer) the chance to discuss their quality metrics in a reasonable manner.
Spectral near field data of LED systems for optical simulations
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.
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.
Bestimmung von winkel- und ortsaufgelösten spektralen Rayfiles
Die Anforderungen an Lichtquellenmodelle im Entwurfsprozess moderner Leuchten für die allgemeine Lichttechnik nehmen im Zuge der steigenden Anforderungen an die Beleuchtungstechnik stetig zu. Dabei rückt zunehmend auch die ort- und winkelaufgelöste Farb- und Spektralverteilung in den Vordergrund. Basierend auf der Annahme, dass die spektrale Variation von Lichtquellen als gewichtete Summe von konstanten Basisspektren beschreibbar ist, soll in diesem Beitrag ein allgemeiner Messansatz zur Erzeugung solcher Lichtquellenmodelle vorgestellt werden Der Schwerpunkt liegt dabei auf der Messung und Rekonstruktion der spektralen Information. Des Weiteren wir das Verfahren auf Basis einer leuchtstoffbasierten Weißlicht-LED getestet und mit dem speziell auf diese LED-Familie zugeschnittenen Stand der Technik – dem Blau/Gelb Rayfile – vergleichen.
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.
Das Beste aus zwei Welten - Kombination von Goniophotometrie und digitaler Bildverarbeitung
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
Vergleich von Lichstärkeverteilungskurven und -körpern (Lvks)
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