Julius Muschaweck

• Diplom-Physiker (equiv. to MS)
• CEO at JMO GmbH

For the 6th time, the International Optical Design Conference (IODC) included an Illumination Design contest. This year, the contest involved designing the optics to couple flux from a cone to a disk using an artificial ‘magic’ material featuring extreme chromatic dispersion where the index of refraction varied between 2 at 486nm and 0.5 at 656nm....

This course first introduces basic concepts of colorimetry, human color vision, the common CIE color spaces, color difference metrics and color rendering metrics. Additive color mixing is what happens when two or more LEDs are combined in a single source. Fortunately, there is an easy to grasp, intuitive visualization of additive color mixing in th...

This tutorial is written to help engineers tasked with designing illumination optics determine where to start, which methods and approaches to use, and how to gain insight into the nature of the problem at hand. Good illumination design uses patterns from both non-imaging optics (such as compound parabolic concentrators) and imaging optics (such as...

The light distribution of a source, in an optical system or at a target is described in a 4D phase space of the position and direction of rays [1]. Étendue is volume in this phase space, and its knowledge allows for calculating the achievable flux. Sometimes, it is easy to analytically calculate the étendue of a certain configuration. In other case...

Refractive eyepiece design forms are often limited by chromatic aberrations and require a mix of glass types to achieve sufficient correction, thus they are not conducive to manufacture in volume. Reflective surfaces are inherently achromatic and can be produced in volume, but rotationally symmetric reflective surfaces are either used with lossy ob...

In illumination optics, color mixing is a key design task, but the realization can be a challenge. While tunable light sources based on multiple LEDs are commonplace, color homogenization is just as important for white LEDs, due to their spatial and angular color variation. In this tutorial, we first look at color mixing from an abstract, phase spa...

An all-reflective electronic viewfinder was designed using tilted freeform surfaces in a fully unobscured package. Tight distortion and telecentricity requirements moved the design from a two-mirror solution to a five-mirror solution.

Presented is a quasi-analytic method for irradiance evaluation through a single refractive surface from a single Lambertian source. The method is compared to Monte-Carlo raytracing for a sample system, producing in much less time an irradiance distribution equal to within the latter’s statistical noise. In addition to its interest to optical analys...

A method for 3D irradiance tailoring is introduced for extended sources, solving the flux conservation integral equation for the required freeform surface parameters; first by converting it into a nonlinear equation system, and then using standard numerical methods.

A working group for the Illuminating Engineering Society (IES) recently published the TM-25 standard file format for disseminating source ray data. This presentation will inform the community of the results.

Optical design requires accurate characterization of light sources for computer aided design (CAD) software. Various methods have been used to model sources, from accurate physical models to measurement of light output. It has become common practice for designers to include measured source data for design simulations. Typically, a measured source w...

A method for the binning of a radiation-emitting, optoelectronic semiconductor component (20) is specified, comprising the following steps: providing a radiation-emitting, optoelectronic semiconductor component (20), determining the color locus (8) of the light emitted by the radiation-emitting, optoelectronic semiconductor component (20) during op...

'External quantum efficiency', that is, the number of photons generated per electron passing through the p-n junction of an LED is probably the most important number to quantify the performance of an LED chip. Although advances in epitaxy have increased the fraction of radiative recombination to extremely high values, the extraction of the precious...

A display assembly comprising a backlight unit having at least two optical waveguide elements lying alongside one another, and configured such that light is emitted with a greater brightness in a boundary region of the optical waveguide elements than outside the boundary regions, a display unit arranged such that during operation of the display ass...

For Solid State Lighting devices thermal management has a great impact on the performance. Therefore, it is necessary to analyze thermal and optical behavior simultaneously due to the mutual interaction between the two. For a remote phosphor configuration the dependence of the device performance on thermal conductivity and refractive indices of pho...

Today, light source ray files are provided in different formats, making the process tedious and error prone. We report progress from an IESNA working group, which is creating a flexible, downward compatible standard file format.

Ray data sets describing light sources for illumination commonly contain starting points, directions and fl flux, and sometimes color. Simply adding luminance in addition to the flux which is already there, we gain useful design options not available otherwise. Adding luminance provides all information needed to apply the abstract, phase space base...

On the general lighting market of LED lamps for professional applications there are still mainly products for single purpose solutions existing. There is a lack of standardised lamp systems like they are common for conventional lighting technologies. Therefore, an LED lamp family system was studied using high power LED with the objective to entirel...

For the purpose of optical simulation, a plethora of formats exist to describe the properties of a light source. Except for the EULUMDAT and IES formats which describe sources in terms of aperture area and far field intensity, all these formats are vendor specific, and no generally accepted standard exists. Most illumination simulation software ven...

Color homogeneity is a key issue for LED lighting. To achieve sufficient flux, efficiency and color rendering, LED luminaires have to use multiple LEDs, whose brightness and color properties differ. To mix greenish white LEDs using phosphor with red monochromatic LEDs is an especially promising approach to achieve both high effiency and good color...

Good primary optics for LEDs are crucial for applications working technically and economically. But what is ``good'?For various optical architectures, we look at the complex interplay between optics, manufacturing, tolerancing, lifetime and cost.

The invention relates to an optical system for a motor vehicle headlight, an illumination device for a motor vehicle headlight and a motor vehicle headlight comprising illumination devices of this type. The inventive optical system comprises an optical primary element (2) and an optical secondary element (3). The optical primary element is provided...

The edge ray theorem has become a tenet for illumination design. For idealized configurations this theorem has proved extremely powerful and has led to new methods of design. However, many real life sources have no clean delimitation and thus the boundary of the phase space is not easy to specify. Optical efficiency expressed by the fraction of the...

The invention relates to a microlens array (1) and to an optical module provided with said type of microlens array. The microlens array is used to bundle light which is emitted by several light sources arranged in the light source array. The inventive microlens array is characterised in that the individual lenses (7) are rotationally symmetrical ab...

Given a set of available LEDs or other light sources with known specifications including spectrum, total luminous flux (in lumens), and efficacy (in lumens per watts), we show how to select that combination which yields light of the desired (photometric) color and, in addition, maximizes various objectives such as efficacy, luminous flux, and color...

Due to antiquated technologies (calculation methods, regulations, lighting and luminaire concepts, production techniques) current outdoor lighting causes a lot of problems like light pollution, glare, energy waste etc. New types of luminaires, and in consequence new outdoor lighting concepts, can be created by combining advanced calculation method...

Given a set of available LEDs or other light sources with known spectrum, total luminous flux (lumen) and efficacy (lumen/Watt), price etc. we show how to select that combination which yields light of desired (photometric) color and, in addition, maximizes efficacy, luminous flux , color rendering index or other objectives.

3-D tailoring is a constructive method for the design of free-form optical elements for illumination. The light of a point source is redirected in a controlled manner to cast a prescribed irradiation pattern on a target surface. Free parameters can be used to control the shape of the surface resulting from the tailoring process. Every change in the...

Due to antiquated technologies (calculation methods, regulations, lighting and luminaire concepts, production techniques) current outdoor lighting causes a lot of problems like light pollution, glare, energy waste etc. New types of luminaires, and in consequence new outdoor lighting concepts, can be created by combining advanced calculation methods...

Freeform optical surfaces embedded in three-dimensional space, without any symmetry, are tailored so as to solve the archetypal problem of illumination design: redistribute the radiation of a given small light source onto a given reference surface, thus achieving a desired irradiance distribution on that surface. The shape of the optical surface is...

The general problem to find the shape of a refractive surface such as to produce a desired brightness distribution on a given target surface from a known point source leads to a boundary value problem with an elliptic partial differential equation of the Monge-Ampere type. This equation has been described and analyzed in the literature. The purpose...

A study was performed on the new methods of reflector design. The tailoring of an optical surface in an attempt to directly compute the distribution of light at the target without resorting to trial and error was discussed. The tailoring methods such as freeform surface tailoring and two-dimensional tailoring were presented.

We present an approach to find optimal reflector shapes for non-tracking solar collectors under practical constraints. We focus on cylindrical absorbers and reflectors with translational symmetry. Under idealized circumstances, edge ray reflectors are well known to be optimal. However, it is not clear how optimal reflectors should be shaped in orde...

Microstructures can be viewed as nonimaging devices where all edge rays involved do not change direction over the aperture(s) of the device. This is equivalent to saying that the distance to source and target is much larger than the dimension of the device, which justifies the name microstructure for these devices. Consequently the shape of a micro...

Known designs of reflectors for cylindrical absorbers with gaps either suffer from radiation losses or from dilution which is equivalent to losing maximum concentration. In order to avoid both kinds of losses the global shape of a micro-structured reflector must be such that the gap and the real absorber occupy equal projected angles as seen from a...

Known designs of reflectors for cylindrical absorbers with gaps either suffer from radiation losses or from dilution which is equivalent to losing maximum concentration. In order to avoid both kinds of losses the global shape of a micro-structured reflector must be such that the gap and the real absorber occupy equal projected angles as seen from a...

In solar tower plants, where a rotationally symmetric field of heliostats surrounds the tower, an axisymmetric secondary concentrator such as a compound parabolic concentrator (CPC) or a tailored concentrator or a cone is the obvious choice. For locations at higher latitudes, however, the reflecting area of the heliostats may be used more efficient...

We derive the theoretical upper limit for concentration of direct solar radiation at low latitudes with nontracking concentrators from the projected solid angle sampled by the apparent motion of the sun, for the case where the energy efficiency is referred to the energy incident on the entrance aperture. Based on the fact that the solar radiation i...

In solar tower plants, where a rotationally symmetric field of heliostats surrounds the tower, an axisymmetric secondary concentrator such as a Compound Parabolic Concentrator (CPC) or a tailored concentrator or a cone is the obvious choice. For locations at higher latitudes, however, the reflecting area of the heliostats may be used more efficient...

The Bayerisches Zentrum für angewandte Energieforschung Bayern (ZAE) performs an in situ test of eight different solar domestic hot water systems in Oberpfalz, Bayern. We present results of the evaluation of the collector loop from one system. This system has been chosen because due to the relatively low load the variability of the collector loop t...

Parabolic trough type solar power plants could reach higher efficiencies by using secondary reflectors, which increase the concentration of the solar irradiance onto the absorber tube. Recently, compact secondary concentrators have been proposed which are constructed according to the edge ray principle; they are composed of an involute part and an...

A dynamic solar collector model in conjunction with a dynamic parameter identification and performance prediction method is presented. It promises to make possible solar collector (loop) testing under instationary outdoor meteorological conditions, variable inlet temperature and variable volume flow rate. Measurements for three test sequences were...

For modelling solar domestic hot water (SDHW) systems, a plug flow store model is presented. It is used in conjunction with the dynamic system testing algorithm to predict the long term performance of SDHW systems from short term test data.The basic property of a plug flow model is its capability of modelling drawoffs without any mixing inside the...