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 entirely substitute
standard conventional lamp families in general lighting applications in the professional market segment. This comprises
the realization of sets of lamp types with compact and linear shapes as well as with light distribution characteristics
ranging from diffuse to extreme collimation and exceptionally high candle power.
Innovative secondary optics concepts are discussed which allow both, the design of lamps with non-bulky shape and to
obtain sufficient colour mixing when using multicolour LED combinations in order to achieve a very high colour
rendering quality.
We investigate the parametrical scaling of LED collimators with folded multiple reflections, described by rational
Bezier spline. One can scale the collimator linearly with source size (maintaining residual divergence). Scaling factor
should be calculated from etendue conservation if one needs to scale the collimator for a different residual divergence.
Both up- and downscaling the collimator (reducing the collimator diameter to obtain the design with larger divergence
and vice versa) are considered. Concentrator shape cannot be linearly scaled if we change the material (for example
polycarbonate is used in design instead of PMMA). Method allows rapid development of collimating optics.
Beam shaping of incoherent light sources (LEDs, halogen lamps) for arbitrary target light distribution is obtained by a
single free-shape mirror. Special design algorithm ensures continuous profile without abrupt changes and shadowing
regions. The mirror is manufactured by single point diamond turning combined with Fast-Tool-Servo (FTS) for
simultaneous figuring of base surface and fine structure (for redistributing the light energy). Lateral and axial resolution
of the fine structure is determined by FTS and considered during the design and data transfer. Directly turned surfaces
can be used as replication tools for polymer or glass moulding and embossing.
The optical properties of OLEDs can be tailored by optimization of the layer stack and by implementation of micro-
and/or nano-optical structures. But the effect of changing the OLED configuration on the device performance crucially
depends on the optical properties of the emissive layer. The aim of this contribution is twofold. First, we will propose
and demonstrate a general and reliable method to determine the intrinsic optical emitter properties via simple optical
characterization and corresponding reverse simulations. Second, the influence of the emitter properties on homogeneous
OLEDs as well as on OLEDs with micro/nano-optical structures is discussed.
We describe rational Bezier spline-based parametric description of non-imaging collimators and implementation into
optical design software. Together with non-linear optimization routines and adapted merit functions this provides flexible
tools for development of light sources with LEDs.
LED-optics for homogeneous illumination of rectangular areas - as required for reading lamps or lighting of imagers - employ a primary optics which acts as collimator and a secondary optics for beam shaping, homogenization and relaying the light onto the illuminated plane. Efficient primary optics are realized by concentrators which are either simple reflecting or combined refractivereflective
devices. Different design algorithms based on the modelling of the concentrators by Bezier splines were developed: A modification of the edge-ray principle allows the formulation of the merit function in geometrical terms (for instance the divergence after collimator), while a more general algorithm with direct Powell optimization allows for combined optimization criteria like efficiency and homogeneity in near- and/or farfield. Concentrator prototypes were realized by direct diamond-turning into PMMA. Telecentric, homogeneous illumination of rectangular areas is achieved by a subsequent secondary optics with tandem lens array integrators. We describe design rules for array integrator optics derived from a simple ABCD-matrix formalism. Based on these rules, sequential real raytracing is used for the actual optics system design and analysis of
aberrations, which deteriorate homogeneity and useful system transmission. We realized miniaturized array integrators with monolithic tandem microlens arrays, which remarkably reduce overall system length compared to light-pipe approaches. Double-sided cylindrical microlens arrays with large fill-factor over 99%, realized by polymer-on-glass replication of reflow lenses, relax system assembly by shifting critical adjustment steps into element manufacturing.
Specifics of non-imaging optical systems require special algorithms for automated optimization. We have implemented two methods into commercially available optical design software, which are robust and numerically effective. The first one is a modification of the edge-ray principle. In this case the optimization criterion should be expressed in geometrical terms (like, for example, collimation of an extended light source). This gives us the possibility to design not only CPClike collimators, but also rather complex refractive-reflective (RXI-like) devices. For the second (more general) case the optimization criterion is expressed in energetic terms. In this case stochastic behavior of the merit function due to Monte-Carlo ray-tracing procedure limits the applicability of standard optimization routines available in optical design software. We have realized a direct optimization algorithm, which does not calculate the derivatives of the merit function leading to reduced sensitivity with respect to local statistical deviations. The proposed algorithm is deterministic and does not suffer from redundant trials of random search. As a parametric description for the objects to be optimized we propose the use of piecewise Bezier splines. This allows relative strong shape bending but requires control for intersections. A "red-blue intersection reporting" algorithm is realized as a constraint for optimization.
Efficient homogeneous illumination of rectangular or circular areas with LEDs is a promising application for doublesided microlens arrays. Such illumination schemes employ a primary optics - which can be realized with a concentrator or a collimation lens - and a secondary optics with one or more double-sided microlens arrays and a collection optics for superposing the light from the individual array channels. The main advantage of this design is the achievable short system length compared to integrating lightpipe designs with subsequent relay optics. We describe design rules for the secondary optics derived from simple ABCD-matrix formalism. Based on these rules, sequential raytracing is used for the actual optics system design. Double-sided arrays are manufactured by polymer-on-glass replication of reflow lenses. With cylindrical lens arrays we assembled high-brightness RGB-illumination systems for rectangular areas. Hexagonal packed double-sided arrays of spherical lenslets were applied for a miniaturized circular spotlight. Black matrix polymer apertures attached to the lens array helped to avoid unwanted straylight.
Successful design of LED light sources requires application of principles of non-imaging optics and their integration into optical design software. We propose some design tools for CPC-like concentrators, which are flexible to cover both different LED types and diverse applications of LED for illumination. The methods are based on the optimization using standard ray-tracing either according to the edge-ray principle (with special ray aiming and integration over the projected images) or a Monte-Carlo procedure (with number of rays, sufficient for resolving concentrator features). The algorithms take skew rays into consideration, what results in 5...15% higher efficiency compared to concentrators designed according to the theoretical CPC equation. The specifics of optimization algorithms (compared with conventional imaging optical design algorithms) are discussed. We also propose different optimization criteria, specific
for diverse light source configurations. Examples of solid and hollow concentrators, optimized for efficiency or light intensity were manufactured by single point diamond turning. Measured characteristics of devices are in good agreement with the design goals.
The paper deals with analytical investigation of technological equipment tolerance requirements for multiplayer optical waveguides structure creation in monolithic glass substrate by laser-induced clearing of (gamma) -induced color centers. It is proved that autocorrelation interval of waveguide boundary deviation is equal to the step of moving mechanism and is considerably more than signal wavelength. Thus the main scattering mechanism is the axis deviation and the local size varying. We propose the new waveguide creation method in single run of optical system by mean of two laser sources. It allows to reduce the scattering on the local size varying. Theoretical estimation of such waveguide scattering losses is 0.1 dB/cm when the step (tolerance) of laser beam moving is 0.1 micrometers .
Researchers of damage formation in processes in glass are directed on studying the interaction mechanisms of powerful impulses of penetrating laser radiation with materials for the purpose of improvement of optical components resistance. However, the processes of glass structure defects formation as local areas with low factor of visible light admittance can find application in a final glassware processing. Application of treatment modes, using these effects, allows: to increase art expression of decorative glassware for furnish of buildings interior; to solve some problems of manufacturing counter devices, and also indication devices of electronic instruments. Mathematical models of defect formation processes in optically transparent materials under an action of powerful pulses of laser radiation are necessary for development of control principles of glass treatment.
A distinctive feature of glass is a wide range of correlation between internal absorption and admittance of electro-magnetic streams in a wide wavelength scope starting from gamma rays and up to infrared radiation. This factor provides an opportunity for search of new realizations of processes for machining, control and exploitation of glassware for home appliances, radioelectronics and illumination.
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