Lingli Wang, Martijn Riemeijer, Georges Calon, Peter Deurenberg, Theo Treurniet, Edwin van Lier, Johan Ansems, Oscar Chao, Virginie Mercier, Koen van Os, Gerard Lijten
In this paper we report on a multi-chip color variable LED linear module with new concepts of optics design, free encapsulation, mechanical assembly and color control. Six dice are mounted close together on a substrate and combined with a faceted dielectric collimator to shape the light output. To achieve a very slim optical collimator (with minimal thickness), we combine a mechanical reflector with a total intern reflection (TIR) collimator. One of the bottlenecks in LED module design is the very high coefficient of thermal expansion (CTE) for organic optical materials (encapsulant). This material is needed to make good optical contact between LED-chip and surrounding optical system. Therefore, it is important that the design can handle large volume changes of the encapsulant during LED operation whilst maintaining good and stable optical performance. Furthermore, the encapsulant needs to be soft to avoid high stresses on fragile components (e.g. bond wires). These problems are solved in our module. To overcome variations in the color of the light output due to temperature changes and ageing, this module is equipped with a temperature and a light sensor. The signals of these sensors are supplied to a color control algorithm, which changes the power levels to each LED color in the appropriate way. This algorithm is capable of reducing the color error Δu'v' from 0.022 (in open loop) to 0.005 for a temperature change of 50 degrees Celsius. Cooling of the linear module is based on natural convection. The operation temperature of the housing is about 300C above ambient temperature. Variable material combinations in the thermal path from the junction to the house have been modeled in order to minimize the internal thermal resistance. A prototype is made and optical performance is measured as well. The optical efficiency of the module is about 75%.
A new lens slope measurement system is developed and realized in the Philips CFT laboratory, which is named a transmission deflectometer. The slopes of two lenses are measured with this measurement system. A high measurement accuracy, 0.05 mrad, over a wide measurement range of ± 17° could be reached.
Photolithography based on proximity printing offers a high throughput and cost effective patterning technology for production of for instance large area liquid crystal displays. The resolution of this technique is limited due to wave-optical effects in the proximity gap between the binary amplitude mask and the substrate. We can improve the resolution drastically by replacing the conventional photomask with a mask causing both amplitude and phase modulation of the illumination wave. We describe a wave-optical design procedure of such masks. The feasibility of the method is demonstrated by results from computer simulations and practical experiments. We show that for a 50 micron gap a 3 micron line/space pattern is resolved clearly for visible light illumination, whereas under conventional conditions the image is completely degraded. The proximity mask used in our experiments was fabricated by e-beam lithography with four height levels and two amplitude transmission values.
Proximity printing is a high throughput and cost effective lithographic technique for production of e.g. large area flat panel displays. The resolution of this technique, however, is limited due to diffraction effects that occur at mask pattern edges. We can improve the resolution drastically by replacing the conventional photomask with a mask which compensates these diffraction effects. The resulting mask modulates phase and amplitude of the exposure beam in such a way that the required image is formed at a predetermined distance behind the mask. In this work we describe the basic principles behind the resolution enhancement technique and explain the mathematical model to design this new type of proximity mask. The feasibility of th method is demonstrated by theoretical calculations as well as by practical experiments. The diffractive structures that have been examined are designed to form an image at a distance of 50 micron behind the mask. The mask contains 2 amplitude and 4 phase levels and the pixel size is 1 micron. Under these conditions a 3-micron line/space pattern is clearly resolved, whereas under conventional conditions the image is completely distorted.
Photolithography based on proximity printing offers a high throughput and cost effective patterning technology for production of for instance large area liquid crystal displays. The resolution of this technique is limited due to wave-optical effects in the proximity gap between the binary amplitude mask and the substrate. We can improve the resolution drastically by replacing the conventional photomask with a mask causing both amplitude and phase modulation of the illumination wave. We describe a wave- optical design procedure of such masks. The feasibility of the method is demonstrated by results from computer simulations and practical experiments. We show that for a 50 micron gap a 3 micron line/space pattern is resolved clearly for visible light illumination, whereas under conventional conditions the image is completely degraded. The proximity mask used in our experiments was fabricated by e-beam lithography with four height levels and two amplitude transmission values.
We report on a new integrated optical pickup for double layer DVD's. The optics is almost integrated by means of diffractive optical elements. Dual focus as well as focal control is done by a liquid crystal cell.
The interferometric complexes for the surfaces and components testing are widely used in optical manufacturing. The necessity of the cheaper methods and devices for optical processing over the entire interference pattern field still exists. This work is devoted to the development of two methods for interferogram processing.
There are many kinds of moiré interferometry. But, they are used to obtain the displacement and strain of object especially for in-plane deformation. And, most of all, the grating must be put on to the object which will be measured. It is inconvenient. Now, we proposed a moiré interferometry, which can measure the curvature of object for out-of-plane deformation, and need not put the grating on to the object. In the schematic of the method, there are one grating (106Lines/in, or 300Lines/in, or 500Lines/in), and the coherent-optimal processor. Between the two-exposures, the recorded plate is moved by ⊿x along the direction of perpendicular to the grating line, and the curvature of the object can be measured directly. In the schematic of the method, spatial filter is used, for allowing the ± orders of the diffracted wave of the grating formed by the collimated wavefront. This method is accuracy, sensitivity, convenience, and can be used for quantitative analysis. A group of shallow shells with different shapes and boundary conditions are measured by this method. The experimental results agree with the theoretical values very well.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.