Modern mobile communication devices have user interfaces that are dominated by high-quality displays. Increased multimedia use imposes high demands on the design of display modules, as the content available for mobile use becomes visually richer. Especially the power dissipation of the display can limit the amount of time available for multimedia consumption and interaction. In the mobile liquid-crystal display (LCD), the energy efficiency is determined by the backlight design. State-of-the-art backlights direct white light through a display subpixel array, with high uniformity and up to 90% efficiency in white light output. Therefore, it is difficult to obtain system-level energy savings by improving the backlight design alone. Diffractive backlights have recently been proposed to reduce the power dissipation of the display module, and slanted grating arrays are among the enabling optical features that allow for reduction in power dissipation beyond what is available in the state of the art. By the use of diffractive grating arrays, the required primary color (red, green, or blue) is directed through the LCD subpixel array with geometrical registration, instead of flooding the whole LCD with white light and filtering the primary colors through the subpixel color filter array. We present a study on grating structures based on slanted grating arrays fabricated in high refractive index materials. The grating design principles and grating outcoupling results are provided, and an outline of a new embedded system design is given. Emphasis is on grating array design aspects for future energy-efficient display system design. The results show that savings in power consumption can be expected with advanced display system design based on embedded slanted grating array backlight light guide plates.
Modern mobile communication devices have user interfaces that are dominated by high-quality displays. Increased
multimedia use imposes high demands on the design of display modules, as the content available for mobile use becomes
visually richer. Especially the power dissipation of the display can limit the amount of time available for multimedia
consumption and interaction. In the mobile liquid-crystal display (LCD), the energy efficiency is determined by the
backlight design. State-of-the-art backlights direct white light through a display subpixel array, with high uniformity and
up to 90 % efficiency in white light output. Diffractive backlights have recently been proposed to reduce the power
dissipation of the display module, and slanted grating arrays are among the enabling optical features that allow for
reduction in power dissipation beyond what is available in the state of the art. By the use of diffractive grating arrays, the
required primary color (red, green, or blue) is directed through the LCD subpixel array with geometrical registration,
instead of flooding the whole LCD with white light and filtering the primary colors through the subpixel color filter
array. This paper presents a study on grating structures based on slanted grating arrays fabricated in high refractive index
materials. The grating design and grating outcoupling results are provided, and an outline of a new embedded system
design is given. Emphasis is on grating array design aspects for future display system design. The results show that
savings in power consumption can be expected with advanced display system design based on embedded slanted grating
array backlight light guide plates.
With the rapid advances in telecommunications networks, mobile multimedia delivery to handsets is now a reality.
While a truly immersive multimedia experience is still far ahead in the mobile world, significant advances have been
made in the constituent audio-visual technologies to make this become possible. One of the critical components in
multimedia delivery is the mobile handset display. While such alternatives as headset-style near-to-eye displays,
autostereoscopic displays, mini-projectors, and roll-out flexible displays can deliver either a larger virtual screen
size than the pocketable dimensions of the mobile device can offer, or an added degree of immersion by adding the
illusion of the third dimension in the viewing experience, there are still challenges in the full deployment of such
displays in real-life mobile communication terminals. Meanwhile, direct-view display technologies have developed
steadily, and can provide a development platform for an even better viewing experience for multimedia in the near
future. The paper presents an overview of the mobile display technology space with an emphasis on the advances
and potential in developing direct-view displays further to meet the goal of enabling multimedia in the mobile
domain.
Optical sensing techniques have obtained remarkable attention in developing biosensors. Especially, methods based on evanescent field probing are suitable for direct immunosensing. However, miniaturized immunosensors are more difficult to realize when compared with catalytic sensors. Miniaturization and the small amounts of reagents will speed up detection but they are also a potential source of errors and instability. Different aspects of miniaturization of immunosensors are discussed. Some modeling methods of the optical biosensing interface are presented. Modeling is important, but there is a lack of detailed optical data of biomolecules. Two integrated optics detectors are described and their use in biosensing applications are evaluated.
A key factor in the analysis of evanescently coupled optical sensors, such as the planar waveguide immunosensor analyzed here, is the efficiency of coupling between the optical waveguide modes and the fluorescent sources located on the surface of the waveguide. This is an important parameter in determining the sensor's sensitivity to the analyte. We calculate this efficiency for several different sensor configurations using the finite-difference time-domain numerical technique, and find that the efficiency of one-way coupling can vary widely depending upon the fluorescent source polarization, phase, and distance from the surface, as well as the waveguide mode number and thickness. In particular, we find that when the layer containing the fluorescent molecules is uniform in refractive index, the coupling efficiency is larger than when the local environment possesses an irregular index.
The finite-difference time-domain method (FDTD) is a powerful numerical technique for solving Maxwell's equations in a discretized space and time grid. Its applications have up to now been in the analysis of electrically large structures in the microwave domain, and the scope of investigations has been extended only recently to the optical region. Because of computer memory limitations, the method is generally restricted to configurations which extend to the order of tens of wavelengths in three dimensions, or hundreds of wavelengths in two dimensions. Optical sensor structures are therefore of suitable size to be modeled with FDTD, and e.g., fluorescence sensor design can benefit from the use of FDTD in optimization of the waveguide structures. In general, the integration of chemical and optical design is difficult, but FDTD can bring the two design approaches closer together. One of the main advantages of FDTD is its ability to include near-field effects, such as distribution of protein molecules on the active surface of optical sensors in the model, which has been shown to be important is estimating the fluorescent excitation and collection efficiencies of molecules on surfaces. In addition, for planar structures, two-dimensional models are adequate for studying many aspects of sensor design. We applied FDTD to design planar fluorescence sensors. Excitation and emission models were analyzed for planar waveguide structures with side collection of emitted light in mind. Planar waveguides were fabricated on fused silica substrates and the characteristics of the waveguides were compared to the model. Good agreement was found with the FDTD modeling to the physical model, and based on this knowledge, an FDTD sensor model was prepared predicting good fluorescence excitation and emission side collection efficiencies.
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.