Polymer display based on a movable membrane designed in MOEMS technology may be an alternative for other display
devices. The display consists of two plastic elements. The first one is a planar waveguide. It is coated in metal with
electric contacts etched in it. The second element is a metalized membrane with a matrix of pillars functioning as pixels.
The simplicity of the setup makes it cheap and easy for mass production. On the other hand, each size of the display has
to be optimized independently, which may be a problem. When deciding on the size of the matrix one has to optimize
several interconnected parameters, which decide on the functioning of the display. In this paper we describe the
modeling process for a 20×20 pixel matrix with an active display matrix area of 5×5 mm2.
We proposed a new kind of setup for the automatic control of the quality of micro lens array, which is based on semiderivative real filter. With the use of the 4f correlator setup with a semiderivative filter placed in the Fourier plane and connected with the camera, it is possible to examine phase objects. Such a setup is shift invariant, so it enables us to simultaneously examine a set of identical elements, such as a micro lens array. Additionally, the same setup allows for a simultaneous measurement of both thin and thick phase objects. It is also possible to measure a wide range of phase gradients.
The article presents the results of simulations where the semiderivative filter was used to measure phase objects such as cylindrical and spherical lenses. A special emphasis was placed upon checking how the proposed setup works for a number of similar phase optical elements, such as microlens arrays. The article also presents an analysis of how various technological limitations can influence the quality and the precision of the results obtained. Further on, it shows the initial results of the use of 3D lithography to produce semiderivative filters.
The proposed pixel matrix display consists of two plastic elements: a planar waveguide which plays the role of a light reservoir and a deformable thin membrane with a matrix of pillars. On the bottom side of the membrane that touches the light reservoir there is an electrode surrounding all pillars and leaving tops of pillars transparent. The light reservoir has a matrix of individual electrical contacts so that the display can be addressed pixel by pixel and switched on by applying a voltage to the electrical contacts on the light reservoir and the membrane electrode. The electrostatic force locally deforms the membrane and puts the pillars in contact with the light reservoir, therefore, coupling light into the membrane. A demonstrator of a polymer-based pixel matrix display is fabricated in MOEMS technology. The proof-of-principle experiment is made on a 20x20 pixel matrix with an active display matrix area of 5x5 mm2, a light emitting diode illumination and 80 V applied to address pixels.
The recently improved ultra-fast aircraft resistance thermometer measures with a time constant of the order 0.1 ms. For an aircraft speed of 100 m/s this time constant corresponds to a spatial resolution of a few centimeters. Measurements made both in the atmosphere and in the low-turbulence wind tunnel at air speed 80 m/s are corrupted with noise of a few kHz frequency. Authors of the thermometer suggest that this noise results from turbulence introduced by vortex shedding from the protective shield. To achieve further improvement of the instrument we have to understand the nature of these aerodynamic disturbances. The present study is carried in two complementary directions. In the first, flow modeling is made with the FEATFLOW 1.2d - a finite element software for the incompressible Navier-Stokes equations. The results of flow simulation are in qualitative agreement with the experiment. In the second, we simulate visualization of the flow using two optical spatial filters: the Foucault filter that gives output intensity signal where bright bias is modulated with 1-D Hilbert transform of an object phase function and modified Zernike phase filter that shifts phase of the spectrum dc term by 0.2π.
There is a need for a frequency-domain real filter that visualizes pure-phase objects with thickness either considerably smaller or much bigger than 2π rad and gives output image irradiance proportional to the first derivative of object phase function for a wide range of phase gradients. We propose to construct a nonlinearly graded filter as a combination of Foucault and the square-root filters. The square root filter in frequency plane corresponds to the semiderivative in object space. Between the two half-planes with binary values of amplitude transmittance a segment with nonlinearly varying transmittance is located. Within this intermediate sector the amplitude transmittance is given with a biased antisymmetrical function whose positive and negative frequency branches are proportional to the square-root of spatial frequencies contained therein. Our simulations show that the modified square root filter visualizes both thin and thick pure phase objects with phase gradients from 0.6π up to more than 60π rad/mm.
Phase object visualization method is useful as a phase shift measurement technique when output image intensity signal is a known function of object phase or its derivative. This paper presents a comparison of performances of three real frequency domain filters: Foucault frequently called knife edge filter, Hoffman known in microscopy as a modulation contrast method and the semi-derivative filter. Its performance is simulated using Virtual Lab 1.O software in
4f imaging system with coherent illumination.
We present a method for elimination of global intensity deformation in gray-scale images using contrast control based on image resolution manipulation. During the process, a Gaussian pyramid representation of an input image is constructed by means of low-pass filtering and sampling of successive pyramid levels, where the input image
constitutes the first (zero) level of the pyramid. In the second step, a Laplacian pyramid is built, through subtracting
successive levels of the Gaussian pyramid. Then, all levels in the Laplacian pyramid are expanded to the original image size and added with weights, to reconstruct the image. An algorithm and a computer routines library written in object programming language C++ are developed.
We study the potentialities of three dimensional micro-optical pathway blocks combining refractive microlens arrays, reflective micro-prisms and diffractive fan-out elements, to enhance the functionalities of short-distance intra-chip optical interconnects. As an example, we demonstrate the possibility to enhance the point-to-point interconnection functionality to that of broadcasting data over a chip. We also investigate the limitations imposed by the physical dimensions of the refractive and diffractive micro-optical components. We then illustrate this example by a quantitatively elaborated design of a fan-out element from a VCSEL array to a detector array with a 1 to 9 signal broadcasting for every source. Furthermore we show that with the use of DOE’s we can achieve a broadcasting functionality that can lead towards reconfigurable optical interconnects, with the aid of wavelength sensitive resonant cavity detectors and WDM-inspired interconnection schemes.
We present a method for elimination of global intensity deformation in greyscale and color images of any size using contrast control. The method is based on image resolution manipulation and uses a representation of an image in the form of a difference-of-low-pass pyramid (DoLP). In the first step, a Gaussian pyramid representation of the input image is prepared through low-pass filtration and sampling of successive pyramid levels. In the second step, the DoLP pyramid is built, and finally all levels in the DoLP pyramid are expanded to the original image size and added with weights, to reconstruct the image. Proper choice of the weights is crucial for efficient elimination of global intensity deformation and leads to contrast enhancement at certain levels of the pyramid. Color images and images of a size different than 2N+1 x 2N+1, where N = 2, 3, ?., require additional processing. They are converted to and from hue-saturation-value (HSV) color space model and geometrically transformed, which can be performed using two proposed methods. An algorithm and a computer routines library written in object programming language C++ are developed. The proposed method is useful in digital archiving of airborne, scanned, photo-copied and optical camera-made photographs, degraded due to ageing processes.