Search

This paper presents a quick and straightforward method to measure the thickness of the micro structures using optical microscope. In optical microscopy, for depth of focus (DOF) method there are two surfaces required, one as a reference. In case of live dies specially in CMOS MEMS the thickness of silicon attached to the CMOS thin layers can't be find accurately because of unavailability of reference surface. The main focus of this paper is the measurement of thickness of silicon attached to the CMOS thin layers as well as CMOS layers itself specially in the broken form. Normally thickness is the vertical displacement of the structures but when these structures are broken it very hard to clamp the microstructures in horizontal position that is why a special sample holder is prepared and reported and sample holding technique to hold the samples in the horizontal position is introduced. Leica DM 12000 optical microscope is used to measure and mark the thickness of CMOS layers and silicon attached to these layers.

In this paper the applications, detailed in previous works, of ultrasonic transducers with the addition of axicon lenses are extended. Axicon lenses were manufactured to generate an angular refracted beam in order to study defectology in welds and other components. To achieve greater depth of focus while maintaining a relationship between focus depth and near field (F/N) less than 0.4, larger diameter transducers were used. Furthermore, its effect on the focus diameter (dF) was also analyzed. For different combinations of lens-transducer, diagrams of axial and transverse sound pressure distribution were obtained. At last, several practical applications are shown where it is possible to exploit the advantages that these transducers offer; for example: sizing of shallow cracks, high resolution corrosion mapping simulation, etc.

For the generation of micro focused hard x‐ray beams on Indus‐2, with large depth of focus and large focal lengths, simulation studies have been performed using parabolic Be compound refractive lenses (CRLs). The use of these lenses is expected to open many new experimental possibilities widely used at other synchrotron sources.

A new phased array inspection scheme, called Technique to Image using Virtual Array Sources (TIVAS), is proposed to image defects at deeper locations with good lateral resolution. An array of virtual focal spots using electronic beam forming and the expanded aperture through electronic linear scanning was employed to achieve significant increase in the focal depths, with improved SNR, when compared to single element array imaging or the conventional phased array focusing technique. The image reconstruction was performed using the well known synthetic focusing approach. In this paper, the role of the depth of focus and the focal spot size on the performance of TIVAS were studied semi‐analytically and through FDTD simulations. It was observed smaller virtual focal spot size provides improved lateral resolution and there is an optimum depth of focus for the smallest focal spot size achievable for a array transducer. Experiments were carried out to validate these findings.

We have integrated a microfabricated phase Fresnel lens (PFL) with an ion trap and used it to image a 174Yb+ ion. The observed collection efficiency was 4.1± 1.3%, in agreement with a predicted performance of 4.6% based on optical characterization and suitable for use in quantum computing. A maximum signal to background scatter noise of 23±4 was measured near saturation intensity (s = 0.7). The depth of focus was 11 μm and the field of view in excess of 100 μm across.

X‐ray optics, such as zone plates, are often used to obtain a spatial resolution better than 100 nm in x‐ray projection images. Such types of optics are not always suited for tomographic imaging due to their limited depth of focus, which restricts the size of the specimen to a few microns. To overcome these limitations, we developed a new lens‐free setup for a nano‐CT system. Spatial resolution of nano‐CT systems is mainly defined by x‐ray source performance. It is dependent on target shape and focusing of the electron beam. The typical way to improve spatial resolution is based on replacement of the bulk metal target to thin film. It allows getting submicron spot size, but significantly reduces x‐ray flux. To overcome flux limitation without compromising with spatial resolution, we invented a new type of target shaped as a rod or needle towards the camera. It allows us to reach 50‐nm resolution with reasonable flux.

We present a pure phase pupil filter design for an extended depth of focus (DoF) with a homogeneous transversal behavior. State of the ort solutions base on complex (amplitude and phase) modulation or on diffractive phase filters, which have either low conversion efficiency due to the blocking of light or very complex structures. Our design is a quartic multiplex phase‐only function with good performance and simple annular structure. Numerical simulation based on the Kirchhoff diffraction integral and experiments performed with a modulation transfer function measurement system combined with a spatial phase modulation liquid crystal device show in agreement a three times enlarged focal depth with homogeneous transversal spot size. Further simulations suggest that the depth of focus can be extended up to a factor 12. However, when using monochromatic polarized light interference effects disturb the uniform intensity along the focal depth.

We show that through an adaptive deformation of digital holograms it is possible to manage the depth of focus in the numerical reconstruction. Deformation is applied to the original hologram with the aim to put simultaneously in‐focus, and in one reconstructed image plane, different objects lying at different distance from the hologram plane (i.e. CCD sensor), but in the same field of view. In the same way it is possible to extend the depth of field for 3D object having a tilted object whole in‐focus.

This work presents a technique for controlling the width of a receiving aperture on an ultrasonic phased array system by appropriately programming Dynamic Depth Focusing (DDF) control electronics normally intended for control of depth of focus. The technique simulates deactivation of array elements through use of phase cancellation between neighboring array elements. Underlying principles are discussed. An experimental demonstration is provided.

X‐ray refractive optical lens systems have been successfully elaborated, designed, fabricated at the Institute for Microstructure Technology at the Forschungszentrum Karlsruhe (Germany) using LIGA technology in recent years. The lenses are structured in a SU‐8 polymer. The capability of the LIGA technique to create an arbitrary profile of the focusing microstructures allow the fabrication of lenses with different curvature radius of parabolic geometry, minimized absorption and a large depth of focus. Also a set of planar lens systems on one substrate can be realized with 17 lenses providing identical focal distances for different X‐ray energies from 2 to over 100 keV. Nickel lenses fabricated by electroforming using polymer templates can be applied for energies larger than 80 keV. The parabolic crossed lenses are used for 2D nano focusing of monochromatic beams. The quasi‐parabolic crossed lenses with a submicron focus and a focus depth of the centimetre range can be used as an achromatic system. Mosaic truncated parabolic lenses with a focusing aperture up to 1 mm are made to increase the X‐ray intensity in the focused spot.

Frequently, velocimeter targets are illuminated by a laser beam passing through a hole in a mirror. This mirror is responsible for diverting returning light from a target lens to a velocity interferometer system for any reflector. This mirror is often a significant distance from the target lens. Consequently, at certain target focus positions the returning light is strongly vignetted by the hole, causing a loss of signal. This note finds that the loss of signal can be prevented and that the useful depth can be greatly increased by attaching a cylindrical lens to the target lens.